三江平原小叶章湿地土壤SO4^2-的吸附与解吸特征

以三江平原小叶章湿地为研究对象,研究了小叶章湿地土壤SO4^2-的吸附和解吸特征。结果表明,小叶章湿地不同层土壤对SO4^2-的等温吸附均可以用Langmuir、Freundrich和Temkin方程来表示,且吸附能力均随土壤深度的增加而增加,这种变化和土壤有机质、pH值和粘粒含量密切相关。土壤的解吸能力不仅和土壤质地密切相关,而且受土壤中吸附SO4^2-的影响,一般当土壤中吸附SO4^2-量较大时,解吸的绝对量大,但解吸率较低,反之亦然。吸附率明显高于解吸率,对于延缓土壤的酸化具有一定的意义。     

离子色谱法测定蔬菜水果中氯离子、亚硫酸盐、硫酸盐含量

确立离子色谱法同时检测蔬菜水果中氯离子、亚硫酸盐、硫酸盐含量的样品处理方法和检测条件。在2%甲醛溶液SO32-的稳定剂的作用下,样品用10 mmol/L氢氧化钠溶液提取后,用IonPacAS9-HC型色谱柱为分离柱和9 mmol/L的碳酸钠淋洗液为流动相,电导检测器进行分析。结果表明,Cl-、SO32-、SO42-在2～10μg/mL浓度范围内线性良好(其相关系数分别为0.9973、0.9999、0.9991),样品中Cl-、SO32-、SO42-的加标回收率分别为83.7%～99.2%、80.6%～98.4%、81.0%～100.4%,检出限分别为0.005、0.05、0.01 mg/kg。     

北疆绿洲不同盐分浓度梯度下土壤的生物活性及其功能多样性

土壤盐分类型与含量对土壤生物活性和功能结构多样性会产生重要影响。本文模拟新疆北疆典型硫酸盐盐土,通过设置不同盐分浓度梯度(3、6、10、20和40 g kg-1),研究了土壤5种主要功能酶、土壤微生物量和土壤呼吸等生物性状的变化特征。结果表明:过氧化氢酶、蔗糖酶、β-葡萄糖苷酶和多酚氧化酶4种酶对盐分梯度响应非常敏感,其中过氧化氢酶、蔗糖酶和β-葡萄糖苷酶这3种酶活性与盐分浓度呈负相关,当盐分浓度达到40 g kg-1时,以上3种酶分别较对照降低25.7%、69.6%、30.0%;在3~6 g kg-1盐分浓度范围,多酚氧化酶随盐分浓度而升高,但在10~40 g kg-1时却显著降低,表现出"低盐促进,高盐抑制"的效应;纤维素酶对盐分浓度变化不敏感。土壤盐分与微生物量和微生物商呈显著负相关,与土壤基础呼吸和呼吸商则显著正相关,如40 g kg-1的盐分浓度导致土壤微生物量和微生物商分别较对照降低73.0%和69.5%,呼吸商升高了6.4倍。土壤过氧化氢酶、蔗糖酶、土壤微生物量、微生物商和呼吸商等可作为硫酸盐盐土早期预警生物指标。在40 g kg-1的含盐量下土壤生物功能结构明显区别于其他处理,且多样性指数显著下降。     

硫酸盐还原菌在废水处理中的应用进展

硫酸盐还原菌（SRB）在废水处理方面有独特的优势,可降解很多其他微生物难以降解的物质。综述了硫酸盐还原菌在废水处理中的特性及作用机理,介绍了硫酸盐还原菌在含重金属废水、硫酸盐废水、酸性矿山废水及难降解有机废水处理中的应用进展,总结了其在废水处理中应用的优缺点。     

硫酸软骨素降血脂保健功能的研究

硫酸软骨素是来源于动物软骨组织的一类重要的酸性粘多糖.本试验以羊的软骨素为添加物,选择体重、年龄相近的100只SR系雄性小白鼠作试验动物,随机分为5组,每组20只.其中,I组饲喂高脂饲料,II、III、IV组在高脂饲料的基础上,分别添加0.5 g/kg、1.0 g/kg、1.5 g/kg的硫酸软骨素,V组饲喂正常饲料,研究其降的功能.结果表明:高脂饲料中添加硫酸软骨素后,随着添加量的增加,能够降低小鼠血液中的总胆固醇(TC)、甘油三酯(TG)、低密度脂蛋白(LDL)、并有升高高密度脂蛋白(HDL)的趋势.     

表面活性剂对蓝点笛鲷幼鱼急性毒性研究

[目的]了解表面活性剂对蓝点笛鲷幼鱼的毒性。[方法]采用半静水法生物测试,以蓝点笛鲷幼鱼为受试生物,研究了十二烷基硫酸钠（SDS）、十二烷基苯磺酸钠（DBS）对其急性毒性,[结果]2种表面活性剂的毒性大小为：SDS〉DBS。其安全浓度分别为0.406 3、0.584 0 mg/L。SDS与DBS对蓝点笛鲷幼鱼的24和48 h的LC50分别为2.022 0、2.858 5 mg/L和1.769 1、2.514 9 mg/L。[结论]SDS与DBS对蓝点笛鲷幼鱼为中等毒性物质。     

农药污染对水稻田土壤硫酸盐还原菌种群数量及其活性影响的研究

在实验室条件下 ,施用杀虫剂 (呋喃丹 )、杀菌剂 (多菌灵 )和除草剂 (丁草胺 )后 ,对黄松稻田土壤、紫色稻田土壤和红壤稻田土的硫酸盐还原细菌 (Sulfate reducingbacteria ,SRB)种群数量和硫酸盐还原活性的影响。结果表明 ,紫色稻田土壤、黄松稻田土壤和红壤稻田土的SRB种群数量和硫酸盐还原活性的范围分别为 (66 83～ 12 7 81)× 10 4 cfug- 1干土、(45 87～ 10 5 0 7)× 10 4 cfug- 1干土和 (3 81～ 61 62 )× 10 4 cfug- 1干土和S- 2 (7 14～ 11 57) μgg- 1d- 1干土、S- 2 (6 84～ 9 0 7) μgg- 1d- 1干土、S- 2 (1 91～ 6 67) μgg- 1d- 1干土 ,且稻田土SRB种群数量和土壤硫酸盐还原活性之间具有正相关性。每kg干土中加入 1mg的丁草胺或呋喃丹 ,能促进SRB的生长及其硫酸盐还原活性。 1kg干土中加入 5mg的多菌灵、50mg的丁草胺或呋喃丹 ,对SRB的生长和硫酸盐还原活性有明显的抑制作用。施用丁草胺和呋喃丹 7d时 ,多菌灵 14d时 ,对水稻田土壤的SRB种群数量和硫酸盐还原活性的抑制影响最大 ,然后逐渐减轻 ,最后显示出某种程度的促进作用     

Sulfate adsorption by variable charge soils: Effect of low-molecular-weight organic acids

Sulfate (SO₄ ^2–) movement and transport in soils has received considerable attention in recent years. In most soils, SO₄ ^2– coexists with a variety of natural organic compounds, especially organic acids. Studies were conducted to assess the effect of low-molecular-weight organic acids (eight aliphatic and five aromatic acids) on SO₄ ^2– adsorption by variable charge soils from Chile and Costa Rica. The effects of type of organic acid, pH, type of soil, and organic acid concentration were investigated. In one experiment, a 1.0 g soil sample was equilibrated with 25 ml 0, 0.5, 1.0, 2.0, 4.0, or 6.0 mM K₂SO₄ in 1 mM NaCl in the presence or absence of 5 mM citric acid. In the second set of experiments, the adsorption of 2 mM SO₄ ^2– in soils at pH 4 or pH 5 in the presence or absence of one of 13 organic acids at a concentration of 2 mM or 5 mM was studied. Results showed that citric acid significantly decreased SO₄ ^2– adsorption by the two soils. Sulfate adsorption decreased with increasing pH of the equilibrium solution. Aliphatic acids, with the exception of cis-aconitic acid, decreased the amount of SO₄ ^2– adsorbed by the two soils, with oxalic, tartaric, and citric acid showing the greatest effect. The differences in pH values of the equilibrium solutions in the presence and absence of organic acids were significantly, but negatively, correlated with the amount of SO₄ ^2– adsorbed, suggesting chemisorption of SO₄ ^2– and the release of hydroxide ions. The ionization fraction values of the organic acids at the equilibrium pH were correlated with the amounts of SO₄ ^2– adsorbed, suggesting that the protonation of surface hydroxyl groups of the mineral phase increased as the strength of the ionization of the acid increased, thus creating more positively charged surfaces. Received: 12 February 1997     

Phosphorus availability in sediments from a tidal river receiving runoff water from agricultural fields

Eutrophication of surface water is a worldwide concern. Sediments may play an important role in buffering phosphorus (P) concentration in the overlying water column. However, information on the spatial variation of sediment P availability as affected by agricultural water discharge and hydrological conditions is limited. In this study river sediments were sampled in spring, summer, fall and winter, respectively from seven locations along a main tributary (Ten Mile Creek, TMC), which receives surface runoff water from agricultural lands and discharges into the Indian River Lagoon, south Florida, USA, and analyzed for P availability. Simultaneously, hydrological variables were measured on the spot and river water samples were collected for analyses of water quality. The results demonstrated that available P in the sediments of TMC as measured by several commonly used extraction procedures had a large spatial variation. The downstream locations had a greater amount of available P in the sediments than the upstream locations, which is attributable to the settlement of finer particles due to slower water flow and increased influence from salt water in the downstream locations where the fresh river water gradually mixed with salt water from the Indian River Lagoon. Phosphorus availability in the sediments appeared to be related to P sorption by iron and aluminum oxides and the competition for adsorbing sites between SO₄²⁻ and PO₄³⁻. This spatial variation of P availability agrees with the elevation of chlorophyll a (Chla) in overlying water body in the downstream locations of TMC, indicating that the internal P source plays an important role in triggering an algal boom in surface water systems.     

有机肥及复配硫酸盐对土壤-水稻系统砷镉有效性的调控

探索了有机肥(OF)及其与硫酸盐复配(SOF)对砷/镉(As/Cd)复合污染水稻土As/Cd水溶性、作物有效性和赋存形态转化的影响。结果表明,OF处理使土壤孔隙水As(Ⅲ)浓度在淹水前10周内下降明显,但使孔隙水Cd显著增加,使土壤固相As/Cd均向生物有效性较高的赋存形态转化;复配硫酸盐对有机肥所引起的土壤As/Cd水溶性变化和固相赋存形态转化不能产生显著逆转作用,但SO_4~(2-)向S~(2-)的还原转化使土壤硫化砷较对照(CK,不施有机肥或硫酸盐)增加了71%。水稻盆栽试验进一步显示,OF处理使水稻幼苗茎叶和根部As积累量降低44%～47%,但使成熟期水稻糙米总As和白米无机As含量分别增加22%和12%;同时,OF处理显著增加了水稻幼苗Cd累积量并使糙米Cd含量达到CK的1.2倍。复配硫酸盐可明显逆转有机肥所引起的水稻糙米As含量升高,但对糙米Cd积累和白米无机As浓度的增加不能产生显著减控作用。综上,向As/Cd污染稻田中施用有机肥对稻米质量安全所产生的潜在威胁值得引起高度关注。