Growing production and consumption of pharmaceuticals is a global problem. Due to insufficient data on the concentration and distribution of pharmaceuticals in the marine environment, there are no appropriate legal regulations concerning their emission. In order to understand all aspects of the fate of pharmaceuticals in the marine environment and their effect on marine biota, it is necessary to find the most appropriate model organism for this purpose. This paper presents an overview of the ecotoxicological studies of pharmaceuticals, regarding the assessment of Mytilidae as suitable organisms for biomonitoring programs and toxicity tests. The use of mussels in the monitoring of pharmaceuticals allows the observation of changes in the concentration and distribution of these compounds. This in turn gives valuable information on the amount of pharmaceutical pollutants released into the environment in different areas. In this context, information necessary for the assessment of risks related to pharmaceuticals in the marine environment are provided based on what effective management procedures can be developed. However, the accumulation capacity of individual Mytilidae species, the bioavailability of pharmaceuticals and their biological effects should be further scrutinized.

Contamination of agricultural soil by heavy metals has become a global issue concerning food security and human health risk. In this study, a soil investigation was conducted to evaluate metals accumulation, potential ecological and health risks as well as to identify sources of metals in paddy soils in Hanzhong City, which is located in a sedimentary basin. Ninety-two (92) surface soil samples (bulk soil) and their corresponding rice samples, 21 irrigation water samples, and 18 fertilizer samples were collected from two typical counties and quantified for the heavy metals (i.e., As, Cd, Cu, Hg, Pb, and Zn) concentrations. The results showed that As, Cd, and Zn were the main contaminants in soils in the studied area. Additionally, elevated Hg content in soils might also pose risks to the local ecosystem. Cadmium and As demonstrated high mobility, and their average contents in rice grains were slightly higher than the permissible threshold (0.20 mg kg⁻¹). Moreover, Pb, As, and Cd intake via rice consumption might result in potential risks to local residents. Metal distribution revealed that pollution in the studied area is non-homogeneous, and agricultural activities (As, Cu, and Cd), transportation emission (Cu and Pb), coal combustion (Hg and As), and smelting activities (Zn, Pb, and Cu) were ascertained as the potential sources based on the Positive matrix factorization (PMF) analysis results.

Determinations of the mobility of metals from tailings is a critical part of any assessment of the environmental impacts of mining activities. The leaching of thorium and uranium from the tailings of different processing stages of a niobium mine was investigated for several pH, ionic strengths and concentrations of natural organic matter (NOM). The pH of the leaching solution did not have a noticeable impact on the extraction of Th, however, for pH values below 4, increased U mobilization was observed. Similarly, only a small fraction of Th (0.05%, ≤15 μg kg⁻¹) and U (1.22%, ≤6 μg kg⁻¹) were mobilized from the tailings in the presence of environmentally relevant concentrations of Ca, Mg or Na. However, in the presence of 10 mg L⁻¹ of fulvic acid, much higher concentrations of ca. 700 μg kg⁻¹ of Th and 35 μg kg⁻¹ of U could be extracted from the tailings. Generally, colloidal forms of Th and dissolved forms of U were mobilized from the tailings, however, in the presence of the fulvic acid, both dissolved and colloidal forms of the two actinides were observed. Single Particle ICP-MS was used to confirm the presence of Th (and U) containing colloids where significant numbers (up to 10⁷ mL⁻¹) of Th and U containing colloids were found, even in 0.2 μm filtered extracts. Although mass equivalent diameters in the range of 6–13 nm Th and 6–9 nm for U could be estimated (based upon the presence of an oxyhydroxide), most of the colloidal mass was attributed to larger (>200 nm) heterocomposite particles.

Incineration has overtaken landfilling as the most important option for disposal of the increasing volumes of municipal solid waste (MSW) generated in China. Accordingly, disposal of the incineration fly ash, which is enriched with a range of heavy metals, has become a key challenge for the industry. This review analyzes the temporal and spatial trends in the distributions of As, Cd, Cr, Cu, Ni, Pb, Zn, and Hg in MSW incineration fly ash between 2003 and 2017, and estimates the inventories of heavy metals associated with the fly ash and the average levels of heavy metals in Chinese MSW based on their mass flow during MSW incineration. It was estimated that MSW incinerators in China released approximately 1.12 × 10², 2.96 × 10³, 1.82 × 10², 3.64 × 10⁴, 1.00 × 10², 7.32 × 10³, 2.42 × 10², and 1.47 × 10¹ tonnes of Cd, Pb, Cr, Zn, Ni, Cu, As, and Hg, respectively, with the fly ash in 2016. Due to the much greater fly ash generation rate, the incinerators based on circulating fluidized bed combustor (CFBC) technology released more heavy metals during incineration of MSW compared to those based on grate furnace combustor (GFC) technology. Results of mass-flow modeling indicate that the geometric mean contents of Cd, Pb, Cr, Zn, Ni, Cu, As, and Hg in Chinese MSW were 3.0, 109, 101, 877, 34, 241, 21, and 1.7 mg/kg, respectively, which are comparable to those in the MSW from other countries. To protect the environment from the significant potential ecological risk posed by heavy metals in the mismanaged fly ash, strict regulation enforcement and compliance monitoring are necessary to reduce the heavy metal pollution brought by improper disposal of MSW incineration fly ash, and more research and development efforts on advanced technologies for stabilization of heavy metals in fly ash and its environmentally sound reuse can help mitigate its environmental risk.

This study assesses for the first time the ingestion of microplastics by giant clams and evaluates their importance as a sink for this pollutant. A total of 24 individuals of two size classes were collected from the Red Sea and then exposed for 12 days to 4 concentrations of polyethylene microbeads ranging from 53 to 500 μm. Experiments revealed that clams actively take up microplastic from the water column and the average of beads retained inside the animal was ∼7.55 ± 1.89 beads individual −1 day −1 (5.76 ± 1.16 MPs/g dw). However, the digestive tract itself cannot be considered the only sink of microbeads in Tridacnids. Indeed, shells play a key role as well. The abundance of microplastic adhering to the shells, which was estimated directly, was positively correlated to the concentration of beads found in the surrounding seawater. Therefore, clams’ shells contribute to the removal of 66.03 ± 2.50% of the microplastic present in the water column. Furthermore, stress responses to the exposure to polyethylene were investigated. Gross Primary Production:Respiration (GPP:R) ratio decreased throughout of the experiment, but no significant difference was found between treatments and controls.

The potential impacts of mining activities on tropical coastal ecosystems are poorly understood. In particular, limited information is available on the effects of metals on scleractinian corals which are foundation species that form vital structural habitats supporting other biota. This study investigated the effects of dissolved nickel and copper on the coral Acropora muricata and its associated microbiota. Corals collected from the Great Barrier Reef were exposed to dissolved nickel (45, 90, 470, 900 and 9050 μg Ni/L) or copper (4, 11, 32 and 65 μg Cu/L) in flow through chambers at the National Sea Simulator, Townsville, Qld, Australia. After a 96-h exposure DNA metabarcoding (16S rDNA and 18S rDNA) was undertaken on all samples to detect changes in the structure of the coral microbiome. The controls remained healthy throughout the study period. After 36 h, bleaching was only observed in corals exposed to 32 and 65 μg Cu/L and very high nickel concentrations (9050 μg Ni/L). At 96 h, significant discolouration of corals was only observed in 470 and 900 μg Ni/L treatments, the highest concentrations tested. While high concentrations of nickel caused bleaching, no changes in the composition of their microbiome communities were observed. In contrast, exposure to copper not only resulted in bleaching, but altered the composition of both the eukaryote and bacterial communities of the coral's microbiomes. Our findings showed that these effects were only evident at relatively high concentrations of nickel and copper, reflecting concentrations observed only in extremely polluted environments. Elevated metal concentrations have the capacity to alter the microbiomes which are inherently linked to coral health.

Aflatoxin B₁ (AFB₁) is a hazard environmental pollutants and the most toxic one of all the aflatoxins. AFB₁ can cause a serious impairment to testicular development and spermatogenesis, yet the underlying mechanisms remain inconclusive. Oxidative stress acts as a master mechanism of AFB₁ toxicity, and can promote autophagy. Abnormal autophagy resulted in testicular damage and spermatogenesis disorders. The objective of this study was to explore the effect of AFB₁ on autophagy in mice testis and its potential mechanisms. In this study, male mice were intragastrically administered with 0, 0.375, 0.75 or 1.5 mg/kg body weight AFB₁ for 30 days. We found that AFB₁ induced testicular damage, reduced serum testosterone level and impaired sperm quality accompanied with the elevation of oxidative stress and germ cell apoptosis. Interestingly, we observed increasing numbers of autophagosomes in AFB₁-exposed mice testis. Meanwhile, AFB₁ caused testis abnormal autophagy with the characterization of increased expressions of LC3, Beclin-1, Atg5 and p62. Furthermore, AFB₁ downregulated the expressions of PI3K, p-AKT and p-mTOR in mice testis. Taken together, our data indicated AFB₁ induced testicular damage and promoted autophagy, which were associated with oxidative stress-related PI3K/AKT/mTOR signaling pathway in mice testis.

Particulate organic matter (POM) significantly affects the distribution of heavy metals in contaminated soil. However, the effect of POM on the fate of heavy metals during in situ-aided phytostabilization of waste slag is unclear. The objective of this study was to investigate the distributions of heavy metals such as Cu, Pb, Zn, and Cd in the POM fractions at a zinc smelting waste slag site under in situ-aided phytostabilization after five years. The results showed that the litters and residues of four plants―Arundo donax, Broussonetia papyrifera, Cryptomeria fortunei, and Robinia pseudoacacia―decomposed to form different POM size fractions. The percentage of the 0.05–0.25 mm POM size fraction was the highest, followed by the >1 mm and 0.5–1 mm POM size fractions, and that of the 0.25–0.5 mm POM size fraction was the lowest. The masses of POM derived from the four plants were in the following order: C. fortunei > B. papyrifera > A. donax > R. pseudoacacia. The contents, enrichment coefficients, and mass loads of heavy metals such as Cu, Pb, Zn, and Cd in the POM increased with decreasing POM size, and those in the 0.05–0.25 mm POM size fraction were the highest. The mass load of heavy metals in the POM occurred in the following order: Cu > Cd > Zn > Pb. The surfaces of the POM with coarser and smaller size fractions were smoother and rougher, respectively, and the smaller POM size fractions had larger specific surface areas. The main functional groups in the different POM size fractions were –COOH, –OH, CO, CC, C–H, Si–O, and –CH₃. The POM fractions played a significant role in determining the distribution of heavy metals in the revegetated waste slag. These findings have important implications for aided phytostabilization, which significantly influences the fate and speciation of heavy metals at the phytoremediation site.

Although agricultural lands are generally assumed to correlate negatively with groundwater quality, the intricate relationship between general land cover and contaminant concentrations present in an aquifer may vary substantially; contingent upon the land type, interacting factors, and scale considered. The Upper Floridan Aquifer (UFA) is a primary source of potable water supply for the state of Florida. The Suwannee River Water Management District (SRWMD), located in northcentral Florida, relies exclusively on the UFA for water supplies. Over much of the SRWMD in the UFA is unconfined, rendering it vulnerable to contamination from surface sources. This study analyses groundwater concentrations of Nitrate-Nitrogen (NO3–N) and Potassium (K) from shallow wells across the SRWMD for assessing the effect of different land covers on groundwater quality over time. Annual potentiometric surface maps were used to delineate semicircular recharge zones of 500 m, 1000 m, and 2000 m radii upstream of sampled well stations. Proportions of agriculture, forest, and urban lands were identified for each buffer zone using USDA Cropland Data Layer. Multivariate regression models were developed to infer relationships between land cover and NO3–N and K concentrations. Results show significant associations among land cover type, water table height, and groundwater quality parameters. Specifically, we find a large proportion of agricultural cover consistently associated with larger increases in groundwater pollutant loads relative to urban or forest cover across all models, after controlling for depth to water table. Our study suggests a need for widespread adoption of cost-effective agricultural best management practices (BMPs) that could help in securing regional water supply.

Satellite aerosol products have been widely used to retrieve ground PM₂.₅ concentration because of their wide coverage and continuous spatial distribution. While more and more studies have focused on the retrieval algorithms, the foundation for the retrieval—relationship between PM₂.₅ and satellite aerosol optical depth (AOD) has not been fully investigated. In this study, the relationships between PM₂.₅ and AOD were investigated in 368 cities in mainland China from February 2013 to December 2017, at different temporal and regional scales. Pearson correlation coefficients and the PM₂.₅/AOD ratio were used as indicators. Firstly, we established the relationship between PM₂.₅ and AOD in terms of the spatio-temporal variations, and discuss the impact of some potential factors for a better understanding of the spatio-temporal variations. Spatially, we found that the correlation is higher in the Beijing-Tianjin-Hebei and Chengyu regions and weaker in coastal areas. The PM₂.₅/AOD ratio shows an obvious north–south difference, with the ratio in North China higher than South China. Temporally, the correlation coefficient tends to be higher in May and September, with the PM₂.₅/AOD ratio higher in winter and lower in summer. As for interannual variations, we detected a decreasing tendency for the PM₂.₅-AOD correlation and PM₂.₅/AOD ratio for recent years. Then, to determine the impact of the weakening of the PM₂.₅-AOD relationship on PM₂.₅ remote sensing retrieval performance, a geographically weighted regression (GWR) retrieval experiment was conducted. The results showed that the performance of retrievals is also decreasing while PM₂.₅-AOD relationship getting weaker. Our study investigated the PM₂.₅-AOD relationship over a large extent at the city scale, and investigated the temporal variations in terms of interannual variations. The results will be useful for the satellite retrieval of PM₂.₅ concentration and will help us to further understand the PM₂.₅ pollution situation in mainland China.