Chelates, used to increase the uptake of heavy metals in phytoremediation, can also increase the mobility of metals. If plants fail to uptake or stabilize all the mobilized metals, then subsurface soil or groundwater can be contaminated. Therefore, the type and concentration of chelate used and proper site management are important for chelate-aided phytoremediation. In this study, we evaluated potential metal leaching from the soil after applying three different chelates. The readily soluble and exchangeable metal (RSEM) and plant-available metal (PAM) of Pb, Zn, Cu, Cd, and Ni in soil amended with ethylene diamine tetra acetic acid (EDTA), ethylene diamine disuccinate (EDDS), or humic acid (HA) were analyzed, and the potential leaching factor (PLF) of the heavy metals was estimated. Results showed that the effects of chelates and their concentration on RSEM and PAM of heavy metal in soil were different. The addition of EDTA increased the CRSEM and CPAM of all heavy metals, although its effects varied with the concentration added. EDDS application increased CRSEM and CPAM of Cu, Ni, and Zn, but EDDS was more effective than EDTA for Cu and Ni. HA did not show a significant impact due to the short duration of the experiment. In most cases with chelates effects, the increase of RSEM was greater than PAM, and the potential of metal leaching increased. Therefore, application of chelates for remediation of metal-contaminated soil should consider not only the capacity of metal uptake in plants but also the potential metal leaching from the system. Additionally, this process should be accompanied by proper water management to minimize leachate in chelate-aided phytoremediation applications.

Urban air pollution is one of the most important environmental problems. Lichens are good bioindicators in air pollution studies because of their dependence on the atmospheric deposition for nutrition. The present study focused on the effects of urbanization on the composition of atmospheric deposition inputs and physiological parameters of transplanted epiphytic lichen Ramalina farinacea. The status of lichens responded to urban pollutants related to vehicle and industrial activity (NO₃⁻, Ca²⁺, Mg²⁺, NO₂, PM₁₀). The content of chlorophyll and FV/FM were positively related to the amount of precipitation (mm) and the Normalized Difference Vegetation Index (NDVI). The increase in lipid peroxidation and electrolyte conductivity, indicating damage to the cell membrane, was found in lichens transplanted to the urban environment. The high variability in electrolyte conductivity indicated that cell membrane injuries were characteristics of the investigated study area.

Effects of surface modification by carboxyl group on Pb²⁺ adsorption performances and stability of peanut shell and its extracts (cellulose, lignin, and hemicellulose) were investigated. Stability of the biosorbents was measured by determining organic compound release amount (TOC). Results showed that adsorption capacity of peanut shell and the extract was poor and stability of them was not good enough. Amount of organic compound released from the unmodified sorbents followed the order: cellulose > lignin > peanut shell > hemicellulose. Hemicellulose was the main organic compound release resource for the raw peanut shell. Due to the poor stability of the raw materials, peanut and its extract could not be used directly in the practical waste water treatment. After modification, adsorption capacity of peanut shell, cellulose, lignin, and hemicellulose increased by 4- to 6-folds. Stability of the modified sorbents also increased significantly, and TOC determined for the modified peanut shell, cellulose, and hemicellulose was lower than 4.0 mg L⁻¹ in the optimum pH range from 4.0 to 6.0 even using for 30 days, which was lower than the drinking water standard in China. Modified peanut shell and its extract except for lignin could be used safely in pH ranged from 4.0 to 6.0. Surface modification could improve the adsorption performances and stability of the biosorbents.

Hydrothermal carbonization (HTC) is an energy-efficient thermochemical process for converting wet waste products into value added materials for water treatment. Understanding how HTC influences the physicochemical properties of the resultant materials is critical in optimizing the process for water treatment, where surface functionality and surface area play a major role. In this study, we have examined the HTC of four wet waste streams, sewage sludge, biosludge, fiber sludge, and horse manure at three different temperatures (180 °C, 220 °C, and 260 °C). The physicochemical properties of these materials were examined via FTIR, SEM and BET with their adsorption capacity were assessed using methylene blue. The yield of solid material after hydrothermal carbonization (hydrochar) decreased with increasing temperature for all samples, with the largest impact on horse manure and fiber sludge. These materials also lost the highest degree of oxygen, while HTC had minimal impact on biosludge and sewage sludge. The differences here were due to the varying compositions of each waste material, FTIR identified resonances related to cellulose in horse manure and fiber sludge, which were not detected in biosludge and sewage sludge. Adsorption capacities varied between 9.0 and 68 mg g⁻¹ with biosludge HTC at 220 °C adsorbing the highest amount. Adsorption also dropped drastically at the highest temperature (260 °C), indicating a correlation between adsorption capacity and HTC conditions. This was attributed to the loss of oxygen functional groups, which can contribute to adsorption. These results suggest that adsorption properties can be tailored both by selection of HTC temperature and feedstock.

Roxarsone (ROX) and copper (Cu) are growth promoters in livestock to promote growth and prevent disease. These chemicals and their metabolites are released to the soil through manure application and have a potential adverse effect on soil-dwelling organisms. The objective of this study was to investigate the combined subacute effect of ROX exposure (0, 80, 240, 720 mg kg⁻¹) and Cu exposure (0, 80, 160 mg kg⁻¹) in earthworms (Eisenia fetida). Growth, reproduction, spermatogenesis under light microscope, and heavy metal residue were investigated during 56-day exposure period. Results showed that Cu exposure of 80 or 160 mg kg⁻¹ alleviated the effect of ROX on cocoon production or hatching. The cocoon number exhibited an increase (P < 0.05) at 80 mg kg⁻¹ ROX on day 28, compared with the 0 mg kg⁻¹ ROX, in the presence of 80 mg kg⁻¹ Cu, whereas there was no effect (P > 0.05) in the presence of 160 mg kg⁻¹ Cu. The hatching success at 80 or 240 mg kg⁻¹ ROX exhibited a decrease (P < 0.05) on day 28, in the absence of Cu, whereas no effect (P > 0.05) was observed in the presence of 80 or 160 mg kg⁻¹ Cu. The other reproductive parameters (cocoon weight, juvenile number, and biomass) demonstrated a decrease (P < 0.05) only at 720 mg kg⁻¹ ROX in the presence or absence of Cu. However, with increasing exposure time, the above reproductive parameters were not affected (P > 0.05) in all groups on day 56. On the other hand, sperm deformity (%) increased (P < 0.05) at 240 or 720 mg kg⁻¹ ROX on day 28, in the presence or absence of Cu; however, the microstructural alteration in seminal vesicles occurred only at 720 mg kg⁻¹ ROX, exhibiting disordered distribution and decreased mature sperm bundles. In addition, ROX or Cu residues in earthworms demonstrated an increase with increasing ROX or Cu exposure concentration. Our present results may provide important insight on combined toxicity of chemicals in soils.

Fipronil is an insecticide commonly used in agriculture. We report here on the sublethal and sub-chronic effects of fipronil on non-target topmouth gudgeon (Pseudorasbora parva) at environmentally relevant levels. The results showed that fipronil did not cause significant changes in brain acetylcholinesterase activities, glutathione S-transferase (GST) activities in the intestine, and GST, glutamic pyruvic transaminase (GPT), and glutamic oxaloacetic transaminase (GOT) activities in the liver tissues at environmentally relevant levels for 96-h exposure. In the further test for a 12-day exposure, dose-dependent responses of the serum GPT and GOT activities were observed in all treated groups with sublethal concentrations of fipronil. Furthermore, fipronil could reduce the liver mitochondrial membrane fluidity of P. parva, especially with high concentration of fipronil at high temperature. The results suggest that serum GPT and GOT in P. parva might be useful biomarkers for effects of fipronil exposure at environmentally relevant level, and reducing fluidity of liver mitochondrial membrane may be one toxic mechanism of fipronil.

Due to the increase of cadmium (Cd)-contaminated land area worldwide, effective measures should be taken to minimize the Cd bioavailability in crops. A study was performed to explore the effectiveness of biochar pyrolyzed from rice straw at 400 °C alone or combined with AM fungi (Funneliformis mosseae) on the corn growth and Cd uptake in corn in Cd-contaminated soil with different levels of phosphorus supplies. The results showed that biochar significantly reduced 66% and 38% of Cd uptake in shoot and root respectively (P < 0.001) attributed to the increase of soil pH and dissolved organic matter. In contrast, AM fungi inoculation of corn plants had little effect on Cd bioavailability due to the AM was suppressed by the highly contaminated acid soil (31.76 mg/kg), and had neither synergistic effect with biochar on decreasing the Cd bioavailability with high or low phosphorus supplies. This study demonstrated that biochar application could be a promising method to immobilize Cd in the contaminated soil to ensure the safety of agro-product while high Cd-contaminated soil would suppress the growth of mycorrhizae, so this remains an open question to be further studied.

This work is a first part of the study in development on the mapping of soiling losses in the region of Rabat-Sale-Kenitra in Morocco. To perform the work, two holders of glass samples have been constructed and installed in two different sites of Sale City for three successive periods (from April to June 2019). At the end of each period, the transmittance losses of the glass samples as well as the mass of deposited soils are systematically measured. SEM (scanning electronic microscopy) analyses are also performed for more investigation and deep understanding. The obtained results show that the relationship between soil mass density and glass transmittance loss is not always linear as could be expected. They also show that soiling losses are strongly depending on the environment and nature of the surrounding installation spaces. The SEM analysis results of the 1st period and the inclined surfaces have shown that particles are greater in the range of 2–11 μm and the majority tends to have a regular shape in the two sites. Nevertheless, the frequencies are different. From this study, it can be concluded that it is highly recommended characterizing the site where soiling measurements are conducted not only by its location/city but also by its environment characteristics.

We propose to identify the influence of organic acids as well as total proteins in the accumulation and translocation of heavy metals from the rhizosphere to the plant organs of cultivated yellow melon var. Natal throughout the vegetative cycle. Physical and chemical attributes and the concentration of Cu, Zn, and Pb were determined in soil samples. Samples of plant tissue and rhizosphere at 0, 15, 30, 45, and 60 days after transplantation were collected and determined the concentration of heavy metals along with the content of total protein in the tissues and organic acids in the rhizosphere. Subsequently, the transfer factor (TF) and bioconcentration factor (BF) were calculated. Oxalic and citric acids and heavy metal contents were slightly higher in the rhizosphere than those found in the soil. The organic acids and total protein showed correlations with the concentration of heavy metals in different organs of the plant. The protein content in the plant tissues and the contents of oxalic and citric acid released by the plant in the rhizosphere can increase or decrease the absorption, accumulation, and translocation of Cu, Zn, and Pb in the different organs of the yellow melon var. Natal. Even the BF and TF showed values higher than one, being indicative of phytoextraction potential in several stages of the vegetative cycle for Cu and Zn, the yellow melon var. Natal cannot be considered as a hyperaccumulator plant for not meeting all necessary criteria for that purpose.

The Diluvio Stream flows in an area with the highest population density in Southern Brazil, where there are indications that urbanization has been negatively affecting the quality of the sediments. In the final section with the highest population density, the stream is channeled, and this is the most waterproofed part of the watershed, without any riparian forest, and surrounded by one of the biggest avenues of the metropolitan city of Porto Alegre. Thus, the aim of this study was to evaluate the spatial variability of the sediment pollution, by potentially toxic metals and macronutrients, from the source to the mouth of Diluvio Stream. Sediment samples were collected in 15 sites, along the entire course of the Diluvio Stream—from its springs to its mouth (18 km). We evaluated the pH, bulk density, grain size, electrical conductivity, total organic carbon (TOC), total phosphorus (P), inorganic P and organic P, total nitrogen (N), and pseudototal elements (Fe, Al, Ca, Mg, Na, K, Mn, Ba, Zn, Pb, Cu, Cr, Ni, Cd). The sediments of Diluvio Stream are predominantly sandy, with higher pollution in the sites with smaller particles and more organic carbon, increasing levels of metals and phosphorus to the Lake Guaíba. The pollution increases from its sources to its mouth, with an anthropogenic origin linked to the releases of wastewater and sewage, the large waterproofed area, the lack of riparian forest, and the large flow of vehicles near to the watercourse. Values of carbon, nitrogen, and phosphorus indicate that most of this derive from anthropogenic activities (as sewage), carrying other pollutants together—such as potentially toxic metals (especially Zn, Cu, and Pb).