The concentration distribution and toxicological assessment of eight heavy metals including lead (Pb), cadmium (Cd), copper (Cu), chromium (Cr), nickel (Ni), mercury (Hg), arsenic (As), and zinc (Zn) in agricultural soils from Kenya, Eastern Africa, were investigated in this study. The results showed mean concentrations of eight heavy metals of Zn, Pb, Cr, Cu, As, Ni, Hg, and Cd in agricultural soils as 247.39, 26.87, 59.69, 88.59, 8.93, 12.56, 8.06, and 0.42 mg kg⁻¹, respectively. These mean values of eight heavy metals were close to the toxicity threshold limit of USEPA standard values of agricultural soils, indicating potential toxicological risk to the food chain. Pollution index values revealed that eight heavy metals severely decreased in the order Hg > Cd > As > Cu > Pb > Zn > Ni > Cr and the mean value of the overall pollution index of Hg and Cd was 20.31, indicating severe agriculture ecological risk. Potential pollution sources of eight heavy metals in agricultural soils were mainly from anthropogenic activities and natural dissolution. The intensification of human agricultural activities, the growing industrialization, and the rapid urbanization largely influenced the concentration levels of heavy metals in Kenya, Eastern Africa. Moreover, the lack of agricultural normalization management and poor enforcement of environmental laws and regulations further intensified the widespread pollution of agricultural soils in Kenya.

The degradation of water resources by diffuse pollution, mainly due to nitrate and pesticides, is an important matter for public health. Restoration of the quality of natural water catchments by focusing on their catchment areas is therefore a national priority in France. To consider catchment areas as homogeneous and to expend an equal effort on the entire area inevitably leads to a waste of time and money, and restorative actions may not be as efficient as intended. The variability of the pedological and geological properties of the area is actually an opportunity to invest effort on smaller areas, simply because every action is not equally efficient on every kind of pedological or geological surface. Using this approach, it is possible to invest in a few selected zones that will be efficient in terms of environmental results. The contributive hydraulic areas (CHA) concept is different from that of the catchment area. Because the transport of most of the mobile and persistent pollutants is primarily driven by water circulation, the concept of the CHA is based on the water pathway from the surface of the soil in the catchment area to the well. The method uses a three-dimensional hydrogeological model of surface and groundwater integrated with a geographic information system called Watermodel. The model calculates the contribution (m³/h or %) of each point of the soil to the total flow pumped in a well. Application of this model, partially funded by the Seine Normandy Basin Agency, to the catchment of the Dormelles Well in the Cretaceous chalk aquifer in the Orvanne valley, France (catchment area of 23,000 ha at Dormelles, county 77), shows that 95 % of the water pumped at the Dormelles Well comes from only 26 % of the total surface area of the catchment. Consequently, an action plan to protect the water resource will be targeted at the 93 farmers operating in this source area rather than the total number of farmers (250) across the entire 23,000 ha. Another model, developed from Epiclès© software, permits the calculation of the under-root nitrate concentrations for each field based on soil type, climate, and farming practices. When the Watermodel and Epiclès© are coupled, nitrate transfers from the soil to the catchment and the river can be modeled. In this study, the initial pollution due to the actual farming practices was simulated and we were also able to estimate the efficiency of the agronomic action plan by testing several scenarios and calculating the time needed to reach the target nitrate concentration in the well.

The behavior of aliphatic hydrocarbons during co-composting of sewage sludge activated with palm tree waste was studied for 6 months using Py-GC/MS. The main aliphatic compounds represented as doublet alkenes/alkanes can be classified into three groups. The first group consists of 11 alkenes (undecene, tridecene, pentadecene, hexadecene, heptadecene, octadecene, nonadecene, eicosene, uncosene, docosene, tricosene) and 15 alkanes (heptane, octane, nonane, decane, undecane, dodecane, tetradecane, pentadecane, heptadecane, octadecane, nonadecane, eicosane, uncosane, docosane, and tricosane), which remain stable during the co-composting process. The stability of these compounds is related to their recalcitrance behavior. The second group consists of five alkenes (heptene, octene, nonene, decene, dodecene) and tridecane as a single alkane that decreases during co-composting. The decrease in these compounds is the combined result of their metabolism and their conversion into other compounds. The third group is constituted with tetradecene and hexadecane that increase during composting, which could be explained by accumulation of these compounds, which are released by the partial breakdown of the substrate. As a result, these molecules are incorporated or adsorbed in the structure of humic substances.

This is the first study demonstrating genotoxic effects and whole transcriptome analysis on community health agents (CHAs) occupationally exposed to pesticides in Central Brazil. For the transcriptome analysis, we found some genes related to Alzheimer’s disease (LRP1), an insulin-like growth factor receptor (IGF2R), immunity genes (IGL family and IGJ), two genes related to inflammatory reaction (CXCL5 and CCL3), one gene related to maintenance of cellular morphology (NHS), one gene considered to be a strong apoptosis inductor (LGALS14), and several transcripts of the neuroblastoma breakpoint family (NBPF). Related to comet assay, we demonstrated a significant increase in DNA damage, measured by the olive tail moment (OTM), in the exposed group compared to the control group. Moreover, we also observed a statistically significant difference in OTM values depending on GSTM1 genotypes. Therefore, Brazilian epidemiological surveillance, an organization responsible for the assessment and management of health risks associated to pesticide exposure to CHA, needs to be more proactive and considers the implications of pesticide exposure for CHA procedures and processes.

Organophosphates (OPs) like dimethoate (DMT), are pesticides used worldwide, which can affect both animals and human. Whereas their toxicity is due to acetylcholinesterase inhibition, their secondary toxic effects have been related to free oxygen radical biosynthesis. The present study was designed to investigate the reprotoxic effects of DMT and the protective role of N-acetylcysteine (NAC) in male rat. DMT (20 mg/ kg/body weight) was administered daily to rats via gavage in corn oil and NAC (2 g/l) was added to drinking water for 30 days. Rats were sacrificed on the 30th day, 2 h after the last administration. Markers of testis injury (steroidogenesis impairment) and oxidative stress (lipid peroxidation, reduced glutathione, and antioxidant status) were assessed. In DMT-exposed rats, the serum level of testosterone was decreased. Further, a significant increase in lipid peroxidation level and a significant decrease in the activities of antioxidant enzymes were observed in the testis of rats during DMT intoxication. Real-time PCR (RT-PCR) analysis demonstrated a decrease in messenger RNA (mRNA) levels for testicular steroidogenic acute regulatory StAR protein, cytochrome P450scc, 3β-hydroxysteroid dehydrogenase (3β-HSD), and 17β hydroxysteroid dehydrogenase (17β-HSD) in the testis after DMT exposure. No significant changes in the oxidative stress status and selected reproductive variables were observed on CTN group, whereas NAC restored the oxidative stress and the steroidogenesis on NAC group. Dimethoate induces reprotoxicity and oxidative stress. N-acetylcysteine showed therapeutic recovery effects against dimethoate toxicity.

The present study was carried out to determine the hydrogeochemical processes and the impact of tanning industries on groundwater in Ambur, Vellore district, Tamil Nadu, India. Thirty groundwater samples were collected during pre monsoon (July 2015) and post monsoon (January 2016) from the open and shallow wells around this region and were analyzed for major ions and chromium. The major ion concentration follows the order of Na⁺ > Ca²⁺ > Mg²⁺ > K⁺ (cations) and Cl⁻ > HCO₃ ⁻ > SO₄ ²⁻ > NO₃ ⁻ (anions) for both seasons. The high concentrations of Na⁺, Cl⁻, and Cr around the tannery regions indicate the impact of effluent discharged from tannery units. In general, the groundwater of this study area is of Na⁺-Cl⁻ type, which is due to the mixing of tannery effluent and cation exchange process. Ionic ratio indicates that the silicate weathering influences the groundwater chemistry. The permissible limit of chromium in the groundwater exceeds in over 50 % of the sampling wells. The factor analysis reveals that the dominant source for ionic contents is due to tannery effluents and cation exchange processes. To overcome this situation, it is essential to improve the performance of the effluent treatment plants so as to remove the salinity of wastewater and to plan for rainfall recharge structures for improving the groundwater recharge.

In the present study, an attempt has been made to grow microalgae Scenedesmus quadricauda, Chlorella vulgaris and Botryococcus braunii in mixotropic cultivation mode using two different substrates, i.e. sewage and glucose as organic carbon sources along with flue gas inputs as inorganic carbon source. The experiments were carried out in 500 ml flasks with sewage and glucose-enriched media along with flue gas inputs. The composition of the flue gas was 7 % CO₂, 210 ppm of NO ₓ and 120 ppm of SO ₓ . The results showed that S. quadricauda grown in glucose-enriched medium yielded higher biomass, lipid and fatty acid methyl esters (FAME) (biodiesel) yields of 2.6, 0.63 and 0.3 g/L, respectively. Whereas with sewage, the biomass, lipid and FAME yields of S. quadricauda were 1.9, 0.46, and 0.21 g/L, respectively. The other two species showed closer results as well. The glucose utilization was measured in terms of Chemical Oxygen Demand (COD) reduction, which was up to 93.75 % by S. quadricauda in the glucose-flue gas medium. In the sewage-flue gas medium, the COD removal was achieved up to 92 % by S. quadricauda. The other nutrients and pollutants from the sewage were removed up to 75 % on an average by the same. Concerning the flue gas treatment studies, S. quadricauda could remove CO₂ up to 85 % from the flue gas when grown in glucose medium and 81 % when grown in sewage. The SO ₓ and NO ₓ concentrations were reduced up to 50 and 62 %, respectively, by S. quadricauda in glucose-flue gas medium. Whereas, in the sewage-flue gas medium, the SO ₓ and NO ₓ concentrations were reduced up to 45 and 50 %, respectively, by the same. The other two species were equally efficient however with little less significant yields and removal percentages. This study laid emphasis on comparing the feasibility in utilization of readily available carbon sources like glucose and inexpensive leftover carbon sources like sewage by microalgae to generate energy coupled with economical remediation of waste. Therefore on an industrial scale, the sewage is more preferable. Because the results obtained in the laboratory demonstrated both sewage and glucose-enriched nutrient medium are equally efficient for algae cultivation with just a slight difference. Essentially, the sewage is cost effective and easily available in large quantities compared to glucose.

Measurements of major ions, trace elements, water-stable isotopes, and geophysical soundings were made to examine the interaction between Urmia Aquifer (UA) and Urmia Lake (UL), northwest Iran. The poor correlation between sampling depth and Cl⁻ concentrations indicated that the position of freshwater-saltwater interface is not uniformly distributed in the study area, and this was attributed to aquifer heterogeneities. The targeted coastal wells showed B/Cl and Br/Cl molar ratios in the range of 0.0022–2.43 and 0.00032–0.28, respectively. The base-exchange index (BEI) and saturation index (SI) calculations showed that the salinization process followed by cation-exchange reactions mainly controls changes in the chemical composition of groundwater. All groundwater samples are depleted with respect to δ¹⁸O (−11.71 to −9.4 ‰) and δD (−66.26 to −48.41 ‰). The δ¹⁸O and δD isotope ratios for surface and groundwater had a similar range and showed high deuterium excess (d-excess) (21.11 to 31.16 ‰). The high d-excess in water samples is because of incoming vapors from the UL mixed with an evaporated moisture flux from the Urmia mainland and incoming vapors from the west (i.e., Mediterranean Sea). Some saline samples with low B/Cl and Br/Cl ratios had depleted δ¹⁸O and δD. In this case, due to freshwater flushing, the drilled wells in the coastal playas and salty sediments could have more depleted isotopes, more Cl⁻, and consequently smaller B/Cl and Br/Cl ratios. Moreover, the results of hydrochemical facies evolution (HFE) diagram showed that because of the existence fine-grained sediments saturated with high density saltwater in the coastal areas that act as a natural barrier, increasing the groundwater exploitation leads to movement of freshwaters from recharge zones in the western mountains not saltwater from UL. The highly permeable sediments at the junction of the rivers to the lake are characterized by low hydraulic gradient and high hydraulic conductivity. These properties enhance the salinization of groundwater observed in the study area. The main factors influencing the salinity are base-exchange reactions, invasion of highly diluted saltwater, dissolution of salty pans, and water chemistry evolution along flow paths.

In this study, we have evaluated the efficacy of propidium monoazide quantitative polymerase chain reaction (PMA-qPCR) to differentiate between viable and non-viable Ancylostoma caninum ova. The newly developed method was validated using raw wastewater seeded with known numbers of A. caninum ova. Results of this study confirmed that PMA-qPCR has resulted in average of 88 % reduction (P < 0.05) in gene copy numbers for 50 % viable +50 % non-viable when compared with 100 % viable ova. A reduction of 100 % in gene copies was observed for 100 % non-viable ova when compared with 100 % viable ova. Similar reductions (79–80 %) in gene copies were observed for A. caninum ova-seeded raw wastewater samples (n = 18) collected from wastewater treatment plants (WWTPs) A and B. The newly developed PMA-qPCR method was applied to determine the viable ova of different helminths (A. caninum, A. duodenale, Necator americanus and Ascaris lumbricoides) in raw wastewater, human fecal and soil samples. None of the unseeded wastewater samples were positive for the above-mentioned helminths. N. americanus and A. lumbricoides ova were found in unseeded human fecal and soil samples. For the unseeded human fecal samples (1 g), an average gene copy concentration obtained from qPCR and PMA-qPCR was found to be similar (6.8 × 10⁵ ± 6.4 × 10⁵ and 6.3 × 10⁵ ± 4.7 × 10⁵) indicating the presence of viable N. americanus ova. Among the 24 unseeded soil samples tested, only one was positive for A. lumbricoides. The mean gene copy concentration in the positively identified soil sample was 1.0 × 10⁵ ± 1.5 × 10⁴ (determined by qPCR) compared to 4.9 × 10⁴ ± 3.7 × 10³ (determined by PMA-qPCR). The newly developed PMA-qPCR methods were able to detect viable helminth ova from wastewater and soil samples and could be adapted for health risk assessment.

Soil organic carbon (SOC) is one of the most important soil properties affecting many other soil and environmental properties and processes. In order to understand and manage SOC effectively, it is important to identify the scale-specific main factors affecting SOC distributions, which in this study occurred in a watershed on the Loess Plateau. Two transects were selected that passed along the upper slopes on each side of the main gully of the Liudaogou watershed. Transect 1 (3411-m length) had 27 sampling sites at 131-m intervals; transect 2 (3597 m length) had 30 sampling sites at 124-m intervals. The two transects were chosen in order to compare landscape patterns of differing complexity that were in close proximity, which reduced the effects of factors that would be caused by different locations. The landscape of transect 1 was more complex due to the greater diversity in cultivation. Multivariate empirical mode decomposition (MEMD) decomposed the total variation in SOC and five selected environmental factors into four intrinsic mode functions (IMFs) and a residual according to the scale of occurrence. Scale-specific correlation analysis was used to identify significant relationships between SOC and the environmental factors. The dominant scales were those that were the largest contributors to the total SOC variance; for transect 1, this was the IMF 1 (scale of 403 m), whereas for transect 2, it was the medium scale of the IMF 2 (scale of 688 m). For both transects, vegetation properties (vegetation cover and aboveground biomass) were the main factors affecting SOC distributions at their respective dominant scales. At each scale, the main effective factors could be identified although at the larger scales, their contributions to the overall variance were almost negligible. The distributions of SOC and the factors affecting it were found to be scale dependent. The results of this study highlighted the suitability of the MEMD method in revealing the main scale-specific factors that affect SOC distributions, which is necessary in understanding and managing this important soil property.