Jianxin Hu

Polybrominated diphenyl ethers (PBDEs) and other flame retardants in the atmosphere and water from Taihu Lake, East China.

Air and water samples were collected from Taihu Lake, East China through 2004 and analyzed for 33 congeners of polybrominated diphenyl ether (PBDE) and other seven brominated and chlorinated flame retardants. The annual concentration of total atmospheric PBDEs was 220 pg m(-3); BDE-209 was most abundant (average 41% of total PBDEs), followed by BDE-47 (17%) and BDE-28 (15%). The relative abundance of tetra- and tri-BDE congeners (including BDE-47, -28, -49, -66, and -17) instead of BDE-99 indicated that a specific penta-BDE formulation might be produced and/or consumed in this region. The source was confirmed by the analysis of air-water gas exchange, which was nearly at equilibrium in spring and summer but displayed strong volatilization flux in autumn and winter, especially for BDE-28, indicating the potential wastewater discharge of PBDEs into the lake. In addition to PBDEs, hexabromobenzene, 1,2-bis(2,4,6-tribromophenoxy)ethane, decabromodiphenylethane, and Dechlorane Plus were detected in air samples, with an annual mean concentration of 23 pg m(-3) for decabromodiphenylethane, and <4 pg m(-3) for the others.

The inventory of sources, environmental releases and risk assessment for perfluorooctane sulfonate in China

With about 100 t/y of the production volume, perfluorootane sulfonates (PFOS) are mainly used for metal plating, aqueous fire-fighting foams (AFFFs) and sulfluramidin China, and the use amount is about 30-40 t/y, 25-35 t/y and 4-8 t/y respectively. Based on the inventory of PFOS production and uses with geographic distribution educed from statistics, environmental risk assessment of PFOS was taken by using EUSES model, as well as its environmental releases were estimated both in local and regional levels in China. While the environmental release from manufacture is significant in Central China region, metal plating was identified as the major PFOS release source in regional level. The East China region shows the most strong emission strength of PFOS. Though the predicted environmental concentrations (PECs) were not exceed current relevant predicted no effect concentrations (PNECs) of the risk characterization for PFOS, higher PECs was estimated around major PFOS release sources showing undesirable environmental risk at local level.

Sulfur Hexafluoride (SF6) Emission Estimates for China: An Inventory for 1990–2010 and a Projection to 2020

Sulfur hexafluoride (SF6) is the most potent greenhouse gas regulated under the Kyoto Protocol, with a high global warming potential. In this study, SF6 emissions from China were inventoried for 1990-2010 and projected to 2020. Results reveal that the highest SF6 emission contribution originates from the electrical equipment sector (about 70%), followed by the magnesium production sector, the semiconductor manufacture sector and the SF6 production sector (each about 10%). Both agreements and discrepancies were found in comparisons of our estimates with previously published data. An accelerated growth rate was found for Chinese SF6 emissions during 1990-2010. Because the relative growth rate of SF6 emissions is estimated to be much higher than those of CO2, CH4, and N2O, SF6 will play an increasing role in greenhouse gas emissions in China. Global contributions from China increased rapidly from 0.9 ± 0.3% in 1990 to 22.8 ± 6.3% in 2008, making China one of the crucial contributors to the recent growth in global emissions. Under the examined Business-as-usual (BAU) Scenario, projected emissions will reach 4270 ± 1020 t in 2020, but a reduction of about 90% of the projected BAU emissions would be obtained under the Alternative Scenario.

Estimating industrial and domestic environmental releases of perfluorooctanoic acid and its salts in China from 2004 to 2012

China has been documented as one of the few remaining producers of perfluorooctanoic acid and its salts (PFOA/PFO) and the worlds major contamination hotspot. However, limited information has been available for evaluating their environmental releases in China and the contribution to global PFOA/PFO burden. Here we present the first source-specific inventory for environmental releases of PFOA/PFO in China from 2004 to 2012, using a bottom-up approach for industrial sources and an inverse approach for domestic sources. Our results show that China became the current worlds largest PFOA/PFO emitter, with cumulative environmental releases reaching 250tonnes (t) over the period of nine years. The eastern region was identified as the hotspot of environmental releases. Most of the national environmental releases were due to the activities of the fluorochemical industry (94.0%) rather than domestic use of PFOA/PFO-related consumer products (6.0%). Fluoropolymer manufacturing and processing, a dominating industrial source, contributed 83.7% of the national environmental releases. In contrast to the general decline trends in annual industrial environmental releases of PFOA/PFO in most industrialized countries, the trend increased in China because of the expansion of production as a result of the global geographical transition in fluorochemical industry. Based on these results, we recommend that the future reduction options are required in industrial sector in China.

Reducing Nitrous Oxide Emissions to Mitigate Climate Change and Protect the Ozone Layer

Reducing nitrous oxide (N2O) emissions offers the combined benefits of mitigating climate change and protecting the ozone layer. This study estimates historical and future N2O emissions and explores the mitigation potential for Chinas chemical industry. The results show that (1) from 1990 to 2012, industrial N2O emissions in China grew by some 37-fold from 5.07 to 174 Gg (N2O), with total accumulated emissions of 1.26 Tg, and (2) from 2012 to 2020, the projected emissions are expected to continue growing rapidly from 174 to 561 Gg under current policies and assuming no additional mitigation measures. The total accumulated mitigation potential for this forecast period is about 1.54 Tg, the equivalent of reducing all the 2011 greenhouse gases from Australia or halocarbon ozone-depleting substances from China. Adipic acid production, the major industrial emission source, contributes nearly 80% of the industrial N2O emissions, and represents about 96.2% of the industrial mitigation potential. However, the mitigation will not happen without implementing effective policies and regulatory programs.

Polybrominated diphenyl ethers in farmland soils: source characterization, deposition contribution and apportionment.

Polybrominated diphenyl ethers (PBDEs), a group of persistent organic pollutants (POPs), are caused for concern recently due to their adverse health effects and environmental ubiquity. In this study, atmospheric and soil PBDE levels in Taizhou, one of the largest WEEE dismantling areas in the world, were measured, ranging from 884 to 2791 pg m(-3) with an average of 1968 pg m(-3) for atmosphere and 2.96 to 200 ng g(-1)dry weight (dw) with the mean of 65.2 ng g(-1)dw for farmland soils, respectively. The close connection between soil PBDE accumulation and atmospheric deposition was also revealed by the estimation of the annual PBDE deposition flux (3.1 ± 0.9 mg m(-2)a(-1)) and the similarity between deposited congener pattern and soil congener profile. Positive matrix factorization (PMF) was conducted to extract possible sources of farmland soil PBDEs and to calculate their contributions. Based on the measured source profiles of PBDE-related activities, five sources were identified representing WEEE dumping, WEEE dismantling, WEEE open burning, residential waste dismantling, and residential waste open burning. WEEE-related recycling activities contributed primary percentage (52%) to farmland soil PBDE concentration, and open burning was an important pathway for PBDEs entering the environment.

Global Inventory, Long-Range Transport and Environmental Distribution of Dicofol

The uncertainties on whether dicofol can be identified as a persistent organic pollutant (POP) in terms of its long-range transport (LRT) potential and global distribution, are always a controversial topic during international regulation deliberations. The lack of monitoring data in remote background regions necessitates a model-based evaluation approach for assessing the global distribution of dicofol. However, few model simulations are available at present, as there is no inventory available for global historical usage of dicofol that has sufficiently high spatial and temporal resolution. To describe the current status of global emission, we first developed an inventory of global dicofol usage for the period of 2000-2012 at 1° × 1° latitude/longitude resolution. We then assessed the LRT potential of dicofol by calculating its Arctic Contamination Potential using the Globo-POP model. In addition, we simulated the global mass distribution and the fate of dicofol in the environment using the BETR-Global model at 15° × 15° latitude/longitude resolution. Our estimated inventory established that over the period of 13 years, a total of 28.2 kilo tonnes (kt) of dicofol was applied and released into the environment. East and Southeast Asia, the Mediterranean Coast, and Northern and Central America were identified as hotspots of usage and release. Dicofol exhibited a higher Arctic Contamination Potential than several confirmed Arctic contaminants, and a larger current volume of consumption than most existing POPs. The results of our BETR-Global simulation suggest that (i) dicofol can indeed be transported northward, most likely driven by both atmospheric and oceanic advections from source regions at midlatitudes, and (ii) dicofol will be enriched in remote background regions. Continuous use of dicofol in source regions will result in exposure both locally and in remote regions, and the examination of the potential for adverse effects is therefore of paramount importance. Proactive restrictions at the international level may be warranted.

Global Performance and Trend of QSAR/QSPR Research: A Bibliometric Analysis

A bibliometric analysis based on the Science Citation Index Expanded was conducted to provide insights into the publication performance and research trend of quantitative structure‐activity relationship (QSAR) and quantitative structure‐property relationship (QSPR) from 1993 to 2012. The results show that the number of articles per year quadrupled from 1993 to 2006 and plateaued since 2007. Journal of Chemical Information and Modeling was the most prolific journal. The internal methodological innovations in acquiring molecular descriptors and modeling stimulated the articles’ increase in the research fields of drug design and synthesis, and chemoinformatics; while the external regulatory demands on model validation and reliability fueled the increase in environmental sciences. “Prediction endpoints”, “statistical algorithms”, and “molecular descriptors” were identified as three research hotspots. The articles from developed countries were larger in number and more influential in citation, whereas those from developing countries were higher in output growth rates.

Historical Emissions of HFC-23 (CHF3) in China and Projections upon Policy Options by 2050

Trifluoromethane (CHF3, HFC-23) is one of the hydrofluorocarbons (HFCs) regulated under the Kyoto Protocol with a global warming potential (GWP) of 14u2009800 (100-year). Chinas past, present, and future HFC-23 emissions are of considerable interest to researchers and policymakers involved in climate change. In this study, we compiled a comprehensive historical inventory (1980-2012) and a projection (2013-2050) of HFC-23 production, abatements, and emissions in China. Results show that HFC-23 production in China increased from 0.08 ± 0.05 Gg/yr in 1980 to 15.4 ± 2.1 Gg/yr (228 ± 31 Tg/yr CO2-eq) in 2012, while actual HFC-23 emissions reached a peak of 10.5 ± 1.8 Gg/yr (155 ± 27 Tg/y CO2-eq) in 2006, and decreased to a minimum of 7.3 ± 1.3 Gg/yr (108 ± 19 Tg/yr CO2-eq) in 2008 and 2009. Under the examined business-as-usual (BAU) scenario, the cumulative emissions of HFC-23 in China over the period 2013-2050 are projected to be 609 Gg (9015 Tg CO2-eq which approximates Chinas 2012 CO2 emissions). Currently, Chinas annual HFC-23 emissions are much higher than those from the developed countries, while it is estimated that by year 2027, Chinas historic contribution to the global atmospheric burden of HFC-23 will have surpassed that of the developed nations under the BAU scenario.

Hydrofluorocarbon (HFC) Emissions in China: An Inventory for 2005–2013 and Projections to 2050

Many hydrofluorocarbons (HFCs) that are widely used as substitutes for ozone-depleting substances (now regulated under the Montreal Protocol) are very potent greenhouse gases (GHGs). Chinas past and future HFC emissions are of great interest because China has emerged as a major producer and consumer of HFCs. Here, we present for the first time a comprehensive inventory estimate of Chinas HFC emissions during 2005-2013. Results show a rapid increase in HFC production, consumption, and emissions in China during the period and that the emissions of HFC with a relatively high global warming potential (GWP) grew faster than those with a relatively low GWP. The proportions of Chinas historical HFC CO2-equivalent emissions to Chinas CO2 emissions or global HFC CO2-equivalent emissions increased rapidly during 2005-2013. Using the business-as-usual (BAU) scenario, in which HFCs are used to replace a significant fraction of hydrochlorofluorocarbons (HCFCs) in China (to date, there are no regulations on HFC uses in China), emissions of HFCs are projected to be significant components of Chinas and global future GHG emissions. However, potentials do exist for minimizing Chinas HFC emissions (for example, if regulations on HFC uses are established in China). Our findings on Chinas historical and projected HFC emission trajectories could also apply to other developing countries, with important implications for mitigating global GHG emissions.