垃圾堆填区渗出液对干旱季节树苗生长的影响

本试验于１９９４年７月至１月在香港望后石垃圾堆填区进行,研究了垃圾堆填区渗出液浇灌对几种亚热带树种生长及其生理学过程的影响．结果表明,在高温低湿、植物遭受水分亏缺的条件下,应用适当浓度的垃圾堆填区渗出液浇灌同水灌和肥水灌溉类似,可显著地提高树苗的移栽成活率,促进树苗的生长,尤其对耐干旱能力低的树种,其效果更为显著．与对照相比,用适当浓度的渗出液或水浇灌显著地改善植株的水分关系,降低叶片的脱落酸（ＡＢＡ）含量,促进气孔的开放．另外,处理植株叶片的光合特性也得到了不同程度的改善．根据以上结果,作者认为,在干旱季节植物遭受严重水分亏缺的条件下,应用适当浓度的垃圾堆填区渗出液浇灌可显著地缓解干旱对树苗生长的影响,为综合治理垃圾堆填区渗出液提供了一条经济、实用和可行的途径．     

Bioaccumulation and depuration of anthracene in Penaeus monodon (Fibricius) through food ingestion

Understanding on the bioaccumulation and depuration of PAHs (polycyclic aromatic hydrocarbons) in Penaeus monodon is important in seafood safety because it is one of the most popular seafood consumed worldwide. In this study, we used anthracene as the precursor compound for PAHs accumulation and depuration in the shrimp. Commercial feed pellets spiked with anthracene were fed to P. monodon. At 20 mg kg⁻¹ anthracene, P. monodon accumulated 0.1% of the anthracene from the feed. P. monodon deputed the PAH two times faster than its accumulation. The shrimp reduced its feed consumption when anthracene content in the feed exceeded 20 mg kg⁻¹. At 100 mg kg⁻¹ anthracene, P. monodon started to have necrosis tissues on the posterior end of their thorax. The bioaccumulation factor (BAF), uptake rate constant (k₁) and depuration rate constant (k₂) of anthracene in P. monodon were 1.15 × 10⁻³, 6.80 × 10⁻⁴ d⁻¹ and 6.28 × 10⁻¹ d⁻¹, respectively. The depuration rate constant is about thousand times higher than the uptake rate constant and this indicated that this crustacean is efficient in depurating hydrocarbons from their tissue.     

基于生物可给性的某冶炼厂土壤重金属健康风险评价

为科学评价重金属污染场地的人体健康风险,以某冶炼厂土壤为研究对象,采用PBET(Physiologically-Based Extraction Test)和IVG(In-Vitro gastrointestinal)两种方法测定了As、Cd、Cu、Pb、Zn的生物可给性,并对比了只考虑重金属总量与基于生物可给性的人体健康风险.结果表明,场地土壤As、Cd、Pb的平均含量分别高达7063,691,3811mg/kg,严重超过国家环境质量标准.在PBET和IVG测试中,5种重金属的平均生物可给性介于1.81%~44.8%与1.78%~30.1%之间.As是PBET中生物可给性最高的重金属元素,而在IVG中Cd的生物可给性最高;含磷矿物的存在使Pb的生物可给性最低.提取液pH值及组成组分与重金属元素间的化学行为是造成两种方法结果差异的主要原因.在模型假设的条件下,土壤原有重金属的总危险商与总致癌系数为27.2与2.95×10^-3.考虑生物可给性使二者降低了59.9%~84.4%与55.6%~79.4%,且两个系数大小均呈现PBET胃液>PBET胃肠液>IVG胃液>IVG胃肠液的规律.调整后可以认为Pb不再具有健康风险,Cd仅具有致癌风险,只有As同时具有非致癌风险与致癌风险.尽管考虑重金属生物可给性后场地仍具有不可忽视的人体健康风险,但经过调整后能更准确地识别重金属的危害程度,避免场地的过度修复.