Chapters authored
Chromium Species and 3D-Fluorescence Spectroscopy in a Soil Irrigated with Industrial Wastewater
Irrigation of agricultural land with wastewater is beneficial because it incorporates organic matter into the soil, as well as organic ions (such as nitrates, sulfates, and phosphates). However, long-term application causes negative effects such as the accumulation of heavy metals. The wastewater used in the agricultural soils, also incorporates organic refractory compounds, which affect the microbial population and fertility. This chapter aimed to identify the chromium species present in agricultural soil irrigated with wastewater (679.6 mg/L for total chromium and 559.5 mg/L for Cr VI), and characterize the dissolved organic matter in the saturated solution soil. In the soil-saturated solutions (pH 6), the most stable Cr (III) species was Cr2O3. These species precipitate and accumulate in the soil in combination with natural organic matter. The highest accumulation of chromium occurred in the first 10 cm of the soil column. The 3D fluorescence analysis exposes the presence of aromatic proteins, microbiological degradation products, and humic and fulvic acids in the soil profile. The excitation-emission matrix (EEM) showed that Cr (VI) species were complexed with humic acids. In the X-ray diffraction analysis, the species Cr2O5, Cr5O12, CrO2, and Cr7C3 were found at depth with the greatest amount of organic matter.
Part of the book: Agricultural Waste and Residues
Mobility of Heavy Metals in Aquatic Environments Impacted by Ancient Mining-Waste
The mobility of heavy metals in aquatic environments, impacted by discharges from mining waste, is one of the major processes causing metal pollution mainly by arsenic (As), cadmium (Cd), lead (Pb), zinc (Zn) and iron (Fe), which could be risky for biota and human health. The heavy metals contained in mining waste constituted by large amounts of sulfides can reach the aquatic compartments by acid mine drainage and runoff and eventually become deposited in sediments and associated with colloidal material, being this one of the main reservoirs and ways of transport. However, the mobility of heavy metal is influenced by their specific chemical properties and undergo several physicochemical phenomena as sorption, oxidation–reduction, hydrolysis and this can be influenced by water flow, the size and composition of geological material. Hence, this work aims to review the processes and mechanism involved in the fate and transport of heavy metals from mining-waste to aquatic compartments and the methods used for identification of the specific chemical species associated with their mobility and ecological risk.
Part of the book: Water Quality