Modeling redistribution of α-HCH in Chinese soil induced by environment factors

This study explores long-term environmental fate of alpha-HCH in China from 1952 to 2007 using ChnGPERM (Chinese Gridded Pesticide Emission and Residue Model). The model captures well the temporal and spatial variations of alpha-HCH concentration in Chinese soils by comparing with a number of measured data across China in different periods. The results demonstrate alpha-HCH grasshopping effect in Eastern China and reveal several important features of the chemical in Northeast and Southeast China. It is found that Northeast China is a prominent sink region of alpha-HCH emitted from Chinese sources and alpha-HCH contamination in Southwest China is largely attributed to foreign sources. Southeast China is shown to be a major source contributing to alpha-HCH contamination in Northeast China, incurred by several environmental factors including temperature, soil organic carbon content, wind field and precipitation. (C) 2011 Elsevier Ltd. All rights reserved.This study explores long-term environmental fate of alpha-HCH in China from 1952 to 2007 using ChnGPERM (Chinese Gridded Pesticide Emission and Residue Model). The model captures well the temporal and spatial variations of alpha-HCH concentration in Chinese soils by comparing with a number of measured data across China in different periods. The results demonstrate alpha-HCH grasshopping effect in Eastern China and reveal several important features of the chemical in Northeast and Southeast China. It is found that Northeast China is a prominent sink region of alpha-HCH emitted from Chinese sources and alpha-HCH contamination in Southwest China is largely attributed to foreign sources. Southeast China is shown to be a major source contributing to alpha-HCH contamination in Northeast China, incurred by several environmental factors including temperature, soil organic carbon content, wind field and precipitation. (C) 2011 Elsevier Ltd. All rights reserved

High contribution of anthropogenic combustion sources to atmospheric inorganic reactive nitrogen in South China evidenced by isotopes

Due to the intense release of reactive nitrogen (Nr) from anthropogenic activity, the source layout of atmospheric nitrogen aerosol has changed. The inorganic nitrogen (NH4+ and NO3-) was essential part of atmospheric nitrogen aerosol and accounted for 69 %. To comprehensively clarify the level, sources, and environmental fate of NH4+ and NO3-, their concentrations and stable isotopes (&delta;15N) in fine particulate matters (PM2.5) were measured in a subtropical megacity of South China. N-NH4+ and N-NO3- contributed 45.8 % and 23.2 % to total nitrogen (TN), respectively. The source contributions of NH4+ and NO3- were estimated by &delta;15N, which suggested that anthropogenic combustion activities including coal combustion, biomass burning, and vehicles were dominant sources. Especially, biomass burning was the predominant source of NH4+ (27.9 %). Whereas, coal combustion was the dominant source of NO3- (40.4 %). This study emphasized the substantial impacts of human activities on inorganic Nr. With the rapid development of industry and transportation, nitrogen emissions will be even higher. The promotion of clean energy and efficient use of biomass would help reduce nitrogen emissions and alleviate air pollution.</p

Concentrations, seasonal variations, and outflow of atmospheric polycyclic aromatic hydrocarbons (PAHs) at Ningbo site, Eastern China

AbstractThirty six pairs of gas and particle (PM2.5) atmospheric samples were collected by high-volume samplers from July 2009 to March 2010 at an eastern background site in Ningbo and analyzed for polycyclic aromatic hydrocarbons (PAHs). The total (gas+particle) air concentrations of 16 PAHs ranged from 11.0 to 103ng m−3, with an average of 46.0α23.4ng m−3. Seasonal trends of PAH concentrations were observed with high concentrations in winter and low in summer, mainly due to regional sources and meteorological conditions. The association with other airborne pollutants and diagnostic ratio analysis indicated that PAHs in Eastern China background were predominantly from coal/biomass combustion. Coal combustion controlled atmospheric PAHs in winter, whilst biomass burning became important in summer and autumn. Located at eastern coastal areas, Ningbo site was chosen to estimate the atmospheric outflow of PAHs. Transport fluxes were characterized by elevated values in spring and winter. Southward transport fluxes dominated during the sampling period, presenting the transport from northern to southern China

Gridded inventories of historical usage for selected organochlorine pesticides in Gansu Province, China

HCHs and DDTs were banned in 1983 in China; however, they are still remaining in various environmental media. Since endosulfan was introduced in China in 1994, it is widely used in agriculture. In this study, temporal and spatial uses of endosulfan, HCHs, and DDTs in Gansu province of China have been presented. It is estimated that the total usage is 701 tons for endosulfan between 1994 and 2007, 1,712 tons for HCHs between 1952 and 1983, and 462 tons for DDTs between 1951 and 1983, respectively. Endosulfan usage increased dramatically in 1998 due to its application on other crops except on cotton. The HCH and DDT usage displayed a rapid increase after 1972, reaching the peak in 1976 and in 1975, respectively; since then, they declined until being banned in 1983. The gridded usage inventories of these three kinds of organochlorine pesticides in Gansu province, with a 1/4A degrees longitude by 1/6A degrees latitude resolution, have been created by using different crops for endosulfan and the area of dry farmland for HCHs and DDTs as surrogate data. The most intensive use was in northwestern regions for endosulfan and southeastern regions for HCHs and DDTs in Gansu province

Assessing environmental fate of β-HCH in Asian soil and association with environmental factors

Chinese Gridded Pesticide Emission and Residue Model was applied to simulate long-term environmental fate of beta-HCH in Asia spanning 1948-2009. The model captured well the spatiotemporal variation of beta-HCH soil concentrations across the model domain. beta-HCH use in different areas within the model domain was simulated respectively to assess the influence of the different sources of beta-HCH on its environment fate. A mass center of soil residue (MCSR) was introduced and used to explore environmental factors contributing to the spatiotemporal variation of beta-HCH soil residue. Results demonstrate that the primary emission dominates beta-HCH soil residues during the use of this pesticide. After phase-out of the pesticide in 1999, the change in beta-HCH soil residues has been associated with the Asian summer monsoon, featured by northward displacement of the MCSR. The displacement from several major sources in China and northeastern Asia shows a downward trend at a 95% confidence level, largely caused by environmental degradation and northward delivery of beta-HCH under cold condition in northern area. The MCSRs away from the India and southern and southeastern Asia sources show a rapid northward displacement at a 99% confidence level, featuring the cold trapping effect of the Tibetan Plateau.Chinese Gridded Pesticide Emission and Residue Model was applied to simulate long-term environmental fate of beta-HCH in Asia spanning 1948-2009. The model captured well the spatiotemporal variation of beta-HCH soil concentrations across the model domain. beta-HCH use in different areas within the model domain was simulated respectively to assess the influence of the different sources of beta-HCH on its environment fate. A mass center of soil residue (MCSR) was introduced and used to explore environmental factors contributing to the spatiotemporal variation of beta-HCH soil residue. Results demonstrate that the primary emission dominates beta-HCH soil residues during the use of this pesticide. After phase-out of the pesticide in 1999, the change in beta-HCH soil residues has been associated with the Asian summer monsoon, featured by northward displacement of the MCSR. The displacement from several major sources in China and northeastern Asia shows a downward trend at a 95% confidence level, largely caused by environmental degradation and northward delivery of beta-HCH under cold condition in northern area. The MCSRs away from the India and southern and southeastern Asia sources show a rapid northward displacement at a 99% confidence level, featuring the cold trapping effect of the Tibetan Plateau

Perfluoroalkyl and polyfluoroalkyl substances in the lower atmosphere and surface waters of the Chinese Bohai Sea, Yellow Sea, and Yangtze River estuary

Polyfluoroalkyl and perfluoroalkyl substances (PFASs), in the forms of neutral polyfluoroalkyl substances in the gas phase of air and ionic perfluoroalkyl substances in the dissolved phase of surface water, were investigated during a sampling campaign in the Bohai Sea, Yellow Sea, and Yangtze River estuary in May 2012. In the gas phase, the concentrations of neutral Sigma PFASs were within the range of 76-551 pg/m(3). Higher concentrations were observed in the South Yellow Sea. 8:2 fluorotelomer alcohol (FTOH) was the predominant compound as it accounted for 92%-95% of neutral Sigma PFASs in all air samples. Air mass backward trajectory analysis indicated that neutral Sigma PFASs came mainly from the coast of the Yellow Sea, including the Shandong, Jiangsu, and Zhejiang provinces of China, and the coastal region of South Korea. The fluxes of gas phase dry deposition, were simulated for neutral PFASs, and neutral Sigma PFASs fluxes varied from 0.37 to 23 pg/m(2)/s. In the dissolved phase of the surface water, concentrations of ionic Sigma PFASs ranged from 1.6 to 118 ng/L, with the Bohai Sea exhibiting higher concentrations than both the Yellow Sea and the Yangtze River estuary. Perfluorooctanoic acid (PFOA) was the predominant compound accounting for 51%-90% of the ionic Sigma PFAS concentrations. Releases from industrial and domestic activities as well as the semiclosed geographical conditions increased the level of ionic Sigma PFASs in the Bohai Sea. The spatial distributions of perfluoroalkyl carboxylic acids (PFCAs) and perfluoroalkane sulfonic acids (PFSAs) were different significantly. The Laizhou Bay was the major source region of PFCAs and the Yangtze River estuary was the major source of PFSAs. (C) 2017 Elsevier B.V. All rights reserved

Polychlorinated biphenyls (PCBs) and hexachlorobenzene (HCB) in the equatorial Indian Ocean: Temporal trend, continental outflow and air-water exchange

Nineteen pairs of air and seawater samples collected from the equatorial Indian Ocean onboard the Shiyan I from 4/2011 to 5/2011 were analyzed for PCBs and HCB. Gaseous concentrations of Sigma(ICES)PCBs (ICES: International Council for the Exploration of the Seas) and HCB were lower than previous data over the study area. Air samples collected near the coast had higher levels of PCBs relative to those collected in the open ocean, which may be influenced by proximity to source regions and air mass origins. Dissolved concentrations of Sigma(ICES)PCBs and HCB were 1.4-14 pg L-1 and 0.94-13 pg L-1, with the highest concentrations in the sample collected from Strait of Malacca. Fugacity fractions suggest volatilization of PCBs and HCB from the seawater to air during the cruise, with fluxes of 0.45-34 ng m(-2) d(-1) and 0.36-18 ng m(-2) d(-1), respectively. (c) 2014 Elsevier Ltd. All rights reserved.Nineteen pairs of air and seawater samples collected from the equatorial Indian Ocean onboard the Shiyan I from 4/2011 to 5/2011 were analyzed for PCBs and HCB. Gaseous concentrations of Sigma(ICES)PCBs (ICES: International Council for the Exploration of the Seas) and HCB were lower than previous data over the study area. Air samples collected near the coast had higher levels of PCBs relative to those collected in the open ocean, which may be influenced by proximity to source regions and air mass origins. Dissolved concentrations of Sigma(ICES)PCBs and HCB were 1.4-14 pg L-1 and 0.94-13 pg L-1, with the highest concentrations in the sample collected from Strait of Malacca. Fugacity fractions suggest volatilization of PCBs and HCB from the seawater to air during the cruise, with fluxes of 0.45-34 ng m(-2) d(-1) and 0.36-18 ng m(-2) d(-1), respectively. (c) 2014 Elsevier Ltd. All rights reserved

First Assessment of NOx Sources at a Regional Background Site in North China Using Isotopic Analysis Linked with Modeling

important role in the formation of atmospheric particles. Thus, NOx emission reduction is critical for improving air quality, especially in severely air-polluted regions (e.g., North China). In this study, the source of NOx was investigated by the isotopic composition (delta N-15) of particulate nitrate (p-NO3-) at Beihuangcheng Island (BH), a regional background site in North China. It was found that the delta N-15-NO3- (n = 120) values varied between -1.7 parts per thousand and +24.0 parts per thousand and the delta O-18-NO3- values ranged from 49.4 parts per thousand to 103.9 parts per thousand. On the basis of the Bayesian mixing model, 27.78 +/- 8.89%, 36.53 +/- 6.66%, 22.01 +/- 6.92%, and 13.68 +/- 3.16% of annual NOx could be attributed to biomass burning, coal combustion, mobile sources, and biogenic soil emissions, respectively. Seasonally, the four sources were similar in spring and fall. Biogenic soil emissions were augmented in summer in association with the hot and rainy weather. Coal combustion increased significantly in winter with other sources showing an obvious decline. This study confirmed that isotope-modeling by delta N-15-NO3- is a promising tool for partitioning NOx sources and provides guidance to policymakers with regard to options for NOx reduction in North China