An overview on the organic pollution around the Qinghai-Tibet plateau: The thought-provoking situation

Effects of uranium mining on soil bacterial communities and functions in the Qinghai-Tibet plateau

The microecological effects of plateau uranium mining are still unknown. In this study, we used 16S rRNA high-throughput sequencing to analyze the impact of plateau uranium mining on the microbial diversity and community structure of tailings soil, tunnel soil, and soil at different depths in an open pit. The results showed that uranium mining significantly reduced soil microbial community richness and diversity indicators, including Chao1, Pielou evenness, and Shannon index (P < 0.05). Uranium mining activities significantly reduced the abundance of RB41, Vicinamidactaceae, and Nitrospira (P < 0.05). Interestingly, the abundance of Thiobacillus, Sphingomonas, and Sulfuriferula significantly increased in the soil samples from various environments and depths during uranium mining (P < 0.05). Beta diversity analysis found that uranium mining resulted in the differentiation of soil microbial communities. Functional enrichment analysis found that uranium mining resulted in the functional enrichment of DNA binding response regulator, DNA helicase, methyl-accepting chemotaxis protein, and Helicase conserved C-terminal domain, whereas cell wall synthesis, nonspecific serine/threonine protein kinase, RNA polymerase sigma-70 factor, and ATP binding cassette transporter were significantly affected by uranium mining (P < 0.05). In addition, we also found that different uranium mining environments and soil depths enriched diverse microbial populations and functions to cope with the environmental pressures that were elicited by uranium mining, including Gaiella, Gemmatimonas, Lysobacter, Pseudomonas, signal transformation histidine kinase, DNA-directed DNA polymerase, and iron complex outer membrane receptor protein functions (P < 0.05). The results have enhanced our understanding of the impact of uranium mining on plateau soil microecological stability and the mechanism of microbial response to uranium mining activities for the first time and aided us in screening microbial strains that can promote the environmental remediation of uranium mining in plateaus.

Coping with extremes: Alternations in diet, gut microbiota, and hepatic metabolic functions in a highland passerine

In wild animals, diet and gut microbiota interactions are critical moderators of metabolic functions and are highly contingent on habitat conditions. Challenged by the extreme conditions of high-altitude environments, the strategies implemented by highland animals to adjust their diet and gut microbial composition and modulate their metabolic substrates remain largely unexplored. By employing a typical human commensal species, the Eurasian tree sparrow (Passer montanus, ETS), as a model species, we studied the differences in diet, digestive tract morphology and enzyme activity, gut microbiota, and metabolic energy profiling between highland (the Qinghai-Tibet Plateau, QTP; 3230 m) and lowland (Shijiazhuang, Hebei; 80 m) populations. Our results showed that highland ETSs had enlarged digestive organs and longer small intestinal villi, while no differences in key digestive enzyme activities were observed between the two populations. The 18S rRNA sequencing results revealed that the dietary composition of highland ETSs were more animal-based and less plant-based than those of the lowland ones. Furthermore, 16S rRNA sequencing results suggested that the intestinal microbial communities were structurally segregated between populations. PICRUSt metagenome predictions further indicated that the expression patterns of microbial genes involved in material and energy metabolism, immune system and infection, and xenobiotic biodegradation were strikingly different between the two populations. Analysis of liver metabolomics revealed significant metabolic differences between highland and lowland ETSs in terms of substrate utilization, as well as distinct sex-specific alterations in glycerophospholipids. Furthermore, the interplay between diet, liver metabolism, and gut microbiota suggests a dietary shift resulting in corresponding changes in gut microbiota and metabolic functions. Our findings indicate that highland ETSs have evolved to optimize digestion and absorption, rely on more protein-rich foods, and possess gut microbiota tailored to their dietary composition, likely adaptive physiological and ecological strategies adopted to cope with extreme highland environments.

Spindle-shaped Cu-Ru mesoporous nanospheres with enhanced enzyme-like activity for visual differentiation of toxic o-/m-aminophenol and recognition mechanisms

To effectively differentiate toxic aminophenol isomers, a kind of spindle-shaped Cu-Ru bimetal mesoporous nanozyme (Cu-Ru MPNZ) with high specific surface was developed by one-pot homogeneous reduction method, directed by hexadecyl trimethyl ammonium bromide (CTAB) in this work. By virtue of the distinctive microstructure, Cu-Ru MPNZ expressed superior bi-functional oxidase- and peroxidase-mimic activity to catalyze the oxidation of 3,3',5,5,'-tetramethylbenzidine (TMB) and 2,2'-azinobis (3-ethylbenzothiazoline-6- sulfonic acid) ammonium salt (ABTS) with low Michaelis-Menten constants and quick reaction rates. Especially, toxic aminophenol isomers could exclusively react with the oxydates of TMB or ABTS to express differentiable signals in color. Under the optimal conditions, Cu-Ru MPNZ was successfully applied for visual differentiation of toxic aminophenol isomers in real aqueous, juices and medicinal samples with low detection limits (1.60 × 10-8 mol/L for o-aminophenol and 3.25 × 10-8 mol/L for m-aminophenol) and satisfactory recoveries (96.6-103.5%). The different recognition mechanisms of Cu-Ru MPNZ to toxic o- and m-aminophenol isomers were proposed for the first time as far as we known. This work will provide a potential way to monitor different organic isomer pollution in future.

Application of the multimedia fugacity model in predicting the environmental behaviors of PCBs: Based on field measurements and level III fugacity model simulation

The comprehensive understanding of PCBs' fate has been impeded by the lack of simultaneous monitoring of PCBs in multiple environmental media in the background areas, which were considered long-term sinks for highly chlorinated PCBs. To address this gap, this study analyzed soils, willow tree barks, water, suspended particulate matter (SPM), and sediment samples collected from the middle reach of the Huaihe River in China for 27 PCBs. The results showed that the levels of ∑27PCBs in the soils were comparable to or lower than the background values worldwide. There were no significant correlations between organic matter and ∑27PCB concentrations in the soils and sediments. Additionally, the contamination of dioxin-like PCBs in the aquatic environment of the study area deserves more attention than in the soils. Applying the level III fugacity model to PCB 52, 77, 101, and 114 revealed that the soil was the primary reservoir, and air-soil exchange was the dominant intermedia transfer process, followed by air-water exchange. Furthermore, simulated results of air-soil and air-water diffusion were compared with those calculated from the field concentrations to predict the potential environmental behaviors of PCBs. Results indicated that the studied river would be a "secondary source" for PCB 52, 77, and 101. However, PCB 52, 77, 101, and 114 would continue to transfer from the air to the soil. This study combines multimedia field measurements and the fugacity model, providing a novel approach to predicting the potential environmental behaviors of PCBs.

Comammox biogeography subject to anthropogenic interferences along a high-altitude river

The recent discovery of comammox Nitrospira performing complete ammonia oxidation to nitrate has overturned the long-held dogma of two-step nitrification on Earth, yet little is known about the effect of urbanization interference on their distribution. Using gene-centric metagenomics, we provided the first blueprints about comammox community, biogeography, and environmental drivers along a high-elevation (> 2000 m) river flowing through the largest city on the vulnerable Qinghai-Tibetan Plateau. Our study confirmed a wide presence and diversity of yet-uncultured comammox clade B across wet and dry seasons, with average 3.0 and 2.0 times as abundant as clade-A amoA genes in water and sediments, respectively. Species identified from freshwater and drinking water treatment plants dominated the comammox guilds (58∼100%), suggesting this plateau river shared a similar comammox assemblage with the above habitat types. Compared with the urban area harboring more abundant canonical Nitrospira identified in wastewater (average 24%), the upstream suburban reach had a smaller human population but larger proportions of comammox in ammonia-oxidizing prokaryotes (24∼72% of abundances) and Nitrospira sublineages I/II. Higher contents of nitrate and nitrite in water, and antibiotics in water and sediments, may restrain comammox niches in nitrifiers over the urban area. Further random forest analysis revealed that lincosamides and quinolones were the most important antibiotic predictors for the niche differentiations between comammox and canonical nitrifiers in water, while macrolides for those in sediments. Finally, by incubation experiments, we demonstrated higher activity contributions of benthic comammox in the suburban area (36.2∼92.8% of potential ammonia-oxidation rates) than in the urban reach, and that the contribution variation had significant negative relations with macrolides and their major components. Overall, this study highlighted that anthropogenic activities hampered the advantage of riverine complete nitrifiers over the canonical two-step ones.

Unveil the role of dissolved and sedimentary metal(loid)s on bacterial communities and metal resistance genes (MRGs) in an urban river of the Qinghai-Tibet Plateau

Though metal resistance genes (MRGs) are of global concern in aquatic ecosystems, the underlying factors responsible for MRGs dissemination, especially in urban rivers on the vulnerable Qinghai-Tibet Plateau, are rarely known. Here, we collected 64 samples including water and sediments during the wet and dry seasons and effluents from six wastewater treatment plants (WWTPs) during the dry season and measured 50 metal(loid)s, 60 bacterial phyla, and 259 MRGs. We observed the distinct difference of metal(loid)s, bacterial communities, and MRGs between water and sediments and the great seasonal changes in metal(loid)s and bacterial communities instead of MRGs. Thirty-one metal(loid)s were detectable in the water, with relatively low concentrations and no significant effects on the planktonic bacterial communities and MRGs. Interestingly, the WWTPs effluent partially promoted the prevalence of dissolved metal(loid)s, bacterial communities, and MRGs along the river. In the sediments, the average concentrations of 17 metal(loid)s exceeded their corresponding background levels in this region and strongly influenced the bacterial communities and the MRGs. Sedimentary Hg and Cd, mainly sourced from the intensive animal husbandry, were the major pollutants causing ecological risks and largely shaped their corresponding resistomes. Moreover, we found that bacterial communities predominantly determined the variation of MRGs in both water and sediments. Metagenome-assembled genomes further reveals the widespread co-occurrence of MRGs and antibiotic resistance genes (ARGs) in MRG hosts. Our study highlighted the concern of effluents discharged from WWTPs and emphasized the importance of controlling the anthropogenic inputs of sedimentary metal(loid)s in the plateau river ecosystems.

Continental-scale spatial distribution, sources, and health risks of heavy metals in seafood: challenge for the water-food-energy nexus sustainability in coastal regions?

Rare information on the seafood safety and the coastal water-food-energy nexus sustainability in terms of seafood safety is available. This study investigated the distribution of heavy metals in 3 kinds of seafood (bivalve molluscs, fish, and crustaceans) collected from coastal areas along the 18,000 km coastline of China. Risk assessment and source apportionment of heavy metals, and the coastal water-food-energy nexus sustainability in terms of heavy metal pollution were also performed. The results showed that total concentrations of 8 heavy metals (Cu, Pb, Zn, Cd, Cr, Hg, As, and Ni) in seafood varied with sampling sites and species by following the order of bivalve molluscs > crustaceans > fish. Estimated daily intake (EDI) analysis indicated that it was safe for humans to consume seafood in all sampling sites. Non-cancer risks posed by heavy metals were acceptable for 99.1% of adult and 97.7% of children. However, Cr and As in 72% of fish samples caused high cancer risks for children. The farmed fish posed relatively low risk in comparison with the wild fish suggested that it might be safer to consume farmed fish than wild fish. Source apportionment demonstrated that the fossil energy consumption (coal combustion and vehicle exhaust), seawater, and metallurgic dust might serve as the possible main sources of heavy metals in seafood. Based on the policy scenario analysis, the fossil-energy-controlling policy and clean coastal water action were beneficial to the seafood safety by reducing target heavy metals in seafood. These findings provided comprehensive information on seafood safety and the water-food-energy nexus sustainability in coastal regions at continental-scale in terms of heavy metal pollution.

Pilot study on long-term simulation of PCB-153 human body burden in the Tibetan Plateau

The historical body burden of 2,2',4,4',5,5'-Hexachlorobiphenyl (PCB-153) in the Tibet Autonomous Region (TAR) population was simulated on the basis of localized exposure factors and dietary data, which present a preliminary attempt to quantify the influence of high lipid dietary patterns, grain transported from inland China, and atmospheric transport on human exposure to polychlorinated biphenyls (PCBs). Herdsman with large animal-based food consumption exhibited the highest body burden that was comparable with that in inland China. The body burden of other residents was within the range of low-to-moderate level. High-lipid diet of urban residents caused their body burden being 1.5--2.5 times higher than that of rural residents. The consumption of grain transported from higher polluted areas can also result in 50%-115% increase in the body burden of Tibetan rural residents compared with when local produced grain is consumed, suggesting that the influence of grain logistic can be as important as dietary patterns. The exposure risk for rural residents associated with grain logistic should not be ignored even if they consumed less high-lipid food. By splitting the inventory, over 80% of the PCB-153 pollution in the TAR was identified to be induced by atmospheric transport from foreign countries. However, the grain logistic contributed approximately half of the overall human body burden of Tibetan residents recently if assuming that the grain shortage was supplied by adjacent Sichuan Province. The combined influence of high-lipid diet, atmospheric transport and food logistic highlights the difficulties of risk control in remote regions that accumulate POPs, such as TAR.

Insights into the Occurrence, Fate, and Impacts of Halogenated Flame Retardants in Municipal Wastewater Treatment Plants

Halogenated flame retardants (HFRs) have been extensively used in various consumer products and many are classified as persistent organic pollutants due to their resistance to degradation, bioaccumulation potential and toxicity. HFRs have been widely detected in the municipal wastewater and wastewater treatment solids in wastewater treatment plants (WWTPs), the discharge and agricultural application of which represent a primary source of environmental HFRs contamination. This review seeks to provide a current overview on the occurrence, fate, and impacts of HFRs in WWTPs around the globe. We first summarize studies recording the occurrence of representative HFRs in wastewater and wastewater treatment solids, revealing temporal and geographical trends in HFRs distribution. Then, the efficiency and mechanism of HFRs removal by biosorption, which is known to be the primary process for HFRs removal from wastewater, during biological wastewater treatment processes, are discussed. Transformation of HFRs via abiotic and biotic processes in laboratory tests and full-scale WWTPs is reviewed with particular emphasis on the transformation pathways and functional microorganisms responsible for HFRs biotransformation. Finally, the potential impacts of HFRs on reactor performance (i.e., nitrogen removal and methanogenesis) and microbiome in bioreactors are discussed. This review aims to advance our understanding of the fate and impacts of HFRs in WWTPs and shed light on important questions warranting further investigation.

Heavy metals pollution and health risk assessment in farmed scallops: Low level of Cd in coastal water could lead to high risk of seafood

Scallops are one of the most common bivalves, large-scale farmed in the coastal areas of China. Three species of scallops (Chlamys farreri, Argopecten irradians and Patinopecten yessoensis) from 10 samples sites along the Bohai Sea and the Yellow Sea were collected to investigate species-specific and tissues-specific bioaccumulation, spatial-temporal distribution and health risks for people. Cd must be paid attention since Cd concentrations in 96% of scallop samples exceeded standard with the highest Cd bioaccumulation potentials (BCF) >10,000 while those of the other metals were less than the corresponding limits except Zn with exceeding-limit percentage of 13%. The metal pollution index values showed that A. irradians could accumulate more metals than the other two species, and scallops in the Bohai Sea were polluted more seriously by heavy metals than in the Yellow Sea. The capacities of tissues in scallops to accumulate metals generally followed the order of digestive gland > gill > adductor muscle. However, Zn accumulated in gill was more than that in digestive gland and muscle. Adults and children would face the non-cancer risks because of the accumulation Cd in scallops based on health risk assessment. Cd was the major contributor of health risk to account for 85% of total hazard quotient and 48% of total cancer risk. Scallops could accumulate Cd rapidly from ambient environments to cause health risks according to the transplantation test. Moreover, the recommended maximum edible amounts of whole scallops were 127/63 g/week for adult/children on the basis of the provisional tolerance weekly intake. Humans are recommended to only consume adductor muscles for reducing health risks.

How persistent are POPs in remote areas? A case study of DDT degradation in the Qinghai-Tibet Plateau, China

Persistent organic pollutants (POPs) can undergo long-range atmospheric transport (LRAT) and deposit in remote areas. How persistent are POPs in remote areas? To answer this question, we measured two parent-DDTs and eight metabolites in soil and air along a transect in the Qinghai-Tibet Plateau, China, to quantitatively evaluate the degree of degradation of DDTs. DDTs were ubiquitous in soil and air with the total DDT concentrations (Σ₁₀DDTs) ranging 37.7-70,100 pg g^-1 dw and 3.4-175 pg m^-3, respectively. The air-soil equilibrium status indicated that the forest/basin soil was a source for most DDTs, while the plateau soil was a sink receiving DDTs from the LRAT and photodegradation in the air (for metabolites). The metabolites accounted for avg. 64.1% of Σ₁₀DDTs in soil, with avg. 93.2% from local degradation, implying the overall high degradation of DDTs. With the significant degradation, the continuous input via LRAT was deemed to be the main reason for the stable level (persistence) of POPs in the Qinghai-Tibet Plateau. Therefore, we emphasize the importance of source control for the risk management of POPs. POPs in the environment might decline rapidly due to a reduction in source input and significant degradation as indicated by our study.

Ecological impact assessment of 110 micropollutants in the Yarlung Tsangpo River on the Tibetan Plateau

In this study, the occurrences of 110 micropollutants in the surface waters and sediments collected at eight sampling sites along the middle reaches of the Yarlung Tsangpo River were investigated in winter. A total of 47 and 45 micropollutants were detected in at least one water or sediment sample, respectively, and their total concentrations reached 790.2 ng/L and 186.5 ng/g on a dry weight basis, respectively. Their composition profiles demonstrated that the majority of micropollutants were polycyclic aromatic hydrocarbons (PAHs) and UV filters. The mixture risk quotient (MRQ) values of the detected micropollutants regularly exceeded 1 for aquatic organisms at all sampling sites, and fish and invertebrates are the more sensitive organisms. The diversity and evenness of the zooplankton levels had a clear negative correlation with the micropollutant occurrences in water. The top 10 mixture components belonging to the UV filter and PAH categories explained more than 80% and 95% of the mixture risk for chronic and acute toxicology, respectively. This study is the first investigation of the presence and risk assessment of 110 micropollutants in the Yarlung Tsangpo River Basin and offers new insights into the ecological security of the water resources of the Tibetan Plateau.

Assessing the contribution of atmospheric transport and tourism activities to the occurrence of perfluoroalkyl acids (PFAAs) in an Alpine Nature Reserve

Perfluoroalkyl acids (PFAAs) are ubiquitous in the global environment, even in remote regions. With increasing production and application of PFAAs in China, their distribution patterns have been widely reported, however with less attention to inland northwestern regions. Long-range transport and direct releases from local activities have been regarded as the main reasons for PFAAs distribution in such a remote area. To identify and quantify the contributions of different sources to PFAAs occurrences, an investigation was conducted in the Tianchi lake, nature reserve. A total of 20 water samples, 8 soil, 4 sediment and 10 fresh snow samples were collected and analyzed in 2015. The mean PFAAs concentrations were 3.38 ng L^-1 in surface water, 1.06 ng g^-1 dw in soil, 0.53 ng g^-1 dw in sediment, and 3.31 ng L^-1 in fresh snow, respectively. High levels of PFAAs were observed in surface water (15.41 ng L^-1) from Western Tianchi pond and surface snow (14.24 ng L^-1) from the site near a ski resort around Tianchi Lake indicating potential pollution by local human activities. The correlation between individual concentrations among water, soil and snow indicated the snow deposition as an important source. Although with limited sample size, principal component analysis associated with multiple linear regression (PCA-MLR) and positive matrix factorization (PMF) analyses have identified two major sources, which are characterized as tourism activities with dominance of perfluorooctanoic acid (PFOA) and long-range transport with abundant perfluorobutanoic acid (PFBA). Their contributions to total levels were 41% and 52%, respectively. These two sources contributed differently to the PFAAs presences in Tianchi and Western Tianchi Lakes. Source analysis indicates that the western Tianchi lake with a relatively small catchment was affected mainly by local activities.

Severe Nitrate Pollution and Health Risks of Coastal Aquifer Simultaneously Influenced by Saltwater Intrusion and Intensive Anthropogenic Activities

Groundwater quality is critical for regional sustainability and human well-beings in coastal regions, because groundwater is an important water resource for these areas facing water scarcity. Anthropogenic activities might induce nitrate pollution, whereas saltwater intrusion could decrease coastal groundwater discharge into sea to subsequently cause the persistent accumulation of pollutants in coastal aquifer. Rare information is available on the nitrate pollution of coastal aquifer under simultaneous influences of saltwater intrusion and intensive anthropogenic activities. This study investigated the distribution, pollution, possible sources, and potential health risks of groundwater nitrate of typical coastal aquifer simultaneously influenced by saltwater intrusion and intensive anthropogenic activities. The average/maximal concentration of groundwater nitrate was 173.70/824.80 mg/L, indicating the severe accumulation of nitrate in the coastal aquifer. Concentrations of nitrate in coastal groundwater were much higher than those in adjacent seawater. Groundwater salinization did not have significant effects on nitrate distribution. Groundwater in 87.6% of sampling sites was not suitable for drinking based on nitrate evaluation criterion. Anthropogenic activities might induce nitrate pollution in approximately 94.7% of sampling sites. Sources, including sewage and manure, soil nitrogen, and ammonium fertilizers, contributed to groundwater nitrate with concentration > 100 mg/L in the study area, whereas sewage and manure were the predominant source affecting groundwater nitrate in 97.5% of sampling sites. Groundwater nitrate exerted unacceptable noncancer health risks for infants, children, teenagers, and adults in more than 87.6% of the study area. Infants and children were the most susceptibly influenced by groundwater nitrate. It is urgent to take effective measures for controlling groundwater nitrate pollution in the study area.

Distribution of the parent compound and its metabolites in serum, urine, and feces of mice administered 2,2',4,4'-tetrabromodiphenyl ether

2,2',4,4'-Tetrabromodiphenyl ether (BDE-47) is a predominant polybromodiphenyl ether congener in the environment. Its absorption, excretion, and metabolism in animals have been investigated; however, the distribution of BDE-47 and its metabolites in excreta and blood at steady-state conditions has been unclear. In the present study, we addressed the issue by determining the amounts of BDE-47, eight monohydroxylated metabolites (OH-BDEs), and 2,4-dibromophenol (2,4-DBP) in serum, urine, and feces of gpt delta transgenic mice orally administered BDE-47 at 1.5, 10, and 30 mg/kg/d for 6 weeks during the 24 h period (for urine and feces) or at 24 h (for blood) post-last dosing. The distribution profiles in the three matrices showed that BDE-47, OH-BDEs, and 2,4-DBP were mostly distributed in urine (59-70%), feces (95-96%), and urine (51-80%), respectively. In each matrix, BDE-47 was the predominant compound under all doses, which accounted for 84-96% in serum, 68-98% in urine, and 37-92% in feces. However, exclusive of BDE-47, OH-BDEs were the predominant class of metabolites in serum (72-86%) and feces (67-87%), whereas 2,4-DBP was the major metabolite in urine (98-99%). Among monohydroxylated metabolites, the dominant compounds were 4-hydroxy-2,2',3,4'-tetrabromodiphenyl ether (4-OH-BDE-42) and 4'-hydroxy-2,2',4,5'-tetrabromodiphenyl ether (4'-OH-BDE-49) in feces (27-33% and 25-43%, respectively), and 3-hydroxy-2,2',4,4'-tetrabromodiphenyl ether (3-OH-BDE-47) in serum (26-43%). Thus, BDE-47 and 2,4-DBP were mostly present in urine, and OH-BDEs were primarily found in feces. Blood was not an important carrier for either BDE-47 or its metabolites. The data provide information for distribution and elimination of BDE-47 and its metabolites in mice at steady-state conditions.

Influence of coastal groundwater salinization on the distribution and risks of heavy metals

Coastal groundwater quality significantly affects the regional sustainable development, due to the water resource shortage in coastal zone. Current studies on coastal groundwater have mainly focused on saline water intrusion and over-extraction. Information on the heavy metal pollution of coastal groundwater with salinization trend is limited. This study investigated heavy metals in groundwater from a typical coastal region with intensive anthropogenic activities and saline water intrusion. The southwestern coastal plains of the study area showed significant groundwater salinization trend. Heavy metals in the coastal groundwater mainly originated from anthropogenic activities and groundwater salinization according to principal component analysis. Relative high concentrations of As, Co, Cr, Cu, Fe, Mn, and Ni occurred in the southwestern coast of the study area with high TDS level, indicating that the concentrations of these heavy metals in shallow aquifer of the study area might be influenced by the groundwater salinization. Average concentrations of heavy metals in groundwater of the study area ranged from 0.03 (Cd) to 686.92 (Fe) μg/L. Fe was the dominant heavy metal in groundwater with the maximal concentration of 2333.76 μg/L and exceeding-standard rate reaching 98.23%. Approximately 13.27% of sampling sites showed moderate or higher heavy metal pollution of groundwater based on heavy metal pollution index. Heavy metals in groundwater exerted low ecological risks. Elements Fe, Ni, and As were the main contributors for ecological risks. Cancer risks of heavy metals for both adults and children were high at all sampling sites. Non-cancer risks for adults and children were unacceptable at 4.42% and 17.70% of sampling sites, respectively. The salinization of the coastal groundwater could also lead to the increase in the ecological and health risks of heavy metals in coastal groundwater. These findings provide initial and important information on heavy metals pollution in coastal aquifer with saline water intrusion.

Preliminary investigation of polychlorinated dibenzo-p-dioxin and dibenzofuran, polychlorinated naphthalene, and dioxin-like polychlorinated biphenyl concentrations in ambient air in an industrial park at the northeastern edge of the Tibet-Qinghai Plateau, China

Ambient air samples collected in an industrial park at the northeastern edge of the Tibet-Qinghai Plateau (China) were analyzed for polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), polychlorinated naphthalenes (PCNs), and dioxin-like (dl) polychlorinated biphenyls (PCBs). The PCDD/F, PCN, and dl-PCB concentrations were 1.18-2.18, 21.9-75.1, and 0.49-0.90 pg/m³, respectively. The concentrations of these compounds were clearly higher than that observed at a remote site and were comparable with those found in ambient air in industrial areas in other locations. A principal component analysis indicated that emissions from local industrial sites (a secondary aluminum smelter, a cement kiln, and a lead-zinc smelter) at which thermal processes are performed were the sources of PCDD/Fs to the air. The combustion-related PCN congener profiles suggested that industrial thermal processes strongly affect PCN concentrations in ambient air at the industrial park. The results clearly indicated that the industrial park is a source of environmental PCDD/Fs and PCNs at the northeastern edge of the Tibet-Qinghai Plateau.

Bioaccumulation and human health risks of OCPs and PCBs in freshwater products of Northeast China

The levels and spatial distribution of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in freshwater products from Northeast China were investigated by gas chromatography coupled to isotope dilution high-resolution mass spectrometry. All samples were on-spot sampled from main production regions of freshwater products in Northeast China, and these samples were used to systematically assess the potential health risks of OCPs and PCBs associated with consumption of these fishery products. Dichlorodiphenyltrichloroethanes (DDTs), hexachlorocyclohexane (HCHs), hexachlorobenzene (HCB) and PCBs were the major pollutants with 100% detection rates, and their levels ranged from 0.086 to 58, 0.038-3.3, 0.093-4.5 and 0.032-1.4 ng g^-1 wet weight, respectively. The estimated dietary intakes of these contaminants were all below their corresponding acceptable daily intakes. Significant regional differences in the levels of OCPs and PCBs (P ≦ 0.001) were found in samples from Liaoning and Inner Mongolia. The results showed that the concentrations of targeted contaminants in aquatic products had species-specific characteristics, and the levels of targeted pollutants in Oncorhynchus mykiss and Eriocheir sienesis were significantly higher than those in other aquatic product species. Advisories on ten species of aquatic products suggested that consumption of Eriocheir sinensis, Oncorhynchus mykiss and Cyprinus carpio at a rate exceeding 15 meals per month would pose a cancer risk. A health risk assessment indicated that exposure to these pollutants through freshwater products consumption would cause a non-ignorable potential carcinogenic risk to humans.

Distribution and health risks of aerosol black carbon in a representative city of the Qinghai-Tibet Plateau

Although aerosol black carbon (BC) exerts strong influences on human health, research on potential health risks of aerosol BC around the Qinghai-Tibet Plateau is very limited. This is the very first study to investigate the distribution of aerosol BC in a typical city of the Qinghai-Tibet Plateau and the resulting health risks. The results showed that the maximal real-time (5-min monitoring interval) concentration of aerosol BC was 22.34 μg/m³, much higher than day- and week-averaged concentrations which were in the range of 1.28-6.15 and 1.93-4.63 μg/m³, respectively. The health risks were evaluated using four different health endpoints including low birth weight (LBW), percentage lung function decrement of school-aged children (PLFD), cardiovascular mortality (CM), and lung cancer (LC). The highest risks of LBW, PLFD, CM, and LC had reached 69.5, 184.4, 67.4, and 31.8 numbers of equivalent passively smoked cigarettes (PSC), respectively. The concentrations and health risks of aerosol BC in the study area are at a middle level among the global cities/regions. In comparison, the cities of the Qinghai-Tibet Plateau are experiencing high potential health risks resulting from aerosol BC to need more effective prevention and control of air pollution.

Pollution, ecological-health risks, and sources of heavy metals in soil of the northeastern Qinghai-Tibet Plateau

The Qinghai-Tibet Plateau, especially the northeastern region, is not a pure land any more due to recently increasing anthropogenic activities. This study collected soil samples from 70 sites of the northeastern Qinghai-Tibet Plateau to evaluate pollution, ecological-health risks, and possible pollution sources of heavy metals. The concentrations of heavy metals in soil were relatively high. Values of geo-accumulation index exhibited that Hg pollution was the most serious meanwhile Hg possessed the strongest enrichment feature based on enrichment factor values. The modified degrees of contamination showed that about 54.3% and 17.1% of sampling sites were at moderate and high contamination degree while pollution load indexes illustrated that 72.9% and 27.1% of sampling sites possessed moderate and high contamination level, respectively. Ecological risk indexes of heavy metals in soil ranged from 234.6 to 3759.0, suggesting that most of sites were under considerable/very high risks. Cancer risks for adults and children were determined as high and high-very high levels while non-cancer risks for children were high although those for adults were low. Industrial source contributed to the main fraction of ecological and health risks. Summarily speaking, heavy metals in soil of the study area has caused significantly serious pollution and exerted high potential ecological and health risks, especially for children who are more susceptible to hurt from pollutants. Therefore, more efficient and strict pollution control and management in study area should be put out as soon as possible.