Postmortem microbial communities in burial soil layers of skeletonized humans

Microorganisms are major ecological participants in the successional decomposition of vertebrates. The relative abundance, or the scarcity, of certain microbial taxa in gravesoil has the potential to determine the ecological status of skeletons. However, there are substantial knowledge gaps that warrant consideration in the context of the surrounding terrestrial ecosystem. In the current study, we hypothesized that i.) soil microbial diversity is disparate in the latter stage of decomposition (skeletonization) compared to the earlier stages (fresh, bloat, active and advanced decay), and ii.) the three layers of gravesoil (top, middle, and bottom) encompass similar microbial taxa and are analogous with control soil. To test these hypotheses, microbial communities in layers of burial soil of skeletonized bodies (treated) and from control soil, obtained from burial plots with no bodies (untreated), were compared using sequencing data of the 16S rRNA gene. The results demonstrated that Acidobacteria was confirmed as the most abundant microbial genus in all treated and untreated soil layers. Furthermore, Proteobacteria demonstrated a relatively low abundance in skeletonized gravesoil which is dissimilar from previous findings that assessed soil from earlier stages of human decomposition. Also, these results determined that soil microbial signatures were analogous in all three soil layers under the effects of similar abiotic and biotic factors, and they were similar to the communities in untreated soil. Therefore, the current study produced empirical data that give conclusive evidence of soil microbial successional changes, particularly for Proteobacteria, for potential use in forensic microbiology research.     

基于GIS的广东食管癌高、低发区土壤与植被比较分析

[目的]比较广东省食管癌高、低发区土壤类型、植被类型及土壤有机碳密度（SOCD）的差异。[方法]在Excel中建立广东省分县的食管癌死亡率数据库,在ArcGIS9.0中制作广东省县界多边形电子地图并与疾病数据库链接。通过县界电子地图与中国土壤、中国植被图的叠加分析,获取广东省分县（94个县）的土壤与植被类型数据。运用空间查询的方法提取食管癌死亡率最高与最低的10个地区进行土壤与植被类型比较。根据土壤与植被类型的分布计算分县的平均SOCD,并与食管癌死亡率进行Spearman等级相关分析。[结果]广东省食管癌高、低发区的土壤与植被类型均存在着差异。男、女性别死亡率与100cm及20cm厚度SOCD均呈负相关,等级相关系数男性为：-0.516与-0.605（P值分别为0.004与0.001）;女性为：-0.535与-0.598（P值分别为0.003与0.001）。[结论]食管癌死亡率与所处地区的土壤有机碳密度具有一定相关性,需要更进一步的研究。     

An adaptable internal dose model for risk assessment of dietary and soil dioxin exposures in young children.

An adaptable model is presented for assessing the blood lipid concentrations of polychlorodibenzodioxins and polychlorodibenzofurans (PCDD/Fs) from dietary (breast milk, formula, milk, and other foods) and soil pathway exposures (soil ingestion and dermal contact) utilizing age-specific exposure and intake estimates for young children. The approach includes a simple one-compartment (adipose volume) toxicokinetic model that incorporates empirical data on age-dependent half-lives and bioavailability of PCDD/F congeners, child body size and intake rates, and recent data on breast milk and food dioxin levels. Users can enter site-specific soil concentration data on 2,3,7,8-chlorinated PCDD/F congeners for specific assessment of body burden changes from soil pathways in combination with background dietary exposures from birth through age 7 years. The model produces a profile of the estimated PCDD/F concentration in blood lipid (in World Health Organization 1998 dioxin toxic equivalents) versus time for a child from birth through age 7 years. The peak and time-weighted average (TWA) internal dose (defined as blood lipid dioxin toxic equivalents) for a variety of specific child exposure assumptions can then be compared to safe internal dose benchmarks for risk assessment purposes, similar to an approach taken by United States Environmental Protection Agency for assessing child lead exposures. We conclude that this adaptable toxicokinetic model can provide a more comprehensive assessment of potential health risks of PCDD/Fs to children because it integrates recent empirical findings on PCDD/F kinetics in humans and allows users to assess contributions from varied dietary and site-specific environmental exposure assumptions.     

枸杞品质及其与土壤肥力关系的研究

目的通过测定宁夏8个不同产区枸杞头茬、盛果期和秋果中总糖、多糖、甜菜碱、氨基酸、总黄酮、类胡萝卜素的量及百粒质量,并分析总糖碱比,研究枸杞中这些指标间以及它们与土壤肥力因子间的相互关系。方法采用HPLC和分光光度等实验方法以及聚类分析、相关性分析和方差分析等生物统计方法。结果枸杞中各指标被归为以总糖、甜菜碱和类胡萝卜素为代表的3类,各指标受各种土壤肥力因子的作用不同。结论总糖、甜菜碱和类胡萝卜素这3种成分及糖碱比值能较科学地评价枸杞的品质;施肥时应综合考虑各种肥力因子对枸杞成分的协同作用,不宜片面考虑其单一的相关性。该研究为枸杞品质评价及合理施肥提供了依据。     

污灌土壤有机提取物对原代大鼠肝细胞DNA损伤的研究

[目的]研究污灌土壤有机提取物对原代大鼠肝细胞DNA的损伤。[方法]选取A、B、C3类污灌农田土壤为研究对象,地下水灌溉的土壤D为对照,采用超声振荡法提取土壤中的有机污染物,并用彗星试验检测土壤有机提取物对原代大鼠肝细胞DNA的损伤情况。[结果]A、B、C、D3个剂量组(0.3g/ml,0.6g/ml,0.9g/ml)土壤有机提取物均可导致DNA迁移长度增加,拖尾率增高;A、B、C与D组相同染毒剂量比较,DNA迁移长度增加,拖尾率增高。[结论]A、B、C、D中均含有大量的DNA损伤物质,且A、B、C所含有机物的毒性要强于D.     

污染土壤电动修复正交试验研究

通过正交试验研究了电动修复Cr6 污染高岭土过程中施加电压、处理时间、含水率、阴极电解产生OH一控制4个因素对污染物去除率和电能消耗的影响.试验选用重铬酸钾作为污染物,配制高岭土中Cr6 初始含量为500mg·kg-1.试验结果表明:阴极pH控制对cr6 去除率影响最大,其次为施加电压和处理时间,含水率影响最小;电压对电能消耗的影响最大,其次为时间和含水率,阴极pH控制对电能消耗影响最小.分析表明控制阴极pH是提高污染土壤电动修复效率的优先选择.     

粪便废水絮凝处理的实验研究

对粪便废水絮凝处理的药剂进行了初步筛选,选定常用絮凝剂硫酸铝、聚合氯化铝和聚丙烯酰胺(包括3种类型)进行了单独絮凝和复配絮凝的实验研究,优选出最佳絮凝剂.结果表明:对于500 mL水样,在pH 7.5、0.2%硫酸铝投加量8 mL、0.2%PAM(阳离子型,分子质量1 500万u)投加量1.5 mL的条件下,废水的色度、浊度、CODCr的去除率分别达到94.3%、96.0%和58.2%,絮凝效果较理想.