Jijun Gao

Concentration level and geographical distribution of nitrobenzene in Chinese surface waters

Nitrobenzene was reported to occur at relatively high concentrations in some Chinese surface water and to cause an environmental pollution event in 2005. To map the distribution of nitrobenzene in the Chinese surface water throughout China, surface water samples were collected from over 600 sites in the 7 major watersheds and three drainage areas. The samples were analyzed for concentration of nitrobenzene. Overall, nitrobenzene was more frequently detected at higher concentrations in the rivers of North China, including Songhua River, Liaohe River, Haihe River, Yellow River, Huaihe River, and Northwest drainage area rivers, compared with those in the rivers of South China, including Yangtze River, Pearl River, Southeast drainage area rivers and Southwest drainage rivers. The detection rate of nitrobenzene was 83.2% for all the samples, with a mean value of 18.1 ng/L and a range of < 0.3-8450.0 ng/L. The highest mean concentration of nitrobenzene was observed in the Yellow River, followed by Huaihe River. The results of this investigation indicated that nitrobenzene should be of particular concern in China and its ecological and health risk should be assessed.

Simultaneous assessments of occurrence, ecological, human health, and organoleptic hazards for 77 VOCs in typical drinking water sources from 5 major river basins, China

Owing to the growing public awareness on the safety and aesthetics in water sources, more attention has been given to the adverse effects of volatile organic compounds (VOCs) on aquatic organisms and human beings. In this study, 77 target VOCs (including 54 common VOCs, 13 carbonyl compounds, and 10 taste and odor compounds) were detected in typical drinking water sources from 5 major river basins (the Yangtze, the Huaihe, the Yellow, the Haihe and the Liaohe River basins) and their occurrences were characterized. The ecological, human health, and olfactory assessments were performed to assess the major hazards in source water. The investigation showed that there existed potential ecological risks (1.30 × 10 ≤ RQtotals ≤ 8.99 × 10) but little human health risks (6.84 × 10(-7) ≤ RQtotals ≤ 4.24 × 10(-4)) by VOCs, while that odor problems occurred extensively. The priority contaminants in drinking water sources of China were also listed based on the present assessment criteria.

Assessing remobilization characteristics of arsenic (As) in tributary sediment cores in the largest reservoir, China

The environmental impact of the Three Gorges Reservoir (TGR) in China has raised widespread concern especially in relation to metal pollution. The diffusive gradient in thin films (DGT) technology was applied to investigate arsenic (As) remobilization in sediment cores collected from the main stream and a tributary in the TGR during July 2015. The results showed that the horizontal and vertical distributions of CDGT-As varied among the four sampling sites. For the same DGT probe, the horizontal distributions of CDGT-As (0-6mm, 6-12mm, 12-18mm) exhibited similarity in the overlying water and different tendencies in the sediment profiles; the vertical variations of CDGT-As showed different mobilization tendencies. Moreover, the mobility patterns of As in the sediment profile showed the diffusion potential of As from the deep sediment to the surface sediment and overlying water were in the order of MX-2< MX-1< CJ < MX-3. In addition, similar distribution characteristics and correlation analysis showed that the mechanisms of As mobility were associated with Fe and Mn. The results also showed that sulphide and As were simultaneous remobilization in the tributary sediment core in the TGR.

PHAHs in large reservoir sediments from Hebei and Hubei provinces, China

This study was undertaken to investigate the current contamination status of polyhalogenated aromatic hydrocarbons (PHAHs) in sediments from large reservoirs located in Hebei and Hubei provinces in China. The concentrations of 21 polybrominated biphenyl (PBB) congeners, seven polybrominated diphenyl ether (PBDE) congeners, and 27 polychlorinated biphenyl (PCB) congeners in sediments were measured using the GC-MS/MS technique. Low-brominated PBBs (including 1, 3, 4, 10, 30, 31 and 53) were the most abundant PBB congeners and PBDEs 28, 47 and 99 were the most prevalent PBDE congeners in these samples. Among the three subfamilies of PHAHs, PCBs were the most predominant pollutants detected. The measured levels of PHAHs were compared with recent results reported in the literature and their respective sediment quality guidelines recommended by USEPA. The levels of PHAHs in the present study were generally lower than their respective threshold-effect levels, or were comparable to those reported in relatively uncontaminated freshwaters from other regions. This suggests that, in these reservoirs, toxic biological effects on aquatic biota—due to PHAH contamination of sediments—can be expected to be negligible. Thus, in terms of PHAHs, the sediments in the selected reservoirs are relatively uncontaminated.

The organic contamination survey and health risk assessment of 16 source water reservoirs in Haihe River basin.

Although contamination by organic pollutants has previously been reported to occur in the Haihe River basin, few studies have been carried out on the levels of source water reservoir contamination and the health risk in the Haihe River basin. To understand the organic pollution status of the reservoirs in the Haihe River basin, samples were collected from 16 source water reservoirs. The samples were analyzed for the representative organic pollutants, which included benzene homologues, chlorobenzene compounds, organophosphorus pesticides, and nitrobenzene compounds, a total in all of 17 compounds. It was observed that the concentrations of the 17 compounds in the 16 reservoirs were all less than the limit laid down by Chinese surface water quality standards. In addition, benzene, toluene, nitrobenzene, p-nitrochlorobenzene, 2,4-dinitrotoluene and 2,4-dinitrochlorobenzene, dichlorvos, demeton, dimethoate methyl parathion, malathion and parathion were frequently detected in the 16 source water reservoirs, especially the organophosphorus pesticides; the detection rates of dichlorvos, dimethoate, methyl parathion, malathion and parathion were all 100% in the 16 source water reservoirs. The detection rate of target compounds suggested that organic pollution had been common in the source water of the Haihe River basin. The health risk assessment results suggested that the noncarcinogenic risk hazard quotient values of the target compounds were less than one, and the cancer risk values were all below 1 × 10(-6), which indicated that the heath risk produced by the target compounds in the 16 reservoirs was at an acceptable level.

Predicting Ni dynamic mobilization in reservoir riparian soils prior to water submergence using DGT and DIFS

The South-to-North Water Diversion Project has been initiated to address the problem of water shortages in north China. However, the environmental impact of this project is currently unclear, especially for the geochemical process of toxic trace metals in reservoir riparian soil following water submergence. The mobility of Ni in Miyun Reservoir riparian soil samples was investigated using diffusive gradients in thin films (DGT), considering five different land use types and three vertical elevations. The DGT-induced fluxes in soil (DIFS) model was applied to simulate the kinetics of Ni mobilization in the soil. The results showed that the average concentration of Ni was 36.58 mg/kg, which was slightly higher than the corresponding background values reported for both Beijing and China. Coincidentally, the highest concentrations of both total Ni and DGT-labile Ni (CDGT-Ni) were observed at the same site (recreational area), indicating that anthropogenic activities may have contributed to the release of Ni. Land use type and vertical elevation had no significant influence on CDGT-Ni. In addition, CDGT-Ni was positively correlated with reducible fraction, CDGT-Fe, CDGT-Mn, and TOC, indicating that Ni in the soils was adsorbed mainly on the Fe/Mn oxides and organic matter. Moreover, the low values of R (CDGT-Ni/Csol-Ni, R < 0.25) indicated that the replenishment of Ni from the solid phase was poor, and the rate of Ni desorption was considerably lower than its depletion rate, thus leaving only a small proportion of Ni was available.

The concentration and distribution of copper(Cu), arsenic(As), cadmium(Cd) and mercury(Hg) in drinking water of Beijing city

To identify the concentration and distribution characteristics of the Cu, Hg, Cd, As in drinking water of Beijing, the research on the concentration and distribution of in the drinking water of Beijing was carried out. According to the study results, As, Cd, Cu and Hg in the drinking water samples of the urban and suburb of Beijign were present at detectable levels 90.8%, 100%, 100%, 100% and 94.5%, 100%, 100%, 92.7%, respectively. The copper concentration in the urban and suburb drinking water samples ranged from 0.47µg/L to 34.04µg/L, averaging 3.37µg/L, and 0.50 to 15.93µg/L, with an average of 2.82µg/L, the cadmium concentrations ranged from the 0.15µg/L to 0.90µg/L and 0.19µg/L to 1.05µg/L, with an average of 0.47µg/L and 0.54µg/L in the urban and suburb samples, the arsenic concentrations ranged from <0.10 to 4.60µg/L and <0.10 to 6.38µg/L, with an average of 0.67µg/L and 0.75µg/L, the mercury concentrations ranged from 0.33µg/L to 1.33µg/L and <0.10µg/L to 1.14µg/L, with an average of 0.57µg/L and 0.44µg/L in the urban and suburb drinking water samples. The cadmium pollution mainly occurred in the Changping town, arsenic mainly in Tongzhou.