南京市典型地区大气多环芳烃污染特征及健康风险评价

采用气相色谱-质谱法,于2016年9月和12月对南京市2个典型地区大气中16种多环芳烃(PAHs)的质量浓度进行分析,并开展了PAHs组成特征、来源解析及人体健康风险评价研究。结果表明,工业区(六合区)和生活区(江宁区)大气(气态和可吸入颗粒态)中16种PAHs的质量浓度分别为914.82和712.27 ng/m~3,苯并[a]芘毒性等效浓度分别为274.1和309.84 ng/m~3,且呈现冬季高、秋季低的特征。比值法源解析结果表明,燃煤污染是六合区PAHs污染主要来源,而江宁区主要表现为交通污染。人体健康风险评价结果表明,六合区和江宁区人群通过大气吸入PAHs的超额致癌风险分别为5.17×10~(-5)和5.85×10~(-5),均略高于可接受水平10~(-6)。     

Potential energy production from organic waste and its environmental and economic impacts at a tertiary institution in Palestine

Municipal solid waste (MSW) is one of the most well-known biomass resources that can be utilized to produce renewable energy. Numerous countries are plagued by the proliferation of waste, particularly organic waste that can be utilized for energy recovery. Palestine suffers from inefficient solid waste management, and only recently have a few projects focused on bioenergy production been implemented. Throughout the years, the city of Tulkarm experiences power outages which cause a challenge to the Palestine Technical University-Kadoorie campus in Tulkarm. Thus, the possibility of energy recovery from the organic portion in Palestine Technical University-Kadoorie was evaluated. The analysis of an economic impact included discussions of a number of economic aspects, including Levelized cost of energy, internal rate of return, present worth, annual worth, and payback period. On the other hand, a carbon dioxide savings analysis and gas emission were evaluated. The outcomes of the energy optimization demonstrated that the suggested system could supply the institution with an average of roughly 7 MWh of electrical energy. According to the economic study, this project offers 0.25 million dollars in present value, 0.144 million dollars in annual value, a 13 percent internal rate of return, a payback period of 6 years, and a levelized cost of energy of 0.11 dollars for each kWh generated. Additionally, the environmental assessment revealed that this system might reduce CO₂ emissions by around 8,343,778 tons. For effective waste management, energy recovery, and emission reduction, it is advised to implement anaerobic digestion technology.     

Factors contributing to US chemical plant process safety incidents from 2010 to 2020

Process safety incidents can result in injuries, fatalities, environmental impacts, facility damage, downtime & lost production, as well as impacts on a company's and industry's reputation. This study is focused on an analysis of the most commonly reported contributing factors to process safety incidents in the US chemical manufacturing industry. The database for the study contained 79 incidents from 2010 to 2019, partly investigated by the Chemical Safety Board (CSB). To be included in the study, the CSB archive of incident investigations were parsed to include only incidents which occurred at a company classified as 325 in the North American Industry Classification System (NAICS), assigned to businesses that participate in chemical manufacturing. For each incident, all of the identified contributing factors were catalogued in the database. From this list of identified contributing factors, it was possible to name the ‘top three’ contributing factors. The top three contributing factors cited for the chemical manufacturing industry were found to be: design; preventive maintenance; and safeguards, controls & layers of protection. The relationship between these top contributing factors and the most common OSHA citations was investigated as well. The investigation and citation history for NAICS 325 companies in the Occupational Safety & Health Administration (OSHA) citations database was then analysed to assess whether there was any overlap between the top reported contributing factors to process safety events and the top OSHA citations recorded for the industry. A database consisting of the inspection and citation history for the chemical manufacturing industry identified by NAICS code 325 was assembled for inspections occurring between 2010 and 2020 (August). The analysis of the citation history for the chemical manufacturing industry specifically, identified that the list of the top contributing factors to process safety incidents overlapped with the most common OSHA violations. This finding is relevant to industry stakeholders who are considering how to strategically invest resources for achieving maximum benefit – reducing process safety risk and simultaneously improving OSHA citation history.     

利用矿化垃圾层预防和控制渗滤液导排系统堵塞

在卫生填埋场中,垃圾渗滤液导排系统堵塞普遍存在,悬浮固体形成的物理堵塞、有机物降解和金属离子沉淀导致的生物-化学堵塞是引起导排系统堵塞的关键因素.本文构建了"矿化垃圾+砾石层导排"的渗滤液下渗装置,通过矿化垃圾预处理渗滤液中悬浮固体和有机物以控制导排系统发生的物理和生物-化学堵塞.结果表明,在矿化垃圾层,渗滤液中化学需氧量(COD)和悬浮固体(SS)去除较多,去除率分别达到了85%和87%,并且Ca²⁺浓度也出现了波动较大的现象;然而,渗滤液在砾石层下渗过程中,其COD、SS和Ca²⁺浓度保持稳定.并且,砾石层可排水孔隙率在长期运行的过程中没有明显变化,表明渗滤液在砾石导排层没有形成明显的沉淀.与此同时,在没有添加矿化垃圾的对照组发现,砾石层可排水孔隙率减少最多的区段是渗滤液的进水点位(可排水孔隙率减少达到了53%),即渗滤液有机负荷最大处的饱和砾石层堵塞最为严重,其无机堵塞物主要是碳酸钙等.因此,在渗滤液流入砾石层前,采用矿化垃圾层部分饱和的方式对渗滤液中有机物和悬浮固体进行预处理,可以预防和控制渗滤液在砾石层形成沉淀堵塞.研究为填埋场的运行管理渗滤液导排系统堵塞提供了新的思路和方法.     

基于地理探测器的土壤重金属影响因子分析及其污染风险评价

地理探测器能快速定量化揭示驱动重金属含量影响因素的强度,这对于重金属空间预测模型构建变量的确定和土壤污染修复措施的精准实施具有重要意义。利用地理探测器模型,对5种土壤重金属元素Cu、Zn、Pb、Cr、Ni的空间分布和11种环境因子的交互作用进行定量评估,通过单因子指数法进行重庆市土壤重金属污染风险评价。结果表明:研究区内土壤Cu、Zn、Cr和Pb的平均含量是重庆市土壤背景值的1.3—1.4倍,Ni含量低于背景值;其中Cu、Pb达到重度污染水平,其余3种重金属为中度或轻度污染水平。5种重金属元素中Cu和Pb为高度变异(变异系数为0.57、0.4),Zn、Cr和Ni为中等变异(变异系数为0.22—0.29),且各重金属元素之间呈显著正相关性,表明研究区重金属富集受人为干扰影响较大,且污染具有复合性或同源性。地理探测器的因子探测发现高程、坡度和土壤类型对5种土壤重金属含量的解释力最显著,说明地势和土壤类型是土壤重金属含量分布差异的最主要影响因素。交互作用探测发现,高程与其他因子交互作用是重金属空间分异的主导因素,气候条件和土壤类型也是重要影响因子。土壤重金属空间分布是多种因素共同作用的结果,而高程、坡度和土壤类型具有较强的解释力,这些因子可作为土壤重金属含量空间预测模型的辅助变量,也可促进重金属污染治理措施的靶向实施。     

典型地区农用地污染调查及风险管控标准探讨

针对《土壤污染风险管控标准——农用地土壤污染风险管控标准》(GB 15618—2018),提出以土壤中全量浓度筛选值和管控值作为衡量农用地土壤污染风险管控的标准,对湖南省部分稻田农用地土壤及点对点稻米样品中镉、铅、砷、汞的总量和有效态浓度及稻米中含量进行监测,根据重金属总量浓度分为低风险、中风险、高风险3组。结果显示:(1)土壤及稻米中镉含量基本为随着风险级别的升高而增加,铅、砷在土壤和稻米中含量无规律性结果,汞监测结果均为未检出。(2)低风险组稻米镉超标率为12. 0%,高风险组稻米镉达标率为33. 3%,表明利用总量浓度对农用地土壤潜在风险进行分组存在一定的局限性。(3)依据4种重金属在土壤中总量及稻米(早稻)中含量情况,对风险级别进行调整并综合判断:有58个样品为低风险组,占样品总数的68. 2%,超标率为零;有15个样品为中风险组,占样品总数的17. 7%,超标率为80. 0%;有12个样品为高风险组,占样品总数的14. 1%,超标率为100. 0%。调整后评价结果与上述标准的划分目标更接近,能够提高上述标准的准确性和实用性。     

A framework for allocating conservation resources among multiple threats and actions

Land managers decide how to allocate resources among multiple threats that can be addressed through multiple possible actions. Additionally, these actions vary in feasibility, effectiveness, and cost. We sought to provide a way to optimize resource allocation to address multiple threats when multiple management options are available, including mutually exclusive options. Formulating the decision as a combinatorial optimization problem, our framework takes as inputs the expected impact and cost of each threat for each action (including do nothing) and for each overall budget identifies the optimal action to take for each threat. We compared the optimal solution to an easy to calculate greedy algorithm approximation and a variety of plausible ranking schemes. We applied the framework to management of multiple introduced plant species in Australian alpine areas. We developed a model of invasion to predict the expected impact in 50 years for each species-action combination that accounted for each species’ current invasion state (absent, localized, widespread); arrival probability; spread rate; impact, if present, of each species; and management effectiveness of each species-action combination. We found that the recommended action for a threat changed with budget; there was no single optimal management action for each species; and considering more than one candidate action can substantially increase the management plan's overall efficiency. The approximate solution (solution ranked by marginal cost-effectiveness) performed well when the budget matched the cost of the prioritized actions, indicating that this approach would be effective if the budget was set as part of the prioritization process. The ranking schemes varied in performance, and achieving a close to optimal solution was not guaranteed. Global sensitivity analysis revealed a threat's expected impact and, to a lesser extent, management effectiveness were the most influential parameters, emphasizing the need to focus research and monitoring efforts on their quantification.     

A proactive process risk assessment approach based on job hazard analysis and resilient engineering

Complex systems often experience a long period of incubation before accidents occur. Therefore, a proactive risk assessment is essential for process safety. The conventional job hazard analysis (JHA) method has been an effective tool to conduct a process risk assessment in the high-risk industrial field. However, the conventional JHA is inadequate for the proactive risk assessment since it is usually conducted during and before one specific operation process. Operations such as startup and maintenance are performed repeatedly on the lifecycle of a plant. Therefore, the risk reduction measures for the industrial process should include not only preventive actions obtained from the conventional JHA but also recovery ones. Resilience engineering (RE) has proven to be helpful for the recovery analysis of a complex system. The objective of this paper is to propose a proactive and comprehensive process risk assessment approach based on JHA and RE. The mechanism of applying RE to address operation process risk is illustrated. The integrated approach can provide guidelines to establish proactive risk reduction measures as well as maintain a low-risk level. Finally, a gas transmission startup process risk assessment case is presented to demonstrate its applicability.     

基于共词分析的城市生活垃圾治理公共政策变迁量化分析

以1979—2020年我国中央政府颁发的411份城市生活垃圾治理政策文本作为研究对象,运用共词与聚类分析方法研究了我国不同时期城市生活垃圾治理公共政策焦点的演变规律。结果发现:纵观我国城市生活垃圾治理公共政策焦点的演变轨迹,在"技术路线"、"垃圾属性"、"管理手段"、"治理结构"和"保障机制"方面发生了显著的政策主题变迁,呈现出垃圾治理朝更加绿色、更加经济方向发展的趋势。未来,应从监管体系、资源评估、财政补贴、空间布局4个方面保障生活垃圾零污染、高价值资源化治理。     

Factors influencing perceptions of aquatic ecosystems

While factors influencing perceptions of drinking water have been well studied, those of aquatic ecosystems have been to lesser extent. We conducted a review to improve awareness of these factors. Environmental factors found to influence public perceptions of aquatic ecosystems were presence/absence of water plants and algae, presence/absence of floating debris, the odor, movement (for flowing waters) and clarity/turbidity of the water, and the type, condition, setting, naturalness, and overall aesthetic appeal of the ecosystem. Sociocultural factors found to influence public perceptions of aquatic ecosystems included age, education, gender, and place-based knowledge. We provide perspectives of how managers can better meet the diverse social demands placed on aquatic ecosystems. The importance and benefits of considering these perspectives may be especially beneficial where significant multi-generational and culturally relevant place-based knowledge exist.