负压二次曝气二氧化氯发生器的研制与应用

以氯酸钠和工业盐酸为基本原料,采用独特的负压二次曝气工艺,在催化剂作用下,经氧化还原反应产生以二氧化氯为主的混合消毒气体,经吸收后形成一定浓度的二氧化氯混合消毒液,与待处理水充分混合,达到杀菌消毒的目的。     

铁矿石对脱除烧结废气中NOx的催化效应

向混合料中加添加剂能够在烧结过程中脱除烧结废气中的NO。实验研究了铁矿石对NO脱除反应的催化效应。在900℃下,分别以5种不同铁矿石作为填料层,用2种标准气体和压缩空气配制的混合气体模拟烧结废气。试验结果表明,铁矿石种类对铁矿石的催化能力有重要影响。D型铁矿的催化能力最强而且不会发生弱化,NO转化率接近100%;其它几种铁矿石的催化能力较差,随着反应时间的延长有明显的弱化现象,但很快即基本趋于稳定状态,NO转化率达到了60%~70%。     

两类藻毒素聚酮合成酶遗传相似性及其二级结构预测分析

研究微囊藻毒素聚酮合成酶、节球藻毒素聚酮合成酶之间的遗传关联性,并对其二级结构进行预测分析.应用聚合酶链反应得到2株蓝绿藻的毒素聚酮合成酶(PKS)基因,并进行基因序列分析.从GenBank中提取产微囊藻毒素、产节球藻毒素藻株的相应基因序列,利用DNAStar和phylip软件分析目的基因一致性及2类藻毒素PKS的进化情况.采用Garnier-Robson法、Karplus-Schulz法预测项圈藻株202A1/35、节球藻株NSOR10PKS蛋白片段的二级结构,Kyte-doolittle法分析蛋白的亲水性,Emini法预测蛋白质的表面可能性.结果表明,2类藻毒素PKS目的基因的相似性非常高;项圈藻属、念珠藻属的微囊藻毒素PKS与节球藻毒素PKS的进化关系较近;2种藻毒素PKS分析片段二级结构具有较大的相似性,其亲水性与表面可能性区域等特征也极为相似.     

燃烧过程颗粒物的形成及我国燃烧源分析

燃料燃烧会排放一次颗粒物和二次颗粒物,一次颗粒物中亚微米粒子主要是由于无机矿物质经蒸发-成核-凝结-凝并的途径形成的;超微米颗粒的产生不同于亚微米颗粒的形成,是由于破碎机理.二次颗粒物是由气态前驱体在大气中转化而成的.我国燃烧源主要是煤燃烧、燃油机动车和农村生活燃料等.深入认识颗粒物的形成及燃烧源的特征对有效控制颗粒物的排放是很有帮助的.     

苦味酸测定中关键问题的研究

目前测定苦味酸的国标方法为《生活饮用水标准检验方法有机物指标》(GB/T 5750.8—2006)中的衍生物-液液萃取-气相色谱法,在实际测试过程中,发现水样pH值和基质效应会影响苦味酸测定。当pH值为8~12时,生成的氯化苦响应强度变化不大;在pH约为13时,响应强度最大。水质中除腐殖酸、硝基甲烷及2,4,6-三硝基甲苯会影响苦味酸测定外,硝基酚类和甲基酚类同样起到正干扰作用,因此,国标方法不能全面和准确地测定水中的苦味酸含量。     

Thermal decomposition mechanism of 65% lysine sulfate powder and its thermal stability based on thermal analysis

Lysine is widely used in the fields of food, medicine and feed, which generally appears in the form of lysine sulfate or lysine hydrochloride dust because of the high instability of the free L-lysine. The L-lysine Sulfate is in high risk of decomposition, spontaneous ignition and even the dust explosion, because the control temperature in its production process is high up to 90 °C. Thus, the thermal behaviors and its thermal stability of 65% lysine sulfate are experimentally explored in Air and Nitrogen using the simultaneous TG-DSC measurements. Results show: (1) the decomposition of 65% lysine sulfate can be divided into three stages both in the atmospheres of air and nitrogen, and most of the weight loss occurred in the first two stages, which are related with the decarboxylation and deamination process. (2) The effects of atmosphere on the decomposition of 65% lysine sulfate mainly occur at the third stage. In this stage, the weight loss in nitrogen is only 14.2%, which is much lower than that in air (34.3%), which is related to the oxidative degradation at high temperature. Besides, the active energy is slightly increased in nitrogen compared to that in air. (3) The initial temperatures of the decomposition of the 65% lysine sulfate are 145 °C and 155 °C, for the air and nitrogen atmosphere, respectively, which are much lower than that (260 °C) of the pure lysine.     

Spatial and Seasonal Response of Municipal Water Use to Weather across the Contiguous U.S.

Weather variability has the potential to influence municipal water use, particularly in dry regions such as the western United States (U.S.). Outdoor water use can account for more than half of annual household water use and may be particularly responsive to weather, but little is known about how the expected magnitude of these responses varies across the U.S. This nationwide study identified the response of municipal water use to monthly weather (i.e., temperature, precipitation, evapotranspiration [ET]) using monthly water deliveries for 229 cities in the contiguous U.S. Using city‐specific multiple regression and region‐specific models with city fixed effects, we investigated what portion of the variability in municipal water use was explained by weather across cities, and also estimated responses to weather across seasons and climate regions. Our findings indicated municipal water use was generally well‐explained by weather, with median adjusted R² ranging from 63% to 95% across climate regions. Weather was more predictive of water use in dry climates compared to wet, and temperature had more explanatory power than precipitation or ET. In response to a 1°C increase in monthly maximum temperature, municipal water use was shown to increase by 3.2% and 3.9% in dry cities in winter and summer, respectively, with smaller changes in wet cities. Quantifying these responses allows urban water managers to plan for weather‐driven variability in water use.     

Assessing Spatial, Temporal, and Analytical Variation of Groundwater Chemistry in a Large Nuclear Complex, USA

Statistical analyses were applied at the Hanford Site, USA, to assess groundwater contamination problems that included (1) determining local backgrounds to ascertain whether a facility is affecting the groundwater quality and (2) determining a ‘pre-Hanford' groundwater background to allow formulation of background-based cleanup standards. The primary purpose of this paper is to extend the random effects models for (1) assessing the spatial, temporal, and analytical variability of groundwater background measurements; (2) demonstrating that the usual variance estimate s ², which ignores the variance components, is a biased estimator; (3) providing formulas for calculating the amount of bias; and (4) recommending monitoring strategies to reduce the uncertainty in estimating the average background concentrations. A case study is provided. Results indicate that (1) without considering spatial and temporal variability, there is a high probability of false positives, resulting in unnecessary remediation and/or monitoring expenses; (2) the most effective way to reduce the uncertainty in estimating the average background, and enhance the power of the statistical tests in general, is to increase the number of background wells; and (3) background for a specific constituent should be considered as a statistical distribution, not as a single value or threshold. The methods and the related analysis of variance tables discussed in this paper can be used as diagnostic tools in documenting the extent of inherent spatial and/or temporal variation and to help select an appropriate statistical method for testing purposes.     

O3/BAF工艺系统中有机物生物降解数学模型

研究臭氧预氧化/曝气生物滤池（O₃/BAF）联合工艺深度处理实际城市污水二级出水过程中,后续BAF系统中有机物的生物降解数学模型。以有机底物浓度、填料层高度两个基本变量为控制条件,研究BAF的总体运行常数和填料特性常数,得出BAF有机物生物降解动力学方程为S_e/S₀=exp(－Kh/qSⁿ₀)。出水与进水COD浓度比值（S_e/S₀）的对数与反应器填料高度（h）之间可表达成一次函数关系。在不同的进水浓度（S₀）下,根据ln（S_e/S₀）~h和关系式m=K/qSⁿ₀,得到方程ln(q_m)=－nln(S₀)+lnK。BAF总体运行常数K和填料特性常数n分别为1.708和0.5063。该模型对BAF工艺有如下指导意义：可以根据设计流量、进水有机物浓度和出水浓度,初步确定BAF的尺寸（如横截面积、高度等）。     

Bioaccumulation and biological effects in the earthworm Eisenia fetida exposed to natural and depleted uranium

The accumulations of both natural (U) and depleted (DU) uranium in the earthworms (Eisenia fetida) were studied to evaluate corresponding biological effects. Concentrations of metals in the experimental soil ranged from 1.86 to 600 mg kg⁻¹. Five biological endpoints: mortality, animals’ weight increasing, lysosomal membrane stability by measuring the neutral red retention time (the NRRT), histological changes and genetic effects (Comet assay) were used to evaluate biological effects in the earthworms after 7 and 28 days of exposure. No effects have been observed in terms of mortality or weight reduction. Cytotoxic and genetic effects were identified at quite low U concentrations. For some of these endpoints, in particular for genetic effects, the dose (U concentration)-effect relationships have been found to be non-linear. The results have also shown a statistically significant higher level of impact on the earthworms exposed to natural U compared to depleted U.