Plant uptake and dissipation of PBDEs in the soils of electronic waste recycling sites

Plant uptake and dissipation of weathered PBDEs in the soils of e-waste recycling sites were investigated in a greenhouse study. Eighteen PBDE congeners (tri- through deca-) were detected in the plant tissues. The proportion of lower brominated PBDEs (mono- through hexa-) in plant roots was higher than that in the soils. A concentration gradient was observed of PBDEs in plants with the highest concentrations in the roots followed by the stems and lowest in the leaves. Reduction rates of the total PBDEs in the soils ranged from 13.3 to 21.7% after plant harvest and lower brominated PBDEs were associated with a higher tendency to dissipate than the higher brominated PBDEs. This study provides the first evidence for plant uptake of weathered PBDEs in the soils of e-waste recycling sites and planting contributes to the removal of PBDEs in e-waste contaminated soils.     

Debrominated, hydroxylated and methoxylated metabolism in maize (Zea mays L.) exposed to lesser polybrominated diphenyl ethers (PBDEs)

A hydroponic experiment was conducted to investigate the debrominated, hydroxylated and methoxylated metabolism of polybrominated diphenyl ethers (PBDEs, BDE-15, -28 and -47) in maize. A total of six debrominated metabolites (de-PBDEs), seven hydroxylated PBDEs (OH-PBDEs, including two unidentified OH-di-PBDEs and one unidentified OH-tri-PBDE) and four methoxylated PBDEs (MeO-PBDEs) were determined in the exposed plants. The metabolic products were detected in maize only after 12 h of exposure to the PBDEs. However, the concentration of each type of the metabolites (de-PBDEs, OH-PBDEs or MeO-PBDEs) decreased at the later exposure time, possibly due to further metabolism. The removal of a bromine atom or the introduction of a hydroxyl/methoxy group was easier at the ortho-positions on the biphenyl structure than at the para-positions. Concentration ratios of the total debrominated, hydroxylated or methoxylated metabolites to the parent congener (BDE-28 or -47) generally followed the order of leaves > stems ? roots, and MeO-PBDEs > de-PBDEs ? OH-PBDEs. These results suggest that metabolism occurred preferentially in leaves and stems than in roots. Less transformation and shorter elimination half-life of OH-PBDEs would contribute to the lower concentrations of OH-PBDEs than of de-PBDEs or MeO-PBDEs in maize.     

XDLVO理论解析不同离子条件下海藻酸钠微滤膜污染

应用extended Derjaguin-Laudau-Verwey-Overbeek(XDLVO)理论定量解析海藻酸钠微滤膜污染中界面微距作用力,探讨不同离子条件对膜污染影响的主控机制.结果表明,对于亲水性膜表面,范德华力促进膜污染,极性作用力阻碍膜污染;而对于疏水性膜表面,范德华力减缓膜污染,极性作用力加速膜污染.海藻酸钠与微滤膜接触时双电层作用力对膜污染贡献相对微弱.离子强度及钙离子对海藻酸钠微滤膜污染的影响主要是通过改变极性作用力来实现的.较高的离子强度会降低极性作用力的排斥性或升高极性作用力的吸引性,从而加重海藻酸钠微滤膜污染.虽然钙离子使出水通量急速下降,但钙离子的存在使得物理清洗效率提高.不同离子条件下初始阶段及后期阶段污染趋势K分别与膜-海藻酸钠粘附自由能及海藻酸钠-海藻酸钠粘聚自由能具有良好的线性相关性,表明XDLVO理论适用于描述不同离子条件下海藻酸钠微滤膜污染行为.     

株洲市区农业土壤中多环芳烃的分布特征研究

采集株洲市区农业土壤表层样品185个,用高效液相色谱法对16种多环芳烃(PAHs)进行检测结果表明,除萘外,其余15种PAHs均有不同程度的检出,以苯并[b]萤蒽、萤蒽和苯并菲等3或4环PAHs为主, ～5521μg/kg之间,平均280μg/kg.地域上,石峰区、芦淞区>天元区>荷塘区;从土地利用类型看,旱地>水田>林地.按Maliszewska-Kordybach土壤污染程度分级标准,株洲市区农业土壤总体上受到PAHs轻度污染,这些PAHs主要来源于工业生产、交通运输等过程中化石燃料的燃烧.     

快速溶剂萃取-气相色谱/串联质谱法测定农作物中的有机氯农药

建立快速溶剂萃取,固相萃取柱净化,气相色谱/串联四极杆质谱检测分析农作物中23种有机氯农药残留的方法。以油菜为样品,加标浓度为5、10、25、50μg/kg时,平均回收率在72%~101%之间,相对标准偏差3%~14%(n=5)。8种农作物(莴笋、黄瓜、蒜苗、辣椒、油菜、茄子、玉米和水稻)加标浓度为25μg/kg时的平均回收率在71%~113%之间,相对标准偏差3%~16%(n=5)。方法检出限0.75~1.76μg/kg之间。