纳米零价铁耦合黏土修复污染土壤的研究进展

黏土负载型nZVI具有低成本、易制备、环境相容性好、综合性能优越的特点.本文在归纳nZVI改性策略的基础上,比较了黏土种类对nZVI形貌和性能的影响,提出了理想黏土载体的优选顺序,分析了复合材料的铁含量、比表面积、nZVI尺寸等与去除性能之间的关系,对nZVI耦合黏土在修复土壤重金属、卤代有机物、硝酸盐、新型污染物等方面的研究进行了总结,并概述了nZVI技术在土壤修复中的负面效应,最后对nZVI耦合黏土修复污染土壤的未来方向进行了展望.     

Sorption of Pesticides on Kaolinite and Montmorillonite as a Function of Hydrophilicity

Pesticides and other organic species are adsorbed by soil via different mechanisms, with bond strengths that depend on the properties of both the soil and the pesticide. Since the clay fraction in soil is a preferential sorbent for organic matter, reference kaolinite and montmorillonite are useful models for studying the mechanism and the strength of sorption. This paper presents the results of batch experiments to investigate the interactions of kaolinite KGa-1 and montmorillonite SWy-1 with the following pesticides and organic species resulting from the natural degradation of pesticides in the environment: atrazine (1-chloro-3-ethylamino-5-isopropylamino-2,4,6-triazine), simazine (1-chloro-3,5-bisethylamino-2,4,6-triazine), diuron [1,1-dimethyl-3-(3,4-dichlorophenyl)urea], aniline, 4-chlorophenol, 2,4-dichlorophenol, and 2,4,6-trichlorophenol. Each of these chemicals has different hydrophilicity. Systems containing 2.0 g of clay were put in contact with 100.0 mL of solutions of the pesticides at known concentration ranging from 1.0 to 5.0 mg/L, and the amount of solute adsorbed was evaluated through RP-HPLC analysis of the pesticide still present in the aqueous suspension. To test for electrostatic interactions between the clay surface and the pesticides, potentiometric titration was used to determine the permanent surface charge of clays. Experiments were performed at different pH values. The results indicate that, for the chemicals studied, neutral molecules are preferentially retained relative to ionized ones, and that montmorillonite is a more effective sorbent than kaolinite.     

生态减污袋去除模拟污水中氨氮及磷的效果试验

研究利用砂土与粘土混合制成的生态减污袋对于模拟污水中氨氮及磷的去除效果。研究发现砂土与粘土比例为1∶1的减污袋对于高浓度模拟污水中氨氮和磷的去除率分别达到73%和63%;而砂土与粘土比例为10∶1的减污袋对于低浓度模拟污水中磷的去除率最高达到49%。对于高浓度污水,采用砂土与粘土比例为1∶1的生态减污袋能取得最好的除磷去氮效果;而对于低浓度污水,采用砂土与粘土比例为10∶1的生态减污袋除磷去氮效果较好并且成本相对较低。     

铜胁迫对黄芪幼苗的生理学毒性与凹凸棒黏土的缓解作用

为探究黄芪幼苗对铜离子（Cu²⁺）胁迫的耐性机理以及凹凸棒黏土对Cu²⁺污染的缓解作用,研究了不同浓度CuSO₄（2~20mmol/L）胁迫对黄芪幼苗的生理学毒性与凹凸棒黏土的缓解作用.结果表明,2mmol/L CuSO₄胁迫使得根系Cu²⁺含量、H₂O₂（过氧化氢）含量、MDA（丙二醛）含量分别较对照显著上升1.82倍、1.04倍、2.14倍.CuSO₄胁迫浓度达8mmol/L时,根系SOD（超氧化物歧化酶）活性、根尖膜损伤程度和叶片Cu²⁺含量分别较对照显著上升1.13倍、1.12倍和2.62倍;同时,叶片PS Ⅱ（光系统II）实际光化学效率[Y（II）]、光化学淬灭系数（qP）、PSⅡ电子传递速率（ETR）和叶绿素含量较对照分别显著降低22.88%、24.44%、21.49%和28.31%,而NPQ和qN（非光化学荧光猝灭系数）则较对照分别显著上升2.35倍和1.58倍.根系POD（过氧化物酶）和CAT（过氧化氢酶）活性、可溶性糖和可溶性蛋白含量在8mmol/L CuSO₄处理下达到最高值后呈下降趋势.CuSO₄浓度为15~20mmol/L时,根系APX活性和叶片光适应下PS II潜在最大光化学效率（F_v'/F_m'）,以及幼苗全株鲜重、全株干重、地下部鲜重、地下部干重较对照显著下降.在非CuSO₄胁迫条件下,基质中凹凸棒黏土的存在使得幼苗根系MDA含量较对照显著降低15.93%,但未对其它所测生理学指标产生显著影响;在20mmol/L CuSO₄胁迫条件下,基质中凹凸棒黏土的存在使得幼苗根系和叶片中Cu²⁺含量分别显著下降30.78%和23.12%;同时显著缓解了20mmol/L CuSO₄胁迫对根系活性氧水平、抗氧化酶活性、膜脂质过氧化程度、根尖膜损伤程度、可溶性蛋白和可溶性糖含量,叶片PS II光化学活性和叶绿素含量的不良影响,以及对幼苗生长的抑制作用.研究结果表明,培养基质中凹凸棒黏土的存在能够显著降低幼苗组织中Cu²⁺的生物有效性,继而缓解CuSO₄胁迫对黄芪幼苗的生理学毒性作用.     

有机改性粘土去除赤潮生物的机制研究

研究了季铵化合物改性粘土的制备条件对其去除赤潮藻效果的影响,探讨了该粘土体系高效除藻的机制.实验表明,十六烷基三甲基铵(HDTMA)可以有效地提高粘土的絮凝能力,同时HDTMA改性粘土中含有亚稳态HDTMA,增加了该改性粘土对赤潮生物的灭杀能力.改性粘土去除赤潮藻的能力与所吸附季铵化合物的杀藻能力、吸附量正相关,当老化时间延长、吸附季铵化合物稳定性增强时改性粘土除藻能力大大降低.结构不同的粘土对于吸附HDTMA的稳定化产生的空间阻力不同,在吸附量相同的情况下3层结构的蒙脱土中会有更多的亚稳态HDTMA产生;由于同离子效应,反应介质中高价金属阳离子的存在提高了亚稳态HDTMA的量,因此相应的改性粘土具有更高的赤潮藻去除能力.在60℃条件下吸附的HDTMA会更有效地占据粘土中的阳离子交换位,达到稳定态;而升高或降低温度都会有利于亚稳态HDTMA的出现,相应的改性粘土具有更高的赤潮藻去除能力.     

Concentrations of inorganic elements in 20 municipal waters in Sweden before and after treatment – links to human health

The water chemistry of 20 municipal water treatment plants in southern Sweden, representing various bedrock situations, and water qualities, were investigated. Four water samples, raw and treated, were collected from each plant and analyzed by predominantly ICP-OES and ICP-MS at four occasions from June to December, 2001. The concentrations of Ca, Mg, K, Na, HCO₃ and a number of micronutrients, varied considerably in treated waters from the studied plants (ranges; Ca: 9.1–53.7 mg L⁻¹, Mg: 1.4–10.9 mg L⁻¹, K: 1.1–4.8 mg L⁻¹, Na; 5.4–75.6 mg L⁻¹, HCO₃: 27–217 mg L⁻¹). The elimination of Fe and Mn from raw water was efficient in all treatments investigated, giving concentrations in treated waters below the detection limits at some plants. Softening filters gave waters with Ca-concentrations comparable to the softest waters in this study. Adjustment of pH by use of chemicals like lye, soda or lime, modified the consumer water composition significantly, besides raising the pH. It was estimated that drinking water contributed to approximately 2.2–13% of the daily Ca uptake, if the gastrointestinal uptake efficiency from food and water was estimated to be around 50%. The corresponding figures for Mg was 1.0–7% and for F 0–59%. None of the studied elements showed any significant time trends in raw or treated waters during the follow-up period. The concentrations of potentially toxic metals such as Al, Pb and U were low and did not indicate risks for adverse health effects (ranges; Al: 0.5–2.3 μg L⁻¹, Pb: 0–0.3 μg L⁻¹, U: 0.2.5 μg L⁻¹).     

我国不同矿物气溶胶源区物质的物理化学特征

在我国不同的矿物气溶胶源区进行采样分析的结果表明,源区气溶胶物质的物理化学特性相差很大.黄土的颗粒最细,91%的黄土颗粒可以形成矿物气溶胶进行长距离输送;沙土较粗,只有15%的沙尘颗粒可以形成矿物气溶胶;2个煤灰样品的粒径差异较大,抚顺煤灰中＜74μm的颗粒高达39%,而呼和浩特煤灰只有7%.不同粒径颗粒的化学分析结果表明,微量元素在细颗粒上有较高的富集.黄土与沙漠土壤的细颗粒的化学性质十分相似,同煤灰的化学性质完全不同,其常量元素与A1的比值(E/Al)十分接近,而且与深海沉积物粘土中的比值(E/A1)     

有机肥料和无机肥料对土壤微量元素含量的影响

五年定位监测的田间试验结果表明，施用有机肥料对土壤铁、锰、铜、锌的消耗具有明显的补充作用，但对有效用的补充仍显不足．因此，土壤硼营养有可能成为作物产量的限制因子．长期单施正要素化肥的土壤有效态铁、锰、铜、锌、硼的含量均明显下降，下降量达3mg／kg以上，其中土壤有效态硼则有潜在缺乏的可能．     

2种黏土矿物对磺胺嘧啶的吸附

选择蒙脱土和高岭土2种典型黏土矿物为吸附体, 通过静态吸附试验研究其对磺胺嘧啶的吸附行为,考察温度和pH值对磺胺嘧啶吸附的影响.结果表明,2种黏土矿物对磺胺嘧啶的吸附等温线均能较好地符合Freundlich和Langmuir吸附方程,且Langmuir方程拟合效果优于Freundlich方程;高岭土对磺胺嘧啶的吸附量大于蒙脱土;温度升高和pH值过高或过低均不利于磺胺嘧啶的吸附.     

用热分析法研究鼎湖山土壤的粘粒矿物

广东鼎湖山自然保护区的土壤主要为山地黄壤和赤红壤。本文用差热-热重-微商热重(DTA-TG-DTG)联合热分析法,对两种土壤的粘粒矿物进行了初步研究,确认两种土壤的粘粒矿物组成主要为伊利石、高岭石、三水铝石、蛭石、针铁矿等。伊利石、三水铝石、蛭石的含量山地黄壤多于赤红壤,而高岭石则相反。两种土壤的风化程度不高,土壤矿物风化主要处于幼年阶段,山地黄壤尤其明显。另外,对不同林型下的赤红壤也进行了对比研究,其粘粒矿物组成和数量差异不大。