响应面法优化袋式除尘器脉冲清灰性能

基于计算流体动力学的方法采用三维、可压缩、非稳态流动数学模型对袋式除尘器脉冲清灰过程进行了数值模拟,得到了滤袋内外压差,并与文献实验值进行了比较,验证了仿真模型的可靠性。基于响应面法研究了喷吹压力、喷吹高度、滤袋直径和滤袋长度对脉冲清灰性能的影响,得到这4个影响因子的二次多项式预测模型,并进行优化。结果表明,喷吹压力为0.3 MPa,喷吹高度为0.2 m,滤袋直径为0.16 m,滤袋长度为6 m时,内外压差峰值最优,优化结果与仿真模拟结果相差小于3%。研究结果为袋式除尘器脉冲清灰系统的设计与优化提供了重要参考。     

Characterization of Cd-, Pb-, Zn-resistant endophytic Lasiodiplodia sp. MXSF31 from metal accumulating Portulaca oleracea and its potential in promoting the growth of rape in metal-contaminated soils

The aim of this study was to characterize the features of a Cd-, Pb-, and Zn-resistant endophytic fungus Lasiodiplodia sp. MXSF31 and to investigate the potential of MXSF31 to remove metals from contaminated water and soils. The endophytic fungus was isolated from the stem of Portulaca oleracea growing in metal-contaminated soils. The maximum biosorption capacities of MXSF31 were 3.0?×?10³, 1.1?×?10⁴, and 1.3?×?10⁴ mg kg^?1 for Cd, Pb, and Zn, respectively. The biosorption processes of Cd, Pb, and Zn by MXSF31 were well characterized with the pseudo-second-order kinetic model. The biosorption isotherm processes of Pb and Zn by the fungus were fitted better with the Langmuir model, while the biosorption processes of Cd was better fitted with the Freundlich model. The biosorption process of MXSF31 was attributed to the functional groups of hydroxyl, amino, carbonyl, and benzene ring on the cell wall. The active biomass of the strain removed more Cd, Pb, and Zn (4.6?×?10⁴, 5.6?×?10⁵, and 7.0?×?10⁴ mg kg^?1, respectively) than the dead biomass. The inoculation of MXSF31 increased the biomass of rape (Brassica napus L.), the translocation factor of Cd, and the extraction amount of Cd by rape in the Cd?+?Pb-contaminated soils. The results indicated that the endophytic fungus strain had the potential to remove heavy metals from water and soils contaminated by multiple heavy metals, and plants accumulating multiple metals might harbor diverse fungi suitable for bioremediation of contaminated media.     

废塑料再生产业园的规划及环境影响评价

论述了我国废塑料再生行业存在的问题和废塑料再生产业园的规划特点。探讨了产业园的合理选址、系统规划布局、同步环境影响评价在废塑料再生产业园建设中的重要性,介绍了环境影响分析和园区清洁生产与循环经济等内容。指出建立废塑料再生产业园,必须通过合理规划布局并及时开展环境影响评价工作,这是保护环境、防控污染的有效措施。     

巢湖入湖河流沉积物中有机磷的形态分级研究

为识别巢湖流域污染物的特征、来源及其沉积物有机磷各形态分布与富营养化的关系,测定了7条巢湖入湖河流沉积物中有机磷各形态的含量,分析不同污染类型人湖河流沉积物中有机磷各形态分布的差异及与其他因素间的相关性。研究发现,不同污染类型人湖河流沉积物中水土保持控制型河流沉积物中有机磷各组分的相对含量顺序为残渣态Po〉富里酸-Po〉HCl-Po〉胡敏酸-Po〉NaHCO3-Po,平均的相对比例为7．5：3．1：1．9：1．5：1．0,而城市污染控制型和面源污染控制型河流沉积物中有机磷各组分的相对含量顺序恰好相同,面源污染控制型河流沉积物Po各形态含量低于城市污染控制型和水土保持控制型河流。中活性P。和OM、TP、Pi、Po、TN、NaHCO3-Pi、NaOH—Pi呈正相关,非活性Po与Po、NaOH-Pi呈显著正相关关系,反映了中活性Po很容易转化为生物可利用磷和非活性Po,且非活性Po仍然具有潜在的生物活性。     

Developing a framework for integrating local and scientific knowledge in internationally funded environment management projects: case studies from Kien Giang Province,Vietnam

Local and scientific knowledge, when adequately and properly integrated, produces enormous benefits for natural resource management in comparison to a single knowledge system being used. Adequate and proper integration has major constraints that include ineffective use of the integrated knowledge, thoroughly inclusive processes, and true public participation. A six-stage framework is developed using the results and conclusions of two case studies regarding sustainable management of eroding mangrove-dominated muddy coasts in Vam Ray, Hon Dat district, Kien Giang Province, Vietnam. The framework does not stop with the creation of integrated knowledge, but should undergo a longer process. The new knowledge developed in this framework is the understanding gained and lessons learnt during the testing of products of multiple knowledge systems in a local context rather than products of integrated knowledge systems themselves. The Vam Ray framework promotes a high level of participation, effective use of products of multiple knowledge systems, maximum integration of local and scientific knowledge, local ownership, and sustainability. Therefore, the Vam Ray framework adds a new dimension to the literature in relation to integration of local and scientific knowledge in natural resource management.     

Nitrogen nutrition in cotton and control strategies for greenhouse gas emissions: a review

Cotton (Gossypium hirustum L.) is grown globally as a major source of natural fiber. Nitrogen (N) management is cumbersome in cotton production systems; it has more impacts on yield, maturity, and lint quality of a cotton crop than other primary plant nutrient. Application and production of N fertilizers consume large amounts of energy, and excess application can cause environmental concerns, i.e., nitrate in ground water, and the production of nitrous oxide a highly potent greenhouse gas (GHG) to the atmosphere, which is a global concern. Therefore, improving nitrogen use efficiency (NUE) of cotton plant is critical in this context. Slow-release fertilizers (e.g., polymer-coated urea) have the potential to increase cotton yield and reduce environmental pollution due to more efficient use of nutrients. Limited literature is available on the mitigation of GHG emissions for cotton production. Therefore, this review focuses on the role of N fertilization, in cotton growth and GHG emission management strategies, and will assess, justify, and organize the researchable priorities. Nitrate and ammonium nitrogen are essential nutrients for successful crop production. Ammonia (NH₃) is a central intermediate in plant N metabolism. NH₃ is assimilated in cotton by the mediation of glutamine synthetase, glutamine (z-) oxoglutarate amino-transferase enzyme systems in two steps: the first step requires adenosine triphosphate (ATP) to add NH₃ to glutamate to form glutamine (Gln), and the second step transfers the NH₃ from glutamine (Gln) to α-ketoglutarate to form two glutamates. Once NH₃ has been incorporated into glutamate, it can be transferred to other carbon skeletons by various transaminases to form additional amino acids. The glutamate and glutamine formed can rapidly be used for the synthesis of low-molecular-weight organic N compounds (LMWONCs) such as amides, amino acids, ureides, amines, and peptides that are further synthesized into high-molecular-weight organic N compounds (HMWONCs) such as proteins and nucleic acids.     

Macroinvertebrate community in relation to water quality and riparian land use in a substropical mountain stream,China

Exploring how water quality and land use shape the benthic macroinvertebrate community composition is of widespread interest in biodiversity conservation and environmental management. In this study, we investigated the structures of benthic macroinvertebrate assemblages and their environmental controls in terms of water quality and riparian land use in the Jinshui River, China. We carried out three campaigns including wet season (August 2009), dry season (November 2009), and normal season (April 2010) based on the hydrological regime in Jinshui basin. The result showed that macroinvertebrate assemblage variations were better explained by water quality factors than land use based on variance partitioning procedure. The land use of 2 km upstream from the sampling sites had explained more variation than that of the whole riparian zone in upstream catchment on macroinvertebrate community, and land use of 2 km upstream also had more interactions with water quality. Canonical correspondence analysis (CCA) indicated that the elements or nutrient of magnesium (Mn), selenium (Se), strontium (Sr), silicon (Si), dissolved inorganic nitrogen (DN), sulfur (S), total organic carbon (TOC), and total nitrogen (TN) in water exhibited a strong relationship with macroinvertebrate assemblages. However, the variance in water quality explained by land use was lower than that explained by water quality in rivers using redundancy analysis. Our study suggested that proximate factors (i.e., water quality) were more important to interpret the macroinvertebrate community compared to ultimate factors (i.e., land use) for macroinvertebrate assemblages in river system.     

湘南4个矿区稻田As污染状况的初步调查

通过实地调查以及土壤和水稻样品分析,研究了湘南郴州柿竹园铅锌矿、郴州界牌岭锡多金属矿、衡阳水口山有色金属矿、衡阳龙王山金矿4个矿区稻田的As污染状况.结果表明:4个矿区的稻田土壤和水稻植株均已受到严重的As污染.矿区稻田土壤As含量范围为30.0～225.7mg·kg-1,超过国家土壤环境质量3级标准;水稻根系、秸秆、谷壳、糙米As含量范围分别为115.6～588.2、4.19～20.88、1.388～5.374、0.214～0.892mg·kg-1,除部分糙米样品外,均超过我国食品中As限量卫生标准.矿区稻田土壤同时受到As和重金属的复合污染,综合污染指数(P)范围为0.76～13.12.矿区稻田的As污染主要由矿产的开采和冶炼造成,其中,水口山有色金属矿区和龙王山金矿区As污染以及As和重金属复合污染最为严重,柿竹园铅锌矿区污染面积较大,界牌岭锡多金属矿区由于发生过地质灾害改变了地表面貌,污染情况更为复杂.     

广西山口红树林生态自然保护区海域沉积物重金属污染状况及潜在生态风险评价

为了解山口红树林生态自然保护区海域沉积物重金属的污染特征,于2018年1-8月采集表层沉积物,分析了沉积物中Cu、Zn、Pb、Cd、Cr、Hg、As的含量。采用单因子污染指数评价法和潜在生态风险指数法进行重金属污染现状和生态风险评价。根据《海洋沉积物质量》GB18668-2002一类标准评价结果,干季、湿季超标的环境因子均为油类、有机碳、硫化物,其余环境因子均小于1,有较大的环境容量。根据潜在生态风险评价结果,干季、湿季各站位重金属综合潜在生态风险指数均小于150,沉积物重金属的潜在生态风险程度较轻,属于低风险范畴。