三峡库区长寿湖水体不同形态汞的空间分布特征

以三峡库区长寿湖为调查对象,采用网格法均匀设点采样分析,并基于Arc GIS地统计模块,研究了长寿湖水体不同形态汞浓度及其空间分布特征.结果表明,长寿湖表层水总汞浓度变化范围为0.50~3.78 ng·L-1,平均值为1.51 ng·L-1;总甲基汞浓度变化范围为0.10~0.75 ng·L-1,平均值为0.23 ng·L-1.表层水体各形态汞的块金效应值分别为总汞50.65%、溶解态汞49.80%、颗粒态汞29.94%和活性汞26.95%,具有中等程度空间自相关性,表明在空间分布上一方面受水体内在属性的影响,另一方面也与渔业养殖、工业活动、农业耕种等人为外源输入干扰因素有关.表层水体溶解态甲基汞块金效应值3.49%,小于25%,表现很强的空间自相关性,其分布主要受到水体内在环境因素等的控制.各采样点水体总甲基汞占总汞的比例均较高,均达到淡水湖泊和河流中总甲基汞占总汞的质量分数上限值30%,暗示长寿湖水体内在环境条件利于汞的甲基化.     

青藏铁路建设中高寒缺氧及保障问题的研讨

“高寒缺氧”是青藏铁路建设面临的主要难题之一,青藏铁路沿线自然条件恶劣、海拔高、气压低,含氧量低,缺氧严重会导致急性高原病严重影响人体健康和劳动能力,同时含氧量低会造成机械功率降低。为保障高原施工人员和铁路建设者的健康和安全,降低机械设备的功率损耗,在青藏铁路的设计和建设中,必须采取高原劳动卫生和劳动保护措施、选用可靠度高、维修量少的运营设备,建立起适合高原特点的管理体制、机构及合理的用工制度等技术保障措施,提供坚强有力的医疗卫生保障,从而提高劳动效率,降低劳动强度、缩短工期,保护员工的安全与健康。     

空分站大型空压机组的噪声治理

介绍了采用局部敞开式隔声罩隔音降噪技术治理空分站大型空压机组噪声的治理方案及取得的效果.     

Distribution and mobility of metals in agricultural soils near a copper smelter in South China

The distribution and mobility of heavy metals in the paddy soils surrounding a copper smelting plant in south China was investigated. We assessed the degree of metal contamination using an index of geoaccumulation. The metals were divided into two groups: (1) Cu, Zn, Pb and Cd, whose concentrations were heavily affected by anthropogenic inputs, and (2) Ni, Co and Cr, which were mainly of geochemical origin. Concentrations of Cu, Cd, Zn, and Pb in the polluted soils were higher than the Chinese soil quality criteria. The chemical partitioning patterns of Pb, Zn and Cu indicated that Pb was largely associated with the residual and NH₂OH HCl extractable fractions. In contrast, Cd was predominantly associated with the MgCl₂ extractable fraction. A large proportion of Cu was bound to the acidic H₂O₂ extractable fractions, while Zn was predominantly found in the residual phase. The fraction of mobile species, which potentially is the most harmful to the environment, was found to be elevated compared to unpolluted soils in which heavy metals are more strongly bound to the matrix. The mobility of the metals was studied by water extraction using a modification of Tessier’s procedure, and the order of mobility was Zn > Cd > Cu  > Pb.     

Determination and distribution characteristics of degradation products of nonylphenol polyethoxylates in the rivers of Taiwan

Concentrations of degradation products of nonylphenol polyethoxylates (NPEOs) were analyzed in river water samples in order to determine the distribution characteristic of these alkylphenolic compounds in 18 major rivers of Taiwan. The degradation products of NPEOs were detected in all river samples, with the dicarboxylates alkylphenolic degradation products (CAPEC) being detected most frequently and at the highest concentrations. Concentrations of NP and NP1EO in rivers ranged from n.d. to 5.1 μg l⁻¹ and n.d. to 0.5 μg l⁻¹, respectively. The total concentrations of shortened carboxylates (i.e., NP1EC + NP2EC + NP3EC) and dicarboxylates alkylphenolic degradation products (CAP1EC + CAP2EC) ranged from n.d. to 63.6 μg l⁻¹ and n.d. to 94.6 μg l⁻¹, respectively. Concentrations of NP2EC, NP3EC and all CAPEC residues were determined semi-quantitatively by comparing with the internal standard. Significantly higher concentrations of CAPEC residues were detected in the river waters as compared to those of NP, NP1EO and NPEC degradation products and the average proportions of these compounds in the samples of the rivers were as follows: NP + NP1EO was 5 ± 2.5%, total NPEC was 25 ± 12%, and total CAPEC was 70 ± 12%. The high concentration ratios of CAPEC/NPEC illustrate that aerobic biodegradation plays a main route in the fate of NPEO in the rivers of Taiwan.     

Accumulation of copper in brown rice and effect of copper on rice growth and grain yield in different rice cultivars

A pot experiment with 38 commonly cultured rice cultivars showed that the effect of Cu (100 mg kg(-1)) on rice growth, grain yield and accumulation of Cu in brown rice varied greatly with different cultivars. Although the average Cu concentration in brown rice of the 38 cultivars was significantly increased (P<0.01) compared with the control, in none of the cultivars did Cu concentration in brown rice exceed the maximum permissible limit of 10 mg Cu kg(-1). This suggests that rice grown in Cu-contaminated paddy soil (100 mg Cu kg(-1)) will not adversely affect human health through the food chain. Because of the significant negative correlation between grain weight and Cu concentration in brown rice with the soil Cu treatment, screening for cultivars with low Cu accumulation in brown rice and high grain yield for Cu-contaminated areas is feasible. The present research led to the recommendation of three such cultivars: Jiahua, Zhenxian 866, Zhe 733. The average grain yield under Cu treatment (100 mg Cu kg(-1) soil) was significantly (P<0.01) reduced compared with the control. The decreases or increases of grain yields mainly resulted from the combined effects of the panicles per pot, spikelets per panicle and filled spikelets per panicle under the soil Cu treatment. Furthermore, there were significant (r=0.869, P<0.01) positive correlations between the RC (relative changes) of spikelets per panicle and filled spikelets per panicle under the soil Cu treatment.     

Effects of metsulfuron-methyl on the microbial population and enzyme activities in wheat rhizosphere soil

The effects of metsulfuron-methyl, a sulfonylurea herbicide, on the wheat soil microorganisms were evaluated by the methods of microbial inoculation culture, and the activities of three enzymes were measured using the colorimetric method. The tolerant microorganisms that can resist 500 microg x g(-1) metsulfuron-methyl in the counting culture medium were studied specially. Metsulfuron-methyl distinctly inhibited the common aerobic heterotriphic bacteria, but the effects on common fungi and common actinomycete were not evident. In the meantime, the number of tolerant fungi increased greatly in the rhizosphere after the application of metsulfuron-methyl in contrast to the significant decrease of the amount of tolerant actinomycete. It indicates that fungi might turn into the dominant microbial type and actinomycete is the sensitive factor in the soil polluted by sulfonylurea residues. The population of aromatic compounds-decomposing bacteria, aerobic azotobacter, and nitrite bacteria all increased in the earlier period, but the aerobic azotobacter decreased rapidly in number 30 days later, and the amount of nitrite bacteria also showed a temporary decrease with time 15 days later. However, the denitrifying bacteria just began to increase significantly after the crops had grown for 50 days. The amount of sulfur-oxidizing bacteria gradually decreased with the growth of crops, and so were the sulfate-reducing bacteria after metsulfuron-methyl application. To all types of microorganisms, there were more microbes in rhizosphere samples than those in nonrhizosphere except aerobic azotobacter. It means the growth of wheat root system can stimulate the growth of most microorganisms. The activities of hydrogen peroxidase and polyphenol oxidase in soil samples after metsulfuron-methyl application were notably lower than those in the control, and the difference of the activities between the samples of rhizosphere and nonrhizosphere was evident. On the contrary, the activity of dehydrogenase was not inhibited by the application of metsulfuron-methyl, and the rhizosphere effect was not obvious either.     

Toxicokinetics/toxicodynamics of arsenic for farmed juvenile milkfish Chanos chanos and human consumption risk in BFD-endemic area of Taiwan

This paper presents a toxicokinetic/toxicodynamic analysis to appraise arsenic (As) bioaccumulation in farmed juvenile milkfish Chanos chanos at blackfoot disease (BFD)-endemic area in Taiwan, whereas probabilistic incremental lifetime cancer risk (ILCR) and hazard quotient (HQ) models are also employed to assess the range of exposures for the fishers and non-fishers who eat the contaminated fish. We conducted a 7-day exposure experiment to obtain toxicokinetic parameters, whereas a simple critical body burden toxicity model was verified with LC50(t) data obtained from a 7-day acute toxicity bioassay. Acute toxicity bioassay indicates that 96-h LC50 for juvenile milkfish exposed to As is 7.29 (95% CI: 3.10-10.47) mg l(-1). Our risk analysis for milkfish reared in BFD-endemic area indicates a low likelihood that survival is being affected by waterborne As. Human risk analysis demonstrates that 90%-tile probability exposure ILCRs for fishers in BFD-endemic area have orders of magnitude of 10(-3), indicating a high potential carcinogenic risk, whereas there is no significant cancer risk for non-fishers (ILCRs around 10(-5)). All predicted 90%-tiles of HQ are less than 1 for non-fishers, yet larger than 10 for fishers which indicate larger contributions from farmed milkfish consumptions. Sensitivity analysis indicates that to increase the accuracy of the results, efforts should focus on a better definition of probability distributions for milkfish daily consumption rate and As level in milkfish. Here we show that theoretical human health risks for consuming As-contaminated milkfish in the BFD-endemic area are alarming under a conservative condition based on a probabilistic risk assessment model.     

序批式生物膜反应器同步硝化反硝化的曝气时问控制及其机制分析

装有鲍尔环填料的序批式生物膜反应器(SBBR)具有很好的同步硝化反硝化(SND)效果.从试验结果可以看出,SBBR具备了生成和保存内碳源以及产生缺氧区的良好条件;当硝化结束后,应立即停止曝气,可以降低出水TN并实现节能.分析了生物膜内各种基质、DO、聚β-羟基丁酸(PHB)的变化曲线.描述了生物膜内发生SND的过程和机制,并提出了SBBR中达到良好SND效果的曝气时间控制方式.     

水溶液中盐的浓度与其电导率的关系研究

采用电导法研究了水溶液中盐的浓度与其电导率的关系。结果表明 ,在低浓度范围内电导率与浓度的平方根呈线性关系 ;在较高的浓度范围内 ,首次发现浓度与电导率的关系和 Langmuir吸附等温式中的压力与吸附量之间的关系类似。利用浓度与电导率间的定量关系确定水溶液中盐的浓度 ,比传统的重量法和滴定法快速且准确。