南水北调中线干渠生态系统结构与功能分析

为分析和掌握南水北调中线干渠生态系统结构与功能的特征参数,根据2015~2019年中线干渠鱼类资源调查数据及实测的鱼类生物学参数数据,应用Ecopath with Ecosim 6.6软件构建了Ecopath食物网模型.模型由18个功能组组成,包括了初级生产者、初级消费者、主要鱼类和有机碎屑等.结果显示：中线干渠生态系统规模总流量、总生产量和总消耗量分别为19186.330,8947.857和1106.002（t/（km²·a））,食物网主要由4个整合营养级（1.00~3.71）构成,最高营养级为大型肉食性鱼类鱤（3.71）.食物网能量传递主要有两条途径,分别为牧食食物链和碎屑食物链,两者传递的能量相当,但牧食食物链传递效率是碎屑食物链的近两倍.交互营养分析结果表明,捕食者对其饵料生物的影响一般为抑制作用,碎屑生物量的增加对大部分功能组的影响为正效应,小型上层鱼类对浮游动物生物量起抑制作用.从各功能组之间的生态位重叠来看,各功能组间捕食者生态位重叠现象不普遍,重叠指数适中,部分肉食性鱼类的捕食者生态位重叠指数达到1.对生态系统总体特征分析发现,中线干渠生态系统的总初级生产量与总呼吸量的比值（P/R）、总初级生产量与总生物量的比值（P/B）、Finn's循环指数（FCI）和Finn's平均路径长度（FML）都表明该生态系统处于发展的幼态期,抵抗外界干扰的能力差.此外,中线干渠生态系统对初级生产力的利用率很低,导致过多的营养物质未进入更高营养级的食物链中进行循环,造成系统能量流动的滞缓.因此,根据生物操纵理论,可通过优化和完善鱼类群落结构,增强对系统初级生产力的利用效率,促进物质循环和能量流动,维持生态系统稳定.     

基于关键种理论的孝义生态产业链的构建

文章在关键种概念的基础上,提出了关键产业的概念,总结了关键产业在生态工业园中发挥的作用和特点,并以关键种理论为指导,构建了以炼焦行业为关键产业的孝义生态产业链。     

垃圾分类对碳减排的影响分析：以青岛市为例

城市生活垃圾(MSW)处理单元是重要的温室气体排放源,垃圾分类可以实现垃圾减量化和提高资源化利用率,但对于温室气体减排的影响还鲜见报道.以青岛市内4区为研究对象,基于生命周期评价方法,研究了垃圾分类前后不同生活垃圾处置模式下的温室气体排放情况.结果表明,垃圾分类可以显著降低处置全过程中的温室气体排放,模式1(混合收集+填埋)、模式2(混合收集+焚烧)、模式3(垃圾分类+厨余垃圾厌氧消化和其他焚烧)和模式4(垃圾分类+厨余垃圾厌氧消化、可回收垃圾资源化和其他焚烧)垃圾处理全过程净碳排放量(以CO₂/MSW计)分别为686.39、-130.12、-61.88和-230.17 kg·t^-1.提高厨余垃圾回收效率并不能显著降低碳排放.随着垃圾回收效率的提高,碳减排量呈线性增加,可回收垃圾回收效率每提高10%,其净碳排放量降低26.6%(16.5 kg·t^-1).适度分离餐厨垃圾、提高可回收垃圾回收效率和降低厨余垃圾厌氧消化沼气泄漏率是目前减少生活垃圾温室气体排放和社会成本的可行策略.     

太湖地区某地农田土壤及农产品中重金属污染及风险评价

对江苏省太湖地区某冶炼厂周围的稻田、菜地土壤及水稻等17种农产品中的Pb、Cd、Hg、As、Cu、Zn、Ni、Cr、Se等9种重金属元素进行采样分析,参照<国家土壤环境质量二级标准>和<食品中重金属限量卫生标准>进行评价,同时,依据美国联邦环境保护署推荐的RfD值和我国居民平均食物消费结构评估了农产品对当地人群的重金属暴露风险.结果显示,供试稻田土和菜地土中的重金属Cd、Pb污染严重;农产品样品中Cd、Pb含量全部超过国家食品中重金属限量卫生标准,且Cd、Pb、As对人群的暴露风险系数甚高.17种农产品中,对重金属富集能力最强的是茼蒿、空心菜、菠菜等茎叶类蔬菜,它们不适宜在该地种植.研究表明,在局部范围内,点源污染可能带来土壤环境的重金属污染及农产品重金属食物安全问题.     

基于贝叶斯网络模型的船舶搁浅事故分析

根据海上交通安全事故统计数据显示,船舶搁浅事故是主要的海上交通安全事故之一。为了研究船舶搁浅事故的发生机理,收集了我国东部海域部分海事局辖区的船舶搁浅事故样本。首先从人为因素、环境因素和船舶因素三方面分析导致船舶搁浅事故的原因,确定网络节点。然后找出每起搁浅事故的事故链,并建立船舶搁浅事故贝叶斯网络模型。再对建立的贝叶斯网络模型进行仿真,选取21起船舶搁浅事故对建立的模型进行验证,确定模型的有效性。最后,利用HUGIN软件找出船舶搁浅事故各影响因素的致因概率,得到导致船舶搁浅事故的致因链。在人为因素方面,瞭望不当和不熟悉航道情况占据的比例最高;在船舶因素方面,舵机设备故障对船舶搁浅事故影响最大;在环境因素方面,风/浪/流对船舶搁浅事故影响最大。     

Performance of a hybrid anaerobic-contact oxidation biofilm baffled reactor for the treatment of decentralized molasses wastewater

A novel hybrid anaerobic-contact oxidation biofilm baffled reactor （HAOBR） was developed to simultaneously remove nitrogenous and carbonaceous organic pollutants from decentralized molasses wastewater in the study. The study was based on the inoculation of anaerobic granule sludge in anaerobic compartments and the installation of combination filler in aerobic compartments. The performance of reactor system was studied regarding the hydraulic retention time （HRT）, microbial characteristics and the gas water ratio （GWR）. When the HRT was 24h and the GWR was 20：1, total ammonia and chemical oxygen demand （COD） of the effluent were reduced by 99% and 91.8%, respectively. The reactor performed stably for treating decentralized molasses wastewater. The good performance of the reactor can be attributed to the high resistance of COD and hydraulic shock loads. In addition, the high solid retention time of contact oxidation biofilm contributed to stable performance of the reactor.     

多溴联苯醚在典型电子垃圾污染区域水生食物链上的生物富集特征

为调查电子垃圾回收活动对当地水生生物造成的多溴联苯醚(PBDEs)污染,测定了广东某电子垃圾回收地附近水库中水生生物样品(水蛇、鱼类、草虾和田螺)和对照区样品(鲮鱼)中18种PBDEs含量,通过对样品氮同位素的测定,探讨了PBDEs在该地淡水食物链上的生物富集特征.研究结果显示,∑PBDEs(总PBDEs含量)在水蛇、鱼类、草虾和田螺中分别为39.6～186、1.82～75.7、4.60～17.1和7.26～17.0μg·g-1(脂重),比华南地区鱼体中∑PBDEs的平均含量高3个数量级,表明电子垃圾回收活动已对当地水生生物造成了PBDEs的严重污染.除BDE66、BDE99、BDE153、BDE183和BDE209外,其他13种PBDE单体在食物链上均存在着生物放大效应,但生物放大能力(B值)与正辛醇-水分配系数logKOW相关性不明显,可能是由于某些PBDE单体在生物体内存在代谢作用.以上结果表明,由电子垃圾回收活动导致的PBDEs污染存在较大的生态风险,应该引起高度关注.     

生物水净化剂对养殖水质及饵料生物的影响

用生物水净化剂对投加无机肥和有机肥的养殖水体进行试验研究。结果表明,无论是投加无机肥或有机肥的养殖水体,生物水净化剂对其水质都有较强的净化作用。与对照组相比较,处理组NH3-N、叶绿素均有不同程度的降低,NH3-N最高降幅达到89.4%,COD得到有效控制,透明度显著增加。在有机肥实验中,生物水净化剂对藻类有明显的抑制作用,浓度越高,对藻类的抑制作用越明显。饵料生物方面,尽管生物水净化剂对大型浮游动物(轮虫和浮游甲壳动物)的直接影响不明显,但它对原生动物有明显的促进作用。因此,生物水净化剂在改善养殖水体水质方面有较高的应用价值。     

Effects of the 2008 flood on economic performance and food security in Yemen: a simulation analysis

Extreme weather events such as floods and droughts can have devastating consequences for individual well being and economic development, in particular in poor societies with limited availability of coping mechanisms. Combining a dynamic computable general equilibrium model of the Yemeni economy with a household‐level calorie consumption simulation model, this paper assesses the economy‐wide, agricultural and food security effects of the 2008 tropical storm and flash flood that hit the Hadramout and Al‐Mahrah governorates. The estimation results suggest that agricultural value added, farm household incomes and rural food security deteriorated long term in the flood‐affected areas. Due to economic spillover effects, significant income losses and increases in food insecurity also occurred in areas that were unaffected by flooding. This finding suggests that while most relief efforts are typically concentrated in directly affected areas, future efforts should also consider surrounding areas and indirectly affected people.     

A multi-echelon supply chain model for municipal solid waste management system

In this paper, a multi-echelon multi-period solid waste management system (MSWM) was developed by inoculating with multi-echelon supply chain. Waste managers, suppliers, industries and distributors could be engaged in joint strategic planning and operational execution. The principal of MSWM system is interactive planning of transportation and inventory for each organization in waste collection, delivery and disposal. An efficient inventory management plan for MSWM would lead to optimized productivity levels under available capacities (e.g., transportation and operational capacities). The applicability of the proposed system was illustrated by a case with three cities, one distribution and two waste disposal facilities. Solutions of the decision variable values under different significant levels indicate a consistent trend. With an increased significant level, the total generated waste would be decreased, and the total transported waste through distribution center to waste to energy and landfill would be decreased as well.