Cell absorption induced desorption of hydrophobic organic contaminants from digested soil residue

Oral ingestion of contaminated soil is an important pathway of human exposure to hydrophobic organic contaminants (HOCs), particularly for children in developing countries. The mobilization potential of various contaminants from ingested soil is often characterized using an in vitro gastrointestinal model, based on the quantities of contaminants remaining in digestive fluid after digestion and separation. Recently, it was experimentally demonstrated that a large fraction of mobilized contaminants sorbed on the digested residue could be released if the dissolved fraction was removed by intestinal absorption. This hypothesis was further tested in this study. Soil spiked with dichlorodiphenyltrichloroethane and its metabolites (DDXs) and polycyclic aromatic hydrocarbons (PAHs) was digested using an in vitro gastrointestinal model. A human colon carcinoma cell line (Caco-2) was cultured in digestive fluid with or without soil residue (pre-equilibrated with the soil) for 2 h. A large proportion of the contaminants (37-68%) was sorbed on the digested residue. Without this residue, 66 ± 13% of DDXs and 73 ± 14% of PAHs dissolved in the fluid, as means and standard deviations, were absorbed by the cell monolayer after exposure. With both digestive fluid and residue, the sorbed fraction of PAHs and DDXs decreased by 38-92%, while the ratios of the cellular to the dissolved concentrations were 2.7-2.8 times higher than those without the residue. This supported the hypothesis that the cell absorption of dissolved HOCs induces desorption of the sorbed fraction from digestive residue, and the desorbed HOCs can be absorbed as well.     

New insights into the sorption mechanism of cadmium on red mud

Effectiveness and mechanism of cadmium (Cd) sorption on original, acidified and ball milling nano-particle red muds were investigated using batch sorption experiments, sequential extraction analysis and X-ray absorption near edge structure (XANES) spectroscopy. The maximum sorption capacity of Cd was 0.16, 0.19, and 0.21 mol/kg for the original, acidified, and nano-particle red muds at pH 6.5, respectively. Both acidification and ball-milling treatments significantly enhanced Cd sorption and facilitated transformation of Cd into less extractable fractions. The Cd L_III-edge XANES analysis indicated the formation of inner-sphere complexes of Cd similar to XCdOH (X represents surface groups on red mud) on the red mud surfaces although outer-sphere complexes of Cd were the primary species. This work shed light on the potential application of red mud to remediate Cd-contaminated soils and illustrated the promising tool of XANES spectroscopy for speciation of multicomponent systems of environmental relevance.     

我国北方沙漠化地区的土地利用结构优化研究

利用多元统计方法中的因子分析,对我国北方沙漠化地区县市级行政区的土地利用结构进行了综合评价。基于中国生态地理区域系统,对含有结构性映射综合得分值的评价单元进行了归并,从而实现了对研究区土地利用结构的综合数值分区。利用典型区土地资源遥感调查和评价结果,以及新近权威性的县市级土地利用详查结果,探讨了相应土地利用结构区内土地利用存在的问题,并提出了土地利用结构优化调整的方向。     

嘉兴市环境库兹涅茨曲线特征分析

环境库兹涅茨曲线(EKC)暗含了对经济增长和环境之间的发展战略。运用EKC理论模型,对嘉兴市工业"三废"排放量与人均GDP之间关系进行分析,发现工业废水、工业废气、工业固体废弃物排放量与人均GDP之间的关系分别为N型、倒U型左侧上升阶段、倒U型左侧接近拐点,表明嘉兴市经济增长还处在加重环境负担的阶段,还未实现环境与经济的协调发展。引起工业废水、工业废气排放量居高不下的原因分别是嘉兴市产业结构特点和能源结构特点。建议优化产业结构,调整能源结构,推进循环经济发展,争取早日跨越环境库兹涅茨曲线拐点,实现环境经济的协调发展。     

循环经济视角下的旅游产业生态化研究

旅游循环经济指导下的旅游产业生态化是实现旅游持续发展的战略途径。基于此,文章尝试将循环经济的理念应用到推进旅游产业生态化中,在循环经济“3R”原则指导下,提出了实现旅游产业生态化的策略,包括旅游企业内部的生态化、旅游企业间的生态化以及旅游产业与其他产业间的生态化。     

钢筋混凝土梁裂缝宽度的有限元分析

文章根据所做试验情况,对钢筋混凝土梁的裂缝宽度进行了有限元模拟.有限元分析结果与试验结果吻合良好.说明有限元分析在某种程度上可以代替试验对钢筋混凝土梁裂缝宽度进行研究分析.     

层次分析法在泉州市和南安市大气环境质量评价中的应用研究

文章根据(GB 3095-2012)《大气环境质量标准》,依据地区大气环境实际情况选择SO2、NO2、PM10构建评价指标体系,采用层次分析法对泉州市和南安市2005年-2010年的大气环境质量进行了综合评价,并从地理位置、气候、经济和能源结构这四个方面分析比较两个城市的评价结果.结果表明:泉州市和南安市的大气环境质量均为一级,从分析结果来看南安市的大气环境质量整体较优于泉州市,这与南安市大气污染型企业较少、台风影响较大、植被覆盖率较高有直接关系.     

T3WS便携式水质快速检测仪在环境监测中的应用研究

便携式水质快速检测仪具有测量速度快、体积小、重量轻、便于携带等特点,特别适用于水质现场快速测定.在T3WS快速检测仪30余个项目中选择六价铬、甲醛、砷、氨氮、硫化物等五项常用指标,进行试管一致性、校准曲线斜率、截距、相关系数、检出限、测定范围、精密度、准确度以及与实验室分析方法比对等试验.结果表明,T3WS快速检测仪测试标准样品测试结果均在允许误差范围内,标准样品及地袁水、废水样品测试结果的相对偏差均小于10％,与实验室分析结果之间最大相对误差分别为-6.1％、15.9％、15％、-7.2％、-21.0％,T3WS便携式水质快速检测仪用于水质现场快速测定结果的精密度与准确度是可以接受的.     

应用概率物种敏感度分布法研究太湖铜水生生物水质基准

运用概率物种敏感度分布法获得太湖水体中铜的急性水质基准值为14.57μg·L-1,慢性水质基准值为3.26μg·L-1;不同类别物种敏感性存在差异,无脊椎动物较脊椎动物更敏感,甲壳类敏感性大于鱼类。概率物种敏感度分布法与传统的物种敏感度分布法相比,更全面合理地考虑多种毒性效应,曲线拟合效果好,受数据量大小影响较小,结果更加稳定。研究结论可为铜水质标准的修订和太湖流域水环境管理提供技术支持。     

草莓蚜虫防治用药对蜜蜂的急性毒性与风险评价

为明确草莓蚜虫防治用药对蜜蜂的影响,按照《化学农药环境安全评价试验准则》和《化学品测试方法》要求测定了20%啶虫脒SP、10%氟啶虫酰胺WG和22%氟啶虫胺腈SC对意大利蜜蜂(Apis mellifera L.)的急性毒性,并采用危害商值(HQ)法进行了风险评价。急性毒性结果显示:20%啶虫脒SP、10%氟啶虫酰胺WG和22%氟啶虫胺腈SC对蜜蜂的急性经口毒性试验结果(48 h-LD50值)分别为4.47μg a.i.·蜂~(-1)、11.2μg a.i.·蜂~(-1)和0.0601μg a.i.·蜂~(-1),对蜜蜂的急性接触毒性试验结果(48 hLD50值)分别为11.0μg a.i.·蜂~(-1)、13.9μg a.i.·蜂~(-1)和0.643μg a.i.·蜂~(-1)。按《化学农药环境安全评价试验准则》中毒性等级划分标准,20%啶虫脒SP、10%氟啶虫酰胺WG和22%氟啶虫胺腈SC对蜜蜂的毒性等级分别为中毒、低毒和高毒。风险评价结果表明,22%氟啶虫胺腈SC对蜜蜂存在中等风险(HQ值为1 622),20%啶虫脒SP和10%氟啶虫酰胺WG对蜜蜂的风险为低风险,其HQ值分别为40.3和6.70。因此,草莓生产中可优先选用10%氟啶虫酰胺WG来防治蚜虫,20%啶虫脒SP次之。而使用22%氟啶虫胺腈SC时,应注意采取措施降低其对蜜蜂的毒性风险,以免造成危害。