The current study was conducted to (1) examine seasonal and spatial distribution of heavy metals and metalloid in sediment from the Saigon River and (2) apportion and quantify their pollution sources. Ninety-six sediment samples were taken in the rainy and dry season on 13 sampling sites, distributed over the lower reaches of the River, to analyze for exchangeable concentration of 11 heavy metals and metalloid (Al, B, Cd, Co, Fe, In, Mn, Ni, Pb, Sr, and Zn), pH, EC, organic carbon content, and particle-size distribution. Generally, the concentration of 11 elements was ranked in the order Mn > Al > Fe > Zn > Sr > In > B > Ni > Co > Pb > Cd. Hierarchical cluster analysis grouped 13 sampling sites into two parts based on the similar concentration of the 11 elements. Three-way analysis of variance showed that the total exchangeable concentration of 11 elements was significantly higher in the rainy season than in the dry season and in the upper part than in the lower part of the river. Principal component analysis/factor analysis and correlation analysis revealed that three pollution sources (PS) may contribute to enriching the 11 examined elements in the sediment. These sources included (PS1) from catchment through water erosion over natural areas, explaining 83%, (PS2) mixed sources from catchment through water erosion over agricultural fields and inside Ho Chi Minh City, accounting for 6%, and (PS3) mixed sources from lowland areas, explaining 7.8% of the total variance of the elements. In brief, the sediment concentration of 11 metals and metalloid varied with season and space and three major pollution sources from river catchment, inside Ho Chi Minh City, and lowland contributively enriched the elements in the sediment of the River.

Antimony (Sb) widely occurs in plastics as a pigment and reaction residue and through the use and recycling of electronic material enriched in Sb as a flame retardant synergist. In this study, clean estuarine sediment has been contaminated by different microplastics prepared from pre-characterised samples of different types of plastic (including a rubber) containing a range of Sb concentrations (256–47,600 μg g⁻¹). Sediment-plastic mixtures in a mass ratio of 100:1 were subject to 6-h extractions in seawater and in seawater solutions of a protein (bovine serum albumin; BSA) and a surfactant (taurocholic acid; TA) that mimic the digestive conditions of coastal deposit-feeding invertebrates. Most time-courses for Sb mobilisation could be defined by a second-order diffusion equation, with rate constants ranging from 44.6 to 0.0216 (μg g⁻¹)⁻¹ min⁻¹. Bioaccessibilities, defined as maximum extractable concentrations throughout each time course relative to total Sb content, ranged from <0.01% for a polycarbonate impregnated with Sb as a synergist exposed to all solutions, to >1% for acrylonitrile butadiene styrene containing a Sb-based colour pigment exposed to solutions of BSA and TA and recycled industrial polyethylene exposed to BSA solution. The potential for Sb to bioaccumulate or elicit a toxic effect is unknown but it is predicted that communities of deposit-feeders could mobilise significant quantities of Sb in sediment contaminated by microplastics through bioturbation and digestion.

Freshwater lakes, especially eutrophic ones, have become a hotspot of methanogenesis. However, the effects of eutrophication and seasonality on methanogenesis activity and methanogenic microbial community remain unclear. In the current study, for two adjacent lakes at different trophic status, their methanogenesis potential in different seasons was evaluated using incubation experiments. The density, diversity, and community structure of methanogens were analyzed based on the mcrA gene. Correlation analysis and redundancy analysis were carried out to identify the environmental factors driving the variations of methanogenesis potential and methanogen community. The results showed that eutrophication could result in active methanogenesis with relatively high seasonal variance. The methanogenesis variation could be well explained by carbon input in association with algal growth, as well as the change of methanogen population density. With the dominance of Methanomicrobiales in both lakes, the hydrogenotrophic pathway had a major contribution to total methane production. The considerable proportion of Methanomassiliicocales in eutrophic lake implied that methylotrophic methanogenesis might be previously underestimated. These results added new insights towards methanogenesis process in eutrophic freshwater lakes.

Nitrogen (N) deposition in China may increase due to urbanization and economic growth. Current research has considered the ecological significance under the assumption of increasing N deposition. Atmospheric N deposition tending toward levelling or declining has been observed in China. Such potential recovery and responses of high N loads ecosystems under decreasing atmospheric N deposition scenarios have yet to be adequately investigated. This work reviews existing literature to consider possible responses of carbon (C) sequestration, biodiversity and species composition, soil acidification, and greenhouse emissions in ecosystems responding to recent patterns of N deposition. Potential effects of N composition and internal ratios may be further explored through state-of-the-art N addition experiments and model development.

A novel denitrifying bacterium YSF15 was isolated from the Lijiahe Reservoir in Xi’an and identified as Comamonas sp. It exhibited excellent nitrogen removal ability under low C/N conditions (C/N = 2.5) and 94.01% of nitrate was removed in 18 h, with no accumulation of nitrite. PCR amplification and nitrogen balance experiments were carried out, showing that 68.92% of initial nitrogen was removed as gas products and the nitrogen removal path was determined to be NO3−-N→NO2−-N→NO→N2O→N2. Scanning electron microscopy and three-dimensional fluorescence spectroscopy were used to track extracellular polymeric substances (EPS). The results show that complete-denitrification under low C/N conditions is associated with EPS, which may provide a reserve carbon source in extreme environments. These findings reveal that Comamonas sp. YSF15 can provide novel basic materials and a theoretical basis for wastewater bioremediation under low C/N conditions.

Food carts are common along streets in cities throughout the world. In North America, food cart vendors generally use propane, charcoal, or both propane and charcoal (P and C) for food preparation. Although cooking emissions are known to be a major source of indoor air pollution, there is limited knowledge on outdoor cooking’s impact on the ambient environment and, in particular, the relative contribution of the different cooking fuels. This field study investigated the air pollution the public is exposed to in the micro-environment around 19 food carts classified into 3 groups: propane, charcoal, and P and C carts. Concentrations near the food carts were measured using both real-time and filter-based methods. Mean real-time concentrations of PM₂.₅, BC₂.₅, and particle counts were highest near the charcoal food carts: 196 μg/m³, 5.49 μg/m³, and 69,000 particles/cm³, respectively, with peak exposures of 1520 μg/m³, 67.9 μg/m³, and 235,000 particles/cm³, respectively. In order of pollution emission impacts: charcoal > P and C > propane carts. Thus, significant differences in air pollution emissions occurred in the vicinity of mobile food carts, depending on the fuel used in food preparation. Local air pollution polices should consider these emission factors in regulating food cart vendor operations.

Numerous studies suggested that phthalates might be associated with increased risk of spontaneous pregnancy loss. However, these results were conflicting and inconclusive. Thus we performed this systematic review and meta-analysis to assess the relationship between phthalate exposure and risk of pregnancy loss. We searched PubMed, EMBASE, Web of Science and major Chinese literature databases for studies investigating phthalates and spontaneous pregnancy loss. Pooled odds ratio (OR) with 95% confident interval (CI) were calculated for risk estimate. A total of 8 studies involving 4713 participants (including 651 cases and 4062 controls) were enrolled in the present meta-analysis. Our pooled results showed that spontaneous pregnancy loss was associated with higher urinary levels of monobutyl phthalate (MBP) (OR: 1.34, 95% CI: 1.04–1.72), mono(2-ethylhexyl) phthalate (MEHP) (OR: 1.57, 95% CI: 1.29–1.90), mono(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP) (OR: 1.59, 95% CI: 1.23–2.07) and mono(2-ethyl-5-oxohexyl) phthalate (MEOHP) (OR: 1.47, 95% CI: 1.15–1.89). Indirect estimate of di-2-ethylhexyl phthalate (DEHP) levels, which were pooled from molar sum of urinary DEHP metabolites and hair DEHP, were also correlated with elevated risk of spontaneous pregnancy loss (OR: 1.79, 95% CI: 1.27–2.53). No significant association was found regarding urinary concentrations of monomethyl phthalate (MMP), monoethyl phthalate (MEP), mono-isobutyl phthalate (MiBP), monobenzyl phthalate (MBzP) or mono(2-ethyl-5-carboxypentyl) phthalate (MECPP). Our findings indicate that phthalate exposure might be a risk factor for spontaneous pregnancy loss. Given indirect estimate of phthalate exposure by evaluating its metabolite levels, our results should be interpreted with caution.

With the development of marine resources and marine transportation, oil spill accidents occur frequently which threaten the marine ecological environment and human life. In this paper, an oil spill model was established. The two-dimensional shallow water equation was discretized by the finite element weighted lumped mass method, and the time is discretized by the forward Euler scheme, then the planar two-dimensional hydrodynamic model was established. The model was verified by measure tidal level data. The oil particle drift model and oil spill weathering model were established in this paper, and it can be used to simulate the oil spill accidents on the sea area by inputting the terrain data, environmental conditions and oil spill information into the hydrodynamic model and oil spill model. The model is applied to Daya Bay, South China Sea, the oil spill behavior and destination under different residual currents were simulated and calculated, the pollution area of oil spill under clockwise residual flow is larger than that under anti-clockwise residual flow. The oil spill model is mainly used to simulate oil spill accidents on the sea surface such as ship oil spill accidents, and the simulation results can provide theoretical basis for taking effective emergency measures and risk assessment after oil spill.

The use of some systemic insecticides has been banned in Europe because they are toxic to beneficial insects when these feed on nectar. A recent study shows that systemic insecticides can also kill beneficial insects when they feed on honeydew. Honeydew is the sugar-rich excretion of hemipterans and is the most abundant carbohydrate source for beneficial insects such as pollinators and biological control agents in agroecosystems. Here, we investigated whether the toxicity of contaminated honeydew depends on i) the hemipteran species that excretes the honeydew; ii) the active ingredient, and iii) the beneficial insect that feeds on it. HPLC-MS/MS analyses demonstrated that the systemic insecticides pymetrozine and flonicamid, which are commonly used in Integrated Pest Management programs, were present in honeydew excreted by the mealybug Planococcus citri. However, only pymetrozine was detected in honeydew excreted by the whitefly Aleurothixus floccosus. Toxicological studies demonstrated that honeydew excreted by mealybugs feeding on trees treated either with flonicamid or pymetrozine increased the mortality of the hoverfly Sphaerophoria rueppellii, but did not affect the parasitic wasp Anagyrusvladimiri. Honeydew contaminated with flonicamid was more toxic for the hoverfly than that contaminated with pymetrozine. Collectively, our data demonstrate that systemic insecticides commonly used in IPM programs can contaminate honeydew and kill beneficial insects that feed on it, with their toxicity being dependent on the active ingredient and hemipteran species that excretes the honeydew.

Aerobic performance in fish is linked to individual and population fitness and can be impacted by anthropogenic contaminants. Exposure to some engineered nanomaterials, including silver nanoparticles (nAg), reduces rates of oxygen consumption in some fish species, but the underlying mechanisms remain unclear. In addition, their effects on swim performance have not been studied. Our aim was to quantify the impact of exposure to functionalized nAg on aerobic scope and swim performance in rainbow trout (Oncorhychus mykiss) and to characterize the contribution of changing rates of protein synthesis to these physiological endpoints. Fish were exposed for 48 h to 5 nm polyvinylpyrolidone-functionalized nAg (nAgPVP; 100 μg L⁻¹) or 0.22 μg L⁻¹ Ag⁺ (as AgNO₃), which was the measured quantity of Ag released from the nAgPVP over that time period. Aerobic scope, critical swimming speed (Ucᵣᵢₜ), and fractional rates of protein synthesis (Kₛ), were then assessed, along with indicators of osmoregulation and cardiotoxicity. Neither nAgPVP, nor Ag⁺ exposure significantly altered aerobic scope, its component parts, or swim performance. Kₛ was similarly unaffected in 8 tissue types, though it tended to be lower in liver of nAgPVP treated fish. The treatments tended to decrease gill Na⁺/K⁺-ATPase activity, but effects were not significant. The latter results suggest that a longer or more concentrated nAgPVP exposure may induce significant effects. Although this same formulation of nAgPVP is bioactive in other fish, it had no effects on rainbow trout under the conditions tested. Such findings on common model animals like trout may thus misrepresent the safety of nAg to more sensitive species.