Prevalence and distribution of fecal indicator organisms in South Florida beach sand and preliminary assessment of health effects associated with beach sand exposure

Fecal indicator levels in nearshore waters of South Florida are routinely monitored to assess microbial contamination at recreational beaches. However, samples of sand from the surf zone and upper beach are not monitored which is surprising since sand may accumulate and harbor fecal-derived organisms. This study examined the prevalence of fecal indicator organisms in tidally-affected beach sand and in upper beach sand and compared these counts to levels in the water. Since indicator organisms were statistically elevated in sand relative to water, the study also considered the potential health risks associated with beach use and exposure to sand. Fecal coliforms, Escherichia coli, enterococci, somatic coliphages, and F(+)-specific coliphages were enumerated from sand and water at three South Florida beaches (Ft. Lauderdale Beach, Hollywood Beach, and Hobie Beach) over a 2-year period. Bacteria were consistently more concentrated in 100g samples of beach sand (2-23 fold in wet sand and 30-460 fold in dry sand) compared to 100ml samples of water. Somatic coliphages were commonly recovered from both sand and water while F(+)-specific coliphages were less commonly detected. Seeding experiments revealed that a single specimen of gull feces significantly influenced enterococci levels in some 3.1m(2) of beach sand. Examination of beach sand on a micro-spatial scale demonstrated that the variation in enterococci density over short distances was considerable. Results of multiple linear regression analysis showed that the physical and chemical parameters monitored in this study could only minimally account for the variation observed in indicator densities. A pilot epidemiological study was conducted to examine whether the length of exposure to beach water and sand could be correlated with health risk. Logistic regression analysis results provided preliminary evidence that time spent in the wet sand and time spent in the water were associated with a dose-dependent increase in gastrointestinal illness.     

陕西省泾惠渠灌区土壤重金属地质累积指数评价

通过对陕西省泾惠渠灌区现场调查及土壤样品的采集,分析了灌区土壤中Hg、Cd、Cr、Pb、As、Cu、Zn等7种元素的含量,应用地质累积指数对灌区土壤进行了评价。结果表明：从区域分布看,阎良区、临潼区、高陵县所属采样点污染较严重;Hg污染最严重,地质累积指数为1.007～3.117,58%的采样点级别为3级,属中度污染到强污染,38%的采样点级别为2级,属中度污染;Zn污染程度次之,地质累积指数为-0.407～1.644,71%的采样点级别为1级,属无污染到中污染;Cd污染变异程度最大,地质累积指数为-2.705～3.312,70%的采样点级别0级,属无污染,但个别采样点达到了强污染;Cu的地质累积指数为-0.535～0.421,Pb为-1.119～-0.144,Cr为-1.005～-0.458,As为-0.562～0.077,除个别点外这些重金属污染级别皆为0级,属无污染。     

国际流行彩色宝石品质分级评估体系的比较及其启示

彩色宝石品质分级标准对彩色宝石市场的形成与发展具有重要意义。彩色宝石品种的多样性和品质影响要素的复杂性,加上不同国家、地区或民族对彩色宝石颜色的偏好不同,在国际市场上要建立一个统一的彩色宝石品质分级评估体系困难重重。通过比较各彩色宝石聚集地（如美国、泰国、中国香港与大陆等）现有的彩色宝石品质分级评估体系,探讨了不同体系对其颜色、净度、切工分级的思想与方法。结果显示,目前国际上不同彩色宝石分级体系在颜色分级术语上强调的要素有一定的差异,对净度分级在思路上有明显的不同,对切工分级则在思路及技术操作上均存在明显差异。因此,要建立统一的国际彩色宝石品质分级体系尚需时日。最后提出,中国可以尝试以宝石的净度和透明度分级为先导,结合颜色、净度与切工分级设计新的彩色宝石二级递进制（时尚首饰级和宝石级）品质评估分级体系。     

全胶结注浆法在煤矿采空区治理工程中的应用

由于煤矿采空区块段顶板基本保持悬空状态,上部岩体易产生沉陷变形,影响地表建筑物地基基础的稳定。全胶结注浆法,就是将水泥粉煤灰浆液直接注入采空区及其上覆岩体裂隙中,浆液固化后胶结岩体裂隙,同时采空区内的浆液形成的结石体对其上覆岩体形成支撑作用,阻止上覆岩体的进一步冒落,保证上部建筑物地基的稳定。山西省晋城富晋精密工业有限公司二期生产项目A区煤矿采空区治理工程应用该技术取得很好的治理效果,全胶结注浆法具有施工简单,安全性高,施工工艺成熟,施工易于管理,质量检测手段简便易行等优点,在同类型矿山采空区的治理中有较大的应用推广价值。     

泰安城区供水安全分析

随着经济的发展和人民生活的改善,城市需水量越来越大,供需矛盾极为突出,供水安全显得十分重要。对泰安城区供水水源状况进行了分析,结果发现研究区现状条件下,丰水年、平水年份供水量基本能够满足需要,但是水质状况不容乐观;枯水年份供水安全则不能保证。为保证枯水年份城市供水安全和研究区将来需水量增加的要求,特提出开源节流、雨洪水利用、分质供水、跨流域调水和供水水质监测等对策。     

基于黄金分割理论的改进BP网络地下水水质评价

利用VB语言编写附加动量的改进BP人工神经网络模型程序,并将其加载到Excel中,以湛江市区地下水为例研究水质状况。该模型采用黄金分割理论和试算相结合的方法对网络模型的隐含层节点数进行了优选,研究结果与其他方法相比显示：改进BP人工神经网络模型在地下水水质评价中能够很好地解决评价因子与水质等级间复杂的非线形关系,评价结果的精度有较大地提高。     

我国地下水污染调查评价中的水质分析技术

在介绍我国地下水污染调查与评价工作的基础上,结合地质矿产实验室的实际情况,总结并探讨了其水质分析的技术体系和最新成果,对开展地下水污染样品的检测和质量管理具有一定的实用价值和指导意义。     

高密度电阻率成像法在水文地质领域中的应用

高密度电阻率成像法(ERT)作为一种高效、准确的地球物理探测手段,在水文地质领域得到了广泛的应用。本文通过文献追踪和分析,重点讨论了电阻率与含水率、渗透系数、含盐量等水文地质表征参数之间的相关性,并就该方法在地下水资源勘查、溶质运移动态监测以及水文地质参数反演等方面的应用进行了剖析,阐述了ERT探测过程中的主要影响因素及各因素之间的相互关系。最后,针对ERT方法在应用过程中存在的问题提出相应的改进建议。     

田湾核电站5号、6号机组负挖爆破设计与质量控制

综述了在商业运行的核电站周边进行核岛负挖爆破的设计和质量控制,尤其对负挖预裂爆破和核岛廊道爆破技术及质量控制要点进行了较详细的表述,为类似核电负挖工程提供借鉴。     

采用高压旋喷桩技术加固煤矿采动区铁路路基实践

依据理论分析和数值计算的成果,对研究区段的旋喷桩加固进行了工程设计、现场施工组织和质量检测,结果表明,采用旋喷桩约束加固具有较好的加固效果和经济效益。