茶园土壤酸化对氟的影响及茶叶氟安全限量的探讨

在分析国内外茶园土壤酸化现状的基础上,概述了关于土壤水溶性氟与土壤pH值关系的研究进展,并通过实地调研和培养实验研究了茶园土壤酸化对土壤水溶性氟的影响.实地调研中土壤水溶性氟含量与土壤pH值无显著相关性.培养实验中,当pH＞4.00时,模拟土壤水溶性氟含量随土壤pH值的下降变化不显著;而当pH＜4.00时,土壤水溶性氟含量随着pH值的下降迅速增加,且达到极显著水平.同时描述了世界各国制订的每人每天最大摄氟量标准,对我国现行茶叶标准与国外一些国家的同类标准之间的差异做了评析.茶叶溶出实验的结果表明,我国茶叶氟安全限量需要进一步完善.     

长三角和珠三角土壤中汞的化学形态、转化和吸附特性

为了解长江三角洲和珠江三角洲农业土壤中汞的积累可能产生的环境影响,选择10个代表性农业土壤样品,研究了土壤中汞的化学形态、积累过程中形态的转化及吸附-解吸行为.研究表明,当无外源汞加入时,长江三角洲和珠江三角洲农业土壤中,汞主要以稳定的残余态形式存在.但随着汞加入量的增加,土壤中可交换态汞显著增加,增加程度与土壤性质有关.土壤pH是影响土壤汞有效性最重要的因素,其对土壤汞的吸附、解吸、形态转化和存在形态均有很大影响.土壤酸化可促进土壤汞的释放,加剧对环境的危害,防治土壤酸化也可有效降低土壤中汞对环境的危害.     

淮河上游全新世黄土-土壤剖面重金属元素分布与环境变化

在野外考察研究的基础上利用X-射线荧光光谱仪测定了河南禹州全新世YPC黄土-土壤剖面Zn、Cu、Co、Ni、Nb、Pb、V、Cr、Mn、Ti重金属元素的含量及其变化,研究表明在黄土堆积期,重金属元素的含量都很低,变化幅度也很小,可作为衡量古土壤层成壤改造的背景值.在全新世古土壤和现代表土中这些元素含量却大大增加,说明在温暖湿润的时期,成壤改造使易溶易迁移元素的淋失导致重金属元素的相对富集.而Pb含量从8cm深度处向上急剧增加,增幅达60%,这是大气污染物沉降积累的客观记录.     

云南不同类别基本农田土壤环境质量的时空差异

按照《农田土壤环境质量监测技术规范》（NY／T395--2000）,连续3年定点定位监测了云南亚热带干热河谷旱（缓）坡农耕地、中海拔旱（陡）坡农耕地和平坝区蔬菜地土壤环境质量。统计分析了监测结果的时间差异和空间差异。空间差异：旱（陡）坡农耕地〉旱（缓）玻农耕地〉平坝区蔬菜地;时间差异：旱（缓）坡农耕地〉平坝区蔬菜地〉旱（陡）坡农耕地。     

石油化工场地环境评价

介绍了石油化工场地环境评价的程序和方法,内容主要包括石油化工场地环境评价的基本内容、土壤和地下水监测点位的布设、样品的采集与保存、样品的预处理及分析、质量控制等.     

Natural and anthropogenic metal inputs to soils in urban Uppsala, Sweden

Urban soils are complex systems due to human activities that disturb the natural development of the soil horizons and add hazardous elements. Remediation projects are common in urban areas and guideline values are set to represent a desired level of elements. However, the natural content of trace elements may not always equal the desired levels. In this study, an attempt is made to distinguish between metals that are present in the soil due to natural origins and to anthropogenic origins. Seventy-five soil samples of the 0–5, 5–10 and 10–20 cm layers were collected from 25 sites in urban areas of Uppsala City and analysed for aluminium (Al), arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), iron (Fe), mercury (Hg), manganese (Mn), nickel (Ni), lead (Pb), tungsten (W) and zinc (Zn) using aqua regia for digestion. In order to highlight elements of geological origin, the results were compared to a similar study carried out in Gothenburg City, which has about three times as many inhabitants as Uppsala and has a more industrial history. A cluster analysis was also performed to distinguish between elements of natural and anthropogenic origin. Contents of As, Al, Fe, Cr, Ni, Mn and W in Uppsala were concluded to be of mainly geological origin, while contents of Cd, Cu, Zn, Pb and Hg seemed to have been impacted upon by mainly urban activities.     

Accumulation and phytoavailability of benzo[a]pyrene in an acid sandy soil

Effects of benzo[a]pyrene (B[a]P) on ryegrass (Lolium perenne L.) growth, plant accumulation and dissipiation of B[a]P in a red sandy soil (Hapli-Udic Argosol) were studied in a pot experiment. The plants were grown for 61 days in soil spiked with B[a]P at 0, 12.5, 25 and 50 mg kg⁻¹. Control pots without plants were also set up. Soil extractable B[a]P, plant shoot and root biomass, and concentrations of B[a]P in plant shoots and roots were determined. Ryegrass biomass was increased by addition of B[a]P and root B[a]P concentrations were significantly correlated with B[a]P application rate, but no such correlation was found for shoot B[a]P concentrations. This indicates that B[a]P enhanced the growth of the ryegrass. The extractable B[a]P concentration in the planted soil was significantly lower than that in the unplanted control soil at the rate of 50 mg B[a]P kg⁻¹. This indicates that ryegrass may help to dissipate B[a]P in soil at concentrations over 50 mg kg⁻¹ soil although the mechanism for this is not understood.     

A review and numerical assessment of the random walk particle tracking method

We review the basic mathematical concepts of random walk particle tracking (RWPT) and its advantages and limitations. Three different numerical approaches to overcome the local mass conservation problem of the random walk methodology are examined: (i) the interpolation method, (ii) the reflection principle, and (iii) the generalized stochastic differential equations (GSDE). Analytical solutions of the spatial moments for a two-layer system are compared to model predictions using the different techniques and results demonstrate that the interpolation method reproduces correctly average velocity, but fails to reproduce macrodispersion at higher hydraulic conductivity contrasts between the two layers. On the contrary, the reflection principle and the GSDE approach underestimate average velocity, but reproduce macrodispersion better for high contrasts. The different behavior is based on an artificial shift of mass for increasing heterogeneities for the GSDE approach and the reflection principle, whereas the interpolation method suffers from the smoothing of the dispersion tensor. The behavior of these approaches was furthermore analyzed in two-dimensional heterogeneous hydraulic conductivity fields, which are characterized by different random function models. Solute transport was simulated correctly by all three approaches for the reference fields having Gaussian structures or non-Gaussian structures with an isotropic spatial correlation, even for a variance of the natural log of hydraulic conductivity of sigma(lnK)(2)=4. However, for the non-Gaussian model with a strong anisotropic spatial correlation and a variance of sigma(lnK)(2)=2 and higher, the interpolation method was the only technique modelling solute transport correctly. Furthermore, we discuss the general applicability of random walk particle tracking in comparison to the standard transport models and conclude that in advection-dominated problems using a high spatial discretization or requiring the performance of many model runs, RWPT represents a good alternative for modelling contaminant transport.     

黄泥土不同粒径微团聚体对Cd2+的吸附与解吸研究

对采自太湖地区黄泥土进行了低能量超声波分离,采用平衡吸附法研究了不同粒径微团聚体颗粒对重金属Cd²⁺的吸附和解吸特点.结果表明,不同粒径微团聚体对Cd²⁺的吸附特性均符合Freundlich方程,模拟方程得到的K值介于152～503之间,以粘粒级和粗砂级为最大.微团聚体对Cd²⁺的吸附容量与其中游离氧化铁含量、CEC呈显著正相关.不同微团聚体Cd的解吸特点不同,粘粒级的解吸率仅为8.4%,远远低于其它粒径的微团聚体,这些结果有助于了解田间条件下土壤重金属化学行为和微观尺度的化学过程.     

潮土施镍对小白菜的生物效应及其临界值研究

研究潮土施Ni对盆栽蔬菜的生态效应,并通过小白菜生物量的变化、地上部茎叶Ni质量比及土壤有效态Ni质量比来表征土壤Ni污染的毒性临界值.结果表明,潮土施Ni对蔬菜未表现出增产效应.施Ni量低于25 mg/kg,其生物产量无明显降低.随施Ni量的增加,生物产量呈显著下降,生物量变化与Ni质量比呈高度负相关.潮土施Ni增加茎叶和根系中Fe,Mn,Ca,Mg元素质量比,降低Cu,Zn元素质量比.4种性质不同的提取试剂提取的土壤有效态Ni质量比与植物Ni吸收均呈高度正相关,较好地反映了植物的危害状况,且以DTPA提取效果最佳.以生物减产量突变点为依据,确定潮土施Ni毒害临界值为:土壤全量Ni为41.86 mg/kg,有效态Ni质量比为2.55mg/kg(DTPA)和茎叶Ni质量比为22.39 mg/kg.