Methods for the preparation of a biodesulfurization biocatalyst using Rhodococcus sp

Several methods to prepare a biodesulfurization (BDS) biocatalyst were investigated in this study using a strain of Rhodococcus sp. 1awq. This bacterium could selectively remove sulfur from dibenzothiophene (DBT) via the "4S" pathway. DBT, dimethylsulfoxide (DMSO), sodium sulphate and mixed sulfur sources were used to study their influence on cell density, desulfurization activity, desulfurization ability, and the cost of biocatalyst production. In contrast to that observed from bacteria cultured in DBT, only partial desulfurization activity of strain 1awq was induced by DBT after cultivation in a medium containing inorganic sulfur as the sole sulfur source. The biocatalyst, prepared from culture with mixed sulfur sources, was found to possess desulfurization activity. With DMSO as the sole sulfur source, the desulfurization activity was shown to be similar to that of bacteria incubated in medium with DBT as the sole sulfur source. The biocatalyst prepared by this method with the least cost could remove sulfur from hydrodesulfurization (HDS)-treated diesel oil efficiently, providing a total desulfurization percent of 78% and suggesting its cost-effective advantage.     

Extraction of arsenate and arsenite species from soils and sediments

The primary objective of this study was to develop a simple method that can be used to extract the more readily mobilizable and bioavailable arsenic species from soil and sediment while at the same time minimizing the transformation between (AsIII) and (AsV), the two most commonly found arsenic species in the environment. Several extraction strategies were evaluated using phosphate as extractant in combination with either ethylenediaminetetraacetic acid (EDTA), hydroxylamine hydrochloride (NH2OH.HCl), or sodium diethyldithiocarbamate trihydrate (NaDDC). The addition of EDTA in the phosphate solution did not prevent AsIII from oxidation. While promising results were shown when 1% NH2OH.HCl was added, conversion of AsIII began to occur with extended extraction time (> 12 h). Good results were achieved using 10 mM phosphate and 0.5% NaDDC where AsIII oxidation was clearly minimized. The combined phosphate and NaDDC solution was applied to several soil and sediment samples. AsIII spiked was quantitatively recovered in all soil types tested.     

三丁基氯化锡对红鳍笛鲷的急性毒性及不同组织生化指标的影响

为研究有机锡化合物对海洋生物抗氧化防御系统和神经系统的影响,以我国东南沿海常见的中下层增养殖鱼类红鳍笛鲷(Lutjanus erythopterus)幼鱼为实验生物,采用半静态毒性实验方法,分别研究了三丁基氯化锡(tributyltin chloride,TBTCl)的急性毒性和96 h暴露时间内对红鳍笛鲷幼鱼鳃、脑和...     

丁坝对河流污染物迁移扩散的影响模拟研究

以深度平均的水流和污染物迁移扩散的通用微分方程为控制方程建立数学模型。设置上游丁坝,模拟分析丁坝长度占河宽的不同比例(10%、20%、40%)以及污水口在坝前2m的位置条件下,丁坝对水流流场及污染物迁移扩散的影响。结果表明:当丁坝长度达到河宽的40%的时候,污染带的宽度最大,而出口端面污染物浓度较低。通过设置合理的丁坝长度比例,可以在一定程度上降低沿程污染物的浓度。     

防护鞋靴有害物质限量值研究

本文对防护鞋靴有害物质限量值研究进行了阐述。参考国内外标准,设定防护鞋靴有害物质限制项目和限量值。在检测分析我国具有市场代表性的16个防护鞋靴产品中有害物质含量数据基础上,判断设定限制项目及限量值的可行性。检测结果表明我国防护鞋靴生产技术水平基本能够达到限量要求,设定的限量值可以作为制定国家标准的参考依据。     

基于高通量分析方法的长江干流重庆段抗生素种类特征及来源初探

采用高通量分析方法对长江干流重庆段11个流域断面、2个市政污水处理厂进水和6个养殖场废水的潜在抗生素进行筛查,并结合抗生素使用调查探讨其来源。结果表明,(1)共检出83种抗生素,其中流域内检出36种,污水处理厂和养殖场废水中检出70种;磺胺间甲氧嘧啶检出率最高,在流域水体和废水的检出率分别为91%和55%,喹诺酮类是检出抗生素的主要类型;(2)长江干流重庆段下游检出抗生素数量高于上游检出抗生素;(3)有20种抗生素可能由上游携带和重庆市内排放2种方式进入流域,7种抗生素可能由上游携带入境,9种抗生素可能由重庆市内排放引入长江。     

Reconsideration on the effect of nitrogen on mixed culture polyhydroxyalkanoate production toward high organic loading enrichment history

Effect of nitrogen on mixed culture PHA production was reconsidered. Enrichment history of PHA accumulating culture was discussed. Higher PHA content and biomass growth were achieved in presence of nitrogen. Enrichment strategy toward higher PHA accumulation was investigated. Microbial community succession in PHA accumulation phase was investigated. In most of the operating strategies for mixed microbial cultures polyhydroxyalkanoate (PHA) production, moderate organic loads and low nitrogen concentrations are used, however, the real waste streams contain variable concentrations of carbon and nitrogen. To evaluate the effect of enrichment history on PHA producer and production the various carbon and nitrogen levels were utilized during the accumulation phase. Different operating strategies were applied in three sequencing batch reactors (SBRs) subjected to aerobic dynamic feeding. The maximum PHA production of the enriched cultures under nutrient excess, limitation and starvation (Cmol/Nmol ratio of 8, 40 and ∞, respectively) was evaluated in batch assays. A higher PHA content and biomass growth were achieved in the nutrients presence in comparison to the nutrient starvation condition. The cultures from the SBR treated under short sludge retention time, high organic loading rate, short cycle length (SBR#3) and nutrient excess reached the maximum PHA content (54.9%) and biomass increase (38.9%). Under nutrient limitation, the negative biomass growth was observed under nutrient starvation because of the sampling loss. The succession of microbial communities in SBRs and batch assays was analyzed using terminal restriction fragment length polymorphism. The SBR#3 had the best overall PHA production performance considering its high PHA content and productivity in all nutrient content, it indicates that nitrogen has a substantial impact on PHA yield especially when high organic loading rate enrichment history is involved.     

Capacity estimation and preliminary strategy for reducing the release of dioxins in China

As a party of the Stockholm Convention on Persistent Organic Pollutants, China must submit its national implementation plan (NIP) for this convention. The strategy and action plan for reducing the release of dioxins in China are the most important components of the NIP. Three problems are key points for developing such strategy and action plan—what are the key sources for applying the best available technology/best environmental practice (BAT/BEP) to reduce the release of dioxins? How about the capacity for reducing the dioxins release from the key sources? Where are the areas of priority for applying BAT/BEP? This paper shows the efforts towards the solution of these problems. The list of key sources covering about half of the total dioxins release was determined considering four criteria. The capacity of key sources were estimated based on the difference between the emission factor corresponding to the actual situation in 2004 and that corresponding to the scenario that all key sources have been applied BAT/BEP to reduce the dioxins release. The priority analysis using the geographical information system (GIS) tool has revealed that castern provinces should be of high priority in the future reduction activities of dioxins release in China.     

利用碎片常数和结构因子法估测农药在正辛醇／水相中的分配系数

本文详细阐述了用碎片常数与结构因子法估测农药在正辛醇与水相体系中分配系数的方法，并对６０种农药分配系数的估测结果与用经典的摇瓶测试法得到的实测值进行了比较，结果表明：估测结果与实测值基本吻合，碎片常数和结构因子估测法可以作为获得农药分配系数的另一种途径。     

甲基异柳磷等四种农药的水解特性研究

本文测定了甲基异柳磷、单甲脒、克草胺、嘧啶氧磷等四种农药在不同温度和不同pH条件下的水解速率、探讨了影响水解的主要因素。结果表明,在中性水溶液中,25℃时四种农药的水解半衰期分别为:甲基异柳磷270.8d,单甲脒6.5d,克草胺602.7d,嘧啶氧磷55.9d;当温度升至50℃时,四种农药的水解速率均有不同程度的增加,增幅为原来的2.0—10.8倍;改变pH亦会影响水解速率,甲基异柳磷和单甲脒均随pH增加水解大大加快;克草胺则在中性及碱性条件下很稳定,在酸性条件下稳定性较差;而嘧啶氧磷在酸碱条件下都不如在中性条件下稳定。