Spatial-temporal distribution and transport flux of polycyclic aromatic hydrocarbons in a large hydropower reservoir of Southeast China: Implication for impoundment impacts.

In order to investigate the impacts of dam-related water impoundment on the spatial-temporal variations and transport of anthropogenic organic pollutants, 15 priority polycyclic aromatic hydrocarbons (PAHs) were analyzed in water samples from the Shuikou Reservoir (SKR) of the Minjiang River. The SKR was formed after the construction of the Shuikou Dam, which is the largest hydropower station in Southeast China. The water samples were collected from the backwater zone of the SKR, in both the wet and dry seasons, corresponding to the drainage and impoundment periods of water flow, respectively. The concentrations of the dissolved PAHs in surface water from the wet season (average of 161 ± 97 ng L-1) were significantly higher (ANOVA, p < 0.01) than those from the dry season (average of 43 ± 21 ng L-1). PAH concentrations in the SKR decreased from upstream (industrialized cities) to downstream (rural towns or counties), indicating high PAH loads caused by intensive urbanization effects. The high proportions of 3-ring PAHs in the wet season were from local sources via surface runoff; while the elevated proportions of 4- to 6- ring PAHs in the dry season reflected atmospheric deposition emerged of these PAHs and/or volatilization of 3-ring PAHs enhanced. Molecular diagnostic ratios of PAH isomers in multimedium and principal component analysis indicated that PAH presence in the SKR was mainly attributed to pyrogenic origin. The isomeric ratios of fluoranthene to fluoranthene plus pyrene in the wet season were homogeneous, implying that there were continuous new inputs along the riverine runoff. However, these ratios showed spatial downward trend in the dry season, indicating continued degradation of PAHs occurred along the transport path during the impoundment period. The input and output fluxes of PAHs in the SKR were 5330 kg yr-1 and 2991 kg yr-1, revealing that the reservoir retained contaminants after impoundment of the hydropower dam

Spatial-temporal distribution and transport flux of polycyclic aromatic hydrocarbons in a large hydropower reservoir of Southeast China: Implication for impoundment impacts

Abstract(#br)In order to investigate the impacts of dam-related water impoundment on the spatial-temporal variations and transport of anthropogenic organic pollutants, 15 priority polycyclic aromatic hydrocarbons (PAHs) were analyzed in water samples from the Shuikou Reservoir (SKR) of the Minjiang River. The SKR was formed after the construction of the Shuikou Dam, which is the largest hydropower station in Southeast China. The water samples were collected from the backwater zone of the SKR, in both the wet and dry seasons, corresponding to the drainage and impoundment periods of water flow, respectively. The concentrations of the dissolved PAHs in surface water from the wet season (average of 161 ± 97 ng L −1 ) were significantly higher (ANOVA, p < 0.01) than those from the dry season (average of 43 ± 21 ng L −1 ). PAH concentrations in the SKR decreased from upstream (industrialized cities) to downstream (rural towns or counties), indicating high PAH loads caused by intensive urbanization effects. The high proportions of 3-ring PAHs in the wet season were from local sources via surface runoff; while the elevated proportions of 4- to 6- ring PAHs in the dry season reflected atmospheric deposition emerged of these PAHs and/or volatilization of 3-ring PAHs enhanced. Molecular diagnostic ratios of PAH isomers in multimedium and principal component analysis indicated that PAH presence in the SKR was mainly attributed to pyrogenic origin. The isomeric ratios of fluoranthene to fluoranthene plus pyrene in the wet season were homogeneous, implying that there were continuous new inputs along the riverine runoff. However, these ratios showed spatial downward trend in the dry season, indicating continued degradation of PAHs occurred along the transport path during the impoundment period. The input and output fluxes of PAHs in the SKR were 5330 kg yr −1 and 2991 kg yr −1 , revealing that the reservoir retained contaminants after impoundment of the hydropower dam

Comparative Study Reveals Insights of Sheepgrass (Leymus chinensis) Coping With Phosphate-Deprived Stress Condition

Sheepgrass [Leymus chinensis (Trin.) Tzvel] is a valuable forage plant highly significant to the grassland productivity of Euro-Asia steppes. Growth of above-ground tissues of L. chinensis is the major component contributing to the grass yield. Although it is generally known that this species is sensitive to ecosystem disturbance and adverse environments, detailed information of how L. chinensis coping with various nutrient deficiency especially phosphate deprivation (-Pi) is still limited. Here, we investigated impact of Pi-deprivation on shoot growth and biomass accumulation as well as photosynthetic properties of L. chinensis. Growth inhibition of Pi-deprived seedlings was most obvious and reduction of biomass accumulation and net photosynthetic rate (Pn) was 55.3 and 63.3%, respectively, compared to the control plants grown under Pi-repleted condition. Also, we compared these characters with seedlings subjected to low-Pi stress condition. Pi-deprivation caused 18.5 and 12.3% more reduction of biomass and Pn relative to low-Pi-stressed seedlings, respectively. Further analysis of in vivo chlorophyll fluorescence and thylakoid membrane protein complexes using 2D-BN/SDS-PAGE combined with immunoblot detection demonstrated that among the measured photosynthetic parameters, decrease of ATP synthase activity was most pronounced in Pi-deprived plants. Together with less extent of lipid peroxidation of the thylakoid membranes and increased ROS scavenger enzyme activities in the leaves of Pi-deprived seedlings, we suggest that the decreased activity of ATP synthase in their thylakoids is the major cause of the greater reduction of photosynthetic efficiency than that of low-Pi stressed plants, leading to the least shoot growth and biomass production in L. chinensis

Concentration, distribution and sources of perfluoroalkyl substances and organochlorine pesticides in surface sediments of the northern Bering Sea, Chukchi Sea and adjacent Arctic Ocean.

Perfluoroalkyl substances (PFAS) and organochlorine pesticides (OCPs) in surface sediments were investigated from the Bering Sea, the Chukchi Sea and adjacent Arctic Ocean in 2010. Total concentrations (dry weight) of Σ14PFAS in surface sediments (0.85 ± 0.22 ng g-1) of the Bering Sea were lower than that in the Chukchi Sea and adjacent Arctic Ocean (1.27 ± 0.53 ng g-1). Perfluoro-butanoic acid (PFBS) and perfluoro-octanoic acid (PFOA) were the dominant PFAS in these areas. The concentrations of Σ15OCPs in the sediment of the Bering Sea (13.00 ± 6.17 ng g-1) was slightly higher than that in the Chukchi and Arctic Ocean (12.05 ± 2.27 ng g-1). The most abundant OCPs were hexachlorocyclohexane isomers (HCHs) and dichlorodiphenyltrichloroethane (DDT) and its metabolites. The composition patterns of HCHs and DDTs indicated that they were mainly derived from the early residues via river runoff. Increasing trends of PFAS, HCHs and DDTs in surface sediments from the Bering Sea to the Arctic Ocean were found, indicating oceanic transport. In summary, the concentrations of OCPs were orders of magnitude greater than the observed PFAS concentrations, and the concentrations of PFAS and OCPs in surface sediments from the Bering Sea to the Chukchi Sea and adjacent Arctic Ocean are at the low to moderate levels by comparing with other coastal and marine sediments worldwide

Occurrence and partitioning behavior of per- and polyfluoroalkyl substances (PFASs) in water and sediment from the Jiulong Estuary-Xiamen Bay, China.

Twenty-four per- and polyfluoroalkyl substances (PFASs) were analyzed in water and sediment from the Jiulong Estuary-Xiamen Bay to study their seasonal variations, transport, partitioning behavior and ecological risks. The total concentration of PFASs in water ranged from 11 to 98 ng L-1 (average 45 ng L-1) during the dry season, 0.19-5.7 ng L-1 (average 1.5 ng L-1) during the wet season, and 3.0-5.4 ng g-1 dw (average 3.9 ng g-1 dw) in sediment. In water samples, short-chain PFASs were dominated by perfluorooctanoic acid (PFBA) in the dry season and perfluorobutane sulfonate (PFBS) in the wet season, while long chain PFASs, such as perfluorooctane sulfonate (PFOS), dominated in the sediment. The highest concentration of PFASs in water were found in the estuary; in contrast, the highest level of PFASs in sediment were found in Xiamen Bay. These spatial distributions of PFASs indicate that river discharge is the main source of PFASs in estuarine water, while the harbor, airport and wastewater treatment plant near Xiamen Bay may be responsible for the high PFBS and PFOS concentrations in water and sediment. The partition coefficients (log Kd) of PFASs between sediment and water (range from 1.64 to 4.14) increased with carbon chain length (R2 = 0.99) and also showed a positive relationship with salinity. A preliminary environmental risk assessment indicated that PFOS and perfluorooctanoic acid (PFOA) in water and sediment pose no significant ecological risk to organisms

Sustainable high-strength alkali-activated slag concrete is achieved by recycling emulsified waste cooking oil

To mitigate the shrinkage of high-strength alkali-activated slag concrete (AASC), this paper introduces emulsified cooking oil (ECO) and emulsified waste cooking oil (EWCO) into the AASC system. The effects of admixing ECO and EWCO on the compressive strength, drying shrinkage, autogenous shrinkage, carbonation, and sulfuric acid resistance of the AASC are systematically explored. The optimization mechanism is also proposed based on the surface tension and microstructural analysis. The experimental results show that the admixing ECO and EWCO slightly reduce the compressive strength of the AASC by 7.8%. Interestingly, the admixing ECO and EWCO significantly reduce the drying shrinkage and autogenous shrinkage, simultaneously improving the resistance to carbonation and sulfuric acid of the AASC. Specifically, the introduction of 2 wt.% ECO and EWCO can reduce the autogenous shrinkage of the AASC by 66.7% and 41.0%, respectively. Microstructural observations reveal that the addition of ECO and EWCO can reduce the internal surface tension of the AASC, improve the transport and diffusion of the pore solution, and increase the absorbable free water of the slag, which in turn reduces the shrinkage of the composites. It also increases the ionic concentration in the pore solution, resulting in a more complete reaction of the AASC, which can optimize the pore structure and thus improve the durability of the AASC. This study proposes a promising way to develop sustainable alkali-activated slag concrete achieved by recycling waste materials