Due to their low temperatures, the Arctic, Antarctic and Tibetan Plateau are known as the three polar regions of the Earth. As the most remote regions of the globe, the occurrence of persistent organic pollutants (POPs) in these polar regions arouses global concern. In this paper, we review the literatures on POPs involving these three polar regions. Overall, concentrations of POPs in the environment (air, water, soil and biota) have been extensively reported, with higher levels of dichlorodiphenyltrichloroethane (DDT) and hexachlorocyclohexane (HCH) detected on the Tibetan Plateau. The spatial distribution of POPs in air, water and soil in the three polar regions broadly reflects their distances away from source regions. Based on long-term data, decreasing trends have been observed for most “legacy POPs”. Observations of transport processes of POPs among multiple media have also been carried out, including air–water gas exchange, air–soil gas exchange, emissions from melting glaciers, bioaccumulations along food chains, and exposure risks. The impact of climate change on these processes possibly enhances the re-emission processes of POPs out of water, soil and glaciers, and reduces the bioaccumulation of POPs in food chains. Global POPs transport model have shown the Arctic receives a relatively small fraction of POPs, but that climate change will likely increase the total mass of all compounds in this polar region. Considering the impact of climate change on POPs is still unclear, long-term monitoring data and global/regional models are required, especially in the Antarctic and on the Tibetan Plateau, and the fate of POPs in all three polar regions needs to be comprehensively studied and compared to yield a better understanding of the mechanisms involved in the global cycling of POPs.

Despite the ban on new manufacture and commercial use of PCBs, municipal sewer systems continue to serve as ongoing secondary sources for contamination in receiving water bodies. Ongoing PCB sources have made it difficult to achieve desired recovery after implementation of sediment cleanup efforts. We report on a 16-month surveillance to determine the inputs, fate, and export of PCBs within a municipal waste collection/treatment system by strategic sampling of the freely-dissolved and biosolids-associated PCBs. The total PCBs entering the treatment plant was found to be 170 g/day of which 100 g/day exited the plant associated with the biosolids and 5.2 g/day was discharged in the form of freely-dissolved PCBs in the effluent. A net loss of 68 g/day was calculated for the plant, attributable to volatilization and biodegradation. Freely dissolved PCBs in the treated effluent was an order of magnitude higher than the water quality criteria for the protection of human health through fish consumption and found to be a major contributor to the dissolved concentration in the receiving river. Predicted bioaccumulation in fish from dissolved PCBs in the effluent exceeded the threshold for human consumption. The biosolids, currently land-applied as fertilizer, contained an average PCB concentration of 760 μg/kg. The sludge produced in this treatment plant is processed in large anaerobic digesters and changes to the homolog distribution point to some microbial dechlorination. Application of biosolids to clean agricultural soil resulted in a 6-fold increase in PCB levels in the earthworm E. fetida which could be eliminated by the amendment of 1% by weight of activated carbon.

Biochar addition to soil may change the hydrophobicity of amended soil and influence soil hydraulic properties. Soil hydrophobicity, i.e. soil water repellency (SWR) can interrupt water infiltration and form preferential flow leading to a potential risk of soil erosion or groundwater pollution. Up to date, the effect of different biochars on soil hydrophobicity remains unclear and the association of SWR with soil hydraulic properties is still unknown. To link the biochar hydrophobicity to SWR and soil water holding capacity (WHC), the surface structure and chemical composition of 27 biochars with different feedstocks and pyrolysis temperatures were characterized, and the SWR and soil WHC of biochar-added soil were investigated. Carboxylic groups on the biochar surface, surface area and pore volume were mostly influenced by pyrolysis temperature, which suggested the dominant factor determining the severity of biochar hydrophobicity was pyrolysis temperature. Hydrophilic soil became hydrophobic after biochar amendment. A higher addition rate led to a stronger SWR of hydrophilic soil. Biochar addition increased soil WHC of hydrophilic soil with low total organic carbon (TOC) content. Biochar did not have significant influence on SWR and soil WHC of hydrophobic soil with high TOC content. It implied that the influence of biochar on SWR and soil hydraulic properties mainly depended on soil original hydrophobicity and TOC content. Therefore, the properties of biochar and influence on soil hydrophobicity and hydraulic properties should be considered before processing biochar application.

Emission from manufacturing facilities to the surrounding environment is one of the important input source of pollutants. However, no information on the levels of organophosphate esters (OPEs) contamination in the environmental media around the manufacturing facility is available to date. In this study, samples from various environmental media, including sediments, water, surface soils, and tree bark, were obtained near an OPE manufacturing plant in Hengshui, Hebei Province, North China. The three main congeners, detected were tris(2-chloroethyl) phosphate (TCEP), tris(2-chloroisopropyl) phosphate (TCIPP), and triphenyl phosphate (TPHP), with the summed OPE concentrations (∑OPEs) ranging from 340 to 270,000 μg kg⁻¹ dry weight (d.w.), 7100 to 33,000 ng L⁻¹, not detected (N.D.) to 14,000 ng kg⁻¹ d.w., and 5300 to 19,000 ng g⁻¹ lipid weight in the sediments, water, soils, and tree bark, respectively. These findings suggest that point sources of OPEs could have widespread effects on its surrounding environments. Sediment and water concentrations of TCEP and TCIPP measured in this study were among the highest concentrations yet reported in the world. Meanwhile, the concentration ranges of TCEP and TCIPP in surface soils were significantly lower than those in the sediment and water, and among the lowest concentrations yet reported in soil data worldwide. This suggests that the manufacturing facility influenced the OPE distribution in different environmental media in different ways. Furthermore, TCEP and TCIPP might have been transported within the water stream from roots into the aboveground plants and then accumulated in tree barks.

There has been an increasing incidence rate of rice false smut in global rice cultivation areas. However, there is a dearth of studies on the environmental concentrations and hazards of ustiloxin A (UA), which is the major mycotoxin produced by a pathogenic fungus of the rice false smut. Here, the concentrations of UA in the surface waters of two paddy fields located in Enshi city, Hubei province, China, were measured, and its toxicity in T. Thermophila was evaluated. This is the first study to detect UA in the surface waters of the two paddy fields, and the measured mean concentrations were 2.82 and 0.26 μg/L, respectively. Exposure to 2.19, 19.01 or 187.13 μg/L UA for 5 days significantly reduced the theoretical population and cell size of T. thermophila. Furthermore, treatment with 187.13 μg/L UA changed the percentages of T. thermophila cells in different cell-cycle stages, and with an increased malformation rate compared with the control, suggesting the disruption of the cell cycle. The expressions of 30 genes involved in the enriched proteasome pathway, 7 cyclin genes (cyc9, cyc10, cyc16, cyc22, cyc23, cyc26, cyc33) and 2 histone genes (mlh1 and hho1) were significantly down-regulated, which might be the modes of action responsible for the disruption of cell cycling due to UA exposure.

Perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic (PFOS) are two perfluorinated chemical products widely existing in the environment. Evidence suggested that PFOA might relate to male reproductive dysfunction in rats and humans. PFOA exposure inhibited the function of Leydig cells. However, it is still unknown whether PFOA affects stem Leydig cells (SLCs). In the present study, we examined the effects of a short-term exposure to PFOA on Leydig cell regeneration and also explored the possible mechanism involved. Thirty-six adult Sprague-Dawley rats were randomly divided into three groups and intraperitoneally injected with a single dose of 75 mg/kg ethane dimethyl sulfonate (EDS) to eliminate all Leydig cells. From post-EDS day 7, the 3 group rats received 0, 25 or 50 mg/kg/day PFOA (n = 12 per group) for 9 consecutive days. Exposure to PFOA significantly decreased serum testosterone levels by day 21 and day 56 post-EDS treatment. Also, the expression levels of Leydig cell specific genes (Lhcgr, Scarb1, Star, Cyp11a1, Hsd3b1, Hsd11b1 and Cyp17a1) and their protein levels were all down-regulated. PFOA exposure may also affect proliferation of SLCs or their progeny since the numbers of PCNA-positive Leydig cells were reduced by post-EDS day 21. These in vivo observations were also confirmed by in vitro studies where the effects of PFOA were tested by culture of seminiferous tubules. In summary, PFOA exposure inhibits the development of Leydig cells, possibly by affecting both the proliferation and differentiation of SLCs or their progeny.

Indoor air contributes significantly to overall exposure, particularly for rural Chinese who often use solid fuels for cooking and/or heating. Unfortunately, overlooked rural indoor air leads to a critical knowledge gap. Simultaneous measurements in the kitchen, living room, and immediately outside of houses using six-channel particle counters were carried out in 18 biomass-burning rural and 3 non-biomass-burning urban households (as a comparison) in winter to characterize dynamic change patterns indoor air pollution and indoor-outdoor relationship. The rural households mainly used wood or crop residues for cooking and heating, while the urban households used pipelined natural gas for cooking and air conditioners for heating. In rural households with significant solid-fuel burning internal sources, the highest concentration was found in the kitchen (101 ± 56 μg/m³), with comparable levels in the living room (99 ± 46 μg/m³) and low levels in outdoor air (91 ± 39 μg/m³). A generally opposite direction of indoor-outdoor exchange was found between the rural and urban households. PM in kitchen air is smaller than that in living rooms and outdoors because solid fuel burning (mainly in rural households) and cooking oil heating (in rural and urban households). Indoor and outdoor PM concentration changed synchronously, with a slight delay in indoor air in urban households but a slight delay in outdoor air in rural households. Cooking, heating, and smoking elevated indoor PM significantly, but different from the cooking activity that produced peaks lasting for about 30 min, emissions from heating created a series of peaks due to frequent disturbance and fuel-feeding and had more significant impacts on the daily average concentration. Distinct indoor-outdoor relationships and dynamic change patterns between the two household categories w/o strong internal biomass burning sources imply that totally different model schemes are needed to quantitatively address indoor air pollution and inhalation exposure.

One of the most persistent pharmaceutical compounds commonly found in treated wastewater is lamotrigine (LTG). It has also been detected in soils and crops irrigated with treated wastewater. Here we focused on the ability of the white-rot edible mushroom Pleurotus ostreatus to remove and transform LTG in liquid cultures. At concentrations of environmental relevance (1 and 10 μg L−1) LTG was almost completely removed from the culture medium within 20 days. To elucidate the mechanism of LTG removal and transformation, we applied a physiological-based approach using inhibitors and a competing agent. These experiments were conducted at a higher concentration for metabolites detection. Based on identification of sulfur-containing metabolites and LTG N2-oxide and the effect of specific inhibitors, cytochrome P450 oxidation is suggested as one of the reaction mechanisms leading to LTG transformation. The variety and number of transformation products (i.e., conjugates) found in the current study were larger than reported in mammals. Moreover, known conjugates with glucuronide, glutathione, or cysteine/glycine, were not found in our system. Since the majority of the identified transformation products were conjugates of LTG, this study highlights the persistence of LTG as an organic pollutant in ecosystems exposed to wastewater.

A novel FeSiCa rich material (IS), chicken manure (CM) and its biochar were investigated for their efficiency in simultaneous remediation of Cd and As uptake by the vegetable Brassica chinensis L. Wet chemistry analysis and X-ray powder diffraction, scanning electron microscopy/energy dispersive X-ray spectroscopy as well as Fourier transform infrared spectroscopy were used to reveal the mechanisms responsible for Cd and As fixation in the amended soils. The IS treatment performed best in reducing Cd uptake, while the combination of IS and CM was the optimal one for As fixation. The precipitation/co-precipitation (in cadmium silicate/phosphate/phosphate hydroxide, cadmium iron and manganese oxides under alkaline conditions, and calcium/magnesium/ferric arsenates) and specific chemisorption (by amorphous iron/manganese oxides) were proved to be more efficient in simultaneously lowering As and Cd phytoavailability than was organic complexation. These findings demonstrate that FeSiCa and FeSiCaC amendments are highly efficient and promising in-situ remediation systems for safe crop production on soils contaminated with Cd and As.

Little information is available about the occurrence of neonicotinoid insecticides in surface water and sediment of the metropolitan regions around the rivers in China. Here we investigate the residual level of neonicotinoids in the Guangzhou section of the Pearl River. At least one or two neonicotinoids was detected in each surface water and sediment, and the total amount of neonicotinoids (∑₅neonics) in surface water ranged from 92.6 to 321 ng/L with a geometric mean (GM) of 174 ng/L. Imidacloprid, thiamethoxam and acetamiprid were three frequently detected neonicotinoids (100%) from surface water. As for the sediment, total concentration was varied between 0.40 and 2.59 ng/g dw with a GM of 1.12 ng/g dw, and acetamiprid and thiacloprid were the common sediment neonicotinoids. Western and Front river-route of the Guangzhou section of the Pearl River suffered a higher neonicotinoids contamination than the Rear river-route, resulting from more effluents of WWTPs receiving, and intensive commercial and human activities. Level of residual neonicotinoids in surface water was significantly correlated with the water quality (p < 0.01), especially items of pH, DO and ORP, and nitrogen and phosphorus contaminants. Compared with reports about residual neonicotinoids in water and sediment previously, the metropolitan regions of the Guangzhou could be confronted with a moderate contamination and showed serious ecological threats (even heavier than the Pearl Rivers). Our results will provide valuable data for understanding of neonicotinoids contamination in the Pearl River Delta and be helpful for further assessing environmental risk of neonicotinoids.