有机溶剂对苏云金芽孢杆菌(Bacillus thuringiensis)几丁质酶的影响

以苏云金芽孢杆菌(Bt)的发酵液为材料,经硫酸铵分级分离、DEAE-32离子交换柱层析分离,获得部分纯化的Bt几丁质酶(EC3. 2. 1. 14)制剂.研究了几种有机溶剂对Bt几丁质酶的影响.结果表明,甲醇、丙三醇、甲醛和戊二醛对几丁质酶有抑制作用;乙醇、丙醇、乙二醇和二甲亚砜在低浓度时对酶有激活作用,随着浓度的升高表现出抑制作用;二氧六环的浓度低于 5%时,对酶的影响不明显,而高于 5%时,对酶则有激活作用;丙酮对酶有激活作用. 图 1参 10     

湿地根际土壤碳矿化及相关酶活性分异特征

研究了中国三江平原小叶章湿地根际土壤基础呼吸速率及相关酶活性，以了解碳矿化及其相关酶活性空间分异特征。结果表明，β-葡萄糖苷酶、淀粉酶、纤维素酶均为碳循环的良好指示酶，它们均存在着显著的空间分异。从表层土向下，由根表土向外，碳矿化速率及其相关的各种酶活性均呈下降趋势。当从田间取出土壤样品时，土壤样品在取出后的最初阶段碳矿化速率较高，2．5h以后达到一个较为平稳的水平，然后呈平缓降低的趋势。β-葡萄糖苷酶、淀粉酶、纤维素酶是碳循环的真正催化剂，而土壤有机碳则是此反应的低物。     

膜-悬浮光催化降解反应器中催化剂活性及其影响因素分析

考察了膜 悬浮光催化降解反应器小试系统在处理自配废水的连续运行中催化剂活性的变化 .试验发现 ,经两周的连续运行 ,催化剂活性有明显降低 ,降为原催化剂活性的 1 4 % .分析引起催化剂活性降低的可能原因有 :催化剂颗粒的聚集、有机污染物和无机垢体在催化剂表面的附着 .采用超声波粉碎、次氯酸钠碱洗和盐酸酸洗的方法来恢复催化剂活性 .结果表明 ,采用 1 0 %的盐酸清洗可使催化剂活性恢复到初始值的 6 4 %左右 ,效果最明显 .推测由于水中硬度在催化剂表面形成的CaCO3沉淀是导致催化剂活性降低的最主要因素 .     

Plant diversity reduces the effect of multiple heavy metal pollution on soil enzyme activities and microbial community structure

It is unclear whether certain plant species and plant diversity could reduce the impacts of multiple heavy metal pollution on soil microbial structure and soil enzyme activities. Random amplified polymorphic DNA (RAPD) was used to analyze the genetic diversity and microbial similarity in planted and unplanted soil under combined cadmium (Cd) and lead (Pb) pollution. A metal hyperaccumulator, Brassica juncea, and a common plant, Festuca arundinacea Schreb, were used in this research. The results showed that microorganism quantity in planted soil significantly increased, compared with that in unplanted soil with Cd and Pb pollution. The order of microbial community sensitivity in response to Cd and Pb stress was as follows: actinomycetes>bacteria>fungi. Respiration, phosphatase, urease and dehydrogenase activity were significantly inhibited due to Cd and Pb stress. Compared with unplanted soil, planted soils have frequently been reported to have higher rates of microbial activity due to the presence of additional surfaces for microbial colonization and organic compounds released by the plant roots. Two coexisting plants could increase microbe population and the activity of phosphatases, dehydrogenases and, in particular, ureases. Soil enzyme activity was higher in B. juncea phytoremediated soil than in F. arundinacea planted soil in this study. Heavy metal pollution decreased the richness of the soil microbial community, but plant diversity increased DNA sequence diversity and maintained DNA sequence diversity at high levels. The genetic polymorphism under heavy metal stress was higher in B. juncea phytoremediated soil than in F. arundinacea planted soil.     

苯并[a]芘对马氏珠母贝鳃组织抗氧化酶活性的影响

将马氏珠母贝（Pinctada martensi）暴露于不同质量浓度（1、4和8μg.L-1）苯并[a]芘B[a]P中,检测暴露后第3、7和10天后,马氏珠母贝鳃组织抗氧化酶（超氧化物歧化酶SOD、谷胱甘肽硫转移酶GST和过氧化氢酶CAT）对苯并[a]芘胁迫的生态毒理效应。结果表明：暴露时间为3、7 d时,SOD活性无明显变化,随着暴露时间的延长,SOD活性在第10天时被激活;在胁迫初期,GST活性被激活,随后表现出逐渐降低的趋势,在暴露后10 d,不同质量浓度组GST活性变化趋于稳定。当暴露质量浓度相同时,表现出明显的时—效关系;而CAT活性在第7天被激活,随着时间的延长,高质量浓度（4和8μg.L-1）组表现出先升高后下降的趋势,并表现出一定的时-效关系。SOD、GST和CAT均可作为B[a]P污染的生物标志物,活性变化相对于SOD,GST和CAT对B[a]P的胁迫更加敏感。     

杀虫双对土壤脲酶影响的研究

通过对土壤脲酶受杀虫双影响的研究．结果表明,杀虫双对不同生态区土壤脲酶活性具有明显的抑制作用,随杀虫双浓度的增加,酶活性持续减小、计算得到了土壤酶活性的生态剂量ＥＤ５０值,获得了北方(?)土和南方红壤污染的;临界浓度为４８９和２４６ｇ/ｋｇ;Ｌａｎｇｍｕｉｒ模型可较好表征酶活性与尿素浓度间的定量关系;土壤脲酶活性和最大表观酶活性均可表征土壤受杀虫双污染程度的大小。     

不同栽杉代数根际土壤肥力及生物学特性变化

通过对位于南平溪后安曹下和邓窠２９ａ龄１代、２代、３代实生杉木的根际养分、微生物、酶及生化活性的为期２ａ的研究,结果表明：随杉木连栽代数增加,根际微域土壤酸化趋势增强,有机质和全氮沉积量下降,速效性养分亏缺程度减弱,根际土壤中三大类微生物所占的比例发生一定的变化,真菌和放线菌所占比例增加,细菌所占比例减少,生理类群数量下降,除接触酶活性变化不大外,其它土壤酶和生化活性均有明显下降,体现了杉木多代连栽根际土壤的基本特征;亦是杉木连栽导致地力衰退重要原因之一     

近地层臭氧浓度升高对稻田土壤氨氧化与反硝化细菌活性的影响

利用中国唯一的稻麦轮作臭氧FACE（free-air O3 concentration enrichment,开放式空气臭氧浓度增高）试验平台,研究近地层臭氧浓度升高对稻田不同生育时期植株氮吸收量、土壤氮含量与脲酶活性、土壤氨氧化细菌与反硝化细菌数量以及成熟期土壤硝化与反硝化作用强度的影响。结果发现,臭氧浓度升高条件下,单株水稻（Oryza sativaL.）的氮吸收量趋于升高,土壤全氮含量趋于下降、脲酶活性趋于增强,在成熟期土壤全氮与对照相比平均下降9%,土壤脲酶活性与对照相比平均升高13%。在水稻整个生长季节,土壤氨氧化细菌和反硝化细菌的数量均呈现出先增多后减少的趋势,且均在开花期达到峰值,但臭氧熏蒸土壤与对照相比趋于升高;在水稻成熟期,土壤中单个氨氧化细菌和反硝化细菌的活性均趋于下降,土壤硝化强度和反硝化强度与对照相比也平均下降17%和24%。结果表明,近地层臭氧浓度升高条件下,稻田土壤氮素转化因为水稻氮素吸收增强而加快,土壤氨氧化细菌和反硝化细菌的数量均趋于增多,但它们的生理代谢活性均趋于下降。     

改性污泥对矿区铜、镉污染土壤的修复

城市污泥的重金属含量超标是限制其资源化利用的主要瓶颈,论文采用石灰＋硫粉＋生物淋滤的方法去除重金属,制备改性污泥,探讨其对矿区Cu、Cd污染农田土壤的修复效果,以期实现以废治污的目标。供试水稻土采自江西某矿区附近农田,土壤Cu和Cd的TCLP（Toxicity characteristic leaching procedure）浸出量分别为40.34 mg·kg-1和660.1μg·kg-1,其中Cu的质量分数超过国际标准值15 mg·kg-1。通过室内土培的方法,将改性污泥分别按土重的0%、1%、3%、5%和10%施入供试土壤培养30 d后,分析土壤Cu和Cd的活性、形态变化以及土壤蛋白酶和脲酶活性等指标评价改性污泥对污染土壤的修复效果及作用机理。结果表明,改性污泥对土壤Cu产生显著的钝化作用,且各施用量对Cu的有效态含量表现出显著差异。当改性污泥的用量为土重的5%时,Cu的有效态含量降至12.03 mg·kg-1,低于国际标准。改性污泥对土壤Cd的钝化效果相对较弱。当改性污泥的用量为1%时,土壤Cd的活性反而有所增加。当改性污泥的用量为5%时,Cd的活性显著降低,土壤Cd的浸出量降至539.6μg·kg-1。土壤重金属形态分析的结果表明,土壤Cu主要以碳酸盐结合态、有机结合态和残渣态存在。改性污泥用量增加,可交换态Cu含量下降,当改良剂用量为土重的5%时,可交换态Cu由8.10%降至4.10%。相反,有机结合态Cu含量由26.45%增加至32.34%。土壤的可交换态Cd含量由36.80%降至30.69%。说明施用改性污泥,土壤可交换态Cu、Cd向有机结合态发生转化。土壤蛋白酶和脲酶的活性变化能较好地指示修复效果,且土壤脲酶的指示效果优于蛋白酶。     

Translocation and biotoxicity of metal (oxide) nanoparticles in the wetland-plant system

• Aquatic plants are more likely to absorb TiO₂ NPs that are beneficial to them. • Ag NPs inhibited the growth of aquatic plants under both 5- and 60-day exposure. • CeO₂ NPs had positive/negative impact on plant in 5/60-day exposure, respectively. • TiO₂ NPs presence could enhance the photosynthesis and increase the plant biomass. • The ENPs changed plant activity, which resulted in changes of wetland performance. Engineered nanoparticles (ENPs) threaten the environment through wastewater discharging. Generally, constructed wetlands (CWs) are efficient methods for ENPs removal. However, the biotoxicity of ENPs on plants in CWs is unclear. Here, we investigated the distribution and bio-impacts of different ENPs (Ag NPs, TiO₂ NPs, and CeO₂ NPs) in plants under 5- and 60-day exposure to 1 and 50 mg/L concentrations. Results showed that ENPs appeared in the vascular bundle and mesophyll cell space, which induced the variation in antioxidase activities (e.g., superoxide dismutase [SOD], peroxidase [POD], and catalase [CAT] activities) as well as overproduction of malondialdehyde (MDA). Additionally, Ag NPs inhibited photosynthesis rate and root activity during two exposure phases. CeO₂ NPs had positive and negative impacts on plants in 5- and 60-day exposure, respectively. Inversely, TiO₂ NPs enhanced photosynthesis and root activity under 60-day exposure. Finally, the contents of the C, N, and P elements in plants fluctuated in response to ENPs stress. All results have a positive correlation with the wetland performance under ENPs exposure except for TiO₂ NPs treatment. Overall, our study systematically reveals aquatic plants' responses to ENPs and provides a reference for building ecological treatment systems to purify wastewater containing ENPs.