An experiment was performed to explore the interactive impacts of zinc oxide nanoparticles (ZnO NPs) and cadmium (Cd) on growth, yield, antioxidant enzymes, Cd and zinc (Zn) concentrations in wheat (Triticum aestivum). The ZnO NPs were applied both in Cd-contaminated soil and foliar spray (in separate studies) on wheat at different intervals and plants were harvested after physiological maturity. Results depicted that ZnO NPs enhanced the growth, photosynthesis, and grain yield, whereas Cd and Zn concentrations decreased and increased respectively in wheat shoots, roots and grains. The Cd concentrations in the grains were decreased by 30–77%, and 16–78% with foliar and soil application of NPs as compared to the control, respectively. The ZnO NPs reduced the electrolyte leakage while increased SOD and POD activities in leaves of wheat. It can be concluded that ZnO NPs (levels used in the study) could effectively reduce the toxicity and concentration of Cd in wheat whereas increase the Zn concentration in wheat. Thus, ZnO NPs might be helpful in decreasing Cd and increasing Zn biofortification in cereals which might be effective to reduce the hidden hunger in humans owing the deficiency of Zn in cereals.

Adult coho salmon (Oncorhynchus kisutch) prematurely die when they return from the ocean to spawn in urban watersheds throughout northwestern North America. The available evidence suggests the annual mortality events are caused by toxic stormwater runoff. The underlying pathophysiology of the urban spawner mortality syndrome is not known, and it is unclear whether closely related species of Pacific salmon are similarly at risk. The present study co-exposed adult coho and chum (O. keta) salmon to runoff from a high traffic volume urban arterial roadway. The spawners were monitored for the familiar symptoms of the mortality syndrome, including surface swimming, loss of orientation, and loss of equilibrium. Moreover, the hematology of both species was profiled by measuring arterial pH, blood gases, lactate, plasma electrolytes, hematocrit, and glucose. Adult coho developed behavioral symptoms within a few hours of exposure to stormwater. Various measured hematological parameters were significantly altered compared to coho controls, indicating a blood acidosis and ionoregulatory disturbance. By contrast, runoff-exposed chum spawners showed essentially no indications of the mortality syndrome, and measured blood hematological parameters were similar to unexposed chum controls. We conclude that contaminant(s) in urban runoff are the likely cause of the disruption of ion balance and pH in coho but not chum salmon. Among the thousands of chemicals in stormwater, future forensic analyses should focus on the gill or cardiovascular system of coho salmon. Because of their distinctive sensitivity to urban runoff, adult coho remain an important vertebrate indicator species for degraded water quality in freshwater habitats under pressure from human population growth and urbanization.

Land application of biochar has been increasingly recommended as a powerful strategy for carbon sequestration and soil remediation. However, the biochar particles, especially those in the nanoscale range, may migrate or carry the inherent contaminants along the soil profile, posing a potential risk to the groundwater. This study investigated the transport and retention of wood chip-derived biochar nanoparticles (NPs) in water-saturated columns packed with a paddy soil. The environmentally-relevant soil solution chemistry including ionic strength (0.10–50 mM), electrolyte type (NaCl and CaCl2), and natural organic matter (0–10 mg L−1 humic acid) were tested to elucidate their effects on the biochar NPs transport. Higher mobility of biochar NPs was observed in the soil at lower ionic strengths, with CaCl2 electrolyte being more effective than NaCl in decreasing biochar NPs transport. The retained biochar NPs in NaCl was re-entrained (∼57.7%) upon lowering transient pore-water ionic strength, indicating that biochar NPs were reversibly retained in the secondary minimum. In contrast, negligible re-entrainment of biochar NPs occurred in CaCl2 due to the primary minimum and/or particle aggregation. Humic acid increased the mobility of biochar NPs, likely due to enhanced electrosteric repulsive interactions. The transport behaviors of biochar NPs can be well interpreted by a two-site kinetic retention model that assumes reversible retention for one site, and irreversible retention for the other site. Our findings indicated that the transport of wood chip biochar NPs is significant in the paddy soil, highlighting the importance of understanding the mobility of biochar NPs in natural soils for accurately assessing their environmental impacts.

Low tech photovoltaic panels (PVPs) installed in the early ’80s are now coming to the end of their life cycle and this raises the problem of their proper disposal. As panels contain potentially toxic elements, unconventional, complex and costly procedures are required to avoid environmental health risks and in countries where environmental awareness and economic resources are limited this may be especially problematic. This work was designed to investigate potential risks from improper disposal of these panels. To accomplish this aim an exhausted panel was broken into pieces and these were placed in water for 30 days. The resulting leached solution was analyzed to determine chemical release or used in toto, to determine its potential toxicity in established tests. The end points were seed germination (on Cucumis sativus and Lens culinaris) and effects on early development in three larval models: two crustaceans, Daphnia magna and Artemia salina, and the sea urchin Paracentrotus lividus. Our results show that the panels release small amounts of electrolytes (Na, Ca and Mg) into solution, along with antimony and manganese, with a concentration under the accepted maximum contaminant level, and nickel at a potentially toxic concentration. Developmental defects are seen in the plant and animal test organisms after experimental exposure to the whole solution leached from the broken panel. The toxic effects revealed in in vitro tests are sufficient to attract attention considering that they are exerted on both plants and aquatic animals and that the number of old PVPs in disposal sites will be very high.

In this work, the novel technology was used to remove heavy metal from sludge. The coupled with biodegradable ethylenediamine disuccinic acid (EDDS) and approaching anode electrokinetic (AA-EK) technique was used to enhance heavy metal removing from sludge. Electric current, sludge and electrolyte characteristics, heavy metal removal efficiency and residual content distribution, and heavy metal fractions percentage of variation were evaluated during the electrokinetic remediation process. Results demonstrated that the coupled with EDDS and AA-EK technique obtain a predominant heavy metal removal efficiency, and promote electric current increasing during the enhanced electrokinetic remediation process. The catholyte electrical conductivity was higher than the anolyte, and electrical conductivity of near the cathode sludge achieved a higher value than anode sludge during the coupled with EDDS and AA-EK remediation process. AA-EK technique can produce a great number of H⁺, which caused the sludge acidification and pH decrease. Cu, Zn, Cr, Pb, Ni and Mn obtain the highest extraction efficiency after the coupled with EDDS and AA-EK remediation, which were 52.2 ± 2.57%, 56.8 ± 3.62%, 60.4 ± 3.62%, 47.2 ± 2.35%, 53.0 ± 3.48%, 54.2 ± 3.43%, respectively. Also, heavy metal fractions analysis demonstrated that the oxidizable fraction percentage decreased slowly after the coupled with EDDS and AA-EK remediation.

Thallium (TI) is one of the most toxic heavy metals and priority pollutant metals. The emerging TI environmental pollution worldwide has posed a great threat to human health. However, based on the World Health Organization (WHO), the risk and severity of adverse health effects of TI in the range of 5–500 μg/L are uncertain. Moreover, evidence regarding the adverse impacts of TI on children’s health is still insufficient. Herein, we aim to investigate the early adverse effects of TI on children’s health and provide references for the WHO to establish stricter safety limits of TI. From 2015 to 2019, urinary TI and many clinical laboratory parameters related to blood routine, hepatic, renal, myocardial, coagulation function and serum electrolyte were measured in six children aged 1–9 years. The urinary TI concentration ranged from 13.4 μg/L to 60.1 μg/L with a mean of 36.1 μg/L and a median of 34.8 μg/L in six children in 2015. Although only four children felt a little poor appetite, several laboratory abnormalities indicated early damage in liver, renal, and myocardial functions in all children in 2015. After treatment and following up for four years, although the children’s TI concentration decreased below 5 μg/L, their liver and renal functions did not completely recover, and their myocardial function worsened. Results indicated that impaired liver, renal, and myocardial functions were closely associated with elevated urinary TI concentration in children. Considering the increasing use of TI in high-technology industries and emerging TI environmental-contamination zones worldwide, establishing stricter safety limits of TI and paying more attention to the adverse health effects of TI on children are urgently required.We found that a relatively low concentration of thallium (13.4 μg/L to 60.1 μg/L) impaired liver, renal, and myocardial function in six children. After treatment and following up these children for four years, although their urinary TI concentration decreased below 5 μg/L, their liver and renal functions did not completely recover, and their myocardial function worsened.

The conductive polyurethane/polypyrrole/graphene (CPU/PPy/Gr) particle electrode was prepared by an in-situ oxidative polymerization method and used as particle electrodes to degrade levofloxacin (LEV) in a three-dimensional electrode reactor. The prepared CPU/PPy/Gr electrode was characterized systematically and the effects of initial pH, initial LEV concentration, aeration volume, voltage, and electrolyte concentration on the degradation efficiency were investigated. Results showed that more than 90% LEV was degraded and the energy consumption was 20.12 kWh/g LEV under conditions of pH 7, 6 V voltage, 2.0 L/min aeration volume, 20 mg/L initial LEV concentration, and 7 mM concentration of electrolyte (Na₂SO₄). A possible electrochemical oxidation pathway of LEV by the CPU/PPy/Gr electrode was proposed. In addition, the biotoxicity of LEV and its oxidation products was calculated using ECOSAR (Ecological Structure Activity Relationships) program in EPISuite. Toxicity evaluation using luminescent bacteria showed that the toxicities of some intermediates were higher than the parent compound. But the toxicity of degradation processes for LEV was effective decreasing. A possible reactive mechanism in the three-dimensional reactor was also recommended. In brief, the prepared CPU/PPy/Gr particle electrode constitutes an insight into the promising practical application in the wastewater treatment.

The objective of the present study was to evaluate the contamination of sewage sludge produced by municipal waste treatment plants in Poland by viable eggs of intestinal parasites of the genera Ascaris, Toxocara and Trichuris (ATT). Ninety-two municipal, mechanical-biological sewage treatment plants located within Poland were selected. These plants belonged to types of agglomerations: group 0 (large), group 1 (medium), group 2 (smaller) and group 3 (small). Samples were collected at the final stage of sewage treatment after the addition of flocculent to sludge, followed by dehydration. The samples were examined by a method adjusted to examine sewage sludge dehydrated using polyelectrolytes. The viability of the isolated eggs was evaluated based on incubation in a moist chamber. Live eggs of intestinal nematodes were found in 99% of samples. Most samples were contaminated by the eggs of Ascaris spp. (95%) and Toxocara spp. (96%). However, Trichuris spp. eggs were detected in 60% of samples. The mean number of eggs in 1 kg of dry mass (eggs/kg d.m.) was 5600 for Ascaris, 3700 for Toxocara and 1100 for Trichuris. The highest number of ATT eggs was detected in samples from sewage treatment plants located in south-eastern and central Poland. The highest number of ATT eggs was found in sewage sludge produced in large sewage treatment plants (agglomeration Groups 0 and 1), with mean values of 15,000 and 8900 eggs/kg d.m. The present study is the first parasitological investigation conducted on a large number of samples (92 samples) taken from various types of municipal sewage treatment plants located throughout Poland (16 regions) after the common introduction of polyelectrolytes during sewage sludge dehydration. The results of this study indicate that sludge produced in municipal sewage treatment plants is highly contaminated with parasite eggs.

Although the aggregation of graphene oxide (GO) has been widely researched, the influence of the GO size on the homoaggregation behavior and its interaction with environmental media are still unexplored. In this work, critical coagulation concentration (CCC) values for GO with different sizes, from micro to nanosheet, were measured with NaCl and CaCl₂ electrolytes, and the results indicated that GO with the largest size presented the smallest CCC value. Aluminum oxide (Al₂O₃) was selected as a natural solid particle representative to mimic the interaction between GO and environmental media. Batch experiments were conducted in solution with different pH and ionic strength. Results indicated that the attachment capacity of large GO onto Al₂O₃ particles was greater than that of small GO. The experimental data were well fitted with Freundlich model. The electrostatic attraction and hydrogen-bonding interaction dominated the interaction process between GO and Al₂O₃. These findings are important for better understanding in the environmental fate and transport of GO.

Understanding of the interaction of graphene with natural polysaccharides (e.g., alginate) is crucial to elucidate its environmental fate. We investigated the impact of alginate on the agglomeration and stability of ¹⁴C-labeled few-layer graphene (FLG) in varying concentrations of monovalent (NaCl) and divalent (CaCl₂) electrolytes. Enhanced agglomeration occurred at high CaCl₂ concentrations (≥5 mM) due to the alginate gel networks formation in the presence of Ca²⁺. FLG enmeshed within extended alginate gel networks was observed under transmission electron microscope and atomic force microscope. However, background Na⁺ competition for binding sites with Ca²⁺ at the alginate surfaces shielded the gelation of alginate. FLG was readily dispersed by alginate under environmentally relevant ionic strength conditions (i.e., <200 mM Na⁺ and <5 mM Ca²⁺). In comparison with the bare FLG, the slow sedimentation of the alginate-stabilized FLG (158 μg/L) caused continuous exposure of this nanomaterial to freshwater snails, which ingested 1.9 times more FLG through filter-feeding within 72 h. Moreover, surface modification of FLG by alginate significantly increased the whole-body and intestinal levels of FLG, but reduced the internalization of FLG to the intestinal epithelial cells. These findings indicate that alginate will act as a stabilizing agent controlling the transport of FLG in aqueous systems. This study also provides the first evidence that interaction of graphene with natural polysaccharides affected the uptake of FLG in the snails, which may alter the fate of FLG in aquatic environments.