Qing-Mei Wang

Spatio-temporal distributions and the ecological and health risks of phthalate esters (PAEs) in the surface water of a large, shallow Chinese lake.

The spatio-temporal distributions and the ecological and health risks of PAEs in surface water of Lake Chaohu, the fifth largest lake in China, were studied based on the monthly monitoring of six PAE congeners from May 2010 to April 2011. The annual total concentration of the six PAE congeners (Σ6PAE) in the surface water ranged from 0.467 to 17.953 μg L(-1), with the average value of 4.042±3.929 μg L(-1). The di-n-butyl phthalate (DnBP) that dominated the Σ6PAE at 65.8% was found at its highest and lowest levels in the western lake (TX) and eastern drinking water source area (JC), respectively. The temporal distributions of Σ6PAE showed that the highest and lowest levels were observed in September 2010 and June 2010, respectively. The different relationships between the runoff and the PAEs with low and high levels of carbon might suggest their different sources. The DnBP had much greater ecological risks than the other studied PAE congeners as indicated by its potential affected fractions (PAFs) and the margin of safety (MOS10). The PAE congeners studied posed little health risk to the nearby male and female citizens.

Distribution, partitioning and sources of polycyclic aromatic hydrocarbons in the water-SPM-sediment system of Lake Chaohu, China.

The residual levels of polycyclic aromatic hydrocarbons (PAHs) in the water, suspended particular matter (SPM) and sediment from Lake Chaohu were measured with a gas chromatograph-mass spectrometer (GC-MS). The spatial-temporal distributions and the SPM-water partition of PAHs and their influencing factors were investigated. The potential sources and contributions of PAHs in the sediment were estimated by positive matrix factorization (PMF) and probabilistic stable isotopic analysis (PSIA). The results showed that the average residual levels of total PAHs (PAH16) in the water, SPM and sediment were 170.7 ± 70.8 ng/L, 210.7 ± 160.7 ng/L and 908.5 ± 1878.1 ng/g dry weight, respectively. The same spatial distribution trend of PAH16 in the water, SPM and sediment was found from high to low: river inflows>western lake>eastern lake>water source area. There was an obvious seasonal trend of PAH16 in the water, while no obvious seasonal trend was found in the SPM. The residues and distributions of PAHs in the water, SPM and sediment relied heavily on carbon content. Significant Pearson correlations were found between LogKoc and LogKow as well as some hydro-meteorological factors. Three major sources of PAHs including coal and biomass combustions, and vehicle emissions were identified.

Residues, Distributions, Sources, and Ecological Risks of OCPs in the Water from Lake Chaohu, China

The levels of 18 organochlorine pesticides (OCPs) in the water from Lake Chaohu were measured by a solid phase extraction-gas chromatography-mass spectrometer detector. The spatial and temporal distribution, possible sources, and potential ecological risks of the OCPs were analyzed. The annual mean concentration for the OCPs in Lake Chaohu was 6.99 ng/L. Aldrin, HCHs, and DDTs accounted for large proportions of the OCPs. The spatial pollution followed the order of Central Lakes > Western Lakes > Eastern Lakes and water area. The sources of the HCHs were mainly from the historical usage of lindane. DDTs were degraded under aerobic conditions, and the main sources were from the use of technical DDTs. The ecological risks of 5 OCPs were assessed by the species sensitivity distribution (SSD) method in the order of heptachlor > γ-HCH > p,p′-DDT > aldrin > endrin. The combining risks of all sampling sites were MS > JC > ZM > TX, and those of different species were crustaceans > fish > insects and spiders. Overall, the ecological risks of OCP contaminants on aquatic animals were very low.

Polybrominated diphenyl ethers (PBDEs) in the surface sediments and suspended particulate matter (SPM) from Lake Chaohu, a large shallow Chinese lake

Suspended particulate matter (SPM) and surface sediment samples were collected from Lake Chaohu to investigate the residues, congener profile, and spatial distribution of polybrominated diphenyl ethers (PBDEs) in a large shadow lake in the middle of the Yangtze River Basin. The concentration of Σ13BDEs (defined as the sum of 13 target congeners excluding BDE 209) and the concentration of BDE 209 ranged from 236.7 to 1373.4 pg/g dry weight (dw) and from 4.2 to 691.2 pg/g dw in the surface sediments, respectively, which were 2-3 orders of magnitude smaller than those found in the SPM. The congener composition was dominated by BDE 47 (50.8%) and BDE 209 (21.3%) in the sediment, while the proportion of BDE 47 to Σ14BDEs in the SPM was slightly higher than that in the sediment. The concentration of Σ14BDEs in the sediment from the drinking water source (WR) area in the eastern part of the lake was very low, with a mean value of 514.8 pg/g, whereas the mean concentration was 102.4 ng/g in the SPM. A cluster analysis (CA) was conducted to further illustrate the dominance of each congener and the similarity of each sampling site. Many factors, including resuspension, photodecomposition, microbial oxidation, local discharge, and dredging, influenced the distribution in the sediment and SPM for the PBDE congeners as well as the spatial distribution of PBDEs. A formula for the PBDE concentrations in the surface sediment and SPM was constructed to understand the potential relationship between sediment and SPM concentrations. Although the formula did not accurately predict specific PBDE congener concentrations in the sediment, it remains a practical and useful way to assess the overall pollution of PBDE in sediment in Lake Chaohu, as it depends only on the concentrations of PBDEs in the SPM.

Atmospheric partitioning and the air–water exchange of polycyclic aromatic hydrocarbons in a large shallow Chinese lake (Lake Chaohu)

The residual levels of polycyclic aromatic hydrocarbons (PAHs) in the atmosphere and in dissolved phase from Lake Chaohu were measured by (GC-MS). The composition and seasonal variation were investigated. The diffusive air-water exchange flux was estimated by a two-film model, and the uncertainty in the flux calculations and the sensitivity of the parameters were evaluated. The following results were obtained: (1) the average residual levels of all PAHs (PAH16) in the atmosphere from Lake Chaohu were 60.85±46.17 ng m(-3) in the gaseous phase and 14.32±23.82 ng m(-3) in the particulate phase. The dissolved PAH16 level was 173.46±132.89 ng L(-1). (2) The seasonal variation of average PAH16 contents ranged from 43.09±33.20 ng m(-3) (summer) to 137.47±41.69 ng m(-3) (winter) in gaseous phase, from 6.62±2.72 ng m(-3) (summer) to 56.13±22.99 ng m(-3) (winter) in particulate phase, and 142.68±74.68 ng L(-1) (winter) to 360.00±176.60 ng L(-1) (summer) in water samples. Obvious seasonal trends of PAH16 concentrations were found in the atmosphere and water. The values of PAH16 for both the atmosphere and the water were significantly correlated with temperature. (3) The monthly diffusive air-water exchange flux of total PAH16 ranged from -1.77×10(4) ng m(-2) d(-1) to 1.11×10(5) ng m(-2) d(-1), with an average value of 3.45×10(4) ng m(-2) d(-1). (4) The results of a Monte Carlo simulation showed that the monthly average PAH fluxes ranged from -3.4×10(3) ng m(-2) d(-1) to 1.6×10(4) ng m(-2) d(-1) throughout the year, and the uncertainties for individual PAHs were compared. (5) According to the sensitivity analysis, the concentrations of dissolved and gaseous phase PAHs were the two most important factors affecting the results of the flux calculations.

Levels, Temporal-Spatial Variations, and Sources of Organochlorine Pesticides in Ambient Air of Lake Chaohu, China

The residual levels of OCPs in the gas phase and particle phase in Lake Chaohu, China, were measured using GC-MS from March 2010 to February 2011. The temporal-spatial variations and sources of OCPs were also analyzed. Twenty types of OCPs were detected in the gas phase with a total concentration of 484.8 ± 550.4 pg/m3. Endosulfan, DDTs and chlordane were the primary OCPs in the gas phase. The mean concentration of OCPs in the gas phase was significantly higher in the summer than in the winter. Seventeen types of OCPs were detected in the particle phase with a total concentration of 18.3 ± 26.1 pg/m3. DDTs were major OCPs in the particle phase. The mean concentration of OCPs in the particle phase decreased at first and then increased during the period. The potential source of the HCHs in ambient air of Lake Chaohu might come from recent lindane usage. DDTs mainly came from historical dicofol usage, and an input of DDT was observed in the spring, which may result from the present use of marine paint that contains technical DDT. Endosulfan and chlordane in the air may be due to the present use of technical endosulfan and chlordane.

Distributions, Sources, and Backward Trajectories of Atmospheric Polycyclic Aromatic Hydrocarbons at Lake Small Baiyangdian, Northern China

Air samples were collected seasonally at Lake Small Baiyangdian, a shallow lake in northern China, between October 2007 and September 2008. Gas phase, particulate phase and dust fall concentrations of polycyclic aromatic hydrocarbons (PAHs) were measured using a gas chromatograph-mass spectrometer (GC-MS). The distribution and partitioning of atmospheric PAHs were studied, and the major sources were identified; the backward trajectories of air masses starting from the center of Lake Small Baiyangdian were calculated for the entire year. The following results were obtained: (1) The total concentration of 16 priority controlled PAHs (PAH16) in the gas phase was 417.2 ± 299.8 ng·m−3, in the particulate phase was 150.9 ± 99.2 ng·m−3, and in dust fall was 6930.2 ± 3206.5 ng·g−1. (2) Vehicle emission, coal combustion, and biomass combustion were the major sources in the Small Baiyangdian atmosphere and accounted for 28.9%, 45.1% and 26.0% of the total PAHs, respectively. (3) Winter was dominated by relatively greater PAHs polluted northwesterly air mass pathways. Summer showed a dominant relatively clean southern pathway, whereas the trajectories in autumn and spring might be associated with high pollution from Shanxi or Henan province.

Simulation of the fate and seasonal variations of α-hexachlorocyclohexane in Lake Chaohu using a dynamic fugacity model.

Fate and seasonal variations of α-hexachlorocyclohexane (α-HCH) were simulated using a dynamic fugacity model in Lake Chaohu, China. Sensitivity analyses were performed to identify influential parameters and Monte Carlo simulation was conducted to assess model uncertainty. The calculated and measured values of the model were in good agreement except for suspended solids, which might be due to disregarding the plankton in water. The major source of α-HCH was an input from atmospheric advection, while the major environmental outputs were atmospheric advection and sediment degradation. The net annual input and output of α-HCH were approximately 0.294 t and 0.412 t, respectively. Sediment was an important sink for α-HCH. Seasonal patterns in various media were successfully modeled and factors leading to this seasonality were discussed. Sensitivity analysis found that parameters of source and degradation were more important than the other parameters. The sediment was influenced more by various parameters than air and water were. Temperature variation had a greater impact on the dynamics of the model output than other dynamic parameters. Uncertainty analysis showed that the model uncertainty was relatively low but significantly increased in the second half of the simulation period due to the increase in the gas-water diffusion flux variability.

Development of Structural Dynamic Model for the Ecosystem Evolution of a Large Shallow Chinese Lake (Lake Chaohu)

Abstract An ecological model focusing on phosphorus cycling was developed for eutrophic Lake Chaohu, China, and calibrated based on monthly observations from May 1987 to April 1988. The model results agreed with the observations. Subsequently, the long-term effects of six proposed restoration strategies for Lake Chaohu were predicted by a 25-year simulation. The results showed that ecological economy water level (EEWL), which makes the water depth lower in the spring than usual, resulted in a significant reduction of the phytoplankton and recovery of submerged vegetation. Therefore, EEWL is recommended as the most practical and effective restoration method. Afterwards, structural dynamic models (SDMs) were introduced into a 5-year simulation to account for the rapid structure transition from phytoplankton domination to submerged vegetation domination. Two parameters (growth and phosphorus uptake rate of phytoplankton) are included in SDM1, and two more parameters (mortality rate of phytoplankton and submerged vegetation) are included in SDM2. In conclusion: (1) Under both scenarios, the parameters in both SDM1 and SDM2 showed a decreasing trend; (2) the exergy in SDMs was generally higher than that in non-SDMs, indicating a better “solution” for the ecosystem with a greater possibility to survive; (3) In SDM2 with more changing parameters, the first two parameters had similar variation trends as in SDM1 but more fluctuations and more realistic final values within theoretical ranges. The exergy was also higher than that in SDM1.