Distribution, toxicity load, and risk assessment of dissolved metal in surface and overlying water at the Xiangjiang River in southern China.

Metal pollution in drinking water source has been under scrutiny as it seriously affects human health. This work examined 12 dissolved metals in the surface and overlying water of the Xiangjiang River, an important drinking water source in southern China, and characterized their distribution, identified their possible sources, assessed their toxicity load, and determined their potential ecological and health risk. No significant difference was found in the metal concentration between surface and overlying water. The average metal concentration fell in the order of Mg > Mn > Ba > Fe > Zn > As > Sb > Ni > Cd > V > Cr > Co, and all was lower than the safety threshold in the drinking water guideline of China. Anthropogenic activities were found to be the main source of metals from correlation analysis, principal component analysis (PCA), and cluster analysis (CA). According to the total heavy metal toxicity load (HMTL), 98.20%, 71.54%, 68.88%, and 7.97% of As, Cd, Sb, and Mn should be removed from the surface water to ensure safety. Most water samples from the surveyed area were found to have high ecological risk as was measured by the ecological risk index (RI). Health risk assessment showed that children are more susceptible than adults to the non-carcinogenic risk of dissolved metals, and the potential carcinogenic risk (CR) of As and Cd should be addressed. The results provide guidance for controlling the metal pollution of the Xiangjiang River and improving its quality as a drinking water source.

Microcystin in source water: pollution characteristics and human health risk assessment.

Frequent cyanobacterial blooms in eutrophic waters produce a variety of toxins such as microcystins (MCs), which are seriously harmful to waterbodies and human health. The spatiotemporal distribution characteristics of the MC-LR concentration in drinking water sources in seven river basins in China were investigated in this study. The removal rate of MC-LR in the purification process of water treatment plants and the human health risk of MC-LR in drinking water are also discussed. The results show that the detection frequency of MC-LR in source water was 55.46% and its concentration ranged from 0.06 × 10-3 to 52 × 10-3 µg L-1 (mean of 12.47 × 10-3 µg L-1), which are both below China's drinking water quality standard for algal toxins. The MC-LR concentration in lakes and reservoirs was higher than that in rivers, and exhibited an obvious spatiotemporal variation. The mean removal rate of MC-LR varied with river basin, and was also slightly higher for the advanced water treatment process (97.46%) in comparison to that of the conventional process (96.74%). The concentration of MC-LR in 8.26% of treated water samples was higher than that of raw water, thus indicating that MC-LR may be further released during the purification process. The risk index of MC-LR in treated water samples ranged from 2.29 × 10-3 to 8.40 × 10-3 (mean of 4.73 × 10-3), which corresponded to an extremely low level of risk. However, intensive monitoring should still be carried out in some high-concentration watersheds during the summer to ensure the safety of public drinking water.

Influencing factors and health risk assessment of polycyclic aromatic hydrocarbons in groundwater in China.

Polycyclic aromatic hydrocarbons (PAHs) are a group of persistent organic pollutants. This study investigated the occurrence of 16 PAHs in groundwater of representative regions of China (the cities of Lanzhou, Shijiazhuang, and Golmud and in Du'an County) using a gas chromatograph mass spectrometer. The total concentrations of 16 PAHs (∑PAHs) were in the range 0-29.06 µg/L (average: 594.8 ng/L). Acenaphthylene (Acy) and Naphthalene (Nap) had the highest detected frequency (74.56 %) and highest average concentration (632.7 ng/L), respectively. The average concentration of ∑PAHs in each study area exhibited the following trend: Lanzhou > Golmud > Du'an dry season > Du'an wet season > Shijiazhuang. The dominant PAHs in the study areas comprised mainly 2-4-ring PAHs, i.e., Nap (38.71 %; Shijiazhuang), BaA (40.09 %; Du'an wet season), Ace (16.84 %; Du'an dry season), Nap (43.51 %; Lanzhou), and BaA (57.43 %; Golmud). Overall, the PAHs of 101 samples were derived primarily from combustion and a small number of samples of PAHs originated from petroleum sources. Owing to strong adsorption in the vadose zone, the concentrations of PAHs in Shijiazhuang groundwater were lower than those in the groundwater of Golmud and Du'an. The groundwater in Du'an, Lanzhou and Golmud exhibits potential carcinogenic risk if consumed without further treatment.

Distribution characteristics and health risk assessment of volatile organic compounds in the groundwater of Lanzhou City, China.

Volatile organic compounds (VOCs) typically exist in the aqueous environment due to global anthropogenic activities. The distribution and contaminated profile (or characteristics) of VOCs in the groundwater of Lanzhou, China, were investigated in this study. Groundwater samples were collected from 30 sampling points in December 2015, and a total of 17 VOCs were analyzed by purge and trap gas chromatography-mass spectrometry. Thirteen types of VOCs were detected at 29 sampling points in the study area. Of these, dichloromethane and toluene, which were found at 22 sampling points, had the highest detection frequency (73.3%), followed by benzene (66.7%), 1,2-dichloroethane (50%), and xylenes (50%). The highest average concentration among the detected VOCs was found for chloroform (5151.5 µg/L). The spatial distribution of VOC contamination in four major urban areas of Lanzhou and the variation in VOC concentration caused by land use transitions were also analyzed. The results showed that Xigu district was the most polluted area in Lanzhou, mainly due to land use for industrial proposes. On the contrary, the samples for Anning district showed lower VOC concentrations because of better groundwater quality, which is associated with the absence of manufacturing industries in this region. The health risk assessment model developed by the United States Environmental Protection Agency was employed in this study to evaluate safety for drinking water use. This study found that despite considering the volatilization of VOCs from water due to heating, six sampling points (G05 in Qilihe district; G07 and G09 in Xigu district; G16, G17, and G15 in Chengguan district) showed non-carcinogenic risks, ranging from 1.63 to 14.2, while three points (G16 in Chengguan district, and G10 and G07 in Xigu district) exhibited high carcinogenic risks for human health, ranging from 2.94 × 10-4 to 6.85 × 10-4. Trichloroethylene, tetrachloroethylene, and 1,2-dichloroethylene were identified as the dominant VOCs, presenting high non-carcinogenic risk. 1,2-dichloroethane and vinyl chloride were the primary factors for high carcinogenic risk. The high-risk areas were concentrated in Xigu and Chengguan districts, suggesting the need to alert the relevant local government departments.

Occurrence, partition and environmental risk assessment of per- and polyfluoroalkyl substances in water and sediment from the Baiyangdian Lake, China.

This work examined the contamination of poly- and perfluorinated compounds (PFASs) in the water and sediment of the Baiyangdian Lake. The total concentration of PFASs in the surface water varied from 140.5 to 1828.5 ng/L, and the highest concentration of PFASs were observed near the entrance of Fuhe river. The topmost contaminant was sodium perfluorohexanesulfonate (PFHxS) and perfluorooctanoic acid (PFOA) in the north and south of the Baiyangdian Lake respectively, which indicated different contamination sources. The total concentration of PFASs in the sediment varied from 0.48 to 30 ng/g, and the distribution of PFASs in the sediment was similar with that in the surface water. The concentrations of polyfluoroalkyl phosphoric diesters (diPAPs) were three to four orders of magnitude lower than those of perfluorocarboxylates (PFCAs) and PFSAs. Although the pore water and the surface water had similar ΣPFASs, the concentration of perfluorodecanoic acid (PFDA) in pore water was 1.4 to 4.4 times higher than that in surface water, and the concentration of perfluoropentanoic acid (PFPeA) in pore water was 20-70% that in surface water. The results of ecological risk assessment showed that the PFASs were currently of no immediate risk to the aquatic life.

Contamination profiles and risk assessment of per- and polyfluoroalkyl substances in groundwater in China.

Per- and polyfluoroalkyl substances (PFASs) have attracted attention due to the potential risk they pose to ecosystems and human health. A total of 169 groundwater samples were collected from four representative regions in order to analyze PFASs concentrations in China. The total concentration of PFASs (∑PFASs) in groundwater ranged from 0.05 to 198.80 ng L-1, with an average of 3.97 ng L-1. All targeted PFASs were detected in the studied areas. The detection frequency and average concentration of perfluorooctanoic acid (PFOA) were the highest (79.29% and 1.61 ng L-1, respectively). The contamination profiles of PFASs in each study area varied due to natural geographical conditions and human activities. According to the results of the potential source identification, the point sources of perfluorooctane sulfonate (PFOS) were mainly concentrated in Lanzhou, and the distribution of PFASs was slightly affected by atmospheric deposition in all the studied areas. The obtained concentrations of PFOA and PFOS may pose no threat to the residents due to water consumption.

High contamination, bioaccumulation and risk assessment of perfluoroalkyl substances in multiple environmental media at the Baiyangdian Lake.

The contamination of perfluoroalkyl substances (PFASs) in the Baiyangdian Lake has exacerbated readily since 2008. This study analyzed the perfluoroalkyl carboxylic acids (PFCAs) and perfluoroalkane sulfonic acids (PFSAs) in the surface water, sediment, and fish of the Baiyangdian Lake. In the surface water, the total concentration of PFASs ranged in 1193-3462 ng L-1 (mean 1734 ng L-1) in the rainy season and 469-1724 ng L-1 (mean 876 ng L-1) in the dry season. The total concentration of PFASs in the sediment ranged in 1.97-13.3 ng g-1 (mean 6.53 ng g-1). It was found that PFCAs and PFSAs with longer chains were more easily adsorbed in the sediment. Among the collected fish samples, the enrichment of PFASs in the tissues fell in the order of liver > cheek > muscle. For the muscle, stomach, and liver tissues of the fish samples, significant correlations existed between the δ15N values and the concentration of perfluorooctane sulfonic acid (PFOS). The contents of PFOS and perfluorooctanoic acid (PFOA) in the fish were not at a level high enough to significantly risk human health.

Risk assessment of organochlorine pesticides in drinking water source of the Yangtze River.

Organochlorine pesticides have been banned for many years, but the residual trace amount of organochlorine in water may still pose ecotoxicological risk. Meanwhile, the potential risk of organochlorine pesticides released from sediments, especially into drinking water sources, is receiving increasing attention. The present study assessed the pollution and potential risk of drinking water sources along the midstream and downstream Yangtze River. Residues of organochlorine pesticides (OCPs) in water, suspended particle matter (SPM), and sediment were evaluated with isotope dilution HRGC/HRMS. The results indicated that OCPs in water, SPM, and sediment ranged in 0.52-92.97 ng/L, 0.10-4.10 ng/L, and 0.038-11.36 ng/g, respectively. The predominant OCPs in water, SPM, and sediment were ß-HCH, p,p'-DDE and PeCB. At site Y1, 8, 13, 18, ß-HCH has a higher proportion in sediment samples, while, α-HCH has a higher proportion in SPM samples. The industrial use of HCHs in the history was the main HCHs source for most water and sediment samples, which indicated an absence of fresh inputs of industrial HCHs. Meanwhile, the abundance of p,p'-DDE in water, sediment and SPM samples could be attributed to long-term aerobic degradation of DDTs. The values of ffsw of HCHs, DDTs and PeCB indicate the transfer from water to sediment. Risk assessment showed that HCHs and DDTs posed low ecotoxicological risk to the Yangtze River.

The correlation study between PCBs and δ15N values or FAs in fish collected from Dongting Lake.

The toxicity of polychlorinated biphenyls (PCBs) and their transformation have been intensively investigated in recent years. However, the potential mechanisms of biotransformation in a lake food web remain unclear. To explore the correlation between the PCBs and δ15N values or FAs, six fish species were collected from Dongting Lake, and various tissues were dissected to analyze the δ15N values, FAs and PCBs. Based on the wet weight (ww), the concentration of ∑PCBs115 ranged from 0.04 to 9.77 ng g-1, and the highest level was found in the gonad of Cyprinus carpio. The toxicity equivalent (TEQ) of PCBs ranged from 0.003 to 2.39 pg g-1, and the highest level was found in the fat of Silurus asotusy. The PCB levels in fish collected from Dongting Lake were at the low end of the global range. PCB28, 52, 95, 99, 101, 105 110, 118, 138, 153, 155 and 209 were found in all tissues. PCBs were distributed in a tissue-specific and species-specific manner in fish. PCB153 and 138 had a positive correlation with the TEQ in liver, gill, intestine and skin of fish on the basis of lipid weight (lw). Docosahexaenoic acid/eicosapentaenoic acid (DHA/EPA) and polyunsaturated fatty acid/saturated fatty acid (PUFA/SFA) had a positive correlation with some PCB congeners in the intestine. PCB52, ∑tetra-PCBs and Ind-PCBs had a positive correlation with the δ15N values in liver of fish on the basis of ww. PUFA/SFA and DHA/EPA might be indicators for the transfer of PCB congeners.

The correlation study between fatty acids and organochlorine pesticides or δ15N values in fish tissues from Dongting Lake, China.

Organochlorine pesticides (OCPs) are ubiquitous environmental contaminants, while their correlations with δ15N values and fatty acids (FAs) in fish tissues remain largely unexplored. In the present study, six species of fish for daily consumption were collected from Dongting Lake, and they were dissected to tissue samples to analyze the δ15N values, FAs and OCPs. The results showed that the δ15N values of fish were ranked in the same order in different fish tissues. The polyunsaturated fatty acids (PUFAs) had a different distribution pattern in fish tissues, while the saturated fatty acid (SFAs) and monounsaturated fatty acids (MUFAs) were not. The composition of HCHs in fish tissues exhibited a tissue-specific and species-specific manner, while such pattern was not detected for DDTs. The correlation analysis indicated that the ratio of DHA/EPA was increased with the increase of δ15N value in the muscle, liver, gill, skin and intestine, indicating the substance flow in freshwater ecosystem. In addition, there were significant positive correlations between the concentrations of some PUFAs and OCPs in the muscle, suggesting that people should pay attention to co-intake of OCPs when they supplemented the PUFAs needed by the human body through fish.

Contamination Profiles of Perfluoroalkyl Substances (PFAS) in Groundwater in the Alluvial-Pluvial Plain of Hutuo River, China.

Over the past decade, concerns about perfluoroalkyl substances (PFAS) have increased rapidly among the scientific community due to their global distribution and persistence in various environmental matrices. The occurrences of 10 PFAS in groundwater in the alluvial-pluvial plain of Hutuo River (APPHR) in the North China Plain (NCP) were analyzed via UPLC-MS/MS and solid phase extraction. Total PFAS concentrations ranged from 0.56 ng/L to 13.34 ng/L, with an average value of 2.35 ng/L. Perfluorooctanoic acid (PFOA) and perfluorohexanoic acid (PFHxA) were dominant PFAS contaminants with high detection rates of 98.39% and 95.16%, respectively, and PFOA was the main pollutant with a mean concentration of 0.65 ng/L. The hydrogeological conditions have an important influence on the concentrations of PFAS in groundwater. Comparatively, the concentration of PFAS in groundwater in the study area is not very high, but it reflects that the groundwater in this region is affected by industrial sources to some extent. Local government should pay more attention on industrial pollution control and groundwater protection in this area.

A clean-up method for determination of multi-classes of persistent organic pollutants in sediment and biota samples with an aliquot sample.

In the present study, we developed a novel method to simultaneously detect eight classes of persistent organic pollutants (POPs), including polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs), polybrominated diphenyl ethers (PBDEs), polybrominated dibenzo-p-dioxins and dibenzofurans (PBDD/Fs), polychlorinated naphthalenes (PCNs), organochlorine pesticides (OCPs), short-chain chlorinated paraffins (SCCPs) and Dechlorane Plus (DP), in sediment and fish tissue samples. The samples were extracted by accelerated solvent extraction (ASE) system, and the extracts were purified and fractionated into fraction1 and fraction2 with multi-layer silica gel column, followed by further fractionation using a basic alumina column (fraction1) and a Florisil column (fraction2), respectively. Finally, fractions were analyzed with different chromatographic columns and different detectors according to the properties of a chemical compound. The limit of detection for eight classes of POPs ranged from 1 to 30 pg/gdw in fish tissue samples, and from 1 to 33 pg/gdw in sediment samples, except for SCCPs (from 5.6 to 7.6 ng/g in fish tissue samples, and from 1.2 to 8.3 ng/gdw in sediment samples). The recoveries of eight classes of POPs spiked in fish tissue and sediment samples ranged from 43% to 120%, and from 45% to 115%, respectively. The relative standard deviation (RSD) was less than 25%. The accuracy of method was satisfactorily demonstrated by analysis of standard reference materials NIST SRM 1649b and WMF-01. In addition, the newly developed method was successfully applied for analysis of sediment and fish samples collected from the Baiyangdian Lake.

Formation process and mechanism of humic acid-kaolin complex determined by carbamazepine sorption experiments and various characterization methods.

To explore the formation process and mechanism of organic matter and organic-mineral complex under humification and mineralization conditions, a series of samples including humic acid, kaolin, and humic acid-kaolin complex were prepared using a subcritical water treatment method (SWT) under specific temperature, pressure and reaction time conditions. HA was used as a surrogate for natural organic matter because it has a similar abundant pore structure, variety of carbon types, and chemical components. These samples were used in carbamazepine (CBZ) sorption experiments and characterized by a variety of techniques. The polymerization of humic acid under the conditions of increased temperature and pressure resulted in an increase in specific surface area and molecular quantity. In addition, the degree of aromaticity rose from 59.52% to 70.90%. These changes were consistent with the transformation from 'soft carbon' to 'hard carbon' that occurs in nature. The results of sorption experiments confirmed the interaction between humic acid and kaolin from the difference between the predicted and actual Qe values. The conceptual model of humic acid-kaolin complex could be deduced and described as follows. Firstly, the aromatic components of humic acid preferentially combine with kaolin through the intercalation effect, which protects them from the treatment effects. Next, the free carboxyl groups and small aliphatic components of humic acid interact on the surface of kaolin, and these soft species transform into dense carbon through cyclization and polymerization. As a result, humic acid-kaolin complex with a mineral core and dense outer carbonaceous patches were formed.

Investigation of nitrogen and phosphorus contents in water in the tributaries of Danjiangkou Reservoir.

As part of the efforts to ensure adequate supply of quality water from Danjiangkou Reservoir to Beijing, surface water samples were taken from the tributaries of Danjiangkou Reservoir in the normal (May), flood (August) and dry (December) seasons of 2014, and characterized for nitrogen and phosphorus contents as specified in the applicable standards. Test results indicated that (i) the organic pollution in the Sihe and Shendinghe rivers was more serious than those in other tributaries, and the concentrations of nitrogen and phosphorus favoured the growth of most algae; (ii) total phosphorus (TP), total nitrogen (TN) and dissolved inorganic nitrogen (DIN) were in the forms of dissolved phosphorus (DTP), dissolved nitrogen (DTN) and nitrate nitrogen [Formula: see text], respectively, in these seasons; (iii) compared with nitrogen, phosphorus was more likely to block an overrun of phytoplankton; (iv) TN, TP, permanganate index (CODMn) and other ions were positively correlated. These findings are helpful for the government to develop effective measures to protect the source water in Danjingkou Reservoir from pollution.

[Distribution Characteristics and Pollution Status of Phthalate Esters in the Groundwater of Hutuo River Pluvial Fan].

A total of 51 groundwater samples were collected from Hutuo River Pluvial Fan in September, 2014, and 6 phthalate esters (PAEs) were analyzed by gas chromatography-mass spectrometry. The distribution characteristics and health risk assessment were investigated in the present study. The results showed that the PAEs could not be detected in only one sample site. The concentration of the six total PAEs ranged between not detectable and 28873.1 ng·L-1, and the PAEs pollution level of the this research area was higher than other regions reported in China. There was obvious difference in the characteristics of space distribution of PAEs constitutes among the three groundwater units. The concentration of PAEs was sequenced from large to small as follows: Gangnan reservoir valley fracture pore water unit (G1)> the pore water unit of the top of Hutuo River Pluvial fan (G2)> the shallow pore water unit of the middle part of Hutuo River Pluvial fan (G3). The results showed that the DMP was dominant in 23 sample sites among all the 39 samples within the G2 and G3 groundwater units, while the concentration of PAEs was relatively higher in the other sample points and the DEHP, DBP were the predominant components, which should be attributed to the industrial point pollution or the pollution originated from surface runoff around the sample sites. The health risk of drinking groundwater polluted by PAEs in the study area was evaluated by the recommended method by US EPA. The non-cancer risk index and the cancer risk index was lower than 1.1×10-2 and 1.2×10-6, respectively, which was both lower than the risk level recommended by US EPA.

[Distribution Characteristics of Fluoroquinolones Antibiotics in Surface Water and Groundwater from Typical Areas in A City].

In order to investigate the characteristics of 5 typical kinds of fluoroquinolones (FQs) pollution in waters from a city, surface water and groundwater samples from main drainage rivers and typical areas were collected, respectively. The conventional test and FQs concentrations analysis of the water samples were conducted. The results showed the concentration and composition of FQs in groundwater differed substantially from those in surface water. The average concentration of FQs in surface water was 789.1 ng x L(-1) with the main components of ofloxacin (OFL) and lomefloxacin (LOM). This value was higher than the average concentration of FQs in groundwater: 342.7 ng x L(-1) with the main components of norfloxacin (NOR) and lomefloxacin (LOM). The enrofloxacin (ENR) exhibited relatively lower levels in both surface water and groundwater as compared to others. The highest FQs concentrations in surface water were found in trenches, followed by tributaries and the main stream. For groundwater, FQs concentrations were relatively higher in the sewage riverside. A decreasing trend of FQs concentration was monitored with the increasing distance of sampling points to the drainage rivers and all components mentioned above showed similar changing trends. The results of this study preliminarily indicated that FQs in groundwater along the riverside probably came from the surface water.

[Contamination characteristics of fluoroquinolones in different kinds of soil profiles in Southeast suburb of Beijing].

Eighty-six soil samples were collected using Geoprobe soil sampler from 11 borehole profiles of Beijing Southeast suburb. The sampling sites could be divided into 8 kinds of landuse. Physical and chemical properties of samples were analyzed. The concentrations of 5 fluoroquinolones (FQs) were analyzed by the high-performance liquid chromatography. Results show that the average value of total concentrations of 5 FQs is 46.1 µg x kg(-1). Ofloxacin (OFL) is the predominant among them, and then is norfloxacin (NOR). Last comes to enrofloxacin (ENR), ciprofloxacin (CIP) and lomefloxacin (LOM). There are significant differences in FQs concentrations and kinds among the 8 land use types of soil profiles. The average value of total concentrations of 5 FQs decrease with an increasing of soil depth. The average concentration of OFL, NOR, LOM and ENR decrease with an increasing of soil depth. But CIP has the opposite result. Based on FQs concentrations from 42 soil samples with a depth among 0 to 3 meters, contamination characteristics of FQs were analyzed by fuzzy hierarchial clustering. Sampling sites of vegetable greenhouse, woods, sewage irrigation zone, groundwater irrigation zone, livestock and poultry farm, sediments from sewage river have similar components and contents of FQs, with less kinds and low concentration. In contrast, sampling sites of pharmaceutical enterprises and refuse landfill have more kinds and medium concentration of FQs.