Cytogenetic status of human lymphocytes after exposure to low concentrations of p,p'-DDT, and its metabolites (p,p'-DDE, and p,p'-DDD) in vitro

Despite that the use of DDT has been restricted for more than 40 years to malaria affected areas, low doses of this pesticide and its metabolites DDE and DDD can be found in the environment around the world. Although it has been shown that these pollutants induce cell and DNA damage, the mechanisms of their cytogenotoxic activity remains largely unknown. This study looks into their possible genotoxic effects, at doses that can be found in body fluids, on human lymphocytes using the cytokinesis-block micronucleus assay and the comet assay. After exposure for 1, 6, and 24 h compounds p,p′-DDT (0.1 μg mL⁻¹), p,p′-DDE (4.1 μg mL⁻¹), and p,p′-DDD (3.9 μg mL⁻¹) showed increase in DNA damage. The most significant results were observed at exposure period of 24 h where number of micronucleated cells increased from control 2.5 ± 0.71 to 23.5 ± 3.54, 13.5 ± 0.71, and 16.5 ± 6.36 for DDT, DDE, and DDD, respectively. Similar effect was observed using comet test where the percentage of DNA in comets tail increased from control 1.81 ± 0.16 to 17.24 ± 0.55, 11.21 ± 0.56 and 9.28 ± 0.50 for each compound, respectively. At the same time Fpg-comet assay failed to report induction of oxidative DNA damage of these pollutants. Additionally, the type of cell death was determined using diffusion assay and necrosis dominated. Our findings suggest that even at low concentrations, these pesticides could induce cytogenetic damage to human peripheral blood lymphocytes and in that manner have the impact on human health as well.     

非诉讼方式在解决水污染纠纷中的法律效果

水污染纠纷的解决方法可以分为诉讼方式、非诉讼方式。在水污染纠纷解决方法的实际法律运行过程,却出现了非诉讼方式发达而诉讼方式非常乏力的奇特现象。这一现象的成因有四个:政治原因、经济原因、文化原因、法律机构原因。     

Water rights and legal pluralism: four contexts for negotiation

Increasing water scarcity is increasing pressure on water management institutions, particularly in the area of water rights. A common response is to formalise water tenure, one of several options for securing access and resolving conflicts concerning water allocation. This article looks at four contexts where negotiation, self-governance and concepts of legal pluralism may help improve water resource management. Existing users and potential new users need to negotiate before water resources are developed. Users can participate in forums with authority to solve basin management problems through self-governance. Negotiated water transfers offer an alternative to water acquisition by expropriation.     

广东省高分辨率温室气体排放清单及特征

根据典型城市调查与统计数据收集得到的广东省活动水平数据,采用自上而下和自下而上相结合的排放因子法和GIS技术,建立了广东省2018年3 km×3 km高分辨率温室气体排放清单.估算范围包括能源活动、工业生产过程、农业活动、土地利用变化和林业、废弃物处理以及电力调入（出）间接排放等6大类CO₂、CH₄和N₂O这3种温室气体.结果表明,广东省2018年CO₂、CH₄和N₂O的排放量分别为8.5×10⁸、1.9×10⁶和1.1×10⁵ t,以CO₂当量计分别为8.5×10⁸、4.0×10⁷和3.4×10⁷ t,合计9.2×10⁸ t.CO₂是广东省主要的温室气体排放种类,占全省温室气体总排放量的92.0%,能源活动和电力调入（出）间接排放是广东省温室气体排放的主要部门,排放占比分别为77.9%和7.6%,合计占比为85.5%.从温室气体排放的空间分布情况来看,全省大部分地区温室气体表现为排放源,部分区域表现为汇;温室气体排放主要集中在珠三角地区,并呈现一定的沿路网和航道分布的特征;温室气体高排放网格主要为大型电厂、钢铁厂和水泥厂等高耗能企业所在地.     

Contagious cooperation,temptation, and ecosystem collapse

Real world observations suggest that social norms of cooperation can be effective in overcoming social dilemmas such as the joint management of a common pool resource—but also that they can be subject to slow erosion and sudden collapse. We show that these patterns of erosion and collapse emerge endogenously in a model of a closed community harvesting a renewable natural resource in which individual agents face the temptation to overexploit the resource, while a cooperative harvesting norm spreads through the community via interpersonal relations. We analyze under what circumstances small changes in key parameters (including the size of the community, and the rate of technological progress) trigger catastrophic transitions from relatively high levels of cooperation to widespread norm violation—causing the social–ecological system to collapse.     

Resource use conflicts in Usangu Plains,Mbarali District,Tanzania

Conflicts over natural resources such as land, water, and forests are ubiquitous. People everywhere have competed for natural resources to enhance their livelihoods. However, the dimensions, level and intensity of conflict vary greatly from one place to another. This study was conducted in Usangu plains, Mbarali district, Tanzania, to investigate resource use conflicts and their underlying causes. Participatory Rural Appraisal (PRA) and household survey using a structured questionnaire were the major tools for data collection. Participant observation and secondary data sources were also used to supplement information. The study revealed the existence of resource use conflicts in the area. About 50% of respondents argued that relationships between the various ethnic groups in Usangu plains were bad. Conflicts were centred on competition for water and land. Crop damage was ranked highest (25% of respondents) as a cause behind many conflicts in the area. The study recommends that the government should redefine land tenure and land rights, enhance crop-livestock linkages and carry out a stakeholder analysis in the Usangu plains.     

关于自然资源核算的研究进展与争议问题

十八届三中全会提出要探索编制自然资源资产负债表,对领导干部实行自然资源资产离任审计.自然资源核算是编制自然资源资产负债表的首要工作,为了促进生态文明建设,建立我国自然资源资产负债表制度,也需要对自然资源进行科学的核算.论文从核算项目分类,理论方法和实践应用三个方面综述了国内外自然资源核算的研究进展,力图厘清国内外自然资源核算研究的共识与争议问题.西方国家资源核算研究起步较早,在理论方法和实际应用方面已取得了丰富的成果.与之相比,我国的研究还主要集中在理论分析层面,自然资源的核算方法多是沿用国外的估价模型,缺乏创新.目前,国内外普遍按照先实物量再价值量,先存量再流量,先分类再综合的原则进行自然资源核算研究.但是,各国的核心项目分类尚未统一,自然资源估价方法的选择还存在争议.在实践方面,联合国等五大机构联合发布的SEEA受到世界各国的广泛追捧,很多国家开始在此基础上探索本国的资源核算体系.通过比较分析国内外的研究进展和共识问题,论文提出了我国自然资源资产负债表编制需要解决的问题,包括确定核算项目,选择估价方法,分步推进自然资源核算和自然资源核算与自然资源资产负债表的衔接.这些问题的解决思路主要从四个方面展开:选择可控或拥有的,产权明晰的自然资源作为核算项目,充分考虑资源要素的经济,生态和社会价值选择估价方法,优先建立单项资源的区域自然资源核算体系,结合各方力量设计我国统一的自然资源核算标准.根据上述思路,开展自然资源核算研究,将资源环境核算纳入国民经济核算,构建自然资源核算框架体系,是编制我国自然资源资产负债表的一项重要内容,对顺利开展生态文明建设具有重要意义.     

Estimating the critical phosphorus loading of shallow lakes with the ecosystem model PCLake: Sensitivity, calibration and uncertainty

There is a vast body of knowledge that eutrophication of lakes may cause algal blooms. Among lakes, shallow lakes are peculiar systems in that they typically can be in one of two contrasting (equilibrium) states that are self-stabilizing: a ‘clear’ state with submerged macrophytes or a ‘turbid’ state dominated by phytoplankton. Eutrophication may cause a switch from the clear to the turbid state, if the P loading exceeds a critical value. The ecological processes governing this switch are covered by the ecosystem model PCLake, a dynamic model of nutrient cycling and the biota in shallow lakes. Here we present an extensive analysis of the model, using a three-step procedure. (1) A sensitivity analysis revealed the key parameters for the model output. (2) These parameters were calibrated on the combined data on total phosphorus, chlorophyll-a, macrophytes cover and Secchi depth in over 40 lakes. This was done by a Bayesian procedure, giving a weight to each parameter setting based on its likelihood. (3) These weights were used for an uncertainty analysis, applied to the switchpoints (critical phosphorus loading levels) calculated by the model. The model was most sensitive to changes in water depth, P and N loading, retention time and lake size as external input factors, and to zooplankton growth rate, settling rates and maximum growth rates of phytoplankton and macrophytes as process parameters. The results for the ‘best run’ showed an acceptable agreement between model and data and classified nearly all lakes to which the model was applied correctly as either ‘clear’ (macrophyte-dominated) or ‘turbid’ (phytoplankton-dominated). The critical loading levels for a standard lake showed about a factor two uncertainty due to the variation in the posterior parameter distribution. This study calculates in one coherent analysis uncertainties in critical phosphorus loading, a parameter that is of great importance to water quality managers.     

城市大气环境监测优化布点模糊优选模型及应用实例

文章根据城市大气环境监测优化布点的模糊性,提出了一种模糊环境条件下的模糊聚类与模糊识别理论模型,并且在山东省肥城等市成功应用。结合统计方法确定出的大气监测优化点位,不但具有代表性和整体性,而且具有较高的分辨率,能快速准确地、最大范围地反映出该区域的环境空气质量状况、大气污染扩散规律、污染源分布特点、污染气象及地理位置特征,为环境管理和政府决策提供可靠依据。