Admissible concentrations in soil (mg kg-1 dry matter)
1. Introduction
As a result of the continuous civilization progress and the increasing human population we have been observing an accelerating process of environmental pollution, frequently leading to its complete degradation. The primary cause of environmental pollution is associated with the rapid development of motorization and industry (particularly power industry and mining), progressing urbanization, improved standards of living worldwide, intensive farming (application of high amounts of mineral fertilizers and herbicides), along with numerous other anthropogenic factors. These sources contribute to increased concentrations of many chemical elements and compounds in the atmosphere, soil, water and plants (including crops with edible parts for human consumption).
The cycle of chemical elements and compounds in nature is influenced not only by human activity, but also nature itself, in which progressing geological processes occur such as volcanic eruptions, shifts of tectonic plates or natural disasters.
In recent years the ecological awareness of the general public has increased, with decontamination of the polluted environment being perceived as an essential requirement. The aim of reclamation of polluted areas is to restore ecosystems polluted by human activity to the condition resembling their former natural state.
There are many methods applied in environment decontamination worldwide, including const-intensive, conventional physico-chemical methods. Scientists continue to search for novel, more effective and economically viable methods of pollutant inactivation. In recent years an increasing body of research has focused on engineering bioremediation, such as e.g. an
At present a major ecological problem is connected with the penetration to the environment of heavy metals, which at higher concentrations are strongly toxic to humans and animals (resulting in e.g. increased disease incidence), and have a negative effect on soil properties as well as quality and physiological activity of plants.
Literature sources present various definitions of an element to be considered a heavy metal. One of these hypotheses says that they are elements with specific gravity greater than 4.5, 5, 6 and 7 g cm-3. It is a physical term, which is understood and used differently in various contexts. There are also many definitions based on atomic number. Some of them are considered to be nutrients for living organisms (essential nutrients e.g. Fe, Cu, Zn, Mn, Ni) and others are redundant or toxic (e.g. Cd, Pb, Hg, Al, As). Their common characteristic is connected with the fact that at excessive concentrations in the environment they have an adverse effect on plant growth and development, and when incorporated in the food chain may also pose a hazard for animals and humans.
2. Soil factors influencing availability of heavy metals to plants
Physico-chemical properties of soil influencing contents of phytotoxic forms of heavy metals include the type of soil, its grain size distribution, reaction, organic matter content, sorption properties and redox potential [43, 67, 68, 73].
Mother rock is a natural source of heavy metals in soils. The amounts of elements coming from mother rock constitute the geochemical background posing no threat to soil fertility [67]. Other sources of heavy metals include geochemical processes and anthropogenic factors. In soil heavy metals are subjected to processes affecting their concentrations and chemical forms [4]. In individual soil horizons their content depends on anthropogenic and climatic factors [67, 114].
Soil reaction is a major factor influencing the form and availability of heavy metals to plants [67]. Soil acidity may lead to their increased concentrations in soil [3, 13, 30, 48, 93, 112] and their excessive uptake by plants [42, 93]. According to Tyler and Olsson [118], concentrations of Cu and Pb increase also at pH 7.5 – 7.8 as a result of formation of stable complexes with ligands, which solubility is connected with solubility of organic substance. Liming results in a reduced content of available forms of heavy metals in soil [39]. Soil reaction is a factor determining the force with which heavy metals are bound by organic substance and mineral compounds [2, 60].
Organic substance found in soil contributes to the limitation of the amounts of heavy metals available to plants [38, 47], since it binds very strongly Cr3+, Fe3+, Pb2+, Ni2+ and Co2+ ions and to a lesser extent also Mn2+ and Zn2+ [68]. Organic matter binds heavy metals into water insoluble forms or forms sparingly soluble in water [79], thus reducing the share of plant-available forms of heavy metals [19], and in this way it limits their toxicity to plants [48, 87].
Heavy metals differ in the force, with which they are bound by the sorption complex and they are connected mainly with the silt fraction [67]. In soil they undergo exchange and biological sorption. They may also be precipitated in the form of insoluble compounds [83]. Availability of heavy metals in soil is influenced by the cation sorption capacity. Introduction of compounds enhancing sorption capacity to soil causes a reduction of amounts of available metal forms in soil [106].
Availability of heavy metals is also dependent on the redox reactions taking place in soil [83]. Oxide forms of heavy metals become readily available to plants at a low redox potential [33].
The application of mineral fertilizers changes amounts of phytoavailable forms of heavy metals in soil. The effect of used fertilizers on physico-chemical and biological properties of soil causes a reduction or an increase of amounts of phytotoxic forms in the soil environment [105]. When applying mineral fertilizers we introduce heavy metals to soil, which contents in fertilizers are connected both with the raw material from which they were produced and the technological process of fertilizer production. The greatest contamination with heavy metals, particularly cadmium, is found in phosphorus fertilizers [52] and calcium fertilizers, mainly being by-products of various branches of industry [27, 69]. Heavy metal contents in phosphorus fertilizers depend on the fertilizer type [52] and solubility [57]. The application of phosphorus fertilizers leads to the transition of soluble phosphate forms into sparingly soluble zinc, copper, cadmium and lead phosphates [30], leading to the reduction of heavy metal contents in plants.
3. Admissible heavy metal contents in soil binding in Poland
In Poland respective boundary heavy metal contents are specified in the Ordinance of the Minister of the Environment of 9 September 2002 on soil quality standards and land quality standards. These standards were established taking into consideration the current and forecasted functions for the following categories of land types (Table 1):
Category A:
Landed property incorporated into an area legally protected on the power of the regulations of the Water Act,
Areas protected on the power of regulations on nature protection if maintenance of the current soil pollution levels does not pose a threat for human health or the environment – for these areas the concentrations meet the standards resulting from the actual status, subject to points 2 and 3;
Category B – land classified as agriculturally utilized area except for land covered by ponds and ditches, forested areas as well as areas covered by trees and shrubs, barren land, as well as developed and urbanized areas except for industrial areas, surface mining land in use and municipal areas;
Category C – industrial areas, surface mining land in use, transportation areas.
Attachment to the Ordinance of the Minister of the Environment of 9 September 2002 (item 1359)
|
|
|
|
|||||||
|
||||||||||
0-0.3 | 0.3-15.0 | >15 | 0-2 | 2-15 | ||||||
|
||||||||||
|
|
|
|
|
|
|||||
1∙10-7 | 1∙10-7 | 1∙10-7 | ||||||||
Arsenic | 20 | 20 | 20 | 25 | 25 | 55 | 60 | 25 | 100 | |
Barium | 200 | 200 | 250 | 320 | 300 | 650 | 1000 | 300 | 3000 | |
Chromium | 50 | 150 | 150 | 190 | 150 | 380 | 500 | 150 | 800 | |
Tin | 20 | 20 | 30 | 50 | 40 | 300 | 350 | 40 | 300 | |
Zinc | 100 | 300 | 350 | 300 | 300 | 720 | 1000 | 300 | 3000 | |
Cadmium | 1 | 4 | 5 | 6 | 4 | 10 | 15 | 6 | 20 | |
Cobalt | 20 | 20 | 30 | 60 | 50 | 120 | 200 | 50 | 300 | |
Copper | 30 | 150 | 100 | 100 | 100 | 200 | 600 | 200 | 1000 | |
Molibdenum | 10 | 10 | 10 | 40 | 30 | 210 | 250 | 30 | 200 | |
Nickel | 35 | 100 | 50 | 100 | 70 | 210 | 300 | 70 | 500 | |
Lead | 50 | 100 | 100 | 200 | 100 | 200 | 600 | 200 | 1000 | |
Mercury | 0,5 | 2 | 3 | 5 | 4 | 10 | 30 | 4 | 50 |
Based on the multiannual analyses the Institute of Soil Science and Plant Cultivation in Puławy, Poland (IUNG) specified boundary heavy metal contents in soils to be utilized agriculturally (Table 2). As it was reported by Ociepa et al. [94], the mean content of heavy metals in agriculturally utilized soils in Poland is lower than in countries of Western Europe or the USA, which results mainly from a lesser share of farms with intensive agricultural production systems and a lesser intensity of industrial processes. The same authors reported that approx. 90% agriculturally utilized area have natural levels of toxic metals. Several percent of this area have elevated contents (I0) of mainly cadmium and zinc, while approx. 3% are polluted (II-V0) with metals. The greatest percentages of polluted soils are found in the Śląskie, MałoPolande and Wrocławskie provinces of Poland.
|
|
|
|||||
|
|
|
|
|
|
||
lead (Pb) |
a b c |
30 50 70 |
70 100 200 |
100 250 500 |
500 1000 2000 |
2500 5000 7000 |
>2500 >5000 >7000 |
zinc (Zn) |
a b c |
50 70 100 |
100 200 300 |
300 500 1000 |
700 1500 3000 |
3000 5000 8000 |
>3000 >5000 >8000 |
copper (Cu) |
a b c |
15 25 40 |
30 50 70 |
50 80 100 |
150 100 150 |
750 500 750 |
>750 >500 >750 |
nickel (Ni) |
a b c |
10 25 50 |
30 50 75 |
50 75 100 |
100 150 300 |
400 600 1000 |
>400 >600 >1000 |
cadmium (Cd) |
a b c |
0, 3 0, 5 1, 0 |
1, 0 1, 5 3, 0 |
2 3 5 |
3 5 10 |
5 10 20 |
>5 >10 >20 |
4. Contents of heavy metal soluble forms and reaction of surface horizon (0 - 20 cm) of soils in green belts adjacent to selected transportation routes in the city of Poznań (western Poland)
Anthropopressure affects physical, biological and chemical properties of soil. Soils in urban areas, located along transportation routes, are exposed to heavy metal pollution, originating from substances produced during combustion of fuels, abrasion of road surfaces and tires, granular materials falling onto the ground during transport, etc. [24, 36]. Platinum metals, which have been employed in production of car catalysts, reach environment and cause contamination of soil, plants and water [84]. Moreover, chemical substances used in winter to eliminate black ice (e.g. sodium or calcium chlorides) as well as deposition of dusts and water migration of elements contribute to soil degradation and deterioration of plant growth conditions. In urban areas strong alkalization of soil is frequently observed, which significantly reduces contents of soluble forms of metallic components [12, 27, 74].
According to the Ordinance of the Minister of the Environment of 9 September 2002 on soil quality standards and land quality standards currently binding in Poland (the Journal of Law Dziennik Ustaw no. 165, item 1359), soil category B comprises soils in urbanized areas, for which the admissible heavy metal level (mg kg-1 dry matter) in the upper 0 - 30 cm layer is Ni 100, Cd 4, Pb 100 and Cr 150, respectively.
Legal regulations pertain to total heavy metal contents in soils; however, many authors claim that it is not always a direct indicator of their bioavailability [44]. In the opinion of Gorlach and Gambuś [53], the most appropriate measure is to assess soil contents of soluble forms of trace elements, as they may be absorbed by plants.
The aim of the studies conducted by the authors was to determine what amounts of soluble forms of heavy metals are available for plants in the 0 - 20 cm layer of soil in green areas located in the vicinity of selected transportation routes in the city of Poznań, Poland. Collected soil samples were tested for soil reaction and contents of selected heavy metals (cadmium, lead, chromium and nickel, classified as metallic micronutrients, essential elements at the same time having a negative effect on plants when found in greater amounts).
|
Soil samples from green areas were collected in October 2012 in the vicinity of transportation routes in the city of Poznań, Poland. Forty five streets were selected for analyses and soil samples were collected using an Egner sampling stick from a 0 - 20 cm layer at a distance of 0.5 - 2.0 m from the roadway. Along each analyzed street 4 bulk samples were collected, comprising 15 individual samples (4 x 15 = 60 individual samples). Heavy metals (Cd, Pb, Cr and Ni) were extracted from soil using Lindsay’s solution containing in 1 dm3: 5 g EDTA (ethylenediaminetetraacetic acid), 9 cm3 25% NH4OH solution, 4 g citric acid and 2 g Ca(CH3COO)2·2H2O. Next they were assayed by flame atomic absorption spectroscopy (FAAS) with an AAS 3 Zeiss apparatus. Active acidity expressed in pH (H2O) was determined by potentiometry (soil : water = 1:2), [50]. Results were analyzed determining their minimum, maximum and mean values (in the case of pH its logarithmic value was considered), standard deviation, coefficients of variation and empirical distribution for individual chemical parameters. Mean results of chemical analyses are presented in Table 3, while stem-and-leaf displays are given in Figs. 1 - 2. |
In these analyses soil pH fell within the range of 4.32 – 8.26, while its coefficient of variation was as low as 9% (Table 3). For most plants optimal soil reaction is pHH2O 6.0 – 6.5. Only 2.2% soils had a highly acid reaction (at pH 4.3 – 5.0), whereas a vast majority had an alkaline reaction pH>7.4 (46.7% soil samples) and a neutral reaction (37.8%), comprising jointly 84.5% samples (Figure 1). Elevated soil pH is connected with an excessive content of alkaline ions, i.e. calcium, magnesium, sodium and potassium. Alkalization of urban soils may result e.g. from the use of salts such as sodium chloride to remove black ice from roadways, as well as strongly alkalizing dusts (containing e.g. CaO, MgO, Na2O, K2O), being by-products of carbon combustion to heat houses [27, 74]. In turn, Kleiber [74] to a much greater degree suggests strong alkalization of soil (pH in H2O up to 10.95) as a factor having a potentially negative effect on plant growth and development.
In the opinion of Klimowicz and Melke [75], in urban areas traffic-related pollution is more dangerous than industrial pollution, since it is spread in relatively large amounts, at low heights, in the respiration zone of humans, animals and plants. Relief features, distance from a roadway and intensity of vehicle traffic have a decisive effect on the contents of heavy metals in soils adjacent to transportation routes in urban green areas. In the soil found at the car market in Słomczyn near Warsaw (one of the biggest car markets in Poland) contents of zinc, lead and copper are as follows (in mg kg-1 d.m.): the car sale point Zn at 612.3, Pb at 397.8 and Ni at 94.5, while at the spare part sale point and warehouse they are: Zn at 679.1, Pb at 420.4 and Ni at 114.0, respectively [115].
Soil pollution with heavy metals is typically assessed on the basis of total contents of elements [44]. Those authors claimed that this assessment should be supplemented with an analysis of heavy metal contents directly available to living organisms.
This study consisted in the determination of contents of soluble heavy metal forms (Table 3). Cadmium content in soils fell within the range of 0.16 – 0.42 mg Cd dm-3 and it was of relatively limited variability (CV=17.50%). As many as 55.1 % samples contained this heavy metal at <0.21 - 0.26 mg Cd dm-3 (Figure 2). Bach [9] in soils of green areas adjacent to transportation routes in the city of Krakow, Poland found contents of soluble cadmium forms to range from 0.21 to 1.54 mg kg-1 d.m. soil. In most tested soils Bach [9] recorded cadmium content from 0.4 to 0.8 mg kg-1 d.m. soil. According to Kabata-Pendias and Pendias [67], natural total cadmium content (the so-called background) in Polish soils is 0.3 mg Cd kg-1 d.m.
Lead content ranged from 0.79 to 42.96 mg Pb dm-3, at the same time being highly variable depending on the location (CV=110.78%). As many as 84.4% tested soils had low contents of this heavy metal (up to 9.22 mg Pb dm-3), while samples with 42.96 mg Pb dm-3 accounted for 2.2.% (Figure 2). A low lead content (max. up to 4.3 mg Pb dm-3) was reported in his study by Kleiber [74]. Lead content (soluble forms) in soils adjacent to transportation routes in the city of Krakow ranged from 11.1 up to 142.8 mg kg-1 d.m. soil, of which the highest proportion (53%) comprised soils with its contents from 40 to 80 mg Pb kg-1 d.m. soil. Mean content of bioavailable Pb forms in soils of allotment gardens located in the right-bank Warsaw was 332.7 mg kg-1 d.m. [41].
The primary source of lead pollution in soils (adjacent to transportation routes) up to 2005 was connected with tetraethyl lead, commonly added to gasoline as an antiknock agent [62]. In turn, the authors of this chapter in their analyses recorded a low content of soluble lead content in the surface soil layer in areas adjacent to transportation routes in the city of Poznań, Poland. No lead pollution in soils adjacent to exit routes leading from Poznań was detected by Hofman and Wachowski [62].
In turn, chromium content ranged from 0.26 to 0.67 mg Cr dm-3. The coefficient of variation for chromium was similar to that calculated for nickel, amounting to CV 22.34%. The greatest proportion (44.4%) of soils was found within the range of chromium contents from < 0.36 to 0.46 mg Cr dm-3 (Figure 2). Results of analyses conducted by Bach [9] indicate that the content of chromium (soluble forms) in soils in areas adjacent to transportation routes in the city of Krakow ranged from trace values to 10.23 mg Cr kg-1 d.m.
The recorded nickel content ranged from 0.43 to 1.25 mg Ni dm-3. The variability of levels for this metal was relatively medium-ranged (CV=23.19%). Most of soil samples (84.4%) were characterized by nickel contents falling within the range of values from < 0.43 to 0.63 mg Ni dm-3 (Figure 2). In soils found in green areas adjacent to transportation routes in Krakow, Poland the content of nickel soluble forms ranged from 1.07 to 6.38 mg kg-1 d.m. soil [9]. In contrast, in soils collected from allotment gardens located in right-bank Warsaw the mean content of bioavailable nickel forms was 28.4 mg kg-1 d.m. [41].
Environmental pollution with heavy metals constitutes a serious problem in some regions of Poland. According to Dmochowski et al. [41], high emissions of heavy metals originating from a dense network of transportation routes with high intensity vehicle traffic causes their accumulation in soils and crops produced in allotment gardens located in Praga Południe, the right-bank district of Warsaw, Poland.
In the opinion of Heck et al. [59], introduction of advanced catalytic systems, containing platinum, rhodium and palladium and constituting a source of environmental pollution also for soils in areas adjacent to transportation routes makes their monitoring a necessary practice. In the nearest future it will be required to create an effective system of environmental pollution monitoring.
|
|
|
|||||
|
|
|
|
||||
1 | 28 czerwca 56 r. | 7.67 | 0, 49 | 0, 23 | 14, 81 | 0, 31 | |
2 | Aleje Niepodległości | 7.58 | 0, 51 | 0, 28 | 10, 74 | 0, 33 | |
3 | Aleje Solidarności | 7.37 | 0, 58 | 0, 27 | 3, 36 | 0, 49 | |
4 | Arciszewskiego | 7.30 | 0, 48 | 0, 20 | 6, 55 | 0, 41 | |
5 | Armii Poznań | 7.72 | 0, 59 | 0, 21 | 42, 96 | 0, 55 | |
6 | Biskupińska | 7.76 | 0, 52 | 0, 23 | 2, 18 | 0, 46 | |
7 | Dolna Wilda | 8.26 | 0, 44 | 0, 18 | 4, 00 | 0, 38 | |
8 | Droga Dębińska | 7.37 | 0, 48 | 0, 23 | 6, 76 | 0, 34 | |
9 | Fredry | 7.30 | 0, 62 | 0, 33 | 6, 83 | 0, 60 | |
10 | Głogowska | 6.86 | 0, 62 | 0, 31 | 3, 56 | 0, 57 | |
11 | Hercena | 7.00 | 0, 58 | 0, 21 | 1, 91 | 0, 46 | |
12 | Hetmańska | 7.45 | 0, 43 | 0, 19 | 3, 92 | 0, 40 | |
13 | Jarochowskiego | 7.60 | 0, 55 | 0, 24 | 3, 24 | 0, 46 | |
14 | Kopanina | 6.64 | 0, 73 | 0, 26 | 7, 45 | 0, 39 | |
15 | Królowej Jadwigi | 6.55 | 0, 86 | 0, 22 | 8, 70 | 0, 35 | |
16 | Krzywoustego | 6.98 | 0, 58 | 0, 28 | 4, 31 | 0, 57 | |
17 | Księcia Mieszka I | 7.17 | 0, 50 | 0, 23 | 18, 89 | 0, 39 | |
18 | Kuźnicza | 6.29 | 0, 70 | 0, 28 | 6, 17 | 0, 43 | |
19 | Lechicka | 8.18 | 0, 55 | 0, 25 | 2, 89 | 0, 52 | |
20 | Leszczyńska | 7.63 | 0, 57 | 0, 28 | 3, 46 | 0, 67 | |
21 | Lodowa | 7.72 | 0, 51 | 0, 21 | 3, 10 | 0, 48 | |
22 | Maczka | 7.48 | 0, 60 | 0, 30 | 6, 07 | 0, 56 | |
23 | Małopolska | 7.47 | 0, 62 | 0, 29 | 2, 97 | 0, 64 | |
24 | Marcelińska | 7.89 | 0, 55 | 0, 26 | 2, 78 | 0, 59 | |
25 | Niestachowska | 5.84 | 0, 71 | 0, 25 | 10, 97 | 0, 38 | |
26 | Nowowiejskiego | 7.14 | 0, 49 | 0, 19 | 3, 02 | 0, 36 | |
27 | Opieńskiego | 7.32 | 0, 47 | 0, 22 | 0, 79 | 0, 39 | |
28 | Opolska | 7.76 | 0, 62 | 0, 28 | 3, 65 | 0, 64 | |
29 | Ożarowska | 7.50 | 0, 51 | 0, 24 | 3, 76 | 0, 41 | |
30 | Piątkowska | 7.40 | 0, 50 | 0, 26 | 2, 64 | 0, 46 | |
31 | Piłsudskiego | 7.50 | 0, 60 | 0, 26 | 2, 10 | 0, 57 | |
32 | Polanka | 6.45 | 0, 60 | 0, 24 | 5, 73 | 0, 41 | |
33 | Poznańska | 6.99 | 0, 44 | 0, 16 | 2, 49 | 0, 26 | |
34 | Przemysłowa | 7.36 | 0, 60 | 0, 28 | 2, 54 | 0, 60 | |
35 | Serbska | 7.79 | 0, 60 | 0, 24 | 2, 34 | 0, 63 | |
36 | Słowiańska | 6.87 | 0, 63 | 0, 23 | 5, 31 | 0, 29 | |
37 | Stablewskiego | 7.55 | 0, 57 | 0, 23 | 3, 28 | 0, 46 | |
38 | Starołęcka | 7.12 | 0, 63 | 0, 29 | 6, 01 | 0, 53 | |
39 | Stróżyńskiego | 7.53 | 0, 49 | 0, 23 | 2, 71 | 0, 46 | |
40 | Szpitalna | 4.32 | 0, 82 | 0, 23 | 11, 84 | 0, 50 | |
41 | Umultowska | 6.79 | 1, 25 | 0, 42 | 3, 03 | 0, 65 | |
42 | Widłakowa | 7.41 | 0, 50 | 0, 22 | 2, 07 | 0, 45 | |
43 | Witosa | 7.09 | 0, 48 | 0, 21 | 6, 07 | 0, 43 | |
44 | Wojska Polskiego | 6.53 | 0, 69 | 0, 26 | 9, 48 | 0, 39 | |
45 | Zwierzyniecka | 7.64 | 0, 52 | 0, 23 | 2, 49 | 0, 40 | |
Content | mean | 7.22 | 0.59 | 0.25 | 6.00 | 0, 47 | |
minimum | 4.32 | 0.43 | 0.16 | 0.79 | 0, 26 | ||
maximum | 8.26 | 1.25 | 0.42 | 42.96 | 0, 67 | ||
Standard deviation | 0, 65 | 0.14 | 0.04 | 6.64 | 0.10 | ||
Coefficient of variation (%) | 9, 0 | 23.19 | 17.50 | 110.78 | 22.32 |
4.1. Concluding remarks
Based on analyses of soils collected from green areas located in the vicinity of selected transportation routes in the city of Poznań, Poland in most examined locations an alkaline reaction pH >7.4 (46.7% soil samples) and a neutral reaction (37.8%) were found, which may significantly affect habitat conditions for plants.
Moreover, most tested soil samples contained low amounts of soluble forms of cadmium, lead, chromium and nickel.
5. Heavy metal contents in leaves of selected ornamental plant species growing in green areas adjacent to selected transportation routes in the city of Poznań (western Poland)
Effects of soil pollution with heavy metals may be identified by analyzing their content in plants. Plants may be considered good bioindicators of environmental pollution with heavy metals. Most frequently healthy leaves are indicator parts of plants; however, it depends on the species and occasionally even on the cultivar.
The aim of the analyses conducted by the authors in September 2012 was to determine contents of selected heavy metals in leaves of trees growing in the vicinity of transportation routes in Poznań (western Poland).
It was decided to conduct analyses on healthy plants with no symptoms of damage. Leaves of trees were collected from the central parts of long shoots, distributed at various sides around the circumference of the crown. A total of 15 - 20 leaves were collected from each tree. Leaves were collected from 10 trees of a given genus (1 bulk sample comprised approx. 150 - 200 leaves). The collected material was dried at a temperature of 45 - 50°C and then homogenized. In order to determine total forms of heavy metals they were mineralized in a mixture of nitric and perchloric acids (v:v=3:1; Σ 30 cm3). Following mineralization Cd, Cr, Pb and Ni contents were determined by atomic absorption spectrometry (AAS) in a Carl Zeiss Jena apparatus. |
High variation was observed in the contents of heavy metals in leaves of tested trees (
Table (5) present contents of heavy metals in leaves of selected genera of trees reported by Tomašević et al. [117], Lawal et al. [81] and Knezevic et al.[76]. In this study cadmium and nickel contents in leaves did not exceed the levels detected by those authors. In contrast, they found markedly lower chromium contents in leaves of
|
|
|
|||
|
|
|
|
||
|
Minimum | 0.25 | Tr. | 0.83 | 0.80 |
Maximum | 1.85 | 1.79 | 3.19 | 2.40 | |
Average | 1.31 | 0.82 | 2.10 | 1.81 | |
|
Minimum | 1.16 | Tr. | 0.55 | 1.90 |
Maximum | 2.87 | Tr. | 3.49 | 2.40 | |
Average | 1.74 | Tr. | 1.55 | 2.23 | |
|
Minimum | 0.47 | Tr. | 1.06 | 0.50 |
Maximum | 2.54 | 2.13 | 5.73 | 2.90 | |
Average | 1.37 | 0.48 | 2.78 | 2.07 | |
|
Minimum | 1.12 | Tr. | 2.43 | 1.60 |
Maximum | 1.71 | 1.69 | 4.61 | 2.50 | |
Average | 1.39 | 0.48 | 3.28 | 2.10 | |
|
Minimum | 0.29 | Tr. | 2.10 | 0.80 |
Maximum | 2.09 | 1.16 | 4.28 | 2.50 | |
Average | 1.18 | 0.46 | 3.19 | 1.63 |
|
|
|
|||
|
|
|
|
||
|
Min | dl | dl | 1.88 | - |
Max | 1.4 | 0.02 | 11.4 | - | |
|
Min | 0.4 | dl | 5.35 | - |
Max | 4.9 | 0.33 | 20.3 | - | |
|
Min | - | 0.17 | 0.77 | 1.14 |
Max | - | 0.37 | 2.25 | 1.92 | |
|
Min | - | - | 0.94 | 3.23 |
Max | - | - | 3.16 | 6.63 |
6. The principle of phytoremediation
Among soil purification methods biological methods are increasingly often focused on as particularly promising [1, 99, 108]. One of these is phytoremediation, based on the activity of living organisms [40]. It is an alternative method, competitive in relation to other technologies extensively applied in pollutant removal from soil. There are methods facilitating deactivation or removal of toxic substances from the substrate. In most cases they are based on methods of physico-chemical extraction, but their application is connected with excessive costs and complete elimination of soil microorganisms. Reconstruction of semi-natural ecosystems in such cases is a lengthy process.
Obvious advantages of this biological method include its applicability at the contamination site, as well as relatively low investment outlays and low operating costs at the simultaneous high effectiveness of the process [95]. In the opinion of Salt et al. [107], other factors promoting its more common use are connected with the fact that it is an environmentally friendly process, which does not disturb soil structure, and that it may use many plant species.
The term phytoremediation originates from Greek
As it was reported by Pandolfini et al. [96], this biological method is based on the practical use of three types of physiological response to substances found in the environment, i.e. exclusion, accumulation and hyperaccumulation.
The term phytoremediation refers to the following methods using higher plants to purify environmental matrices [49, 98, 108, 119]:
phytodegradation – the use of plants and microorganisms to degrade organic pollutants,
phytostabilization – the use of plants to reduce bioavailability of pollutants in the environment,
phytoextraction – the use of plants absorbing pollutants and accumulating them in organs removed from fields together with crops in order to purify soil from heavy metals and organic substances,
phytovolatilization – the use of plants to volatilize pollutants and release them to the atmosphere,
rhizofiltration – the use of plant roots to absorb pollutants from water and sewage,
rhizodegradation – the use of plants to supplement the bioremediation process performed by microorganisms colonizing the rhizosphere.
In the opinion of Negri et al. [91], the above mentioned phytoremediation technologies act at three different detoxication levels on pollutants accumulated in the environment, i.e. the pollution-loaded soil matrix (phytostabilization, rhizofiltration and rhizodegradation), plants (phytodegradation, phytoextraction, rhizofiltration) and the atmosphere (phytovolatilization). Studies are also being conducted on the application of plants in the technology to excavate heavy metals, referred to as phytomining [5, 90, 97]. Soils with high heavy metal contents are planted with plants capable of growing under such adverse conditions and accumulating selected elements in their biomass. Such biomass is next treated as the so-called bio-ore. The biomining technlogy to extract heavy metals from soil, created by R. L. Chaney, J.S. Angle, A.J. Baker and J.M. Li, was patented in 1989 [45].
7. Continuous and induced phytoextraction
Phytoextraction, a phytoremediation method observed in 1885 by Bauman [11], is an excellent concept of soil purification, which is not yet commonly applied. In many centers worldwide research is being conducted on phytoextraction in the search for plant species capable of accumulating heavy metals in their aboveground parts. Within phytoextraction of heavy metals from soil we may distinguish the so-called continuous and induced phytoextraction.
Plants used in phytoextraction of heavy metals from soil should exhibit:
good tolerance to high concentrations of heavy metals
capacity to absorb and accumulate heavy metals in their aboveground parts
rapid growth
high increase in biomass
resistance to diseases, pesticides and adverse atmospheric conditions
low cultivation requirements
easy harvesting and processing.
In continuous phytoextraction heavy metals are absorbed by plants and accumulated continuously with plant growth [14, 20, 46, 85, 110].
Apart from it being economically attractive, continuous phytoextraction is also environmentally friendly, leaving the site suitable for cultivation of other plants [37, 63].
In urbanized areas continuous phytoextraction may be used in two types of sites. One comprises degraded soils in post-industrial areas, while the other, highly promising as a future application of phytoextraction, is connected with soils in the vicinity of transportation routes and in urban green areas. The potential of ornamental plant species most frequently planted in urban locations is investigated in many research centers worldwide. Such species include also
Zhou and Wang [124] when investigating the effect of cadmium on growth in three ornamental plant species stated that
Phytoremediation of heavy metals from contaminated areas, including urbanized areas, according to Porębska and Gworek [101] may be conducted using many species of ornamental plants and vegetables, e.g.
Antonkiewicz and Jasiewicz [6] assessed suitability of
Antonkiewicz et al. [7] when investigating phytoextraction of heavy metals (Cd, Pb, Ni, Zn and Cu) from soil using Virginia fanpetals (
Many authors for phytoextraction of soils polluted with heavy metals recommended sunflower, corn, rape, amaranth, willows, Miscanthus and strong growing cereals, while for phytoextraction in urban soils he recommended plants with high tolerance to pollution, e.g. London plane, northern red oak, Japanese larch, poplars, field maple, ashes and dogwoods, desert false indigo, false Spirea and forsythia.
Larcher et al. [80] conducted pilot-scale studies in the industrial area of Turin (Italy) using two plant species in phytoremediation of soil to remove heavy metals. They found
In urban green areas the predominant forms are lawns and turf-covered areas in escarpments, embankments, spoil tips, belts separating roadways, parking lots, gas stations, landfills and industrial waste dumps. Depending on the use of turf areas it is highly important to select appropriate species and cultivars of lawn grasses. It results from experiments conducted by Bosiacki and Zieleziński [23] on the potential of three grass species (
Studies are also conducted on induced phytoextraction using plants producing large amounts of biomass, but additionally such substances as e.g. chelating carriers affecting mobility of individual elements and enhancing pollutant accumulation in plant organs (particularly aboveground parts) are introduced to the environment [35, 92, 123].
Chelating substances are to transform forms of heavy metals sparingly soluble or insoluble in water into forms available to plants. Studies are being conducted using different chelators, both natural and synthetic (e.g. humus substances, low molecular organic acids, citric acid, tartaric acid, amino acids as well as EDTA, EGTA, EDDS, HEDTA, CDTA, EDDHA, DTPA, NTA). Some of them are biodegraded in soil, while others in combination with a heavy metal may be leached to ground waters contaminating them. For this reason it is essential in this technology to determine an appropriate dose and date for the application of a given chelating agent.
It results from preliminary studies (unpublished data) conducted in 2012 by Bosiacki at the Department of Plant Nutrition, the Poznań University of Life Sciences, Poland that EDTA introduced to mineral soil contaminated individually with cadmium at 1.5 mg dm-3 in the form of cadmium sulfate (3CdSO4 8H2O), lead 100 mg dm-3 as lead acetate [(CH3COO)2Pb 3H2O] and nickel 50 mg dm-3 as nickel sulfate (NiSO4 6H2O) caused an increase in the contents of these metals in leaves of
Identification of compounds complexing toxic heavy metals and at the same time biodegradable in the soil medium is crucial for induced phytoremediation.
At present studies are being conducted at the Department of Plant Nutrition, the Poznań University of Life Sciences, Poland on the application of a biodegradable compound in phytoextraction of heavy metals from contaminated soils.
8. The phenomenon of hyperaccumulation
As it was stated by Brooks [28] the discovery and description of a phenomenon termed hyperaccumulation has contributed to the practical use of plants to remove metallic pollutants from soil. According to Boyd and Martens [25] and Brown et al. [29], plant species referred to as hyperaccumulators are genetically and physiologically capable of accumulating large amounts of heavy metals with no symptoms of toxicity. Threshold values of metal concentrations have been used to define metal hyperaccumulation, including 100 mg kg-1 dry weight of shoots for Cd, 1000 mg kg-1 for Cu, Ni, Pb and 10 000 mg kg-1 for Zn [10, 28, 86]. Cline et al. [34] stated that concentrations of heavy metals in tissues of hyperaccumulator plants should be 1 - 2%. Van der Ent et al. [120] recommend the following concentration criteria for different metals and metalloids in dried foliage:100 µg g-1 for Cd, Se and Ti; 300 µg g-1 for Co, Cu and Cr; 1000 µg g-1 for Ni, Pb and As; 3000 µg g-1 for Zn; 10000 µg g-1 for Mn, with plants growing in their natural habitats. There are over 400 known plant species from 45 families classified as hyperaccumulators. Most species belong to the families
Most natural hyperaccumulators are plants characterized by slow growth and production of low amounts of biomass. These traits result in a limited applicability of these plant species in phytoextraction of heavy metals from soil [37]. An example in this respect may be provided by
Studies are being conducted worldwide on the use of plants producing large amounts of biomass (for energy generation purposes) in the phytoextraction of heavy metals from polluted soils. They include annual plants such as e.g. cereals and rape, and perennials e.g. willows, which capacity for phytoextraction of heavy metals was confirmed by Greger and Landberg [56] and Boyter et al. [26]. Other perennial species of energy crops include
Ociepa et al. [94] stated that plants grown for energy purposes may play a considerable role in view of the assumptions of the Common Agricultural Policy and the environmental protection policy of the European Union. One of such plant species is
In the years 2008 – 2011 at the Department of Plant Nutrition, the Poznan University of Life Sciences, Poland, studies were conducted to assess applicability of
|
The vegetation experiment was conducted in an unheated plastic tunnel with suspended sides, of 6 x 30 m in size. at the Marcelin Experimental Station of the Poznan University of Life Sciences. Seedlings of Phytoremediation of cadmium and lead by Substrates: mineral soil (sand) and mineral soil with highmoor peat (1:1 v/v) Doses of cadmium: control (native contents of cadmium), 3, 5 and 10 mg dm-3) Doses of lead: control (native contents of cadmium), 250, 1000 and 5000 mg dm-3). In mineral soil the method according to Mocek and Drzymała [88] was used to determine particle density (which amounted to 2.65 g cm-3) and bulk density (1.62 g cm-3). Total porosity of mineral soil was 38.9%. Moreover. grain size distribution of mineral soil was determined by the densimetric method according to Prószyński [88]. On the basis of the percentages of fractions the grain size class of soil was identified (according to the guidelines of the Polish Society of Soil Science) - sand. Prior to the establishment of the experiment, Corg content in mineral soil was determined according to the Tiurin method [51]. Content of organic carbon in sand (the Tiurin method) was 0.55% (0.95% humus). while the percentage of organic matter in the mixture of sand and highmoor peat (from loss on ignition) was 10.05%. In the substrate composed of a mixture of mineral soil with highmoor peat (1:1 v/v) the percentage of organic substance was determined by loss on ignition the substrate by the direct method at high temperature in the presence of oxygen, under the influence of which organic substance is decomposed (carbon is released in the form of CO2. hydrogen in the form of H2O and nitrogen as N2, while the other elements remain in ash). Experiments were conducted using highmoor peat by Hartmann (sphagnum peat. ground. fractional with acid reaction (pH 4.50). This peat has a high water capacity, at the same time retaining an elastic structure. The weight of 1 dm3 peat was 490 grams. In order to obtain an appropriate pH for growing of The following nutrient determination techniques were applied: N – NH4 and N – NO3 by microdistillation (Bremner modified by Starck), P by colorimetry using the vanadium-molybdenum method, K, Ca and Na by flame photometry, Mg by atomic absorption (AAS), Cl and S – SO4 by nephelometry [78]. In October in each year of the study prior to harvesting plant height was measured. Dry weight of plants was recorded and samples of plant material were collected for analyses. Harvested plant material (entire aboveground mass) was dried in an extraction drier at a temperature of 105ºC for 48 h. Next the material was ground and at 2.5 g from each sample it was digested in a mixture of concentrated HNO3 (ultra pure) and HClO4 (analytically pure) at a 3:1 ratio [18]. Content of cadmium and lead in the plant material were determined by flame atomic absorption spectrophotometry (FAAS), AAS-3 spectrophotometer by Zeiss. Moreover, content of metals in the reference material ( In the first and second year of the study samples of substrate were collected after harvest, from which metals were extracted using the Lindsey’s solution containing in 1 dm3: 5 g EDTA (ethylenediaminetetraacetic acid), 9 cm3 25% NH4OH solution, 4 g citric acid and 2 g Ca(CH3COO)2 2H2O. Next this metal was assayed by flame atomic absorption spectrophotometry (FAAS), AAS-3 spectrophotometer by Zeiss. Results of content of cadmium and lead in substrates and aboveground parts of |
Analyses conducted by physiologists classify
Proposed methods to manage Miscanthus after phytoextraction of heavy metals from soil include combustion (ashes – hazardous waste), bio-ore, paper and pulping industry, production of particleboards as well as chemical industry (packaging plastics).
The aim of the conducted analyses was to determine the effect of increasing doses of cadmium, lead introduced to mineral soil (sand) and to mineral soil with an addition of highmoor peat (at a 1:1 ratio, v/v), on the tolerance index of
Ti < 1 value lower than one - inhibition of growth or plant death
Ti = 1 value equal one - no effect of increased metal contents on yielding
Ti > 1 value greater than one - positive effect of metal on yielding.
In the first year of growth of
|
|
||||
|
|
||||
|
|
|
|
||
Cd | 3 |
|
|
|
0.88 |
5 | 0.99 |
|
0.83 |
|
|
10 | 0.70 |
|
0.95 | 0.85 | |
Pb | 250 | 0.80 |
|
0.78 | 0.99 |
1000 |
|
|
0.99 | 0.90 | |
5000 | 1.00 | 0.98 | 0.93 | 0.58 |
In the opinion of Arduini et al. [8] and Kozak et al. [77],
Kalembasa and Malinowska [72], when testing different clones of
Based on studies conducted by the authors of this chapter it was found that cadmium applied at 3 and 5 mg dm-3 mineral soil in the first year of growth of
In a mixture of mineral soil with highmoor peat, to which 3 mg Cd dm-3 were introduced both in the first and second year of growth of
|
|
||||||||
|
|
||||||||
|
|
|
|
|
|
||||
Mineral soil | Control | 0.98-1.29 | 0.31 | 0.12 |
|
1.29-1.52 | 0.23 | 0.10 |
|
Cd 3 | 1.31-1.99 | 0.68 | 0.24 |
|
1.14-2.59 | 1.45 | 0.51 |
|
|
Cd 5 | 1.33-3.69 | 2.36 | 0.78 |
|
1.78-4.69 | 2.91 | 0.97 |
|
|
Cd 10 | 3.56-8.34 | 4.78 | 1.62 |
|
6.16-12.62 | 6.46 | 2.81 |
|
|
Mineral soil + highmoor peat | Control | 0.64-1.33 | 0.69 | 0.25 |
|
0.95-1.46 | 0.51 | 0.19 |
|
Cd 3 | 1.34-1.93 | 0.59 | 0.22 |
|
1.38-1.90 | 0.52 | 0.20 |
|
|
Cd 5 | 2.39-3.96 | 1.57 | 0.67 |
|
2.68-4.78 | 2.10 | 0.97 |
|
|
Cd 10 | 5.23-9.34 | 4.11 | 1.55 |
|
5.54-11.17 | 5.63 | 2.48 |
|
A significantly greater lead content in aboveground parts of
|
|
||||||||
|
|
||||||||
|
|
|
|
|
|
||||
Mineral soil | Control | 1.23-1.77 | 0.54 | 0.21 |
|
1.76-2.74 | 0.98 | 0.38 |
|
Pb 250 | 29.87-48.25 | 18.38 | 7.44 |
|
27.37-46.78 | 19.41 | 7.71 |
|
|
Pb 1000 | 56.89-75.43 | 18.54 | 6.92 |
|
53.45-73.56 | 20.11 | 7.58 |
|
|
Pb 5000 | 71.46-280.62 | 209.16 | 85.24 |
|
58.56-131.34 | 72.78 | 29.19 |
|
|
Mineral soil + highmoor peat | Control | 1.14-1.62 | 0.48 | 0.18 |
|
1.12-1.67 | 0.55 | 0.21 |
|
Pb 250 | 27.89-40.99 | 13.10 | 5.65 |
|
21.67-45.62 | 23.95 | 8.00 |
|
|
Pb 1000 | 48.67-61.78 | 13.11 | 4.74 |
|
40.56-62.38 | 21.82 | 7.80 |
|
|
Pb 5000 | 73.56-110.34 | 36.78 | 12.56 |
|
53.56-137.89 | 84.33 | 31.89 |
|
In the conducted analyses the cadmium and lead concentration indexes were calculated for aboveground parts of
C = a : b
a - content in a plant growing in polluted substrate
b - content in a plant growing in unpolluted substrate.
The greatest concentration index was recorded for lead in the first year of growth in the case of plants growing in mineral soil (Table 9). Plants growing in mineral soil were characterized by a greater concentration index for cadmium and lead in the first year of growth. An identical dependence was found in plants growing in a mixture of soil and peat, except for plants growing in a substrate contaminated with 5000 mg Pb dm-3, in which a higher lead concentration index was found in the second year of growth.
Miscanthus sp. was tested on heavy metal contaminated arable soil in Southern Poland [110]. The authors concluded that this species accumulates high amounts of metals what may cause high emission of contaminants during biomass combustion.
According to Kalembas [70] in ash of
|
|
||||
|
|
||||
|
|
|
|
||
Cd | 3 | 1.45 | 1.48 | 1.65 | 1.38 |
5 | 3.06 | 2.53 | 3.06 | 2.84 | |
10 | 7.69 | 6.69 | 7.69 | 7.22 | |
Pb | 250 | 25.51 | 15.94 | 23.33 | 23.13 |
1000 | 40.37 | 28.09 | 36.38 | 35.72 | |
5000 | 136.49 | 45.23 | 63.25 | 69.90 |
Both in soil and in a mixture of soil and peat a lower cadmium content was recorded after the second year of culture except for substrates contaminated with 10 mg Cd dm-3, in which this dependence was not observed (Table 10).
When analyzing lead content in tested substrates after the completion of growth a lower Pb content was found also in the second year except for a mixture of mineral soil with peat, to which lead was not introduced (table 11).
In the substrate being a mixture of soil with peat lower contents of cadmium and lead were observed in comparison to those recoded in mineral soil in all the experimental variants (Tables 10 and 11).
Control (native content of Cd mg dm-3) |
mineral soil | 0.09 c | 0.07 b |
soil + peat | 0.07 b | 0.05 a | |
Weak pollution (Cd 3 mg dm-3) |
mineral soil | 2.23 d | 1.09 b |
soil + peat | 1.79 c | 0.77 a | |
Medium pollution (Cd 5 mg dm-3) |
mineral soil | 4.12 d | 2.65 c |
soil + peat | 2.51 b | 1.32 a | |
Strong pollution (Cd 10 mg dm-3) |
mineral soil | 6.37 b | 6.39 b |
soil + peat | 5.43 a | 5.22 a |
|
|
|
|
|
|
||
Control (native content of Pb mg dm-3) |
mineral soil | 24.84 c | 15.18 b |
soil + peat | 6.95 a | 4.79 a | |
Weak pollution (Pb 250 mg dm-3) |
mineral soil | 227.71 d | 192.68 c |
soil + peat | 130.31 b | 104.74 a | |
Medium pollution (Pb 1000 mg dm-3) |
mineral soil | 837.70 d | 575.34 b |
soil + peat | 665.30 c | 236.88 a | |
Strong pollution (Pb 5000 mg dm-3). |
mineral soil | 3755.06 d | 3304.71 c |
soil + peat | 2431.14 b | 1401.27 a |
9. The amount of ash (%) after incineration of aboveground parts of Miscanthus × giganteus
Aboveground parts of
stage I - preliminary carbonization at a temperature of 100°C for 1 h
stage II – combustion at 450°C for 5 h.
Incineration was performed on 20 randomly selected samples of aboveground dry matter of
The amount of ash left after combustion of aboveground parts of
Among all observations after the combustion process the highest percentage (40%) was found for the amount of ash within the range of 8.44 to 8.88%. The amount of ash within the range of 8.00 to 8.44% ranked second constituting 30% observations.
In a study conducted by Kalembasa [70] largest content of raw ash was obtained from the
|
|
|
||
Amount of ash after combustion in (%) |
V = (6.68-7.12] IV = (7.12-7.56] III = (7.56-8.00] II = (8.00-8.44] I = (8.44-8.88] |
1 1 4 6 8 |
1/20 1/20 4/20 6/20 8/20 |
1/20 2/20 6/20 12/20 20/20 |
Total | 20 | 1 |
Concluding remarks
The study was financed from funds for science in the years 2008 - 2011 as a research project no. N N305 085535
Acknowledgments
The authors express their gratitude to the Management Board of the Municipal Green Areas in Poznań and the Management Board of the Municipal Road Network in Poznań for facilitating the soil monitoring project.
References
- 1.
Alizadeh SM., Zahedi-Amiri G., Savaghebi-Firoozabadi G., Etemad V., Shirvany A., Shirmardi M. Assisted phytoremediation of Cd-contaminated soil using poplar rooted cuttings. Int. Agrophys., 2012;26 219-224. - 2.
Alloway BJ. Heavy metals i soils. Blackie Gong. and London. New York: John Willey & Sons; 1990; p319. - 3.
Alloway BJ., Ayres DC. Chemical pollution base. Warszawa: PWN; 1999 (in Polish). - 4.
Amir S., Hafidi M., Merilna G., Revel JC. Sequential extraction of heavy metals during composting of sewage sludge. Chemosphere 2004; 59 801 – 810. - 5.
Anderson CWN., Brooks RR., Chiarucci A., Lacoste CJ., Leblanc M., Robinson BH., Simcock R., Stewart RB. Phytomining for nickel, thallium and gold. Journal of Geochemical Exploration 1999;67 407-415. - 6.
Antonkiewicz J., Jasiewicz C. Estimation of usefulness of different plant species for phytoremediation of soils contaminated with heavy metals. Acta Sci. Pol. Formatio Circumectus 2002;1(1-2) 119-130 (in Polish). - 7.
Antonkiewicz J., Jasiewicz C., Lošák T. Using Sida hermaphrodita Rusby for extraction of heavy metals from soil. Acta Sci. Pol. Formatio Circumectus 2006;5(1) 63-73 (in Polish). - 8.
Arduini I., Masoni A., Ercoli L., Mariotti M. Growth and cadmium uptake of Miscanthus sinensis as affected by cadmium. Agric. Mediterran. 2003;133(3-4) 169-178. - 9.
Bach A. Studies on soil pollution with heavy metals in green areas adjacent to transportation routes and assessment of their salinity rates with a determination of soil pH. Uniwersytet Rolniczy im. Hugona Kołłątaja w Krakowie. A study commissioned by the City Office of Krakow; 2011 Available on-line 14.06.2012 <http:www.bip.krkow.pl.> (in Polish). - 10.
Baker AJM., McGrath SP., Reeves RD., Smith JAC. Metal hyperaccumulator plants: a review of the ecology and physiology of a biochemical resource for phytoremediation of metal-polluted soils. In: Terry N., Banuelos G. (ed.) In Phytoremediation of Contaminated Soil and Water. Lewis Publishers 2000; p85-107. - 11.
Bauman A. Das verhalten von Zinksalzen gegen pflanzen und im boden. Landwirtisch. Verss 1885;31 1-53. - 12.
Bielicka A., Ryłko E., Bojanowska I. Contents of metals in soils and vegetables from Gdansk and Straszyn allotments. Ochrona Środowiska i Zasobów Naturalnych 2009;40 209-216. - 13.
Blake L., Goulding KWT. Effects of atmospheric deposition, soil pH and acidification on heavy metal content in soils and vegetation of semi-natural ecosystems AT Rothamsted Experimental Station. UK. Plant and Soil 2002;240 235 – 251. - 14.
Blaylock M., Huang J. Phytoextraction of metals. In: Raskin I, Ensley B (ed.) Phytoremediation of toxic metals: using plants to clean up the environment. New York: Wiley; 2000. p53-69. - 15.
Bosiacki M. Accumulation of cadmium in selected species of ornamental plants. Acta Sci. Pol. Hortorum Cultus 2008;7(2) 21-31. - 16.
Bosiacki M. Phytoextraction of cadmium and lead by selected cultivars of Tagetes erecta L. Part I. Effect of Cd and Pb on yielding. Acta Sci. Pol. Hortorum Cultus 2009;8(2) 3-13. - 17.
Bosiacki M. Phytoextraction of cadmium and lead by selected cultivars of Tagetes erecta L. Part II. Contents of Cd and Pb in plants. Acta Sci. Pol. Hortorum Cultus 2009;8(2) 15-26. - 18.
Bosiacki M., Roszyk J. The comparing methods of mineralization of plant material on the content of heavy metals. Apar. Bad. Dydakty 2010;XIV(4) 37-41 (in Polish). - 19.
Bosiacki M., Tyksiński W. Dependence between the content of organic carbon and the content of cadmium and lead in horticultural substrates. Acta Agrophysica 2006;7(3) 517-526 (in Polish). - 20.
Bosiacki M., Wojciechowska E. Phytoextraction of nickel by selected ornamental plants. Ecological Chemistry and Engineering S 2012;19(3) 331-345. - 21.
Bosiacki M., Wolf P. Evaluation of the usefulness of selected soecies of grasses to phytoremediation of cadmium and lead. Part I. Cadmium. Apar. Bad. Dydakty. 2008;13(3) 19-27 (in Polish). - 22.
Bosiacki M., Wolf P. Evaluation of the usefulness of selected soecies of grasses to phytoremediation of cadmium and lead. Part II. Lead. Apar. Bad. Dydakty. 2008b;13(3) 28-36 (in Polish). - 23.
Bosiacki M., Zieleziński Ł. Phytoextraction of nickel by selected species of lawn grasses from substrates contaminated with heavy metals. Acta Sci. Pol., Hortorum Cultus 2011;10(3) 155-173. - 24.
Botre C., Tosi M., Mazzei F., Bocca B., Petrucci F., Alimonti A. Automotive catalytic converters and environmental pollution: Role of the platinum group elements in the redox reactions and free radicals production. International Jurnal of Enviromnent and Health. 2007;1(1) 142-152. - 25.
Boyd RS., Martens SN. Nickel hyperaccumulated by Thlaspi montanum var. montanum is acutely toxic to an insect herbivore. Oikos 1994;70 21-25. - 26.
Boyter MJ., Brummer JE., Leininger WC. Growth and metal accumulation of Geyer and mountain willow grown in topsoil versus amended mine tailings. Water Air Soil Pollut. 2009;198 17-29. - 27.
Breś W. Anthropopressure factors causing trees to die off in Urban landscape. Nauka Przyr. Technol . 2008;2(4) 31(in Polish). - 28.
Brooks RR. Plants that Hyperaccumulate Heavy Metals. Wallingford, UK: CAB International 1998. - 29.
Brown SL., Chaney RL., Anle JS., Baker AJM. Zinc and cadmium uptake of Thlaspi caerulescens grown in nutrient solution. Soil Sci. Soc. Am. J. 1995;59125-133. - 30.
Brümmer G., Gerth J., Herms U. Heavy metals species, mobility and availability in soils. Z. Pflanzenern Bonenk 1986;149 382 – 389 ( in Deutsch) . - 31.
Brümmer G., Herms U. Influencing factors of heavy metals. Solubility, retention and availability in the soil. Bielefelder Ökol. Beitr. 1985;1 117 – 139 ( in Deutsch) . - 32.
Chaney RL., Brown SL., Y-M Li. Potential use of metal hyperaccumulators. Mining Environm. Manag. 1995;9 9-11. - 33.
Chłopecka A. The effect of various compounds of cadmium, copper, lead and zinc to form these metals in the soil and their content in plants. IUNG Seria R 1994 ( in Polish). - 34.
Cline RG., Powell PE., Szaniszko PJ., Reid PP. Comparison of the abilities of hydroxamic, synthetic and other natural organic acids to chelate ion and other ions in nutrient solution. J. Amer. Soc. Soil Sci. 1982;46 1158-1164. - 35.
Cooper EM., Sims JT., Cunningham SD., Huang JW., Berti WR. Chelate-assisted phytoextraction of lead from contaminates soils. J. Environ. Qual. 1999;28 1709-1719. - 36.
Crucq R., Frennet A. Catalysis and automotive pollution control. Elsevier Science Publishers B.V., Amsterdam 1987. - 37.
Cunnigham SD., Berti WR., Huang JW. Phytoremetiation of contaminated soils. Trends Biotechnol. 1995;13 393-397. - 38.
Curyło T., Jasiewicz C. Comparison of the impact of multi-organic fertilizer and mineral and mineral yield and intake of heavy metals by plants. Fol. Univ. Agr. Stet.– Agr. 1998;72 35-41 ( in Polish). - 39.
Czekała J., Jakubus M., Gładysiak S. The content of soluble forms of trace elements, depending on the pH of the soil and the extraction solution. Zesz. Probl. Post. Nauk. Rol. 1996;434(1) 371 – 376 ( in Polish). - 40.
Dhankher OP., Doty SL., Richard B. Meagher RB., Pilon-Smits E. Biotechnological approaches for phytoremediation. In: Arie Altman and Paul Michael Hasegawa (ed.) Plant Biotechnology and Agriculture. Oxford: Academic Press 2011; pp. 309-328. - 41.
Dmochowski D., Prędecka A., Mazurek M., Pawlak A. Hazards related to the emission of heavy metals in view of ecological safety. Example of allotments in urban areas. The Polish Journal of Aviation Medicine and Psychology 2011;3(17) 257-265 ( in Polish). - 42.
Domska D., Bobrzecka D., Wojtkowiak K. Changes in the content of some nutrients in the soil depending on their acidity. Zesz. Probl. Post. Nauk. Rol. 1998;456 255 – 559 ( in Polish ). - 43.
Fergusson JE. The heavy elements. Chemistry, environmental impact and health effects. Pergamon Press. Oxford 1990. - 44.
Filipek-Mazur B., Tabak M. Soil, traffic pollution, copper, zinc, chromium, sequential extraction. Ecological Chemistry and Engineering A 2011;18(11) 1533 -1538. - 45.
Gałuszka A., Migaszewski Z. Problems of sustainable use of mineral resources. Problems of Sustainable Development 2009;4(1) 123-130 ( in Polish ). - 46.
Gangrong Shi., Qingsheng Cai. Cadmium tolerance and accumulation in eight potential energy crops. Biotechnology Advances, 2009;27 555-561. - 47.
Gawęda M. The effect of organic matter in soil on the lead level in edible parts of lettuce and carrot. Acta Hort. 1995;379 221-228. - 48.
Gębski M. Factors influencing soil and fertilizer on heavy metal uptake by plants. Post. Nauk. Roln. 1998;5 3 – 16 ( in Polish ). - 49.
Gerhardt KE., Huang XD., Glick BR., Greenberg BM. Phytoremediation and rhizoremediation of organic soil contaminants: Potential and challenges. Plant Sci. 2009;176 20–30. - 50.
Golcz A. Soil salinity and acidity. Research Methods In Plant Sciences vol. 3. Soil Sickness. In Narwal SS., Politycka B., Fengzhi Wu, Sampietro DA. (ed.) Studium Press LLC, Huston USA. 2011; p43-53. - 51.
Golcz, A., Bosiacki, M. Soil Organic Matter, Research methods in plant sciences vol. 3. Soil Sickness. In Narwal SS.. Politycka B.. Fengzhi Wu. Sampietro DA. (ed.) Studium Press LLC. Huston US, 2011; p68-78. - 52.
Gorlach E., Gambuś F. Phosphate and compound fertilizers as a source of soil contamination with heavy metals. Zesz. Prob. Post. Nauk Roln. 1997;448a 139-146. - 53.
Gorlach E., Gambuś F. Potentially toxic trace elements in soils (excess, harmfulness and countermeasures). Zesz. Prob. Post. Nauk Roln. 2000;472 275-296 ( in Polish ). - 54.
Greef JM., Deuter M. Syntaxonomy of Miscanthus ×giganteus (GREEF et DEU), Angew. Bot. 1993;67 87–90. - 55.
Greff J., Deuter M., Jung C., Schondelmaier J. Genetic diversity of European Miscanthus species revealed by AFLP fingerprinting. Genetic Resources and Crop Evolution 1997;44 185-195. - 56.
Greger M., Landberg T. Use of willow in phytoextraction. Int. J. Phytoremed. 1999;1 115-123. - 57.
He QB., Singh BR. Crop uptake of cadmium from phosphorus fertilizers. I. Yield and cadmium content. Water, Air, and soil Poll. 1994;74: 251 – 265. - 58.
Heaton E., Voigt T., Long SP. A quantitative review compering the yields of two candidate C-4 perennial biomass crops in relation to nitrogen, temperature and water. Biomass & Bioenergy 2004;27 21-30. - 59.
Heck RM., Farrauto RJ., Gulati S. Catalytic air pollution control. John Wilwy and Sons INC., New York 2002. - 60.
Herms U., Brümmer G. Influencing factors of heavy metal solubility and retention in soil. Z. Pflanzenern Bonenk. 1991;147 400 – 424 ( in Deutsch ). - 61.
Hodkinson TR., Chase MW., Takahashi C., Leitch IJ., Bennett MD., Renvoize SA. The use of DNA sequencing (ITS and trn L-F ), AFLP, and fluorescent in situ hybridization to study allopolyploidMiscanthus (Poaceae). American Journal of Botany 2002;89 279-286. - 62.
Hofman M., Wachowski L. Platinum and lead along the main exit routes from the city of Poznan. Environmental pollution control, Journal of Polish Sanitary Engineers Association 2010;32(3) 43-47 (in Polish). - 63.
Huang JW., Chan J., Berti WR., Cunningham SD. Phitoremediation of lead+contaminated soils Role of synthetic chelate in lead phytoextraction. Environ. Sci. Technol. 1997;31 800-805. - 64.
IUNG Report on the condition of soil and agriculturally utilized area in Poland 1980 -1990. IUNG 1992 (in Polish). - 65.
Iżewska A. Contents of heavy metals in Miscanthus sacchariflorus as an indicator of usefulness of sewage sludge and composted sludge]. Zesz. Probl. Post. Nuk Rol. 2006;512 165-171(in Polish). - 66.
Jóźwiak M. Influence of cement industry on accumulation of heavy metals in bioindicators. Ecological Chemistry and Engineering. S 2009;16(3) 323-334. - 67.
Kabata–Pendians A., Pendias H. Biochemistry trace elements. Warszawa: PWN 1999 ( in Polish). - 68.
Kabata–Pendians A., Pendias H. Trace elements in soils and plants. USA: CRC Press. Boca Raton. FL. 2001. - 69.
Kabata-Pendias A., Piotrowska M. 1987. Trace elements as a criterion for the suitability of agricultural wastes. IUNG Puławy: 1987; Seria P 39. - 70.
Kalembasa D. The amount and chemical composition of ash obtained from biomass of energy crops. Acta Agrophysica 2006;7(4) 909-914 (in Polish). - 71.
Kalembasa D., Malinowska E. Contents of cadmium, lead and nickel at different development stages of selected Mscanthus genotypes. Ecological Chemistry and Engineering. A 2009;16(4) 349-356. - 72.
Kalembasa D., Malinowska E. Chemical composition and yield of biomass in selected clones of Miscanthus grasses. Element cycle in nature. Instytut Ochrony Środowiska. Warszawa: Monograph 2005;3 315-318 (in Polish). - 73.
Kalembasa S., Godlewska A. Cao effect of the addition of sewage sludge to the content of heavy metals in different extracts. Zesz. Probl. Post. Nauk. Rol. 1998;456 193 – 196 ( in Polish). - 74.
Kleiber T. 2009. Nutritional resources of soil in the localities of monumental large-leaved linded ( Tilia platyphyllos f. aurea ) alleys. Ecological Chemistry and Engineering 2009;16(3) 277-286. - 75.
Klimowicz Z., Melke J. The content of heavy metals in soils in the vicinity of traffic roads using chosen stretches of road as examples. Roczniki Gleboznawcze 2000;T. LI(3/4) 37–46. - 76.
Knezevic M., Stankovic D., Krstic B., Sijacic Nikolic M., Vilotic D. Concentrations of heavy metals in soil and leaves of plant species Paulownia elongata S.Y.Hu and Paulownia fortunei Hemsl. African Journal of Biotechnology 2009;8(20) 422-5429, 19 October, 2009, DOI: 10.5897/AJB09.844. - 77.
Kozak M., Kotecki A., Dobrzański Z. The Miscanthus giganteus response to chemical contamination of soil. Górecki H. (red) Chemistry and biochemistry in the agricultural production and environment protection. Czech-Pol_Trade, Prague: 2006; 520-524. - 78.
Kozik E., Golcz A. Plant nutrients. Research Methods In Plant Sciences vol. 3. Soil Sickness. In Narwal S.S., Politycka B., Fengzhi Wu, Sampietro D.A. (ed.) Studium Press LLC, Huston USA 2011; 21-41. - 79.
Łabętowicz J., Rutkowska B. Factors determining the concentration of trace elements in the soil solution. Post. Nauk Roln. 2001;6 75-85 ( in Polish). - 80.
Larcher F., Vigetti A., Merlo F., Ajmone-Marsan F., Devecchi M. New methods for the recovery of post industrial areas: choosing plants for phytoremediation. ISHS Acta Horticulturae 881: II International Conference on Landscape and Urban Horticulture, Bologna, Italy: 2010. - 81.
Lawal AO., Batagarawa SM., Oyeyinka OD., Lawal MO. Estimation of heavy metals in neem tree leaves along Katsina – Dutsinma – Funtua Highway in Katsina State of Nigeria J. Appl. Sci. Environ. Manage. 2011;15(2) 327 – 330. - 82.
Liu Jia-Nv, Zhou Qi-Xing, Sun T., Ma Lena Q, Wang S. Growth responses of three ornamental plants to Cd and Cd–Pb stress and their metal accumulation characteristics. Journal of Hazardous Materials 2008;151(1) 261-267. - 83.
Majewska M., Kurek E. Microorganisms - factor that modifies the concentration of cadmium in the soil solution. Post. Nauk Roln. 2002;1 3-13 ( in Polish). - 84.
Matusiewicz H., Gała P. Optical emission spectrometry for determination of trace amounts of platinum metals (Pt, Pd, Ru, Rh, Ir) and Ca, Mg, Pb, Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd in environmental samples. Ecological Chemistry and Engineering S 2009;16(4) 497-532. - 85.
Maxted AP., Black CR., West HM. Crout NMJ., McGrath SP., Young SD. Phytoextraction of cadmium and zinc by Salix from soil historically amended with sewage sludge. Plant Soil 2007;290 157-172. - 86.
McGrath SP., Zhao FJ. Phytoextraction of metals and metalloids from contaminated soils. Current Opinion in Biotechnology 2003;14 277-282. - 87.
Mercik S., Kubik I. Chelation of heavy metals by humic acids and the effect of peat to download Zn, Pb, Cd by plants. Zesz. Prob. Post. Nauk Roln.1995;422 19-30 ( in Polish). - 88.
Mocek A., Drzymała S. The genesis, analysis, classification of soils. Poznan: Publishing company by Poznan Uniwersity of Life Sciences 2010 (in Polish). - 89.
Naidu SL., Long SP. Potential mechanisms of low-temperature tolerance of C-4 photosynthesis in Miscanthus × giganteus an in vivo analysis. Planta 2004;220 145-155. - 90.
Nedelkoska TV., Doran PM. Characteristics of heavy metal ustaje by plant species with potential for phytoremediation and phytomining. Minerals Engineering 2000;15(5) 549-561. - 91.
Negri MC., Hinchman RR., Gatliff EG. Phytoremediation using green plants to clean up contaminated soil, groundwater and wastewater. International Tropical Meeting on Nuclear and Hayardous Waste Managemant, Spectrum 96, American Nuclear Societz, Seattle, WA: 1996. - 92.
Neugschwandtner RW., Tlustos P., Komarek M., Szakova J. Phytoextraction of Pb and Cd from a contaminated Agricultural soil Rusing different EDTA application regimes: laboratory versus field scale measures of effciency. Geoderma 2008;144 446-454. - 93.
Nowak W., Wojtasik A. The content of cadmium and nickel in carrots grown on two soil types using different fertilizers. Zesz. Prob. Post. Nauk Roln. 1997;448a 269-272 (in Polish). - 94.
Ociepa A., Lach J., Gałczyński Ł. Benefits and limitations arising from the development of soils polluted by heavy metals under the crops of industrial-energetic plants. 2, 1: 231-235. Proceedings of ECOpole 2008;2(1) 231-235 (in Polish). - 95.
Orban A. Compendium of soil Clen-Up technologies and Soil Remediation Companies. ECE/CHEM/115, United Nations, New York: 1997. - 96.
Pandolfini T., Gremigni P., Gabbrielli R. Biomonitoring of soil health by plants. CAB International Wallingfford 1997; 325-347. - 97.
Patra HK., Mohanty M. Phytomining: an innovative post phytoremrdiation management technology. International Quarterly Journal of environmental sciences 2013;3 15-20. - 98.
Phytoremediation Work Team US EPA. Phutoremediation decision tree., ITRC Work Group, November 1999. - 99.
Pilon-Smits EAH. Phytoremediation. Annual review of Plant Biology 2005;56 15–39. - 100.
Pogrzeba M., Krzyżak J., Sas-Nowosielska A., Majtkowski W., Małkowski E., Kita A. A heavy metal environment al threat resulting from combustion of biofuels of plant origin. Environmental Heavy Metal Pollution and Effects on Child Mental Development. NATO Science for Peace and Security, Series C: Environmental Security 2011;1 213-225. - 101.
Porębska G., Gworek B. Evaluation of the usefulness of plants to remediation of soils contaminated with heavy metals. Ochrona Środowiska i Zasobów Naturalnych 1999;17 81-89. - 102.
Pyter R., Heaton E., Dohleman F., Voigt T., Long S. Agronomic Experiences with Miscanthus × giganteus in Illinois, USA. Jonathan R. Mielenz (ed.), Biofuels: Methods and Protocols, Methods in Molecular Biology. Humana Press, a part of Springer Science+Business Media, LLC 2009;581 41-52. - 103.
Raskin I., Kumar NPBA., Dushenkov V., Salt DE. Bioconcentration of heavy metals by plants. Curn. Opin. Biotechnol. 1994;5 285-290. - 104.
Sady W. Fertilization of field-grown vegetables. Kraków: 2000; p33 (in Polish). - 105.
Sady W., Rożek S. The effect of physical and chemical soil properties on the accumulation of cadmium in carrot. Acta Hort. 2002;571 73-75. - 106.
Sady W., Rożek S., Domagała-Świątkiewicz I. Bioaccumulation of cadmium in carrots, depending on the selected soil properties. Zesz. Nauk. AR Kraków 2000;364 171-173 ( in Polish). - 107.
Salt DE., Blaylock M., Kumar NPBA., Dushenkov V., Ensley BD., Chet I., Raskin I. Phytoremediation a novel strategy for the removal of tonic metal from the environment using plants. Biotechnology 1995;13 468-474. - 108.
Salt DE., Smith RD., Raskin I. Phytoremediation. Ann. Rev. Plant Physiol. Plant Mol. Biol. 1998;49 643-649. - 109.
Schonoor JL. Phytoremediation of soil land groundwater. GWARTAC Technology Report TE-02-01 (March 2002). - 110.
Schwartz C., Echevarria G., Morel JL. Phytoextraction of cadmium with Thlaspi caerulescens. Plant Soil 2003;249 27-35. - 111.
Schwitzguebel JP. van der Lelie D., Glass DJ., Vangonsveld J., Baker AJM. Phytoremediation: European and American trends, successes, obstacles and needs. J. Soils Sediments 2002;2 91-99. - 112.
Smal H., Misztal M., Ligęza S., Stachyra J. Effect of soil acidification on the content of selected trace elements in the soil solution in laboratory test conditions. Zesz. Prob. Post. Nauk Roln. 1998;456 565-571. - 113.
Sowa I., Wójciak-Kosior M., Kocjan R. The content of some trace elements in selected medicinal plants collected in the province of Lublin.. Acta Sci. Pol., Hortorum Cultus 2012;11(6) 15-22. - 114.
Strączyńska S., Strączyński S. Cadmium in soils derived from different source rocks of the massif ‘Śnieżnik’. Cadmium in the environment - environmental issues and methodological. Zesz. Nauk. Kom. PAN 2000;26 73 – 76 ( in Polish). - 115.
Szczepocka A. Criteria for estimating soil pollution from heavy metals. Zeszyty Naukowe Szkoły Głównej Służby Pożarniczej 2005;32 13-29 (in Polish). - 116.
Szempliński W., Dubis B. Preliminary studies on yielding and energetical efficiency of selected crops grown for biogas generation. Fragm. Agron. 2011;28(1) 77–86 (in Polish). - 117.
Tomašević M., Rajšić S., Đorđević D., Tasić M., Krstić J., Novaković V. Heavy metals accumulation in tree leaves from urban areas. Environ Chem Lett 2004;2 151–154 DOI 10.1007/s10311-004-0081-8. - 118.
Tyler G., Olson T. Concentration of 60 elements in the soil solution as related to the soli acidity. Europ. J. Soli. Scie. 2001;52 151- 165. - 119.
US EPA Technology Innovative Office. A citizen’s guide to phytoremediation. Technology fact sheet, EPA 542-F-98-011, August 1998. - 120.
Van der Ent A., Baker AJM., Reeves RD., Pollard AJ., Schat H. Hyperaccumulators of metal and metalloid trace elements: Facts and fiction. Plant Soil 2013;362 319-334. - 121.
Vangronsveld J., Herzig R., Weyens N., Boulet J., Adriaensen K., Ruttens A., Thewys T., Vassilev A., Meers E., Nehnevajova E., van der Lelie D., Mench M. Phytoremediation of contaminated soils and groundwater: lessons from the field. Environ Sci Pollut Res. 2009;16 765-794. - 122.
Vassilev A., Schwitzguebel JP., Thewys T., van der Lelie D., Vangronsveld J. The use of plants for remediation of metal contaminated soils. Scientific World J. 2004;4 9-34. - 123.
Wenzel WW., Unterbruner R., Sommer P., Sacco P. Chelate-assisted phytoextraction using canola ( Brassica napus L.) in outdoors pot and lysimeter experiments. Plant Soil 2003;249 83-96. - 124.
Zhou Qi-Xing., Wang Xiao-Fei. Ecotoxicological effects of cadmium on three ornamental plants. Chemosphere 2005;60(1) 16-21.