Petroleum-contaminated soil extent recorded by δ15N and δ13C of plants and soils

Petroleum contamination in terrestrial environments caused by industrial activities is a significant problem that has received considerable attention. Carbon and nitrogen isotopic compositions (δ13C and δ15N) effectively describe the behavior of plants and soils under petroleum contamination stress. To better understand plant and soil responses to petroleum-contaminated soil, δ13C and δ15N values of the plants (Trifolium repens, Leguminosae with C₃ photosynthesis pathway, and Agropyron cristatum with C₄ photosynthesis pathway) and the soil samples under one-month exposure to different extents of petroleum contamination were measured. The results showed that petroleum contamination in the soil induced the soil δ15N values to increase and δ13C values to decrease; from 1.9‰ to 3.2‰ and from ?23.6‰ to ?26.8‰, respectively. However, the δ13C values of Agropyron cristatum decreased from ?29.8‰ to ?31.6‰, and the δ13C values of Trifolium repens remained relatively stable from ?12.6‰ to ?13.1‰, indicating that they have different coping strategies under petroleum-contaminated soil conditions. Moreover, the δ15N values of Trifolium repens decreased from 5.6‰ to 0.8‰ near the air δ15N values under petroleum-contaminated soil, which implies that their nitrogen fixation system works to reduce soil petroleum stress. The δ13C and δ15N values of Agropyron cristatum and Trifolium repens reflect changes in the metabolic system when they confront stressful environments. Therefore, stable isotopic compositions are useful proxies for monitoring petroleum-contaminated soil and evaluating the response of plants to petroleum contamination stress.     

含镉稻米的分布及治理技术概述

镉是一种重要的重金属污染物,可经土壤、粉尘和农作物进入食物链.稻米易于富集土壤和环境中的镉,给消费者健康带来潜在风险.我国土壤中的镉含量存在地域不均一性,个别地区由于地质原因或工业、采矿污染,土壤镉含量偏高,导致当地生产的稻米镉超标.为应对稻米镉污染问题,目前已开展了土壤修复治理、水稻品种改良和稻米降镉加工利用等方面的研究.总结了中国土壤和稻米镉污染现状,分析了影响稻米富集镉的主要因素,概述了国内外稻米镉污染治理的新方法,为开展镉污染稻米治理及利用提供建议.     

可压缩核废料污染问题的变网格特征有限元法

对多孔介质中可压缩核废料污染问题提出并分析了一类特征线修正的变网格混合元方法 ,即对流动方程采用混合元方法 ,对浓度方程和传热方程采用变网格特征有限元法 .从而在不增加计算量的基础上可采用对时间t的大步长计算 ,充分地发挥了有限元数值解法的高精度优越性 ,并在相当一般的情况下得到了L2 模误差估计 .     

黄石市几种市售蔬菜的重金属污染分析

对黄石市4个市场的6种大宗蔬菜的Pb、As、Cd、Cu、Zn、Hg、Cr、Ni等重金属含量进行了检测分析,并根据相关标准对其进行评价。结果表明,黄石市售蔬菜重金属污染主要表现为As、Pb污染。叶菜类(莴笋叶和小白菜)重金属含量最高,其次是瓜豆类(黄瓜和四季豆),茄果类(茄子和番茄)含量最低。叶菜类叶中重金属含量明显高于茎。调查的6种蔬菜中,莴笋叶和小白菜遭受到严重污染,黄瓜受到轻度污染,四季豆处于警戒水平,仅番茄和茄子是安全的。相关部门应对蔬菜质量引起高度重视。     

一种新型多功能柴油添加剂

将表面活性剂、油性溶剂和水等混合制得了一种新型多功能柴油添加剂．汽车怠速试验与发动机台架试验表明，该添加剂能改善燃烧，并较大幅度降低柴油发动机尾气中CO、NOx、HC及碳烟等污染物的排放．文中还分析了影响添加剂降污性能的主要因素，采用微爆燃烧机理较好地解释了其降污机理．     

植物修复重金属-有机物复合污染河道疏浚底泥的研究

针对目前国内普遍存在的排污河道污染问题,通过盆栽试验研究了玉米、印度芥菜、超积累油菜、紫花苜蓿在施用不同配比的排污河道疏浚底泥上对重金属-有机物复合污染的修复情况及超积累的机理.结果表明,随着底泥配比的增加,植物发芽率的抑止程度也增加;适应底泥中高浓度复合污染的植物,底泥施用能促进其生长,提高植物体内的叶绿素含量.植物体内积累的重金属Zn、Pb、Cd以生长在底泥与土壤比为2:1的印度芥菜为最大,分别为1 521 mg/kg、453 mg/kg和11.7 mg/kg;Cu、Ni积累量以生长于底泥中的玉米为最大,分别为128 mg/kg和89.1 mg/kg.在本实验条件下,底泥中有机物以种植玉米的底泥为最大,为76.89%.通过环境扫描电子显微镜及配套的能谱分析发现,重金属在植物体内的聚集存在;经X荧光光谱仪和X射线衍射仪分析,确证了配合体之间及重金属和配合体相互形成架桥而聚集成团,形成重金属结合物积累在植物体内,且在植物根部发现积累了Cu的有机氯化物.种植前后底泥的X射线衍射对比表明,种植后重金属的晶格结构和存在形态发生了变化.     

遥感技术在江西德兴铜矿矿区污染研究中的应用

以德兴铜矿矿山为例，首先从遥感影像中提取植被的生长信息以确定污染的分布状况。在对矿区典型植被光谱反射特性综合分析基础之上，总结对照区和污染区植被的波谱特征差异和各污染区的受污染程度。最后，对矿区土壤的重金属污染治理提出一些建议。     

我国水环境污染物总量控制研究的现状与展望

随着排入水体的污染物的增多和人们生活水平的提高，污染物浓度的控制已难以真正控制水环境污染．于是在水质规划中首先提出了总量控制的方法．总量控制是在污染严重、污染源集中的区域或重点保护的区域范围内，通过有效的措施，把排入这一区域的污染物总量控制在一定的数量之内，使其达到预定环境目标的一种控制手段．本文在分析了我国水环境的基本特征基础之上，阐述了我国水环境污染物总量控制的现状及存在的问题，进而指出我国水环境污染物总量控制的发展方向．     

仓储稻谷霉菌污染情况调查

报告了稻谷霉菌的污染现状。对湖南省 42个粮库的 42个稻谷样品进行采样调查 ,主要霉菌属曲霉属、青霉属、毛霉属的检出率平均为 90 .4%、76 .5 %、5 2 .1% ,平均含菌量为 2 .75× 10 4 个 /克 ,曲霉中主要带毒菌黄曲霉、杂色曲霉、构巢曲霉的检出率为 6 4.3%、33.7%、13.0 % ,发现霉菌污染率与储藏时间无显著相关性 ,而与储藏条件密切相关。     

Origin of two differentiation trends in the Emeishan flood basalts

Both the Bowen and Fenner differentiation trends have been recognized in the Emeishan flood basalts.While the Longzhoushan laveas in Panxi paleorift evolved on a trend of silica enrichment (Bowen trend),the lavas from Guizhou evoled along the Fenner trend leading to the magmas with high Fe2O3 (23%) and low SiO2(44%) contents,This provides evidence for the existence of Fe-rich and Si-poor magmas in nature ,Such contrasting differentiation trends,marked by different timing of crystallization of Fe-Ti oxides,are correlated with the extent of crustal contamination of the magmas ,Linited crustal contamination in the Guizhou lavas is coupled with the low oxygen fugacity which delayed the onset of magnetite crystallization .In contrast,significant involvement of crustal components in the Long-Zhoushan lavas increased fo2 which in turn triggered early crystallization of magnetite.The close spatial association between the Longzhoushan lavs and the synchronous V-Fe-Ti deposit-bearing layered intrusions suggests a potential relationship between them.