含硫苯衍生物对发光细菌的毒性效应及其定量结构活性相关分析

利用发光细菌法测定了29种氯取代和硝基取代的苯硫(砜、亚砜)基乙酸酯的毒性,通过定量结构活性相关(QSAR)分析发现:此类化合物的毒性主要与其取代基的电荷效应相关,电荷的区域分布对化合物的毒性效应有重要影响.推测该化台物的毒性机理是毒物分子与发光反应中的主要辅酶FMNH_2形成了氢键.还发现:在这类链状毒物分子中,远离活性中心一端的基团具有脱毒作用.     

有机磷农药对海洋扁藻毒性构效关系的密度泛涵理论研究

采用密度泛函理论方法,在B3LYP/6-311G**水平上,计算了11个有机磷农药化合物的结构参数,将结构参数作为理论描述符,导出了有机磷类化合物的分子结构参数与2种盐度(S=20,S=30)下扁藻毒性(-lgEC50)的定量关系式(式(3)和(6)),并用交叉验证法验证,相关系数R分别为0.923 2和0.893 3,交叉验证相关系数q2分别为0.527 0和0.540 5.在此基础上,预测了11种有机磷农药的毒性.研究表明,所得预测方程有较好的稳定性和较强的预测能力.可用于有机磷化合物的-lgEC50预测.     

Modelling global-scale potential grassland changes in spatio-temporal patterns to global climate change

Grassland is one of the most widespread vegetation types worldwide and plays a significant role in global carbon cycling. Understanding the sensitivity of grassland to climate change and the effect of climate changes on the grassland ecosystems is a key issue in global carbon cycling. One of the goals of this study was to evaluate the three net primary productivity (NPP)–climate models, i.e. the Miami model, the Schuur model and the classification indices-based model. Results indicated that the classification indices-based model was the most effective model at estimating large-scale grassland NPP. In this research, changes in the spatial pattern of global potential grassland from recent past (1950–2000) to future (2001–2050) A2a scenario were analysed with the integrated orderly classification system of grassland (IOCSG) approach in a Geographic Information System (GIS) environment. NPP was evaluated with the classification indices-based model. Results indicate that under recent past climatic conditions, the main parts of global grassland are the savanna and tundra and alpine grassland and will be converted into the savanna, steppe and semi-desert grassland in A2a scenario. As a whole, areas of grassland will increase by 31.76 million hectares. The classification indices-based model estimated a 12.40% increase of total NPP in grassland from recent past to A2a scenario. It will impose a new issue for future grassland researches to support sustainable development and to provide action relevant knowledge to meet the challenge of climate change.     

Long-range transport of acidifying substances in East Asia—Part II: Source–receptor relationships

Region-to-grid source–receptor (S/R) relationships are established for sulfur and reactive nitrogen deposition in East Asia, using the Eulerian-type Community Multiscale Air Quality (CMAQ) model with emission and meteorology data for 2001. We proposed a source region attribution methodology by analyzing the non-linear responses of the CMAQ model to emission changes. Sensitivity simulations were conducted where emissions of SO₂, NO_x, and primary particles from a source region were reduced by 25%. The difference between the base and sensitivity simulations was multiplied by a factor of four, and then defined as the contribution from that source region. The transboundary influence exhibits strong seasonal variation and generally peaks during the dry seasons. Long-range transport from eastern China contributes a significant percentage (>20%) of anthropogenic reactive nitrogen as well as sulfur deposition in East Asia. At the same time, northwestern China receives approximately 35% of its sulfur load and 45% of its nitrogen load from foreign emissions. Sulfur emissions from Miyakejima and other volcanoes contribute approximately 50% of the sulfur load in Japan in 2001. Sulfur inflows from regions outside the study domain, which is attributed by using boundary conditions derived from the MOZART global atmospheric chemistry model, are pronounced (10–40%) over most parts of Asia. Compared with previous studies using simple Lagrangian models, our results indicate higher influence from long-range transport. The estimated S/R relationships are believed to be more realistic since they include global influence as well as internal interactions among different parts of China.     

青藏高原人口、资源、环境与发展互动关系探讨

青藏高原是我国西部地区的特殊地理区域 ,高原人口、资源、环境与经济是否相互协调 ,关系到我国、西部及整个高原的经济社会的持续、健康发展。论文简要分析了可持续发展的概念及其意义 ,认为可持续发展模式是青藏高原现实与未来的必然选择。从高原人口、资源、环境、经济等互动关系的定量分析着手 ,提出人口增长较快、素质不高是高原可持续发展所面临的基础性障碍 ;资源较为富裕 ,但人口对资源压力逐步增大 ,是制约高原持续发展的潜在威胁 ;人口与资源、经济匹配不当 ,承载力相对不足 ,构成高原持续发展的巨大负担 ;不合理开发利用资源 ,严重威胁着脆弱的环境和生态系统 ,是高原持续发展的潜伏危机 ;最后指出适度控制人口 ,合理开发利用资源 ,优化经济结构 ,保护生态环境 ,是实现高原可持续发展的根本措施。     

自相关拓扑指数与有机物生物活性的定量关系

采用自相关拓扑指数作为分子描述符，研究有机污染物的遗传毒性和急性毒性与分子结构的定量关系，建立了良好的构效关系方程。     

Characteristics of indoor/outdoor PM2.5 and elemental components in generic urban, roadside and industrial plant areas of Guangzhou City, China

Quantitative information on mass concentrations and other characteristics, such as spatial distribution, seasonal variation, indoor/outdoor （I/O） ratio, correlations and sources, of indoor and outdoor PM2.5 and elemental components in Guangzhou City were provided. Mass concentration of PM2.5 and elemental components were determined by standard weight method and proton-induced X-ray emission （PIXE） method. 18 elements were detected, the results showed positive results. Average indoor and outdoor PM2.5 concentrations in nine sites were in the range of 67.7-74.5μg/m^3 for summer period, and 109.9-123.7 μg/m^3 for winter period, respectively. The sum of 18 elements average concentrations were 5362.6-5533.4 ng/m^3 for summer period, and 8416.8-8900.6 ng/m^3 for winter period, respectively. Average concentrations of PM2.5 and element components showed obvious spatial characteristic, that the concentrations in roadside area and in industrial plant area were higher than those in generic urban area. An obvious seasonal variation characteristic was found for PM2.5 and elemental components, that the concentrations in winter were higher than that in summer. The I/O ratio of PM2.5 and some elemental components presented larger than 1 sometimes. According to indoor/outdoor correlation of PM2.5 and element concentrations, it was found that there were often good relationships between indoor and outdoor concentrations. Enrichment factors were calculated to evaluate anthropogenic versus natural elements sources.     

基于线性溶解能关系预测污染物在被动采样材料与环境介质之间的分配系数

半透膜采样装置(SPMD)作为一种重要的被动采样器,被用于监测有机污染物的环境水平.SPMD的采样材料是置于低密度聚乙烯"口袋"中的三油酸甘油酯.根据有机污染物在被动采样材料与环境介质之间的平衡分配系数(包括被动采样材料/空气分配系数K(sA).和被动采样材料/水分配系数K(sw))值,可估算SPMD的采样速率,也可计...     

湖泊水-沉积物界面DIC和DOC交换通量及耦合关系

以乌梁素海和岱海为研究对象,采用柱状芯样模拟法,开展了2个湖泊水-沉积物界DIC和DOC交换通量及耦合关系研究.结果表明,在夏季90 d的时间内,乌梁素海明水区沉积物表现为上覆水中DIC和DOC的碳源,DIC和DOC的平均释放速率分别为71.07 mmol·(m2·d)-1和185.09 mmol·(m2·d)-1;岱海浅、深水区沉积物整体上表现为上覆水中DIC和DOC的碳汇,浅水区DIC和DOC的平均释放速率分别为155.75 mmol·(m2·d)-1和-1 478.08 mmol·(m2·d)-1,深水区DIC和DOC的平均释放速率分别为-486.53 mmol·(m2·d)-1和-1 274.02 mmol·(m2·d)-1;岱海浅水区和乌梁素海水-沉积物界面DIC与DOC耦合作用(含量、释放速率、总量变化量的同步变化)主要受微生物摄取、微生物或非生物降解及水生植物的影响;岱海深水区水-沉积物界面DIC与DOC耦合作用则主要与Ca CO3共沉淀作用及沉积物中无机碳形态分布特征等有关.总体上,不同类型湖泊或同一湖泊不同湖区的DIC或DOC源/汇功能差异是湖泊类型、离岸距离、湖泊水文地球化学及无机碳形态分布等多种因素综合作用的结果.