包埋固定化微生物的特性研究

文章通过实验研究了PVA与海藻酸钠混合载体包埋固定化微生物系统降解有机物的过程,并对其特性进行了分析。结果发现运行初期凝胶体有凝胶溶出现象,第一天凝胶有机物溶出高达2 173 mg,随后溶出量减少,7～8天溶出停止;同时发现包埋后的微生物活性有损伤和恢复的过程,损伤时相对活性为0.27经过恢复可达到0.85;另外,凝胶的粒径和比重等物理特性也随时间变化,最后趋于稳定。一年多运行实验发现包埋凝胶体的抗持久性也较好。这些特性的探讨将为工程应用提供理论指导。     

江西省陆地生态系统氮平衡的时空分布规律研究

利用系统物质平衡模型,对1995-2005年江西省陆地生态系统的N收支平衡进行了核算,并分析了不同来源N收支量的时间序列特征以及N盈余强度的空间分布特征,探讨了自然灾害和政策实施对N平衡的影响.结果表明:江西省陆地生态系统的N输入量变化范围是(155.5-184.2)×107kg·a-1,平均值为168.5 ×107 ...     

应用分子生物学与同位素示踪技术研究厌氧氨氧化菌活性及功效

厌氧氨氧化是一个新发现的氮循环途径,与反硝化作用都产生氮气,但准确衡量厌氧氨氧化活性及功效的相关方法还是个难题.本研究联合应用分子生物学与同位索示踪技术,以北京某污水处理厂的活性污泥为实验样品,研究其中厌氧氨氧化菌的存在、活性和功效.厌氧氨氧化菌的分子生物学分析是通过16S rRNA进行,选择两步引物分别为pla46-...     

Antimicrobial activity of thin metallic silver flakes, waste products of a manufacturing process

The aim of the research was to develop new products and processes from a manufacturing waste from an Italian metallurgic company. The company produced thin silver metallic films and the production scraps were silver flakes. The possibility to use the silver flakes in water disinfection processes was studied. The antimicrobial activity of the flakes was investigated in batch using Escherichia coli as Gram-negative microorganism model. The flakes did not show any antimicrobial activity, so they were activated with two different processes: thermal activation in reducing atmosphere and chemical activation, obtaining, respectively, reduced flakes (RF) and chemical flakes (CF). The flakes, activated with either treatment, showed antimicrobial activity against E. coli. The kill rate was dependent on the type of activated flakes. The chemical flakes were more efficient than reduced flakes. The kill rate determined for 1 g of CF, 1.0 ± 0.2 min⁻¹, was greater than the kill rate determined for 1 g of RF, 0.069 ± 0.004 min⁻¹. This was confirmed also by the minimum inhibitory concentration values. It was demonstrated that the antimicrobial capability was dependent on flakes amount and on the type of aqueous medium. Furthermore, the flakes maintained their properties also when used a second time. Finally, the antimicrobial activities of flakes were tested in an effluent of a wastewater treatment plant where a variety of heterotrophic bacteria were present.     

Historical trends of heavy metal contamination and their sources in lacustrine sediment from Xijiu Lake, Taihu Lake Catchment, China

Concentrations of Cd, Cr, Cu, Pb, Zn and Hg in Xijiu Lake sediment from the Taihu Lake catchment, China, were analyzed. Their contamination state was investigated based on the geoaccumulation index and enrichment factors. Statistical analysis was used to differentiate the anthropogenic versus natural sources of heavy metals (HMs), and the anthropogenic accumulation fluxes were calculated to quantify anthropogenic contribution to HMs. The results indicated that the lake sediment had been heavily contaminated by Cd, enrichment of Zn and Hg was at a relatively high level, while that of Cu and Pb was in the lower-to-moderate level and Cr was in the low enrichment level. Sources of Cr in the sediment were mainly from natural inputs, while other metals, especially Cd, were predominantly derived from anthropogenic sources. In the past century, anthropogenic accumulation fluxes of Pb, Zn and Hg increased by 0.1-47.3 mg/(cm².yr), 2.4-398.1 mg/(cm².yr), and 3.7-110.3 ng/(m².yr), respectively, accounting for most inputs of HMs entering the sediment. The contamination state of HMs varied with industrial development of the catchment, which demonstrated that contamination started in the early 20th century, reached the maximal level between the mid-1970s and mid-1990s, and decreased a little after the implementation of constraints on high contamination industries, although the contamination of some HMs, such as Cd, Zn and Hg, is still at high levels.     

羟基多溴联苯醚对鲤鱼急性毒性及定量结构活性关系

羟基多溴联苯醚是一类具有环境风险的新兴污染物,它们已经在众多环境介质甚至人体内广泛存在。参照GB/T13267-91标准方法,采用静态生物急性毒性试验,测定了6种羟基多溴联苯醚(2′-OH-BDE7、4′-OH-BDE17、2′-OH-BDE28、2′-OH-BDE68、4′-OH-BDE90和2′-OH-BDE123)对普通鲤鱼的急性毒性96 h-LC50值,分别为697、1 130、854、550、644和522 ng.mL-1。除4′-OH-BDE17为高毒物质外,其他5种OH-PBDEs均为剧毒物质,高溴代的2′-OH-BDE123毒性最大。选用OH-PBDEs的KOW参数及由MOPAC软件PM3算法计算出的16个量子化学参数(EHomo、qBr+、ELumo等)为描述符,运用一元线性回归分析分别研究了96 h-LC50与他们之间的相关关系。结果表明:lgKOW和ELumo与6种羟基多溴联苯醚的96 h-lg LC50表现出较好的相关性,复相关系数均大于0.96,根据方程得到的96 h-lg LC50预测值与实验值基本相同,进一步对环境中广泛检出的其它OH-PBDEs的96 h-LC50值也进行了预测。     

土壤中微生物及其环境效益的浅析

关于土壤微生物活性,已经成为目前土壤方面研究的热点问题。有些学者曾经对微生物在土壤环境中的作用表示怀疑,他们过分强调物理化学作用在土壤形成和土壤环境效应中的作用,而忽视微生物的研究。随着土壤学研究的深入,关于土壤成因、土壤生产力和环境现象已经越来越复杂,单纯依靠物理和化学的知识已经无法解释某些复杂的实验现象,现在必须依靠微生物来解释某些现象。本文将对土壤微生物在土壤研究中的作用进行简述,同时分析土壤环境变化对微生物数量和活性的影响,并简述一些微生物研究的进展。     

聚糖原菌富集实验及其内源过程探究

细胞衰减是微生物内源过程的一个重要组成部分,可分为由细胞死亡引起的数量衰减和由细胞活性降低引起的活性衰减两部分.通过挥发性脂肪酸（VFA）吸收速率(VFAUR)测定、荧光原位杂交技术（FISH）以及LIVE/DEAD细胞染色技术,研究了富集聚糖原菌（GAOs）在序批式反应器（SBR）系统中好氧环境下的衰减特征.结果表明,当T=30℃、进料中m(COD)∶m(P)=100时,SBR系统中GAOs富集比例达94%.测定和计算表明,SBR富集系统中GAOs衰减速率和死亡速率分别为0.132 d^-1和0.034 d^-1,其数量衰减和活性衰减占其细胞总衰减比例分别为26%和74%.可见,GAOs数量衰减只占其细胞总衰减中很小一部分,而绝大部分衰减由活性衰减所引起.     

水中天然有机物的分类特性及其卤代活性

利用XAD树脂对原水中的天然有机物进行富集分类 ,将其分为腐植酸、富里酸、亲水酸和其它亲水物质等 4种有机组分 .考察了原水中各有机组分的分布及其在加氯消毒过程中的三卤甲烷生成量、生成速度及耗氯量情况 .研究结果表明 ,原水中的主要成分是富里酸 ,占有机物总量的50.7% ,其它3种成分所占比例相对较小 ;原水具有较高的三卤甲烷生成能力 ,富里酸是生成三卤甲烷的主要有机组分 ;对各有机组分卤代活性的研究表明 ,腐植酸、富里酸和亲水酸具有较高的卤代活性 ,其它亲水物质的卤代活性较低 ;从各有机组分的三卤甲烷生成速度及与氯反应速度来看 ,腐植酸、富里酸及亲水酸具有较快的三卤甲烷生成速度 ,与氯的反应速度也较快 ,而其它亲水物质的三卤甲烷生成速度及与氯的反应速度均较低 .     

2,4-二氯苯酚低浓度长期暴露对鲫鱼肝脏抗氧化系统的影响

在室内模拟条件下,研究了低浓度2,4-二氯苯酚(2,4-DCP)长期暴露(40d)对鲫鱼(Carassius auratus)幼体肝脏抗氧化系统的影响结果表明:过氧化氢酶(CAT)活性、谷胱甘肽过氧化物酶(Se-GPx)活性、氧化型谷胱甘肽(GSSG)含量可被显著诱导;超氧化物歧化酶(SOD)活性在0.005mg·L^-1 2,4-DCP污染胁迫下即被显著诱导;还原型谷胱甘肽(GSH)含量几乎持续受到抑制;谷胱甘肽还原酶(GR)活性则先受到抑制后逐渐回升;谷胱甘肽硫转移酶(GST)的活性变化较小,仅在2个低浓度组中有轻微诱导.GR、GSH,尤其是SOD,对2,4-DCP较为敏感,可以作为水生生态系统中2,4-DCP污染的一项早期监测指标.