Concentrations and inventories of polycyclic aromatic hydrocarbons and organochlorine pesticides in watershed soils in the Pearl River Delta,China

The concentration levels, source, and inventories of polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticides (OCPs) in 55 surface vegetable soils in the watershed of the Pearl River Delta (PRD) were analyzed and compared with those of the surface sediments in the Pearl River Estuary (PRE) and northern South China Sea (SCS). The 16 priority PAHs on US EPA list range from 58 to 3,077 microg/kg (average: 315 microg/kg). The concentrations of DDTs and HCHs range from 3.58 to 831 microg/kg (average: 82.1 microg/kg) and from 0.19 to 42.3 microg/kg (average: 4.42 microg/kg). The ratios of DDT/ (DDD+DDE) are higher than 2 in majority of the soil samples, suggesting that DDT contamination still exists. The PAH ratios suggest that the source of PAHs is petroleum, and combustion of fossil fuel, biomass, and coal. The average concentrations of PAHs and the linear regression slope between PAHs and TOC for the soils and the sediments are quite similar. It was estimated that the soil mass inventories at 0-20 cm depth are 1,292 metric tons for PAHs and 356 metric tons for OCPs in the studied region. The average PAHs inventory per unit area for the soil samples investigated in PRD is about 0.86 time that of surface sediments in the Pearl River Estuary, and about 2.43 times that of surface sediments in the northern South China Sea. PAHs in the soils in PRD have similar source to those of the surface sediments in PRE. All of those may suggest that PAHs in PRE and SCS are probably mainly inputted from the soils in PRD via soil erosion and river transport.     

磷酸三(1,3-二氯-2-丙基)酯导致小鼠神经毒性结局的潜在靶点研究

磷酸三(1,3-二氯-2-丙基)酯(TDCPP)在环境介质及生物样本中被广泛检出,为探究TDCPP的潜在神经毒性以及作用机制,以C57BL/6小鼠为动物模型,考察经300 mg·kg-1·d-1的TDCPP持续染毒35 d后,小鼠大脑皮层神经功能相关因子及血清代谢组学的变化.结果显示,小鼠在TDCPP染毒35 d后,大...     

四川酸性物湿沉降模式及预测

酸沉降是一复杂的大气物理和化学过程，涉及诸多复杂影响因素。目前，我国酸雨湿沉降模式还仅限于模拟云下洗脱成酸过程，而对云中的成酸过程还未进行深入研究，这不仅在理论上不完善，而且更重要是在许多情况下与我省实际情况不符。本课题针对四川省特定的地理，气象特点和严重的大气污染情况，并借鉴国外研究成果，提出了考虑酸性沉降的云中和云下成酸过程和各种影响因素的综合酸雨湿沉降模式，并根据此模式来估算和预测四川省酸雨     

A WATER QUALITY‐BASED APPROACH FOR WATERSHED WIDE BMP STRATEGIES1

ABSTRACT: Watershed management strategies generally involve controlling nonpoint source pollution by implementing various best management practices (BMPs). Currently, stormwater management programs in most states use a performance‐based approach to implement onsite BMPs. This approach fails to link the onsite BMP performance directly to receiving water quality benefits, and it does not take into account the combined treatment effects of all the stormwater management practices within a watershed. To address these issues, this paper proposes a water quality‐based BMP planning approach for effective nonpoint source pollution control at a watershed scale. A coupled modeling system consisting of a watershed model (HSPF) and a receiving water quality model (CE‐QUAL‐W2) was developed to establish the linkage between BMP performance and receiving water quality targets. A Monte Carlo simulation approach was utilized to develop alternative BMP strategies at a watershed level. The developed methodology was applied to the Swift Creek Reservoir watershed in Virginia, and the results show that the proposed approach allows for the development of BMP strategies that lead to full compliance with water quality requirements.     

浅论健美操教学方法

随着人民群众生活水平的不断提高,健美操运动越来越受到广大青少年的喜欢,现已成为各大中专院校的一项重要教学内容,通过多年的教学实践,对当前健美操教学中常用的教学方法进行全面综合、比较与分析,提出8种行之有效的教学方法,以期与各位同仁共同提高健美操教学质量,使健美操这一优秀的健身方法成为全民健身的重要形式和手段。     

快速断电安全技术中半导体中性点开关结构性能的研究

对我国目前半导体中性点开关的结构 ,工作过程 ,性能进行了分析 ;现行中性点开关所存在的问题为电路拓扑结构不合理 ,关断时间过长或过短 ,过长不满足快速断电安全技术的要求 ,过短又易引起过电压 ,使中性点开关失控。笔者提出了采用绝缘门极双极性晶体管 (IGBT) ,构成半导体中性点开关的可行方案。同时指出 ,开发新型快速断电安全技术装置 ,将大大提高我国煤矿安全技术水平     

基于多Agent技术的交通事故救援系统的研究

着重介绍了目前人工智能领域的研究热点问题———Agent技术的概念与原理 ,以及多Agent组的概念和分类 ;提出了基于多Agent技术的交通事故救援系统的流程框架 ;论述了该系统每一个Agent成员所能够完成的主要功能 ;通过该系统的实现 ,可以提高交通事故的及时报警与快速解决的效率 ,实行更加有效的交通流量合理分配 ;在利用既有交通基础设施的基础上增强了出行者的出行便利。笔者认为 ,随着Agent技术和网络技术研究的不断深入 ,基于Agent的应用研究必将有着更广泛的应用前景     

矿井主通风机叶轮磨损失效的评价

矿井主通风机叶轮严重磨损威胁着矿井安全生产 ,研究主通风机叶轮磨损和正确地评价叶轮的磨损失效 ,对煤矿安全生产具有重大的现实意义。应用气—固两相流动理论分析了主通风机叶轮的磨损部位 ,结论与现场叶轮的实际磨损相吻合。提出了叶轮磨损过程的 3个阶段。利用材料磨损理论分析了主通风机叶轮磨损机理 ,得出了叶轮磨损是以气体动力学磨料的冲蚀磨损为主 ,低应力擦伤型磨料磨损、腐蚀磨损为辅的结论。依据国家标准 ,结合矿井主通风机工作特点 ,从安全角度提出了矿井主通风机叶轮磨损永久失效的判据 ,并给出了判定标准。     

盾构施工对周围建筑物的安全影响及处理措施

讨论了盾构施工对周围建筑物的安全影响 ;分析了盾构通过建筑物时的组织方法 ;论述了盾构施工影响区域的划分和对建筑物影响进行预测的手段 ;提出了盾构通过建筑物时的施工控制参数和常见的工程处理措施。笔者就盾构施工引起的建筑物安全问题及其应对措施进行了论述和总结 ,为工程技术人员提供了有益的参考。     

桥梁实用延性抗震设计方法研究

针对铁路桥梁中应用广泛的单柱式桥墩 ,考虑多种跨度 ,多种墩高和多种场地及多种地震烈度的情况 ,在进行大量的桥墩结构线性和非线性弹塑性动力计算分析的基础上 ,通过对大量数据的统计分析 ,得到桥墩线弹性最大弯矩比和非线性位移延性比参数的变化规律 ,基于概率性的结构随机地震反应理论 ,建立了由线弹性动力分析结果来估算桥墩结构的位移延性响应的方法。