Assessment of the Pollution Status and Human Health Risk in Soils from an Agricultural Valley in Northwest Mexico Abstract San Juan de los Planes agricultural valley (SJPV) was studied to determine the pollution of the soils and the source of the pollutants, and revise possible ecological risks and health risks for the inhabitants due to the presence of these elements. On average, the total concentration order was As > Zn > Cu > Co > Cd. A multivariate analysis was made to identify the source of the elements and a correlation analysis to relate the concentrations and soil properties. Seven geochemical indices, two ecotoxicological, and two health risk indices were estimated. The enrichment factor (EF) showed minor or no enrichment, and the geoaccumulation index (Igeo) defined the valley as uncontaminated to moderately contaminated. The contamination factor (Cf), contamination degree (CD), and modified contamination degree (mCD) showed low or moderate contamination. The pollution load index (PLI) and comprehensive pollution index (Pn) indicated that four sites are moderately to seriously polluted with As and Cd. The potential ecological risk factor (Er) classified the area with a low potential, and the potential ecological risk index (RIEc) resulted as low ecological risk for 87% of the sites. The hazard index (HI) revealed that the contents of As and Cd can cause non-carcinogenic health problems and the carcinogenic risk index (RI) showed that As is a potential threat to the inhabitants. Given that the pollution with As and Cd is occurring in only four of the sites and that they were correlated with silt fraction, it can be said that this is related to the agrochemicals and not from the mining activities uphill.

Study on Mercury Methylation in the Amazonian Rivers in Flooded Areas for Hydroelectric Use Abstract This study aimed to estimate in laboratory the temporal production of methylmercury during the filling of reservoirs of hydropower plants and to correlate it to the ecosystem of different locations in northern Brazil: Jirau hydropower plant in the Madeira River in the state of Rondônia (white waters—under construction), Cana Brava hydropower plant in the Tocantins River in the state of Goiás (clear waters—completed), and the Negro River in the Amazon (black waters—comparative). After collecting water, soil, and sediment samples in the regions mentioned, a microcosm was created to reproduce the conditions close to those found in nature. Water/soil/Hg0/Hg2+ and water/sediment/Hg0/Hg2+ were added to glass recipients. Next, methylmercury concentration was monitored by atomic fluorescence spectrometry, total organic carbon by TOC 5000A, and physical and chemical parameters such as pH, redox potential, and dissolved oxygen, for 25 days. The results obtained allow concluding that organic matter plays an important role, providing excess methyl groups to react with inorganic Hg and form organic Hg. The Negro River, which has higher contents of organic matter in its soil, water, and sediment, presented higher potential of mercury methylation in both experiments performed, followed by rivers Madeira and Tocantins.

Copper and Zinc in Rhizosphere Soil and Toxicity Potential in White Oats ( Avena sativa ) Grown in Soil with Long-Term Pig Manure Application Abstract Successive applications of pig manure increase Cu and Zn contents in soils and may cause toxicity to plants. However, plants may have defense strategies that reduce Cu and Zn availability in rhizosphere soil. The study aimed to evaluate growth of white oats (Avena sativa) and Cu and Zn availability in rhizosphere soil subjected to long-term applications of pig slurry (PS) and pig deep litter (PL). The study was carried out with samples of a Typic Hapludalf soil from an 11-year experiment with annual fertilization of 180 kg N ha−1 as pig slurry (PS180) and pig deep litter (PL180) and a control (C) treatment. White oats were grown in pots with soil collected at 0.0–0.10 m depth. Thirty-five and 70 days after emergence (DAE), rhizosphere (RS) and bulk soil (BS) were analyzed to determine Cu and Zn availability. Plant growth, tissue Cu and Zn concentration, and content (concentration X dry weight) were measured. The application of pig manure for 11 years increased available soil Cu and Zn, as well as tissue concentration and content. Dry matter yield and plant height in PL180 were similar to those found in plants grown in the control treatment, while plants grown in PS180 had higher dry matter than in C. We found few differences in soil chemical characteristics and Cu and Zn contents between RS and BS. The high Cu concentrations in roots, especially in soil treated with PL180, show that Cu retention in the roots prevents excess Cu transport to white oat shoots.

Removal of Crystal Violet from Natural Water and Effluents Through Biosorption on Bacterial Biomass Isolated from Rhizospheric Soil Abstract It was investigated the potential of Rhodococcus erythropolis AW3 as a biosorbent for the removal of crystal violet (CV) dye from natural water and real effluents. The biosorbent was characterized by flow cytometry, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy X-ray dispersive spectroscopy (EDS), and point of zero charge (pHZPC). Batch biosorption experiments were performed to optimize different parameters involved in the biosorption process. The equilibrium was reached at 90 min at the optimum biosorbent dose of 0.50 g L−1 and pH of 9.0. Results indicated that Langmuir isotherm model was the most suitable to represent the experimental data, and the highest biosorption capacity was 289.8 mg g−1. Kinetic data were well fitted with the pseudo-second-order model. The thermodynamic study showed that the process was favorable, exothermic, and associated with an increase of entropy. Finally, it was demonstrated that the biosorption process using Rhodococcus erythropolis AW3 could be successfully applied to remove CV from natural water and effluents derived from clinical and industrial activities.

Gold Mine Impact on Soil Quality, Youga, Southern Burkina Faso, West Africa Abstract The present study aims to assess the impact of a gold mine located in the southeastern part of Burkina Faso on local soil quality. This information is needed in order to determine any health hazards and potential remediation strategies as the mining site is expected to be turned over to the local community after the closure of the mine. For the purpose, total minor and trace elements analysis as well as a sequential extraction were performed and results were interpreted using different methodologies: enrichment factor (EF), geoaccumulation index (Igeo) computed using two separate background samples, and comparison to selected national standard. The soil analysis revealed a moderate to significant soil EF and Igeo with hotspots located closer to the ore processing plant and on the east side of the site, with a maximum arsenic concentration of 286.55 ± 12.50 mg/kg. Sequential extraction revealed, however, that less than 2% of the arsenic is found in the exchangeable part. Cobalt and zinc are more distributed in the different fractions than arsenic. Geogenic and anthropogenic contributions were revealed by the study. Graphical Abstract .

Short-Term Effects of Olive Mill Wastewater Land Spreading on Soil Physical and Hydraulic Properties Abstract In this study, we investigated the effect of olive mill wastewater on selected soil physical and hydraulic properties. Olive mill wastewater was added to each column every week at different loading rates (0, 50, 100, and 200 m3 ha−1). Physicochemical and hydraulic properties were determined for surface (0–8 cm) and subsurface layers (8–16 and 16–24 cm). The highest loading rate (200 m3 ha−1) showed an increase in aggregate stability from 18% (control) to 31 and to 38%, penetration resistance from 1.8 kg cm−2 (control) to 3.5 and to 4.5 kg cm−2, hydraulic conductivity from 43 cm day−1 (control) to 15.3 and 3.3 cm day−1, and water repellency from < 5 s (control) to 120 and 261 s in the first and second months for the surface layer, respectively. The opposite was observed for the infiltration rate, where it decreased from 39.01 mm h−1 (control) to 1.26 and 0.42 mm h−1 for the first and second months, respectively. This study showed that application of olive mill wastewater deteriorated the physical and hydraulic properties of soil proportional to loading rates and more specifically at the surface layer.

Effects of Calcium Phosphates on the (Im)Mobilization of Metals and Nutrients, on the Biological Activity and on the Plant Health from Multi-contaminated Urban Soils Abstract Two smelters in the North of France emitted potentially toxic metals for more than a century and today, the resulting contamination represents a risk to human health and affects also the biodiversity. To limit health risks and to improve the soil quality, a study using calcium phosphates (monocalcium phosphate, dicalcium phosphate and a mixture of both salts) and Lolium perenne L was conducted. Through this preliminary investigation, we will try to shed some light about (i) the effects of a sustainable amount of calcium phosphates on the agronomic, biological (microbial and fungi communities) and physiological parameters (chlorophyll a and b, antocyanins, carotenoids) as well as the phytoavailability of potentially toxic metals and nutrients in time, and (ii) the potential use of contaminated biomass from ryegrass as a source of new valorisation ways instead of using it as contaminated compost by gardeners. Although slight variations in pH and significant increases of assimilable phosphorus after adding calcium phosphates were registered, the physiology of plants and the biological parameters were statistically unchanged. The germination of the ryegrass seeds was favoured with calcium phosphates regardless the contamination level of the studied soils. No clear effects of calcium phosphates on the microbial and fungi communities were detected. In contrast, results indicated relationships between the physicochemical parameters of soils, their contamination level and the composition of fungal communities. Indeed, for one of the soils studied, calcium could limit the transport of nutrients, causing an increase in fungi to promote again the transfer of nutrients. Surprisingly, the phytoavailability of Pb increased in the most contaminated soil after adding dicalcium phosphate and the mixture of phosphates whereas a slight decrease was highlighted for Cd and Mn. Although minor changes in the phytoavailability of potentially toxic metals were obtained using calcium phosphates, the ability of ryegrass to accumulate Zn and Ca (up to 600 and 20,000 mg kg−1, respectively) make possible to qualify this plant as a bio ‘ore’ resource.

Ecophysiological Responses of a Willow Cultivar ( Salix miyabeana ‘SX67’) Irrigated with Treated Wood Leachate Abstract As wood preservatives leach from exposed treated wood, they contaminate soil and water, creating an environmental problem that needs to be addressed. Treating this contamination is particularly challenging since it includes mixed compounds, such as heavy metals and trace elements, as well as xenobiotic organic pollutants like polychlorinated dibenzo-dioxin/furan congeners (PCDD/Fs) that are very toxic and are under very strict discharge regulations. Cultivating fast-growing willow shrubs, either in soil or in treatment wetlands, offers a flexible and inexpensive treatment option. The main objective of this study was to evaluate the tolerance of a frequently used willow cultivar (Salix miyabeana ‘SX67’) to irrigation with leachate contaminated with pentachlorophenol (PCP) and chromated chromium arsenate (CCA), two important wood preservatives. We designed a mesocosms experiment with willow grown in three different substrates and irrigated over 12 weeks with three different leachate concentrations. Willow proved to be tolerant to irrigation with the raw leachate, with only leaf area decreasing with increasing leachate concentration. However, the type of growing substrate influenced willow ecophysiological responses and overall performance, and seemed to affect contaminant dynamics in the plant-soil system. All contaminants accumulated in willow roots, and Cu and PCDD/Fs were also translocated to aerial parts. Overall, this study suggests that Salix miyabeana ‘SX67’ could be a good candidate for treating water or soil contaminated with wood preservatives.

Bioremediation vs. Nanoremediation: Degradation of Polychlorinated Biphenyls (PCBS) Using Integrated Remediation Approaches Abstract Integration of physicochemical and biological approach represented by sequential application of nanoscale zerovalent iron (nZVI dispersion) and bioaugmentation by bacterial strains isolated from the PCB-contaminated site seems to be an innovative way to remove the PCB contamination, which still persists in the environment. First, nanoremediation of the minimal mineral medium artificially contaminated with Delor 103 and of historically contaminated sediment was performed in 70% and 46% PCB removal efficiency. Integrated remediation was carried out as bionanoremediation initiated by addition of bacterial strains and finished by addition of nZVI dispersion Nanofer 25S. Nanobioremediation initiated by nZVI and followed by the addition of bacterial strains A. xylosoxidans, S. maltophilia, and O. anthropi was more effective and led to the increase of PCB degradation to 75%, 85%, and 99%. The bacterial mixed culture (BMC) consisted of 7 bacterial strains with PCB-degrading activity was used for integrated remediation, as well. By the nanobioremediation of the historically contaminated sediment, 78% degradation of PCBs was achieved by combining the nZVI and BMC, with the addition of non-ionic surfactant Triton X-100. The sediment was periodically reinoculated with fresh nZVI dispersion and BMC inoculum. The possible toxic effects of nZVI in concentration used in integrated remediation 2 g l−1 were evaluated on bacterial strains used for integrated remediation. The cell concentrations of the bacterial strains A. xylosoxidans, S. maltophilia, and O. anthropi, expressed as CFU ml−1, decreased in the presence of nZVI by 75%, 52%, and 61%, respectively.

Comparison of the Contaminants in the Wastewater Produced in the Ex Situ Underground Ortho- and Meta-Lignite Gasification Abstract This work comprises results of the laboratory tests on formation and potential release of contaminants from underground gasification of lignites. Four large scale and multi-day trials were carried out using ex-situ gasification facilities. Two different kinds of lignite were tested, i.e. Velenje lignite (Slovenia) and Oltenia lignite (Romania). Gasification tests were conducted in the artificial coal seams under two distinct pressure regimes—atmospheric and high pressure regime (35 bar and 10 bar for the Velenje and Oltenia samples respectively). The UCG wastewater samples were periodically collected from the gas purification module to measure the rate of the wastewater and contaminants production at each phase of the experiment and to assess the effect of gasification pressure and lignite physicochemical properties. The group of target contaminants included: phenols, aromatic hydrocarbons, and some non-specific water parameters. The effect of gasification pressure was confirmed, especially for BTEX and phenols and significant drops in the contents of these compounds were observed at elevated pressures. The effect of pressure was more pronounced for the geologically older coal (Velenje), i.e. drop in the average concentrations from 1994 μg/l (atmospheric) to 804 μg/l (35 bar) and from 733 mg/l (atmospheric) to 17 mg/l (35 bar) for BTEX and total phenols, respectively. The differences in the macromolecular structure and ash content of the both coals were found to be the main reason behind the differences in the contents of organic and inorganic species respectively. The study also shown that composition of UCG wastewaters significantly varied over the time of the particular experiments, which reflected changes in the gasification thermodynamic conditions and development of oxidation and pyrolysis zones. During the atmospheric gasification experiments, the values of BTEX for the Velenje lignite dropped from 3434 μg/l to 1364 μg/l and for the Oltenia lignite from 1833 μg/l to 978 μg/l. A similar downward trend in the concentrations of BTEX was observed for the pressurized experiments. For the Velenje trial a drop from 1111.6 μg/l to 211.2 μg/l and for the Oltenia - from 1695 μg/l to 688 μg/l was observed. Concentrations of phenolic compounds during the atmospheric gasification experiments varied significantly during both atmospheric trials and no significant trends were noticed.