泥沙对总氮测定结果的干扰影响分析

分析了泥沙含量对总氮测定结果的干扰影响,结果表明:水样中泥沙的含量与其对水样总氮的贡献有显著的正相关性;泥沙对总氮测定结果有干扰影响,随泥沙含量增加,A275的测定值及总氮降低率逐渐增大,且当泥沙(SS)含量≥45 mg/L时,其A275/A220的值在20%以上,总氮降低率在15%以上,从而总氮测定值产生较大的误差。消解后离心法或消解后0.45μm滤膜过滤法能有效地消除泥沙的干扰,并均具有操作简单和准确度高的优点。     

Insights into the changes of amino acids,microbial community,and enzymatic activities related with the nutrient quality of product during the composting of food waste

● The highest seed germination index was achieved at 0.3 g/g total solids of food waste. ● Proline was identified as the key amino acid related with the composting process. ● Amino acid metabolism sequences predominated during the whole composting process. This study systematically investigated the changes of amino acids as the composting process of food waste proceeded. It is found that the addition of 0.3 g/g total solids of food waste achieved the highest seed germination index of the product (268 %). The microbial community results indicated that the abundance of amino acid metabolism sequences remained at high levels during the whole composting process. Proline was identified as the key amino acid related with the nutrient quality of product during the composting of food waste. Further plant germination and hydroponic experiments found, that compared with those without the addition of proline, the addition of 50 mg/L proline increased seed germination rate by 20 %, increased shoot length by 3 %, increased root biomass of seedlings by 82 %, and increased leaf biomass of seedlings by 76 %, respectively. Firmicutes, γ-Pseudomonadota, Chloroflexi and Planctomycetes were the key identified bacteria related with the increase of proline during the composting of food waste. Meanwhile, the enzymatic tests of the activities of superoxide dismutase, peroxidase and malondialdehyde indicated that proline did not cause oxidative damage on the growth of plants. This study provided novel insights into the changes of amino acids, microbial community, and enzymatic activities related with the nutrient quality of product during the composting of food waste.     

Case study on prevention of fire hazards in coating epoxy-based FRP work with illumination

In this study, we investigated and analyzed the causes of fire hazards on the basis of actual accidents that occurred during epoxy resin fiberglass-coating operations. Results of this study showed that during this process, two major factors could cause a fire. One factor was related to the heat produced during the mixing of the epoxy resin and a polyamide curing agent. From the results of thermal analysis, it was found that the T_onset of the epoxy resin and the polyamide curing agent was 52.8 °C by DSC and T_d10 was 58.9 °C by DT/TGA, causing an exothermic hazard. Further, the results of a pseudo-adiabatic analysis performed in a Dewar vessel showed that the temperature increased from 23.5 °C to 177 °C.The other factor that could increase fire hazard was the illumination source used during the coating operation. Depending on the type of illumination source used, the temperature could increase above 350 °C. The decomposition temperature (T_d10) of PVC was 276.3 °C. The experiments involving epoxy resin fiberglass coating using an illumination source showed serious burn marks, and the polyvinyl chloride (PVC) electrical cable emitted small flames. Therefore, it can be concluded that fire was caused by the combination of two factors—the exothermic reaction between epoxy resin and the polyamide curing agent and the effect of prolonged illumination, both of which caused an increase in temperature leading to auto-ignition of the PVC electric cable.     

个体防护装备是减少生产性农药中毒的有效途径

本文根据国内外一些农药中毒的统计数据,结合农药入侵人体途径及农药中毒的健康影响,阐述在改进农药喷洒设备、工艺等措施外,合适的个体防护装备是农业作业中所必需的。     

老港填埋场新鲜渗滤液性质研究

用系列滤膜对老港填埋场2003年3月份新鲜渗滤液进行了梯度分离．并研究了其CODcr、氨氮、TOC、IC、TC、TS、FS、电导率、pH、色度,浊度的变化趋势与不同孔径膜之间的关系。结果表明,随着膜孔径的减小,CODcr、氨氮、TOC、IC、TC、TS、FS、色度、浊度等都有不同程度的降低,但降低不大,说明可溶性部分物质对新鲜渗滤液的污染性贡献最大;电导率、pH则先增大后减小。     

Markets and climate are driving rapid change in farming practices in Savannah West Africa

Agricultural practices have constantly changed in West Africa, and understanding the factors that have driven the changes may help guide strategies to promote sustainable agriculture in the region. To contribute to such efforts, this paper analyzes drivers of change in farming practices in the region using data obtained from surveys of 700 farming households in five countries (Burkina Faso, Ghana, Mali, Niger and Senegal). The results showed that farmers have adopted various practices in response to the challenges they have faced during the last decade. A series of logit models showed that most changes farmers made to their practices are undertaken for multiple reasons. Land use and management changes including expanding farmed areas and using mineral fertilization and manure are positively related to perceived changes in the climate, such as more erratic rainfall. Planting new varieties, introducing new crops, crop rotation, expanding farmed area and using pesticides are positively associated with new market opportunities. Farm practices that require relatively high financial investment such as use of pesticides, drought-tolerant varieties and improved seeds were positively associated with the provision of technical and financial support for farmers through development projects and policies. Changes in markets and climate are both helping to promote needed changes in farming practices in West Africa. Therefore, policies that foster the development of markets for agricultural products, and improved weather- and climate-related information linked to knowledge of appropriate agricultural innovations in different environments are needed.     

Characteristics and transport of organochlorine pesticides in urban environment: air, dust, rain, canopy throughfall, and runoff

Characteristics and transport of organochlorine pesticides (OCPs) in urban multiple environments, including air, dust, rain, canopy throughfall, and runoff water, are explored in this study. Hexachlorocyclohexanes (HCHs) dominated in both air and rain water, and dichlorodiphenyltrichloroethane (DDT) related substances showed a higher affinity to dust. Relatively high concentrations of DDT and dichlorodiphenyldichloroethylene (DDE) in air, rain and dust imply that technical DDT in the environment has been degrading, and there may be unknown local or regional emission sources that contain DDTs in the study area. Source identification showed that DDTs in Beijing urban environments with a fresh signature may originate from the atmospheric transport from remote areas. The ratio of α-/γ-HCH in dust, rain, canopy throughfall and runoff were close to 1, indicating the possible use of lindane. OCPs in runoff were transported from various sources including rain, dust, and canopy throughfall. In runoff, DDTs and hexachlorobenzene (HCB) were mainly transported from dust, and HCHs were mainly from rain and canopy throughfall.     

Effects of different carbon sources on the removal of ciprofloxacin and pollutants by activated sludge: Mechanism and biodegradation

This research investigated the effects of ciprofloxacin(CIP)(0.5, 5, and 20 mg/L) on SBR systems under different carbon source conditions. Microbial community abundance and structure were determined by quantitative PCR and high-throughput sequencing, respectively.The biodegradation production of CIP and possible degradation mechanism were also studied. Results showed that CIP had adverse effects on the nutrient removal from wastewater.Compared with sodium acetate, glucose could be more effective...     

Biosorption of Pb(II) by biomass of KC-2: kinetic, equilibrium and characteristic studies

Performance and characteristics of biosorption of Pb(II) had been studied in a batch system using the fungal strain biomass, KC-2. The biosorption performance was investigated by analysing the effects of such factors as the initial pH, initial Pb(II) concentration, and contact time at 303 K. The maximum Pb(II) adsorption was obtained at pH 5.0. The experimental data were described by the pseudo first-order, pseudo second-order and intraparticle diffusion kinetic models, and were closely followed the pseudo second-order kinetic model. The equilibrium experimental data were well fitted to Langmuir model and the maximum biosorption capacity was 84.03 mg g(-1). The adsorption mechanism was examined by FTIR, SEM and EDAX analysis. Results indicated that carboxylic, hydroxyl and amine groups were involved in the biosorption and ion exchange mechanism existed.     

河南油田提高稠油脱水技术的研究与应用

筛选高效破乳剂,采取更加合理有效的加药方式,提高脱水效果,降低生产成本至关重要。河南油田井楼油矿针对稠油筛选出高效破乳剂,通过管道破乳应用,得出:FS-21二代破乳剂脱水效果明显比一代有较大提高,原油含水率较低;并且在站外加药,脱水效果明显高于站内加药,药剂用量要比站内少;使用的160多天内FS-21二代破乳剂适用性良好。进一步提高了稠油整体脱水效果,取得了明显的经济效益。