三唑酮对大型溞21天慢性毒性效应

三唑类杀菌剂是一种在农业上广泛应用的广谱性杀菌剂.三唑类杀菌剂在农田施用后能够向土壤深处迁移和扩散,从而污染土壤和地下水体,因此三唑类杀菌剂对土壤生态环境能够造成一定的破坏.选择三唑酮为研究对象,参照经济合作与发展组织(Organization for Economic Co-operation and Develop...     

Interactions between mangroves and exotic Spartina in an anthropogenically disturbed estuary in southern China

Cordgrass (Spartina alterniflora) was introduced to China in 1979 from the United States for reducing coastal erosion. It grows vigorously in China and has spread over much of the Chinese coast, from Leizhou Peninsula to Liaoning, a range of more than 19 degrees of latitude. On the southern coast of China, S. alterniflora has invaded mangrove-dominated habitats during the last two decades, but little is known about interactions between native mangroves and invasive S. alterniflora. We studied the distribution and competitive interactions between native mangroves and S. alterniflora in the Zhangjiang Estuary at four tidal sites along a salinity gradient: oligohaline upstream, mesohaline, polyhaline, and euhaline downstream. S. alterniflora occurred at all four sites, and several mangrove species occurred at all but the downstream euhaline site. S. alterniflora has invaded the estuary widely and has spread to the lower tidal margins of mangroves. It has not invaded mangrove areas with a closed canopy but has established in the mangrove zone where the canopy was opened by human disturbance. Ramets of S. alterniflora transplanted into the understory of mangrove stands with closed canopies died within 10 weeks, but 37.5% survived and grew well on open mud flats. S. alterniflora had virtually no competitive effect on mangrove seedlings planted at the upstream oligohaline site. However, S. alterniflora competitively reduced biomass of mangrove seedlings to 33% over a period of 14 weeks at the mesohaline and polyhaline sites where human disturbance has opened the mangrove canopy. In contrast, S. alterniflora marginally facilitated growth and survival of experimental seedlings at the downstream euhaline site. In China, mangroves occur along the coastline south of Whenzhou, but they have been severely disturbed and removed widely, mainly by mariculture activities. Natural vegetation patterns and our experimental results suggest that, without intervention, S. alterniflora could gradually replace these mangroves in mid-salinity regions of Chinese estuaries.     

Costs and prices for renewable energy development in industrialized countries and applications to China

Developing renewable energy is now becoming a hot topic as it is important in dealing with climate change issue and energy supply issue. With the growing demand of energy, it has become urgent to develop the effective policies and measures that would enable people to maintain the living standards. Among all the measures, price is an essential one. In order to evaluate the costs and prices of the electricity from renewable energy sources (RES-E) and their effects to the market, this paper firstly focus on the extra costs of the RES-E by breaking it into four parts, including investment, construction, connection and operation. Then, the policy choices made in some typical industrialized countries are examined to find answers to the problems RES-E can raise. Finally, the choices made in China are examined in comparison to industrialized countries so as to determine how the current situation could be improved.     

温度和停留时间对DDT污染土壤热脱附效果的影响

采用热处理方法分别对自配DDT及其衍生物(DDTs,包括p,p'-DDT、o,p'-DDT、p,p'-DDD和p,p'-DDE)污染土壤在5个温度(100,200,300,400,500℃),6个停留时间(5,10,20,30,40,50 min)下的DDTs去除率及热处理前后的DDTs残留浓度变化进行了研究。研究结果表明:热脱附对DDTs污染土壤修复效果显著。当温度达到300℃以上时,热脱附技术的优势开始显现。300℃下40 min时的DDTs去除率与400℃及500℃处理10 min时相当,均能达到97%以上。对热处理前后土壤中DDTs的残留浓度进行检测,结果表明:土壤中的主要污染成分p,p'-DDT在200℃以上时大量减少,主要转化为p,p'-DDE。p,p'-DDE在200～300℃时大量生成,400～500℃被去除。根据能耗分析结果得出较佳热处理条件为400℃,10 min。     

扎龙湿地龙湖重金属污染情况及其潜在生态风险评价

为了探讨龙湖中重金属污染情况,测定了龙湖中9个取样点的重金属元素含量,并从中选取Mn、Cu、Pb、As 4种重金属元素进行水质评价。通过灰色关联评价分析,所采集的9个样点中有8个样点都属于Ⅴ类水质、1个样点属于Ⅳ水质。采用Hakanson潜在生态风险指数法对龙湖沉积物进行重金属潜在生态风险评价分析,4种重金属的潜在风险顺序为Cu>As>Pb>Mn,其中每个样点的Cu元素都达到了极强的潜在生态危害,As元素的潜在生态危害程度都达到了强度生态危害。     

公路路网建设项目声环境影响评价研究

以甘肃省某市新区基础设施建设中的路网建设为例,根据公路路网的交通参数、道路地形地貌条件、路面设施等,利用导则推荐模式预测路网噪声贡献值。该新区路网中道路距离多在500m以上,不论道路平行还是相交,噪声影响以主干道为主,以次干道为辅,相互影响;根据路网噪声环境影响的特点,提出切实可行的声环境影响减缓措施。     

定费用时尿素热解脱硝系统的可靠性研究

针对费用最小化理论在可靠性分配中的局限性,建立更切合实际的固定费用下可靠度极大化思想。将该思想运用到尿素热解脱硝系统中,针对系统结构功能特征及运行特点,深入分析各系统间逻辑功能关系,提出了完整的尿素热解脱硝系统可靠性分配模型。并引入可靠性成本预估函数,以固定费用为约束,建立数学模型,实现了系统可靠性指标的最优化分配。最后以脱硝系统为例,获得具有实际意义的数值解,证明了该方法的可用性及正确性。     

河源城南污水处理厂尾水深度处理效果的研究

河源市城南污水处理厂利用垂直流人工湿地对该厂A2-O工艺处理的尾水进行深度处理,研究了人工湿地对尾水中TN、NH4+-N、TP、COD、BOD5的去除效果。结果表明:人工湿地对污水处理厂尾水具有较好的深度处理效果,垂直流人工湿地处理系统对尾水中TN、NH4+-N、TP、COD和BOD5平均去除率分别达到97.4%、97.8%、95.06%、91.87%和95.87%以上,其出水水质基本达GB 18918—2002《城镇污水处理厂污染物排放标准》一级A标准,地表水Ⅲ类标准。     

基于改进成功流法的消防系统可靠性研究

在多信号输入系统的可靠性研究中,传统GO法存在计算复杂、易出现误差和遗漏的缺点。将卡诺图化简法引入传统GO运算,利用其“合并同项,简化运算”的特点构建研究多信号输入系统可靠性的新GO模型。将其应用于预作用喷水灭火系统,对具有多启动方式的给水泵进行可靠性分析,并与事件树运算结果比较,证明新GO模型适用于具有多信号输入系统的可靠性研究。研究表明,通过采取措施降低多信号元器件故障概率可以提高系统整体可靠性。     

The origin of high hydrocarbon groundwater in shallow Triassic aquifer in Northwest Guizhou,China

Original high hydrocarbon groundwater represents a kind of groundwater in which hydrocarbon concentration exceeds 0.05 mg/L. The original high hydrocarbon will significantly reduce the environment capacity of hydrocarbon and lead environmental problems. For the past 5 years, we have carried out for a long-term monitoring of groundwater in shallow Triassic aquifer in Northwest Guizhou, China. We found the concentration of petroleum hydrocarbon was always above 0.05 mg/L. The low-level anthropogenic contamination cannot produce high hydrocarbon groundwater in the area. By using hydrocarbon potential, geochemistry and biomarker characteristic in rocks and shallow groundwater, we carried out a comprehensive study in Dalongjing (DLJ) groundwater system to determine the hydrocarbon source. We found a simplex hydrogeology setting, high-level water–rock–hydrocarbon interaction and obviously original hydrocarbon groundwater in DLJ system. The concentration of petroleum hydrocarbon in shallow aquifer was found to increase with the strong water–rock interaction. Higher hydrocarbon potential was found in the upper of Guanling formation (T₂g³) and upper of Yongningzhen formation (T₁yn⁴). Heavily saturated carbon was observed from shallow groundwater, which presented similar distribution to those from rocks, especially from the deeper groundwater. These results indicated that the high concentrations of original hydrocarbon in groundwater could be due to the hydrocarbon release from corrosion and extraction out of strata over time.