有机化合物生物富集因子的计算机预测研究

有机化合物在生物体内的富集,通常用生物富集因子(bioconcentration factor,简称BCF)来表达,这是化合物生态环境毒性评估的重要指标。为合理预测有机化合物是否易于生物富集,首先从美国环保局网站收集了624个具有不同BCF值的化合物,然后采用7种分子指纹结合5种机器学习方法(包括支持向量机、C4.5决策树、k最近邻法、随机森林法和朴素贝叶斯法),构建了化合物BCF的分类预测模型,所有模型均采用独立外部验证集进行验证。其中,使用Chemo Typer分子指纹结合支持向量机方法得到的二分类模型,整体预测准确度最好,达到了85.4%。通过采用信息增益、频率分析等方法,进一步确定了化合物中易于引起生物富集的关键子结构,包括芳基氯、二芳基醚、氯代烷烃等。研究中所用到的方法为有毒化学品的生态风险评价提供了良好可靠的预测工具。     

乌江流域水沙特性变化分析

对乌江流域水沙特性变化进行分析,是解决长江上游泥沙问题、提高水资源利用率和防灾减灾的根本出发点,同时可为喀斯特地区水土流失治理和生态恢复提供理论依据.文章通过对乌江流域主要水文站鸭池河站、乌江渡站和思南站的降雨-径流-泥沙随时间的变化、降雨-径流和径流-泥沙的相关性和双累积曲线进行分析,研究结果为:降雨量、径流模数和输沙模数随时间的变化无明显趋势,历年输沙模数是鸭池河>乌江渡>思南.1980年以后由于实施了大量水土保持工程使得输沙模数大量减少.在年均径流模数相同的情况下,1971-1979年这一时期的产沙量要高于1961-1970年.从1971年开始输沙模数相对于径流而言出现趋势性增多,这主要是由人类活动造成.三个站点的双累积曲线变化趋势相似,说明人类活动对河流泥沙的影响,既取决于人类活动的方式、程度,也受制于流域环境条件.     

生物可降解络合剂聚天冬氨酸治理土壤重金属污染

土壤重金属污染会产生严重的生态环境问题,土壤淋洗技术可达到土壤修复的目的,其中络合剂的选择是达到安全、有效修复效果的关键.聚天冬氨酸(PASP)可生物降解,对环境安全.文章选择PASP作为重金属的络合剂,研究其修复土壤重金属污染的效果.结果表明,PASP对金属离子Cd、Zn和Ca均有较好的提取率,均超过50%,并且络合剂/重金属的摩尔比越高,提取效果越好,受pH的影响就越少,提取速率开始比较快,而后趋于平缓.在PASP络合物的形态分布中,在pH较低阶段,PASP-Cd络合物所占的比例较大,随着pH的升高,PASP-Zn和PASP-Ca的比例增加,同时微生物对聚天冬氨酸的降解作用对治理效果产生负面影响.PASP可作为环保型的络合剂,达到修复土壤重金属污染的目的.     

生态系统数据管理中的数据文档文件

生态系统的数据结构不同于商用数据结构。本文参考美国ＬＴＥＲＮ的Ｓｅｖｉｌｌｅｔａ站生态系统的数据管理模式，结合中国科学院封丘农业生态实验站的实际情况，着重介绍了生态系统的数据文档文件的特点、结构和应用，而这些都是研究生态系统数据管理的最基础工作。     

不同染料化合物在天然锰矿界面的脱色特性

本文考察了染料化合物在天然锰矿界面脱色特性,并探讨溶液ｐＨ值、环境温度、不 照射及颗粒物浓度和粒径对脱色效果的影响。实验表明,溶液ｐＨ值是影响染料脱色效果的最主要因素,光照对不同染料化合物脱色有不同程度的影响。颗粒物浓度升高及粒径降低有利于染料脱色,温度升高,直接耐晒红Ｆ３Ｂ脱色率提高,将不同温度下,该染料脱色率随时间的变化按一级反应动力学方程模拟,再依据阿累尼乌斯方程,求得直接耐晒红Ｆ３Ｂ在天然     

五种农药对三唑酮光解的影响

本文研究了氯氰菊酸，溴氰菊酯，多菌灵，γ－六六六及辛硫磷等五种农药对杀菌剂三唑酮光化学降解的影响，当三唑酮分别与这五种农药以等剂量混合光照后，三唑酮的光解速度加快１．４４－２．４２倍，表现了较强的光敏降解效应，其敏化光解效率我照时间延长而逐渐提高，当三唑酮分别与这五种农药以２：１剂量比混合光照后，仅溴氰菊酯．多菌灵表现敏化降解效应，而氯氰菊酯，γ－六六六及辛硫磷则显示光猝灭降解效应，五种农药对三唑     

Distinct community assembly processes underlie significant spatiotemporal dynamics of abundant and rare bacterioplankton in the Yangtze River

• Season and landform influenced spatiotemporal patterns of abundant and rare taxa. • Different stochastic processes dominated abundant and rare subcommunity assembly. • River flow and suspended solids regulated assembly processes of rare taxa. The rare microbial biosphere provides broad ecological services and resilience to various ecosystems. Nevertheless, the biogeographical patterns and assembly processes of rare bacterioplankton communities in large rivers remain uncertain. In this study, we investigated the biogeography and community assembly processes of abundant and rare bacterioplankton taxa in the Yangtze River (China) covering a distance of 4300 km. The results revealed similar spatiotemporal patterns of abundant taxa (AT) and rare taxa (RT) at both taxonomic and phylogenetic levels, and analysis of similarities revealed that RT was significantly influenced by season and landform than AT. Furthermore, RT correlated with more environmental factors than AT, whereas environmental and spatial factors explained a lower proportion of community shifts in RT than in AT. The steeper distance–decay slopes in AT indicated higher spatial turnover rates of abundant subcommunities than rare subcommunities. The null model revealed that both AT and RT were mainly governed by stochastic processes. However, dispersal limitation primarily governed the AT, whereas the undominated process accounted for a higher fraction of stochastic processes in RT. River flow and suspended solids mediated the balance between the stochastic and deterministic processes in RT. The spatiotemporal dynamics and assembly processes of total taxa were more similar as AT than RT. This study provides new insights into both significant spatiotemporal dynamics and inconsistent assembly processes of AT and RT in large rivers.     

Ni/Fe双金属降解四氯化碳和四氯乙烯的对比试验

以四氯化碳(CT)和四氯乙烯(PCE)为目标污染物,以批试验方法研究Ni/Fe双金属对CT和PCE的还原性脱氯.结果表明:Ni/Fe双金属可有效去除水中的CT和PCE;Ni/Fe双金属对CT和PCE的降解反应均符合准一级反应动力学方程;在相似的反应条件下,Ni/Fe双金属对CT和PCE脱氯的反应速率常数(kobs)之比为1.48和1.67,说明Ni/Fe双金属对CT的脱氯速率要快于对PCE的脱氯速率;Ni/Fe双金属可对PCE完全脱氯,但对CT脱氯过程中产生少量三氯甲烷(TCM).     

高浓度难降解乳化废水湿式氧化动力学

以高浓度难降解乳化废水为处理对象,在2L高压间歇反应釜中,研究了温度对湿式氧化的影响和动力学特征。结果表明,升高温度不但促使反应向直接氧化成终产物方向偏移,也使中间产物加速氧化,使CODcr和TOC去除率显著提高,220℃时可分别达86．4％和79．5％;通用动力学模型能较好预测湿式氧化过程,并得到基于CODcr的表观活化能：有机物直接氧化成终产物为6．19kJ／mol;中间产物氧化成终产物为24．47kJ／mol。     

Occurrence and distribution of antibiotics in coastal water of the Bohai Bay, China: impacts of river discharge and aquaculture activities

The presence of 21 antibiotics in six different groups was investigated in coastal water of the Bohai Bay. Meantime, to illuminate the potential effects caused by the river discharge and aquaculture activities, wastewater from three breeding plants and surface water from six rivers flowing into the Bohai Bay were also analyzed for the selected antibiotics. The result revealed that measured antibiotics in the North Bobai Bay were generally higher than those in the South, highlighting the remarkable effects of high density of human activities on the exposure of antibiotics in environment. The antibiotics found in the six rivers were generally higher than those in the Bohai Bay reflecting the important antibiotics source of river discharge. This study reveals that the high consumption of some antibiotics in aquaculture activities may pose high ecological risk to the bay.