Copper has become one of the most important heavy metal pollutants in the environment because of its wide application and high toxicity, but research on water quality criteria (WQCs) on copper is limited, especially the derivation of seawater WQC. In addition, the toxicity of copper in the seawater system is affected by various environmental factors. Therefore, establishing a WQC that meets the characteristics of the regional environment is a top priority. The correlations between four factors of temperature, salinity, pH, dissolved organic carbon (DOC) and the toxic effect values of copper were analyzed in this study, and the temperature was determined as the most influential factor among the four factors in the Bohai Sea. A specific correlation between temperature and the toxic effects of copper was identified, and WQCs were derived based on the identified correlation and the variations of the Bohai Sea's temperature in different seasons by species sensitivity distribution (SSD) method. Under the condition of the winter, spring, autumn, and summer with an average water temperature of 0.09, 15.96, 17.83, and 24.87 °C, the obtained short-term water quality criteria (SWQCs) were 44.29, 4.70, 4.31, and 3.33 μg/L; the long-term water quality criteria (LWQCs) were 18.14, 1.93, 1.77 and 1.36 μg/L. The findings indicated the importance of introducing specific environmental conditions during the derivation process. This work could provide valuable information for pollution prevention and aquatic life protection in the Bohai Sea and provide a valuable reference for the derivation of criteria in other regions alike.

The problem of potentially toxic elements (PTEs) in farmland is a key issue in global pollution prevention and control and has an important impact on environmental safety, human health, and sustainable agricultural development. Based on the climate background of high–latitude cold regions, this study simulated freeze–thaw cycles through indoor tests. Different initial conditions, such as biochar application rates (0%, 1%, 2%) and different initial soil moisture contents (15%, 20%, 25%), were set to explore the morphological changes in cadmium (Cd) and lead (Pb) in soil and the response relationship to the changes in soil physicochemical properties. The results indicate that soil pH decreases during freeze–thaw cycles, and soil alkalinity increases with increasing biochar content. Freeze–thaw cycles caused the total amount of PTEs to have a U–shaped distribution, and the amount of PTEs in the soluble (SOL) and reducible (RED) fraction increased by 0.28–56.19%. Biochar reduced the amount of Cd and Pb migration in the soil, and an increase in soil moisture content reduced the availability of Cd and Pb in the soil. Freezing and thawing damaged the soil structure, and biochar reduced the fractionation of small particle aggregates by enhancing the stability of soil aggregates, thereby reducing the soil's ability to adsorb Cd and Pb. In summary, for farmland soil remediation and pollution control, the application of biochar has a certain ability to optimize soil properties. Considering the distribution of PTEs in the soil and the physicochemical properties of the soil, the application of 1% biochar to soil with a 20% moisture content is optimal for regulating seasonally frozen soil remediation.

The widespread presence and persistence of perfluorooctane sulfonate (PFOS) in wastewater treatment plants, as well as its toxicity and bioaccumulation potential, necessitates the investigation on their impact on bioreactor performance. A 48-day exposure test was adopted to study the effects of low (10 μg L-1) and high (1000 μg L-1) PFOS concentrations in a sequencing batch reactor on the performance, composition, and microbial community of activated sludge. The results suggested that adding PFOS at low and high concentrations lowered the removal efficiency of total nitrogen by 22.48% (p < 0.01) and 16.30% (p < 0.01) respectively, while enhanced that of total phosphorus by 1.87% (p > 0.05) and 7.07% (p < 0.05) respectively, compared with the control group. The addition of PFOS also led to the deterioration of activated sludge dewatering performance. Composition and spectroscopic measurements revealed that the PFOS dosage changed the composition of the activated sludge. Furthermore, the PFOS altered the structure and function of the activated sludge microbial community as well as key enzyme activities.

Facing the challenge of global microplastics (MPs) pollution, full characterization of MPs biohazards is urgent. Recent intensive studies revealed that the toxicity depends on the material, size, and exposure concentration of MP. To better elucidate MPs biohazards, we investigated the impact of polystyrene-MPs of size 0.1 μm at a low dose of 50 μg/L on the neuromuscular, retinal, and reproductive phenotypes of fruit fly model, by voltage-clamped electrophysiology, electroretinogram, and reproductive assay, respectively. We found that MPs decreased the frequency of spontaneous junction currents of synapse and altered the receptor potential amplitude of the retina. Furthermore, MPs lowered the rate of embryo-laying of fruit flies. The differential gene expression of ligand-receptor interaction, endocytosis, phototransduction, and Toll/Imd signaling pathways might underlie these MPs-induced phenotypes. These findings call for further investigation on the potential biohazards of low-dose MPs.

The main intent of the current research was to appraise if combined application of hydrogen sulfide (H₂S, 0.2 mM) and silicon (Si 2.0 mM) could improve tolerance of tomato plants to arsenic (As as sodium hydrogen arsenate heptahydrate, 0.2 mM) stress. Plant growth, chlorophylls (Chl), PSII maximum efficiency (Fv/Fm), H₂S concentration and L-cysteine desulfhydrase activity were found to be suppressed, but leaf and root As, leaf proline content, phytochelatins, malondialdehyde (MDA) and H₂O₂ as well as the activity of lipoxygenase (LOX) increased under As stress. H₂S and Si supplied together or alone enhanced the concentrations of key antioxidant biomolecules such as ascorbic acid, and reduced glutathione and the activities of key antioxidant system enzymes including catalase (CAT), superoxide dismutase (SOD), dehydroascorbate reductase (DHAR), glutathione reductase (GR), and glutathione S-transferase (GST). In comparison with individual application of H₂S or Si, the joint supplementation of both had better effect in improving growth and key biochemical processes, and reducing tissue As content, suggesting a putative collaborative role of both molecules in improving tolerance to As-toxicity in tomato plants.

This review summarizes the most relevant information on PBDEs’ occurrence and their impacts in cetaceans at global scale, with special attention on the species with the highest reported levels and therefore the most potentially impacted by the current and continuous release of these substances. This review also emphasizes the anthropogenic and environmental factors that could increase concentrations and associated risks for these species in the next future. High PBDE concentrations above the toxicity threshold and stationary trends have been related to continuous import of PBDE-containing products in cetaceans of Brazil and Australia, where PBDEs have never been produced. Non-decreasing levels documented in cetaceans from the Northwest Pacific Ocean might be linked to the increased e-waste import and ongoing production and use of deca-BDE that is still allowed in China. Moreover, high levels of PBDEs in some endangered species such as beluga whales (Delphinapterus leucas) in St. Lawrence Estuary and Southern Resident killer whales (Orcinus Orca) are influenced by the discharge of contaminated waters deriving from wastewater treatment plants. Climate change related processes such as enhanced long-range transport, re-emissions from secondary sources and shifts in migration habits could lead to greater exposure and accumulation of PBDEs in cetaceans, above all in those species living in the Arctic. In addition, increased rainfall could carry greater amount of contaminants to the marine environment, thereby, enhancing the exposure and accumulation especially for coastal species. Synergic effects of all these factors and ongoing emissions of PBDEs, expected to continue at least until 2050, could increase the degree of exposure and menace for cetacean populations. In this regard, it is necessary to improve current regulations on PBDEs and broader the knowledge about their toxicological effects, in order to assess health risks and support regulatory protection for cetacean species.

Pollution from vehicle tires has received world-wide research attention due to its ubiquity and toxicity. In this study, we measured various tire-derived contaminants semi-quantitatively in archived extracts of passive air samplers deployed in 18 major cities that comprise the Global Atmospheric Passive Sampling (GAPS) Network (GAPS-Megacities). Analysis was done on archived samples, which represent one-time weighted passive air samples from each of the 18 monitoring sites. The target analytes included cyclic amines, benzotriazoles, benzothiazoles, and p-phenylenediamine (PPD) derivatives. Of the analyzed tire-derived contaminants, diphenylguanidine was the most frequently detected analyte across the globe, with estimated concentrations ranging from 45.0 pg/m³ in Beijing, China to 199 pg/m³ in Kolkata, India. The estimated concentrations of 6PPD-quinone and total benzothiazoles (including benzothiazole, 2-methylthio-benzothiazole, 2-methyl-benzothiazole, 2-hydroxy-benzothiazole) peaked in the Latin American and the Caribbean region at 1 pg/m³ and 100 pg/m³, respectively. In addition, other known tire-derived compounds, such as hexa(methoxymethyl)melamine, phenylguanidine, and various transformation products of 6PPD, were also monitored and characterized semi-quantitatively or qualitatively. This study presents some of the earliest data on airborne concentrations of chemicals associated with tire-wear and shows that passive sampling is a viable techniquefor monitoring airborne tire-wear contamination. Due to the presence of many tire-derived contaminants in urban air across the globe as highlighted by this study, there is a need to determine the associated exposure and toxicity of these chemicals to humans.

In acidic medium, hazardous heavy metals of lead-zinc tailing (LZT) are easily leachable and mobilizable. Thus, the hazard, amount, form, and complexity of the leached heavy metals under acidic precipitation become a major environmental concern. This work investigates the gangue minerals, toxicity, speciation, leaching characteristics of heavy metals in LZT under simulated acid rain, as well as immobilization effects and mechanisms using a sustainable binder. In LZT, dolomite, quartz, calcite, and muscovite are the main gangue minerals, tiny hazardous metallic minerals were absorbed in the surface. The results revealed that Pb, Zn, Cr, and Cd were the predominant harmful elements, particularly Pb and Zn. Zn is leached completely and is the concerned hazardous element under simulated acid rain. In the acid rain neutralization ability test, the amount of leachable Pb, Cr, Ca, and Si maintained in equilibrium, leached Zn, Cd, Al, and Mg depended on the addition of acid. Pb and Ca were sedimented in residues. Immobilization of Pb, Zn, Cr, and Cd depended on the stability of Ca(OH)₂/C–S–H of hydrates, and 70% LZTHP after curing 7 days can be used for some practical engineering projects. This work opens up deeply understandings for the leached heavy metals under acidic precipitation and improves the sustainable and safe in the field of immobilization of heavy metals.

Microplastic pollution affects freshwater and marine biota worldwide, microplastics occurring even inside the organisms. With highly variable effects, from physical damage to toxicity of plastic compounds, microplastics are a potential threat to the biodiversity, community composition and organisms' health. This emerging pollutant could overstress diadromous species, which are exposed to both sea and river water in their life cycle. Here we have quantified microplastics in young European eel Anguilla anguilla, a critically endangered catadromous fish, entering three rivers in southwestern Bay of Biscay. River water, sediments and seawater were also analysed for microplastics. The microplastic type was identified using Fournier-Transform Infrared spectroscopy and then searched for their hazard potential at the European Chemical Agency site. Both riverine and sea microplastic pollution were predictors of eels’ microplastic profile (types of microplastics by shape and colour): A. anguilla juveniles entering European rivers already carry some marine microplastics and acquire more from river water. Potentially hazardous plastic materials were found from eels, some of them dangerous for aquatic life following the European Chemical Agency. This confirms microplastics as a potential threat for the species. Between-rivers differences for microplastics profiles persistent over years highlight the convenience of analysing and preventing microplastics at a local spatial scale, to save diadromous species from this stressor. Since the origin of microplastics present in glass eels seems to be dual (continental + seawater), new policies should be promoted to limit the entry of microplastics in sea and river waters.

GABA, a four-carbon non-protein amino acid, plays an important role in animals and plants. We previously found GABA could alleviate alkali stress in apple seedlings. However, its physiological mechanism under heavy metal cadmium (Cd) stress need to be further studied. Thus, we explored its biological role in response to Cd stress. It was verified that 0.5 mM GABA could effectively alleviate Cd toxicity. Using NMT technique, we found that exogenous GABA could significantly reduce the net Cd²⁺ fluxes in apple roots, and Cd content was significantly lower than that in roots under Cd stress. Further analysis indicated exogenous GABA could significantly reduce the expression of genes related to the uptake and transport of Cd in apples under Cd stress. In addition, exogenous GABA could significantly increase the content of amino acids in apple roots under Cd stress. GAD is a key enzyme in GABA synthesis, we obtained transgenic apple roots of overexpression MdGAD1. Compared with the control, transgenic roots accumulated less Cd, maintained lower Cd uptake by roots, and lower expression of related transport genes. These results showed that GABA could effectively alleviate Cd toxicity in apple seedlings and provide a new perspective of GABA to alleviate Cd stress.