Effects of soil properties on heavy metal accumulation in flowering Chinese cabbage (Brassica campestris L. ssp. chinensis var. utilis Tsen et Lee) in Pearl River Delta,China

This study was conducted to investigate the effects of soil properties on the heavy metal accumulation in flowering Chinese cabbage (Brassica campestris L. ssp. chinensis var. utilis Tsen et Lee) at the field scale. The concentrations of cadmium (Cd), mercury (Hg), and chromium (Cr) in topsoil and vegetable samples from Nanhai district of Foshan city in the Pearl River Delta (PRD) were analyzed. The results showed that 56.5% of the soil samples exceeded the grade II of the Chinese Soil Environmental Quality Standard (GB 15618-1995) for Hg concentrations, while 8.70% and 17.4% of the vegetable samples exceeded the criteria of the Chinese Safety Qualification of Agricultural Products (GB 18406.1-2001) for Cd and Hg concentrations, respectively. The calculated bio-concentration factor (BCF; i.e., the ratio of the metal concentration in the edible parts of flowering Chinese cabbage to that in soil) values were ranked as: Cd (0.1415) > Cr (0.0061) > Hg (0.0012) (p < 0.01), which demonstrated that Cd was easier to be accumulated in the edible parts of flowering Chinese cabbage than Hg and Cr. Furthermore, the following relationships between (bio-concentration factor) BCF values (BCFs) and soil physicochemical properties were concluded from our results: i) the mean BCFs of coarse-textured soils were higher than those of fine-textured soils; ii) the BCFs decreased with increasing soil pH; iii) the soils with high organic matter(OM) and Cation exchange capacity (CEC) have low BCFs, resulting from their high sorption capacities for Cd, Hg, and Cr. The stepwise linear multiple regression analyses showed that total metal concentrations and available calcium in soils were two main factors controlling the accumulation of Cd, Hg, and Cr in the flowering Chinese cabbage.     

Water–gas exchange of organochlorine pesticides at Lake Chaohu, a large Chinese lake

Organochlorine pesticides (OCPs), a potential threat to ecosystems and human health, are still widely residual in the environment. The residual levels of OCPs in the water and gas phase were monitored in Lake Chaohu, a large Chinese lake, from March 2010 to February 2011. Nineteen types of OCPs were detected in the water with a total concentration of 7.27?±?3.32 ng/l. Aldrin, DDTs and HCHs were the major OCPs in the water, accounting for 38.3 %, 28.9 % and 23.6 % of the total, respectively. The highest mean concentration (12.32 ng/l) in the water was found in September, while the lowest (1.74 ng/l) was found in November. Twenty types of gaseous OCPs were detected in the atmosphere with a total concentration of 542.0?±?636.5 pg/m³. Endosulfan, DDTs and chlordane were the major gaseous OCPs in the atmosphere, accounting for 48.9 %, 22.5 % and 14.4 % of the total, respectively. The mean concentration of gaseous OCPs was significantly higher in summer than in winter. o,p′-DDE was the main metabolite of DDT in both the water and gas phase. Of the HCHs, 52.3 % existed as β-HCH in the water, while α-HCH (37.9 %) and γ-HCH (30.9 %) were dominant isomers in the gas phase. The average fluxes were ?21.11, ?3.30, ?152.41, ?35.50 and ?1314.15 ng/(m²?day) for α-HCH, γ-HCH, HCB, DDT and DDE, respectively. The water–gas exchanges of the five types of OCPs indicate that water was the main potential source of gaseous OCPs in the atmosphere. A sensitivity analysis indicated that the water-gas flux of α-HCH, γ-HCH and DDT is more vulnerable than that of HCB and DDE to the variation of the parameters. The possible source of the HCHs in the water was from the historical usage of lindane; however, that in the air was mainly from the recent usage of lindane. The technical DDT and dicofol might be the source of DDTs in the water and air.     

温度对哑硝化及氧化哑氮释放的影响

采用批次实验的方法探讨了3种不同温度（15℃,25℃,35℃）对亚硝化及其过程中温室气体氧化亚氮释放情况。结果表明,温度对亚硝化过程及氧化亚氮的释放有显著影响。在15～35℃范围内,随着温度的升高,氨氧化率和亚硝化积累率逐渐升高,N2O释放量也逐渐增大,35℃可以作为适宜的亚硝化温度,平均氨氧化率为50．9％,亚硝化积累率为55．6％,NO-2-N与Nrl4-N出水浓度比为1．1,氨氧化率,亚硝化积累率和出水中亚硝氮与氨氮浓度比较合适,从而可以为厌氧氨氧化工艺提供合适的进水,但在此温度下平均N2O释放量相对较高,为1．494la,g／gMLSS。     

Comparison of Analytical Techniques for Measuring Hydrocarbon Emissions from the Manufacture of Fiberglass-Reinforced Plastics

ABSTRACT

Research Triangle Institute and the U.S. Environmental Protection Agency conducted several projects to measure hydrocarbon emissions associated with the manufacture of fiberglass-reinforced plastics. The purpose of these projects was to evaluate pollution prevention techniques to reduce emissions by altering raw materials, application equipment, and operator technique. Analytical techniques were developed to reduce the cost of these emission measurements. Emissions from a small test mold in a temporary total enclosure (TTE) correlated with emissions from full-size production molds in a separate TTE. Gravimetric mass balance measurements inside the TTE generally agreed to within ± 30 % with total hydrocarbon (THC) measurements in the TTE exhaust duct. Pure styrene evaporation tests served as quality control checks for THC measurements and generally agreed to within ± 5 %.     

K-Ca-Mg-Cl-H_2O体系中硫酸钙结晶介稳区的研究

对K-Ca-Mg-Cl-H2O体系中硫酸钙结晶介稳区进行了研究。以一定浓度氯化钙溶液与硫酸镁溶液反应结晶的方式,采用激光散射法测定了不同浓度复合盐溶液和温度下硫酸钙过饱和度与结晶之间的关系,并测定了与之平衡的溶解度,从而确定该体系中硫酸钙结晶介稳区宽度,探讨了影响结晶介稳区的因素,以及硫酸钙结晶和结晶相与复合盐溶液浓度、温度、结晶介稳区之间的关系。     

Concentrations, spatial distributions and congener profiles of polychlorinated biphenyls in soils from a coastal city--Tianjin, China

A total of 82 surface soil samples collected from central urban sites, surrounding rural sites, coastal sites and background sites in Tianjin were analyzed for 84 PCB congeners. The mean values of total PCBs concentrations for surrounding rural sites, central urban sites, coastal sites, background sites and the whole Tianjin region were 4.45, 3.20, 12.65, 1.96 and 4.02 ng g(-1), respectively. No "urban fractionation effect" was found in Tianjin, which reflected the influence of local emission sources for PCBs such as industries and township enterprises in surrounding rural sites. In contrast, a "primary fractionation effect" was found in Tianjin region. The PCBs concentrations for whole Tianjin region showed a strong east-west gradient and the percentages of lighter molecular weight PCBs homologs (sum of di- to tetra-PCBs) to the total PCBs concentrations increased from east to west. The seven indicator PCBs concentrations were well correlated with the total PCBs concentrations with the correlation coefficients as 0.76 for Tianjin region and 0.74 for central urban sites, respectively. Predominant PCB homolog groups were penta- and tri-PCBs for Tianjin region. 10 dioxin-like PCBs concentrations were well correlated with total PCBs concentrations for all the sampling sites (R=0.79, P<0.0001). The TEQ concentrations for 10 dioxin-like PCBs were 5.3424 ng kg(-1) for Tianjin region and showed a strong east to west gradient. The spatial distribution of PCBs levels, homolog composition patterns and TEQ concentrations were all obviously influenced by local emission sources for PCBs in the east part of Tianjin region.     

Distribution and accumulation of endocrine-disrupting chemicals and pharmaceuticals in wastewater irrigated soils in Hebei, China

This study investigated the occurrence of 43 emerging contaminants including 9 endocrine-disrupting chemicals and 34 pharmaceuticals in three sites in Hebei Province, north China. Each site has a wastewater irrigated plot and a separate groundwater irrigated plot for comparison purpose. The results showed that the concentrations of the target compounds in the wastewater irrigated soils were in most cases higher than those in the groundwater irrigated soils. Among the 43 target compounds, nine compounds bisphenol-A, triclocarban, triclosan, 4-nonylphenol, salicylic acid, oxytetracycline, tetracycline, trimethoprim and primidone were detected at least once in the soils. Preliminary environmental risk assessment showed that triclocarban might pose high risks to terrestrial organisms while the other detected compounds posed minimal risks. Irrigation with wastewater could lead to presence or accumulation of some emerging contaminants to some extent in irrigated soils.     

Combining Lattice Boltzmann method and genetic algorithm to optimize the layout of artificial floating islands in river network in China

Environmental Science and Pollution Research - How to solve the pollution problem of water environment in river network is a hot issue in the world. Artificial floating island is an efficient way...     

1953-2009年林西站气象要素变化分析

对林西气象站1953-2009年气温、风速、降水量月、季、年观测资料进行了统计,分析了近57年三个要素的年际变化和突变特征,为气象站的迁站资料评估提供参考依据。结果显示,该站近57年平均气温显著升高,平均风速明显减小,两个要素都有明显的突变特征。分析认为,这种变化特征除与区域气候变化的响应有关外,主要与该地城镇的发展及测站周边逐步出现较高建筑物的影响有关。     

高寒地区输电线路锥管板条装配式基础抗冻拔性能试验研究∗

高寒地区分布大量多年冻土,传统的现浇基础由于其抗冻拔性能差、施工周期长,不易采用,考虑受力合理, 施工快速便捷,提出一种可灵活拼装的锥管板条装配式基础。为了分析该种形式基础的抗冻拔特性,开展了5、-10、-15 ℃三种温度梯度条件下的冻结试验,分析了温度场、地基冻胀力、冻胀位移、基础本体应变的变化规律。研究结果表明：① 基础顶部冻拔位移小于地基冻胀位移,由于基础的“约束冻胀”作用,距基础边缘最远处冻胀位移最大;② 地基冻胀力与相应处冻胀位移之间呈正相关,冻胀力随温度降低而增大,且增加幅度随着温度的降低而加大;③ 基础本体所受拉应力远小于材料屈服强度,地基表面首先出现发状细微裂纹,随着后期冻胀力的释放, 裂缝逐渐扩张、延伸;④ 对于以承受上拔荷载为主的输电线路基础可采用回填非冻胀材料、基础表面光滑处理、优化结构形式等工程措施提高其抗拔性能。