Dynamics of copper and tetracyclines during composting of water hyacinth biomass amended with peat or pig manure

Composting is one of the post-treatment methods for phytoremediation plants. Due to a high potential of water hyacinth to accumulate pollutants, the physicochemical parameters, microbial activity as well as fates of copper (Cu) and tetracyclines (TCs) were investigated for the different amended water hyacinth biomass harvested from intensive livestock and poultry wastewater, including unamended water hyacinth (W), water hyacinth amended with peat (WP), and water hyacinth amended with pig manure (WPM) during the composting process. Pig manure application accelerated the composting process as evidenced by an increase of temperature, electrical conductivity (EC), NH₄-N, as well as functional diversity of microbial communities compared to W and WP treatments. Composting process was slowed down by high Cu, but not by TCs. The addition of peat significantly increased the residual fraction of Cu, while pig manure addition increased available Cu concentration in the final compost. Cu could be effectively transformed into low available (oxidizable) and residual fractions after fermentation. In contrast, less than 0.5% of initial concentrations of TCs were determined at the end of 60-day composting for all treatments in the final composts. The dissipation of TCs was accelerated by the high Cu concentration during composting. Therefore, composting is an effective method for the post-treatment and resource utilization of phytoremediation plants containing Cu and/or TCs.     

Occurrence and human dietary assessment of sulfonamide antibiotics in cultured fish around Tai Lake,China

As the most important fishery medicines, sulfonamides are widely used to prevent diseases caused by pathogens in aquaculture. However, relatively little is known about the residues and dietary risks associated with cultured fish around Tai Lake. In the present study, a sampling strategy for a complete aquaculture period was conducted. Specifically, 12 selected sulfonamide antibiotics were measured among 116 fish samples recruited from four sampling periods, four species, four areas, and 18 fish ponds. All 12 antibiotics were detected at detection frequencies of 4.31–28.45%. Total sulfonamides were detected in 77.59% of the fish samples, with 57.76% of fish samples containing from 0.1 to 10 μg kg^?1. Sulfadiazine (SDZ), sulfamethoxazole (SMZ), sulfamethazine (SDD), and sulfamonomethoxine (SMM) were the main types of antibiotics used, and these were present at high concentrations (>100 μg kg^?1) with high occurrences, especially in the middle of the aquaculture season. Dietary assessment showed that residual antibiotics in all fish that were being sent to market were far below the maximum residue limit (MRL) of total sulfonamides and that there was almost no risk associated with fish consumption. The results of the present study will facilitate development of effective measures to produce safe aquatic products and meaningful suggestions for consuming aquatic products.     

An investigation of a heat pump system using CO2/propane mixture as a working fluid

In order to decrease the heat rejection pressure of heat pump using pure working fluid, CO₂ or R744, other natural component including hydrocarbons (R290, R600a, R600, R1270, R170, R601) and dimethyl ether (RE170) is added to CO₂, respectively, and then six binary mixtures are achieved. By environmental and thermodynamic comparisons, R290 is selected to be the most appropriate component candidate to mix with CO₂, and meanwhile to weaken the flammability and explosivity for pure R290. Then, the system performances of heat pump using mixture of CO₂ and R290 were experimentally studied when R290 is added to CO₂ with a small fraction, and compared with that of the pure CO₂. The experimental test rig is designed and set up for the transcritical heat pump system. When the refrigerant charge is variable, the heating coefficient performance, optimum heat rejection pressure, compressor power, mass flow rate of refrigerant, and total heat coefficient of gas cooler were researched. The variation ratios of heating coefficient performance and heating capacity with deviation from the optimum refrigerant charge were also investigated. The optimum refrigerant charge of CO₂/R290 is obtained and the research results show that the addition of R290 to CO₂ can efficiently reduce the heat rejection pressure and improve the system performance. The results in the present work could provide useful guidelines for the design and operation of heat pump system using CO₂-based mixture.     

铜基钯镍退镀液中铜的再生利用

采用硫氰酸盐沉铜法回收铜基钯镍退镀液中的铜。沉铜的优化工艺条件为初始Cu~(2+)质量浓度3.84 g/L、Cu~(2+)与Na SCN及Na_2SO_3摩尔比1∶4∶0.6、沉铜反应温度30℃,陈化时间24 h,沉铜反应后退镀液中Cu~(2+)残留量仅为0.025 mg/L。在此条件下加入聚乙二醇1.5 g/L,并提高分散液温度至50℃,可制得平均粒径为0.472μm的CuSCN超细粉体。CuSCN粉体为类球形,为含α、β两种晶型的混晶。     

水污染分析校准用汞溶液的研制

研制了水污染分析校准用汞溶液。采用原子荧光光谱法对样品进行了均匀性和稳定性检验,对样品的量值进行了验证并进行了不确定度评定。检验结果表明:汞溶液均匀性良好,室温条件下可稳定36个月以上;样品的标准值为100 mg/L,扩展不确定度为2 mg/L。样品量值与美国AccuStandard公司同种标准物质具有一致性。可用于水中汞检测的测定标准、质量控制、分析方法研究以及实验室能力验证等方面。     

燃料NO生成的总包反应速率

基于全面化学反应体系,对燃料ＮＯ的反应特性进行了详细的数值计算和理论分析,指出了目前应用较多的ＤｅＳｏｅｔｅＮＯ总反应模型的不足,同时,通过引入燃料氮氧化过程中关联组分Ｏ与ＯＨ离子的浓度和,用多元回归的方法得到了燃料ＮＯ生成的总包反应速率表达式。     

4种农药对3种拟菊酯杀虫剂在不同光源下的光解效应

以太阳光、氙灯、高压汞灯为光源,研究了哒嗪硫磷、多菌灵、克百威、丁草胺4种农药对氯氰菊酯、溴氰菊酯、氰戊菊酯3种拟菊酯杀虫剂的光解速度及光解效应的影响。结果表明：哒嗪硫磷、多菌灵对氯氰菊酯等3种拟菊酯杀虫剂在3种不同光源的光照处理下均表现出光敏降解效应;然而在太阳光及高压汞灯光源的光照处理下,克百威和丁草胺对３种拟菊酯杀虫剂具有光猝灭降解作用。太阳光照射下氯氰菊酯等3种拟菊酯杀虫剂的光解率与其单位面积上的药剂剂量成反比;而哒嗪硫磷等4种农药对3种拟菊酯杀虫剂的光敏或光猝灭效率与此4种农药的剂量成正相关     

海洋盐沼环境中金属的行为研究

详细论述了海洋盐沼环境中金属的行为及其化学／物理影响因素,其中包括盐沼区域的划分、影响金属的因素、金属的行为、盐沼植物与金属的关系。指出,重金属对盐沼植物生物初期有一定程度的危害,利用某些盐沼植物可监测重金属的污染状况。     

城市自来水中途生物性污染危险程度的预测研究

为了准确而又快速地预报自来水中途生物性污染的危险程度,防止介水传染病发生,本文对生活污水样品进行了大量的实验研究,同时收集和分析了国内历次污染事件资料。经大显筛选实验发现,水中氨氮是代表大肠菌群进行预测预报污染程度的最佳化学指标。发生污染事件的危险性可分为四级,相应的大肠菌群故分别为１００－、２００－、１０００－、１００００－。     

用CuSO4-KAl(SO4)2-Na2MoO4作催化剂快速测定COD

本文提出以CuSO_4-KAl(SO_4)_2-Na_2MoO_4作催化剂,在H_2SO_4-H_3PO_4混酸中快速测定废水COD新方法。正交实验测定的最佳条件是:CuSO_4 0.4g;KAl(SO_4)_2 1.8g;Na_2MoO_4 0.5g;H_2SO_4:H_3PO_4=3(体积比);回流时间0.5h。通过对废水COD的测定,取得与标准法相近的结果。回流时间缩短为0.5h,试剂费用降低50％。