Polystyrene nanoparticles (PS NPs), originated from breakdown of large plastic wastes, have already caused much concern for their environmental risks on health. This current study was aimed to reveal the toxicological mechanism of PS NPs on developing zebrafish and macrophage cells. To fulfill this purpose, 42 nm PS NPs were exposed to the early development stage of zebrafish for 5 days, the decreased heart rate and locomotor activity of zebrafish larvae were observed. The fluorescent PS NPs were used to precisely assess the accumulation of PS NPs in zebrafish larvae, and the results indicated that PS NPs not only accumulated in digestive system, but also infiltrated into the liver. More importantly, the transcriptomic analysis revealed that a total of 356 genes were differentially expressed and the KEGG class map showed significant differences in the MAPK pathway upon PS NPs treatment. Meanwhile, the induction of oxidative stress and inflammation were also observed in zebrafish larvae. Furthermore, PS NPs also induced oxidative damage and inflammatory response in RAW 264.7 cells, which activated p38 MAPK signal pathway and finally induced cell apoptosis. Our study provides a new understanding of MAPK signaling pathway involved in toxicity mechanism.

It is necessary to understand the interactions between different pesticides in ecotoxicology because pesticides never appear as individual compounds but rather in combinations with other compounds. In this study, we planned to explicate the combined toxic effect of myclobutanil (MYC) and thiamethoxam (THI) on the zebrafish (Danio rerio) by adopting multiple biomarkers. Results unraveled that the 96-h LC₅₀ values of MYC to D. rerio at various life phases ranged from 5.2 to 10.3 mg L⁻¹, which were lower than those of THI ranging from 147 to 246 mg L⁻¹. Combinations of MYC and THI exhibited synergetic toxicity to zebrafish embryos. The activities of antioxidative enzymes (T-SOD, Cu/Zn-SOD and POD) and detoxification enzyme (GST) were obviously varied in most of the MYC, THI and combined exposures compared to the control. The mRNA expressions of eight genes (Cu-sod, cas3, il-8, cxcl, erα, crh, cyp17 and dio1) involved in antioxidation, apoptosis, immunity and endocrine were obviously altered in the combined exposure of MYC and THI compared to their individual exposures. Our findings hinted the threats when YMC and THI co-existed, which would be beneficial for the risk assessments of pesticide mixtures.

Litter is an ecological, economic, and social problem that impacts marine environments around the world. To create prevention and mitigation measures to solve this issue, it is necessary to understand the amounts and sources of this type of pollution. Cassino Beach is an extensive sandy beach located in South Brazil (∼220 km in length) that presents multiple uses, such as touristic, portuary and fishery activities. In order to evaluate the spatial and seasonal variation of litter amounts, types and sources at Cassino Beach, litter (>2.5 cm) was collected over 27 months at two urban and two non-urban sites. At each site, the litter present in three 200 m² areas was sampled and evaluated. A total of 19,457 items were collected, mostly composed by plastic (∼88%). Paper, metal, and cloth items were also present, but in low amounts. Fragments and cigarette butts were the major types of plastic litter, with abundances of 28.4% and 17.0%, respectively. Urban sites presented higher amounts of litter, with those related to beach use being more common, emphasizing the contribution of beachgoers to litter input at these sites. During the summer season, when beach use increases, the highest total litter concentration was found. Undefined and/or beach use-related sources were dominant in all sites and seasons. Mapping the predominant materials, types and potential sources of litter creates important baseline data that can contribute not only to beach monitoring, but also to the development of litter reduction strategies.

It is highly likely that the toxicity of water accommodated fractions (WAF) will influence marine microalgae, and consequently lead to potential risk for the marine ecological environment. However, it was often neglected whether WAF can influence the transformation of relative compounds in organisms. The metabolism of amino acids (AAs) can be used to track physiological changes in microalgae because amino acids are the basis of proteins and enzymes. In this study, using marine Chlorophyta Platymonas helgolandica as the test organism, the effects of different concentrations of WAF on AA compositions and stable carbon isotope ratios (δ¹³C) of individual AAs of Platymonas helgolandica were investigated. The results showed that the WAF of #180 fuel oil had an obvious suppressing effect on the growth and chlorophyll a content of microalgae. The growth inhibitory rate at 96 h was 80.66% at a WAF concentration of 0.50 mg L⁻¹ compared with the control. Furthermore, seven among the 16 AAs, including alanine, cysteine, proline, aspartic acid, lysine, histidine and tyrosine, had relatively high abundance. Under the glycolysis pathway, the cysteine abundance was higher than control, meaning that the biosynthesized pathway of alanine through cysteine as a precursor could be damaged. Phosphoenolpyruvate (PEP) was an important synthesis precursor of alanine (leucine) and aromatic AA family (Phenylalanine and tyrosine), and played an important role in δ¹³CAAₛ fractionation under the WAF stress. Under the TCA pathway, to protect cell metabolism activities under WAF stress, the δ¹³C value of threonine and proline abundance in microalgae with the increase in WAF stress. Therefore, δ¹³CAAₛ fractionation can be used as a novel method for toxicity evaluation of WAF on future.

Fish meal (FM) is an industrial product, mainly obtained from whole wild-caught fish, that is used as a high protein feedstuff component in aquaculture and intensive animal farming. Contamination of FM by microplastics (MPs), the synthetic polymer particles known to be nearly ubiquitous in the marine environment, is a likely consequence of their ingestion by zooplankton and other small marine animals that through the food chain end up in the fish commercialized not only for direct human consumption but also for the industrial production of FM. Unfortunately, analytical tools for quantifying contamination of FM by synthetic polymers are not available. A newly developed procedure described here allows quantification of the total amounts of polyolefins (including ethene and propene homo- and copolymers), polystyrene (PS), and poly(ethylene terephthalate) (PET), respectively, in FM. The multi-step procedure involves a sequence of solvent extractions, hydrolytic treatments to remove the biogenic matrix mainly consisting of proteins and some lipids, and selective depolymerization for PET. The gravimetric and SEC-UV techniques employed for the quantification of polyolefins and PS, respectively, only allowed to estimate their concentration in FM at around or below 100 mg/kg each, a more accurate quantification being prevented by the interference from the organic matrix and, in the case of polyolefins, by the limited sensitivity of the quantification by gravimetry. On the other hand, the contamination by PET MPs could accurately be quantified at 12.9 mg/kg based on the dry FM mass. Ways to overcome the sensitivity limitations for PS and polyolefins by using e.g. pyrolysis-GC/MS are highlighted.

Microplastic (MP) pollution in the environment has aroused great concern. However, our knowledge of MP abundance and distribution in soil environment is scarce. This work investigated the MPs in the farmland and grassland at a remote area of China, namely, the eastern area of the Qinghai–Tibet Plateau (QTP). The average numbers of MPs were 53.2 ± 29.7 and 43.9 ± 22.3 items/kg in shallow and deep soil, respectively, from 35 soil samples. A remarkable difference in MP abundances was observed among soil samples from mulch farmland, greenhouses, farmland without covering, and grassland. The MPs were mostly in the form of a film and transparent in color in this study. The dominant polymers of MPs in the soil samples were polyester (PE) and polypropylene (PP). This study revealed the characteristics of MP distribution among different land use at the QTP, and MPs may stem from the fragmentation of plastic mulch in farmland soil. Notably, MP abundance increased with the increase in mulching time in facility agriculture. Additionally, human disturbances and increased mulching time in facility agriculture promote the fragmentation of soil MPs. This study provides important data for follow-up research on MPs in a plateau terrestrial ecosystem.

Trace organic compounds (TOrCs) and microplastics (MPs) have been recognized as emerging pollutants that cause severe water pollution related problems due to their non-degradable and bio-accumulative nature. Many studies on oxidation processes such as ozone have been conducted to efficiently remove TOrCs in water treatment. However, there has been a lack of research on the removal efficiency of TOrCs in the oxidation process when they co-exist with MPs and form transformation byproducts (TBPs) during this process. This study evaluates the effects of MPs on TOrC removal during ozonation at various ozone concentrations and based on the mass of MP particles in distilled water. The adsorption of TBPs and TOrCs was also evaluated using the Freundlich and Langmuir isotherm equations. The toxicity of these compounds was evaluated to confirm the risk to aquatic ecosystems. The results show that triclosan (TCS) had the highest absorption capacity amongst the TOrCs and TBPs tested. Polyvinylchloride exhibited the highest adsorption efficiency compared with polyethylene and polyethyleneterephthalate (TCS 0.341 mg/g) due to its high adsorption capacity and hydrophobicity. In the toxicity test, 2,4-dichlorophenol and 4-chloroaniline as TBPs had a relatively higher toxicity to Vibrio fischeri (a marine bacterial species) than Daphnia magna (a freshwater plankton species).

Due to a close contact with water column, submerged macrophytes are easily disturbed by environment change in freshwater ecosystems, especially at the seedling stage. In recent decades, freshwater ecosystems have been subject to severe cadmium (Cd) pollution, which can cause toxic effects on the growth of submerged macrophytes. Moreover, the temperature rise resulting from climate warming and water level decline may further aggravate such effect, especially in shallow lakes. Here, we investigated the independent and interaction effects of Cd exposure levels (0, 0.5, 1, and 2.5 mg L⁻¹) and temperature (15, 25, and 30 °C) on morphological and physiological traits of Myriophyllum aquaticum (Vell.) Verd. Seedlings generated from propagules and seeds. The temperature rise and Cd exposure generally resulted in a significant increase of Cd concentrations and antioxidant enzyme activities in leaves, as well as a decrease of chlorophyll a and b concentrations. The number and length of leaves generated from propagules always show a downward trend with the increase of Cd exposure, regardless of the temperature. Moreover, the lowest leaf number and length always occurred at high temperature (i.e. 30 °C) when the Cd exposure level increased to 1 and 2.5 mg L⁻¹. For the seedlings generated from seeds, the temperature rise caused an increase of leaf emergence rate under low Cd exposure levels, but resulted in a significant decrease with the Cd exposure level. This study indicates the negative effects of Cd exposure and temperature rise on submerged macrophytes at the seedling stage, and highlights that temperature rise would enhance Cd toxicity.

Nitrogen (N) runoff loss from croplands due to excessive anthropogenic N additions is a principal cause of non-point source water pollution worldwide. Quantitative knowledge of regional-scale N runoff loss from croplands is essential for developing sustainable agricultural N management and efficient water N pollution control strategies. This meta-analysis quantifies N runoff loss rates and identifies the primary factors regulating N runoff loss from uplands (n = 570) and paddy (n = 434) fields in the Yangtze River Basin (YRB). Results indicated that total N (TN) runoff loss rates from uplands and paddy fields consistently increased from upstream to downstream regions. Runoff depth, soil N content and fertilizer addition rate (chemical fertilizer + manure) were the major factors regulating variability of TN runoff loss from uplands, while runoff depth and fertilizer addition rate were the main controls for paddy fields. Multiple regression models incorporating these influencing factors effectively predicted TN runoff loss rates from uplands (calibration: R² = 0.60, n = 242; validation: R² = 0.55, n = 104) and paddy fields (calibration: R² = 0.70, n = 189; validation: R² = 0.85, n = 82). Models estimated total cropland TN runoff loss load in YRB of 0.54 (95% Cl: 0.23–1.33) Tg, with 0.30 (95% Cl: 0.15–0.56) Tg from uplands and 0.24 (95% Cl: 0.08–0.77) Tg from paddy fields in 2017. Guangxi, Jiangxi, Fujian, Hunan and Henan provinces within the YRB were identified as cropland TN runoff loss hotspots. Models predicted that TN runoff loss loads from croplands in YRB would decrease by 0.8–13.7% for five scenarios, with higher TN load reductions occurring from scenarios with decreased runoff amounts. Reducing upland TN runoff loss should focus primarily on soil N utilization and runoff management, while reducing N fertilizer addition and runoff provided the most sensitive strategies for paddy fields. Integrated management of water, soil and fertilizer is required to effectively reduce cropland N runoff loss.

Cadmium (Cd), which is considered a carcinogenic metal, promotes breast cancer (BC) progression, but the precise mechanism remains unclear. Herein, MCF-7 and T47-D cells were treated with 0.1, 1, and 10 μM cadmium chloride (CdCl₂) for 24, 48 and 72 h. In our study, Cd exposure significantly accelerated the proliferation, migration and invasion of MCF-7 and T47-D cells. Notably, Cd inhibited autophagic flux by suppressing ATG5-dependent autophagosome formation but had no significant effect on autophagosome-lysosome fusion and lysosomal function. The genetic enhancement of autophagy through ATG5 overexpression suppressed the Cd-mediated increases in proliferation, migration and invasion, which indicated a carcinogenic role of autophagy impairment in Cd-exposed BC cells. GSEA and GeneMANIA were utilized to demonstrate that the Cd-induced decrease in ACSS2 expression mechanistically inhibited ATG5-dependent autophagy in BC cells. Importantly, ACSS2 overexpression increased the level of H3K27 acetylation in the promoter region of ATG5, and this result maintained autophagic flux and abolished the Cd-induced increases in proliferation, migration and invasion. We also verified that the expression of ACSS2 in BC tissues was low and positively related to ATG5 expression. These findings indicated that the promoting effect of Cd on BC cell proliferation, migration and invasion through the impairment of ACSS2/ATG5-dependent autophagic flux suggests a new mechanism for BC cell proliferation and metastasis stimulated by Cd.