Sorption of the natural endocrine disruptors,oestrone and 17 beta-oestradiol in the aquatic environment

Adsorption of hydrophobic contaminants at the particle/water interface is one of the key processes controlling their fate in the aquatic environment. The sorption of the natural female hormones oestrone and 17-oestradiol has been studied under simulated riverine conditions. Both the kinetics and the effects of varying fundamental environmental parameters (e.g. sediment properties) on the thermodynamic equilibrium partition coefficient (K _p) have been studied in continuous and batch sorption experiments, respectively. Results showed that the sorption of oestrone and 17-oestradiol by sediment was relatively slow, reaching equilibrium in 50 days. In addition, relatively small adsorption of both oestrone and 17-oestradiol onto the sediment was observed, with K _p values between 200 and 250 mL g^–1. The comparable K _p values of the two compounds reflect their structural similarity. It can be concluded that the two endocrine disruptors, oestrone and 17-oestradiol remain primarily in association with the aqueous phase.     

超临界流体萃取在研究土壤和沉积物结合态残留中的应用

许多有机污染物在土壤和沉积物中形成持久稳定的结合态残留；结合态残留对土壤和沉积物的解毒过程、污染物长期分配行为、生物可用性和生物毒性都具有重要影响。为了揭示结合态残留的形成机制及其对污染物环境行为和毒理学参数的影响，从土壤或沉积物中提取出不同结合状态的有机污染物就显得非常重要。超临界流体萃取(SFE)可以实现选择性萃取，从而得到有关污染物一基体间相互作用的信息。文章介绍了SFE应用类型、超临界流体种类以及影响SFE萃取率的因素，对SFE模拟有机污染物长期吸附／解吸行为和生物可用性研究进行了论述，并认为SFE势必发展成为土壤或沉积物中结合态残留形成机理研究、土壤修复和生态风险评价的一种强有力的技术。     

Effect of Invasive Plant Species on Temperate Wetland Plant Diversity

Abstract:  Invasive species are a major threat to global biodiversity and an important cause of biotic homogenization of ecosystems. Exotic plants have been identified as a particular concern because of the widely held belief that they competitively exclude native plant species. We examined the correlation between native and invasive species richness in 58 Ontario inland wetlands. The relationship between exotic and native species richness was positive even when we controlled for important covarying factors. In addition, we examined the relationship between the abundance of four native species (  Typha latifolia, T. angustifolia, Salix petiolaris, Nuphar variegatum ) and four invasive species (  Lythrum salicaria, Hydrocharis morsus-ranae, Phalaris arundinacea, Rhamnus frangula ) that often dominate temperate wetlands and native and rare native species richness. Exotic species were no more likely to dominate a wetland than native species, and the proportion of dominant exotic species that had a significant negative effect on the native plant community was the same as the proportion of native species with a significant negative effect. We conclude that the key to conservation of inland wetland biodiversity is to discourage the spread of community dominants, regardless of geographical origin.     

农田土壤中的磷向水体释放的风险评价

通过对比土壤的固磷能力和磷素水平可以评估不同类型土壤中的磷向水体释放的风险。研究表明，磷吸持指数（SI）可以作为土壤最大吸磷量的替代指标来表征土壤的固磷能力。在太湖地区，影响水土界面磷素迁移能力的主要因素是土壤有效磷水平和土壤固磷能力。SI值30左右为一临界值，SI大于此值的土壤对于施磷具有较大的缓冲能力，而SI低于此值的土壤对施磷非常敏感，磷流失风险将随施磷量的增加而呈直线上升趋势。     

乌贼墨黑色素对Pb2+-Cu2+二元体系的吸附性能研究

为探索新型生物吸附剂，以乌贼墨黑色素（SIM）为吸附剂，研究Pb²⁺、Cu²⁺单组分溶液及Pb²⁺-Cu²⁺二元混合体系中SIM对Pb²⁺和Cu²⁺的吸附效果并构建等温吸附模型.结果表明，pH值、SIM添加量、吸附时间对SIM吸附Pb²⁺和Cu²⁺的吸附量影响较大，而吸附温度对吸附效果影响较小；单组分吸附与二元混合体系吸附对比表明，二元混合体系中Pb²⁺和Cu²⁺存在竞争吸附.应用L （Langmuir）和F （Freundlich）等温吸附模型拟合了SIM对Pb²⁺、Cu²⁺单组分金属离子的吸附过程，其中L模型与试验结果拟合度更高；应用Non-modified Langmuir、Modified Langmuir isotherm、Extended Langmuir、Extended Freundlich和SRS模型5种模型对Pb²⁺-Cu²⁺二元混合体系的等温吸附过程进行拟合，其中Extended Langmuir模型与试验结果拟合度最佳.应用红外光谱（FTIR）分析SIM吸附金属离子的原理时发现，SIM上羟基、-NH和不饱和键是金属离子的吸附位点，且SIM对Pb²⁺的吸附能力优于对Cu²⁺的吸附.     

Cesium migration in saturated silica sand and Hanford sediments as impacted by ionic strength

Large amounts of 137Cs have been accidentally released to the subsurface from the Hanford nuclear site in the state of Washington, USA. The cesium-containing liquids varied in ionic strengths, and often had high electrolyte contents, mainly in the form of NaNO3 and NaOH, reaching concentrations up to several moles per liter. In this study, we investigated the effect of ionic strengths on Cs migration through two types of porous media: silica sand and Hanford sediments. Cesium sorption and transport was studied in 1, 10, 100, and 1000 mM NaCl electrolyte solutions at pH 10. Sorption isotherms were constructed from batch equilibrium experiments and the batch-derived sorption parameters were compared with column breakthrough curves. Column transport experiments were analyzed with a two-site equilibrium-nonequilibrium model. Cesium sorption to the silica sand in batch experiments showed a linear sorption isotherm for all ionic strengths, which matched well with the results from the column experiments at 100 and 1000 mM ionic strength; however, the column experiments at 1 and 10 mM ionic strength indicated a nonlinear sorption behavior of Cs to the silica sand. Transport through silica sand occurred under one-site sorption and equilibrium conditions. Cesium sorption to Hanford sediments in both batch and column experiments was best described with a nonlinear Freundlich isotherm. The column experiments indicated that Cs transport in Hanford sediments occurred under two-site equilibrium and nonequilibrium sorption. The effect of ionic strength on Cs transport was much more pronounced in Hanford sediments than in silica sands. Effective retardation factors of Cs during transport through Hanford sediments were reduced by a factor of 10 when the ionic strength increased from 100 to 1000 mM; for silica sand, the effective retardation was reduced by a factor of 10 when ionic strength increased from 1 to 1000 mM. A two order of magnitude change in ionic strength was needed in the silica sand to observe the same change in Cs retardation as in Hanford sediments.     

农药在土壤上吸着/解吸及其对生物利用率影响的研究进展

正确预测有机污染物在环境中的归宿 ,在很大程度上依赖对它们的吸着 -解吸动力学行为的认识。自 2 0世纪 80年代起 ,吸着 -解吸动力学逐渐受到重视。本文介绍了国内外有关农药在土壤 /沉积物上的吸着 -解吸动力学和吸着 -解吸对土壤有机污染物的生物利用率的影响等方面的近期研究成果 ,着重从实验方法、模型、机理等方面进行了详细的综述     

东京根霉对重金属Cr^3＋、Mn^2＋和Zn^2＋的吸附研究

利用固定化发酵中产生的废菌体——东京根霉（Rhizopustonkinesis）去除废水中Cr^3＋、Mn^2＋和Zn^2＋,研究了预处理、pH、温度、金属离子初始浓度、吸附时间等条件对吸附量的影响。结果表明，用NaOH浸泡4—6h、在pH=5—6，温度25-35℃时吸附效果最好，用Langmuir、Freundlich和Temkin方程对其吸附等温线进行拟合，相关性都比较好；用不同的吸附动力学方程描述东京根霉吸附金属离子的最优和最次模型分别为Elovich方程和一级扩散方程，双常数方程和抛物线扩散方程拟合介于前二者之间。     

The influence of high initial concentration aqueous-phase TCE on the performance of iron wall systems

Flow-through column tests were conducted to investigate the performance of iron wall remediation systems for the degradation of aqueous-phase trichloroethylene (TCE). Concentration profiles under steady-state transport conditions were generated by measuring TCE concentrations at sample ports located at various locations along the length of the column. The results indicated that a pseudo-first-order model is adequate at describing degradation kinetics for low initial TCE concentrations, but not for higher initial concentrations. The deviation from pseudo-first-order kinetics can be explained by interspecies competition for reactive sites between TCE and a dominant reaction product. A modification of the pseudo-first-order model that accounts for product interference predicts laboratory data for high initial concentration profiles, but deviates slightly as initial concentrations approach the solubility of TCE. The data clearly demonstrate the importance of accurately describing reaction kinetics for the purpose of designing iron wall treatment systems.