腐殖酸及酸雨对贫铀在土壤中迁移的影响研究

 利用经过完善的贫铀迁移模型,研究腐殖酸(HA)及酸雨对贫铀在土壤中迁移的影响.结果表明,对照组(北京地区土壤)DU迁移到达9~11cm,分别添加2%、5%、10%HA的实验组DU迁移依次降低,分别为21~23cm、15~17cm、11~13cm,说明腐殖酸促进了DU迁移; pH值为4.0和3.0的模拟酸雨,分别使贫铀迁移至29~31cm及35cm以上,说明酸雨促进了贫铀迁移;在酸雨和腐殖酸综合作用下贫铀迁移仅到5~7cm,说明腐殖酸和酸雨综合作用抑制了贫铀迁移.     

亲水荷电超滤膜的制备及对腐殖酸的分离性能

为改善聚醚砜(PES)超滤膜的抗污染性能和提高对腐殖酸(HA)的截留率,以介孔二氧化硅(MS)为添加剂,采用相转化法制备了亲水性PES/MS复合超滤膜,并对膜表面进行荷电改性.研究了MS对膜的断面结构、表面化学性质和过滤性能的影响,考察了荷电改性PES/MS超滤膜对水中HA的分离性能以及溶液pH值、离子强度和钙离子浓度等因素对荷电膜超滤过程的影响.SEM表征结果显示,MS颗粒在PES/MS复合膜的表面分散均匀,膜孔的连通性改善.亲水荷电改性后,膜表面接触角由68°降至57°,zeta电位由-6.31mV降至-11.45mV,膜对HA的去除率由72%提高到95%,通量衰减率由29.8%减小到4.9%.结果表明,对PES超滤膜进行亲水荷电改性可有效提高对HA的截留率,同时减轻膜污染;另外,溶液的pH值、离子强度和钙离子浓度对荷电超滤膜的过滤性能有较大影响,调节合适的溶液环境可在提高截留率的同时,减轻膜污染.     

小分子有机酸对紫色土及其溶液中Pb的赋存影响

以紫色土中铅(Pb)为研究对象,采用以0.01 mol·L~(-1)硝酸钠(NaNO_3)为背景电解质的一步提取法,研究了不同浓度下乙酸,酒石酸和柠檬酸对土壤中Pb的释放作用,并通过土壤重金属形态的分步提取法和地球化学平衡软件Visual MINTEQ v3.0,进一步分析和预测了小分子有机酸作用下土壤中Pb以及土壤溶液中Pb的形态变化.在此基础上,分析了小分子有机酸对Pb作用的环境意义与环境风险.结果表明,3种小分子有机酸均显著增加了紫色土中Pb的释放量,活化效果表现为柠檬酸酒石酸乙酸.在有机酸作用下,土壤中交换态Pb总量增加,碳酸盐结合态Pb和铁锰氧化物结合态Pb总量降低;土壤溶液中Pb以有机结合态为主,占总Pb质量的45.16%~75.05%,游离态次之,占22.71%~50.25%,且随着浓度增加,柠檬酸和酒石酸作用下的土壤溶液中的游离态Pb和无机结合态Pb增加,而有机结合态Pb减少,乙酸则呈相反趋势.总体上看,小分子有机酸提高了紫色土中Pb的生物有效性,且存在地下水的淋溶风险,其中柠檬酸的淋溶风险远大于酒石酸和乙酸.     

煤基腐殖酸对外源砷胁迫下玉米生长及生理性状的影响简

为了筛选用于砷污染土壤治理的煤基腐殖酸,采用盆栽实验研究了施用不同种类和浓度的煤基腐殖酸及EDTA对外源砷胁迫下玉米株高、株鲜重、株干重、根干重、砷积累量、叶片抗氧化酶（POD,SOD和CAT）活性和脯氨酸含量的影响。结果表明,11种供试煤基腐殖酸均促进了玉米生长,提高了叶片POD、SOD和CAT活性。其中6和10号腐殖酸可降低土壤砷活性和显著抑制玉米吸收和积累砷,而8和9号腐殖酸增加了土壤活性砷和显著促进了玉米对砷的吸收和累积,且不同程度地强于EDTA。除8和9号外,其余腐殖酸均可明显降低玉米叶片脯氨酸的含量。EDTA可显著促进玉米吸收和积累砷,且加剧了砷对玉米的危害。因此,8和9号供试煤基腐殖酸可以替代EDTA活化土壤砷,与植物配合以提高砷污染土壤的植物修复速度和效果,而6和10号供试煤基腐殖酸则可用于土壤砷钝化剂,以保证作物产品的安全。     

几种印染助剂对壳聚糖稳定纳米铁去除酸性品红的影响

以氯化铁为铁源,硼氢化钠为还原剂,壳聚糖为稳定剂,采用液相还原法制备壳聚糖稳定纳米铁（CS-nZⅥ）;研究了印染废水中常见助剂NaNO₃、Na₂SO₄、NaH₂PO₄、K₂Cr₂O₇、EDTA二钠盐存在下,超声波辅助CS-nZⅥ对酸性品红（AF）降解的影响。结果表明,反应15 min,0.01 g CS-nZⅥ对25 mL、100 mg/L AF的去除率高达99.9%;各种助剂的存在使得纳米铁表面不同程度失活,阻碍反应的进行,使得AF的去除率下降。NaNO₃、K₂Cr₂O₇、EDTA二钠盐与纳米铁发生反应,与AF存在明显的竞争作用。重复利用实验表明,CS-nZⅥ重复利用7次仍具有一定的反应活性。此外,CS-nZⅥ对加标（50 mg/L）实际废水中AF的去除率达到99%以上,表明CS-nZⅥ是一种潜在的环境修复材料。     

Evidence for Atmospheric Deposition Impacts On the Enchytraeid Worm Population of Uk Upland Ombrotrophic Peats

The results of four experiments on acidification effects upon the Enchytraeid worm populations of ombrotrophic peats are reported. in the first, populations were measured in peats from Calluna vulgaris-dominated microcosms collected from along a gradient in N deposition in the UK and subjected for 18 months to simulated precipitation with a solute composition appropriate for their site of collection. There was a significant decline in Enchytraeid population along the N deposition gradient for Calluna-dominant microcosms, but when grasses took over from the Calluna, Enchytraeid numbers increased significantly. in the second experiment, two sets of peat moorland microcosms from a single site, supporting Calluna and Calluna-grass mixed vegetation, were subjected for 12 months to ambient and 2- and 6-times the ambient N deposition. Additional N was added in two forms, as ammonium sulphate and as nitric acid. the high N treatments significantly reduced the Enchytraeid populations for both vegetation types. in a third experiment, the pH preference for the Enchytraeids was assessed using interconnected tubes of peat covering the pH range 2.2-8.7. the preferred pH range after 8 months was 2.7-3.7. in the final experiment, it was found that recolonization with Enchytraeids after initial removal was more rapid under grass dominant vegetation than under Calluna dominant vegetation.     

Competition of Hydrogen and Manganese Ions for Adsorption Sites in Sitka Spruce Litter

The competition of hydrogen and manganese ions for adsorption sites in Sitka spruce litter was investigated in a factorial design, simulated acid rain experiment, which involved leaching of litter with simulated throughfall solutions at three pH levels (5.3, 4.3 and 3.3) and three manganese concentrations (0 to 0.2 mg1^-1). the throughfall solution at the lowest pH was the most efficient in removing exchangeable manganese from litter. the manganese concentration in the leachates was approximately proportional to the hydrogen ion concentration in the simulated throughfall solution. Under field conditions, throughfall manganese concentration also naturally tends to increase as a consequence of enhanced foliar leaching of manganese in response to increasing precipitation acidity. the manganese concentration in the simulated throughfall also affected manganese concentration in the leachates, however, and contributed to a buildup of exchangeable manganese in litter, thus counteracting to some extent possible adverse effects of excess leaching due to increased throughfall acidity.     

被动扩散管监测空气中二氧化氮分析方法的改进

利用被动扩散法测定空气中的二氧化氮是最近几年许多发达国家所采用的方法。在二氧化氮（以后以NO2记）被动监测分析方法及Saltzman法的基础上，对所选用的化学试剂及试剂的用量、操作方法等方面进行了改进与研究,实验结果表明用对氨基苯磺酸取代对氨基苯磺酰胺,更具有可操作性、经济性和适用性。     

金属浓度,半透膜孔径,水温及配位体对半透膜囊吸收铜的影响

在实验室条件下，研究了影响树脂－半透膜囊吸收铜的主要因素，重点探讨了水相铜含量，半透膜孔径，温度以及天然河水中的有机配位体对吸收的影响。结果表明，半透膜囊吸收量与水相游离铜浓度，水温及半透膜孔径的非整数次幂成正比，其中包括ＥＤＴＡ，河水富里酸，以及河水中的各种天然有机物在内的配位体均与铜生成不能被半透膜囊吸收的络合物，研究结果进一步证实了半透膜囊对水环境中游离态微量金属进行长期监测的可行性。     

大气中硝酸和颗粒物硝酸盐的测定

研究了用扩散管差分法和多种叠滤膜法测量大气中粒物硝酸盐和气体硝酸，扩散管差分法可以测量颗粒物硝酸盐和气体硝酸，避免了采样时颗粒物硝酸盐的人为损失。Ｆｌｏｕｒｏｐｏｒｅ聚四氟乙烯膜等惰性膜也可以采集颗粒物硝酸盐，其后的ＮａＣｌ浸渍膜采集硝酸，而玻璃纤维膜几乎同时采集了颗粒物硝酸盐和硝酸。