时空效应下PM2.5的环境库兹涅茨曲线——基于动态空间面板视角

经济发展与环境保护的平衡一直是人们关心的话题,为分析空气质量水平与经济发展程度之间的关系,即环境库兹涅茨曲线,本研究利用2013—2017年中国省级PM_(2.5)污染数据,运用动态空间面板数据模型,从而控制相邻省份的空气质量水平与本地上期污染水平,实证分析中国PM_(2.5)环境库兹涅茨曲线的存在性及空间溢出性.结果表明:①PM_(2.5)的环境库兹涅茨曲线在省级基础上表现为倒U形,即随着初期经济水平的发展,大气污染会不断增加,在经济发展到一定水平后,大气污染开始降低;②东部、中部省份的空气污染表现与全国一致,而西部省份尚无显著趋势,只有第一产业产量与空气污染水平呈负相关;③中国整体的PM_(2.5)污染具有显著的空间溢出性;④对二氧化硫和氮氧化物进行环境库兹涅茨曲线研究,发现全国平均而言还处在大气污染的上升阶段.研究表明,中国各地区处在大气污染发展路径的不同阶段上,而且空气污染的治理模式应采取区域联合分块治理的策略.     

农业排水沟渠硝态氮吸收动力学特征及相关性分析

为揭示农业排水沟渠NO_3~--N吸收动态变化特征,选择溴化钠(Na Br)为保守示踪剂、硝酸钾(KNO3)为添加营养盐,于2016年10月至2017年4月在合肥地区某一源头溪流开展5次示踪试验,并以TASCC方法和Michaelis-Menten(M-M)方程模拟NO_3~--N吸收动力学特征,结果表明,背景浓度条件下排水沟渠完全混合子渠段U_(amb)和V_(f-amb)的变化范围分别为11.40~69.13μg·(m~2·s)~(-1)[均值为34.45μg·(m~2·s)-1]、0.07~0.43 mm·s~(-1)(均值为0.24 mm·s~(-1)),相应地Sw-amb变化范围为92.51~405.74 m(均值为199.06 m),明显小于排水沟渠长度(也就是2.5 km),表明沟渠具有较强的NO_3~--N滞留潜力.M-M方程较好地拟合了NO_3~--N吸收动力学特征,参数Umax变化范围为158~1 280μg·(m~2·s)~(-1)[均值为631.13μg·(m~2·s)~(-1)],Km变化范围为0.16~5.52 mg·L~(-1)(均值为1.46 mg·L~(-1)).相关分析表明,Sw-amb与NO_3~--Namb呈显著负相关、Uamb与NO_3~--Namb呈极显著正相关,其它螺旋指标与NO_3~--N背景浓度的相关性均不明显;水文因素对NO_3~--N滞留影响也不显著,而沟渠槽道地貌特征指标Фw、ФA与大部分螺旋指标都呈显著相关性,表明槽道地貌特征对NO_3~--N滞留影响相对较为重要.     

钢渣固定床对水中Pb(Ⅱ)和Cd(Ⅱ)的吸附研究

采用钢渣吸附剂分别对Pr(Ⅱ)和Cd(Ⅱ)进行固定床吸附实验,考察了不同运行参数如进水流速、进水初始浓度和吸附柱高度对动态吸附过程的影响,并应用Thomas模型对在不同条件下得到的穿透曲线进行拟合。实验结果表明进水流速、进水初始浓度和吸附柱高度对动态吸附过程存在影响,穿透时间随床层高度的增加而增加,但是随进水流速和进水初始浓度的增加而减少。Thomas方程穿透曲线拟合效果较好,相关系数R2值均在0.9以上,运用该方程可准确预测吸附柱的操作参数。     

建筑业碳排放与经济增长脱钩及影响因素研究——以陕西省为例

为研究建筑业碳排放与经济增长之间的关系及影响其弹性脱钩的主要因素,建立了建筑业碳排放库兹涅茨曲线和弹性脱钩模型,并以陕西省为例进行了实证研究。结果表明:该地区建筑业碳排放库兹涅茨曲线近年来呈"N"形上升趋势,尚未到达拐点;产业节能和产业减排弹性脱钩是实现碳排放与经济发展脱钩的主要影响因素。     

中国东中西部经济带的水环境库兹涅茨假说实证及其影响因素研究

“八五”至“十二五”期间,中国取得巨大的经济成果的同时带来了严重的水环境污染问题.文章分析了东中西部三大经济带经济发展及COD和氨氮两种主要水污染排放的差异,及其与经济发展的关系进行了EKC假说的实证研究.研究结果表明,部分污染物的拟合曲线尚处于上升阶段,未能出现典型的倒U型曲线,可能导致水环境质量恶化.环境基础设施建设、人口分布和产业结构等因素与COD和氨氮的排放量密切相关,因此,中国必须采取各种环境管理和技术手段,促使区域水污染物排放量指标与经济发展的拟合曲线出现转折点,改善水环境质量.     

Investigation of the Curve Number Method For Surface Runoff Estimation In Tropical Regions

This study tests the applicability of the curve number (CN) method within the Soil and Water Assessment Tool (SWAT) to estimate surface runoff at the watershed scale in tropical regions. To do this, surface runoff simulated using the CN method was compared with observed runoff in numerous rainfall‐runoff events in three small tropical watersheds located in the Upper Blue Nile basin, Ethiopia. The CN method generally performed well in simulating surface runoff in the studied watersheds (Nash‐Sutcliff efficiency [NSE] > 0.7; percent bias [PBIAS] < 32%). Moreover, there was no difference in the performance of the CN method in simulating surface runoff under low and high antecedent rainfall (PBIAS for both antecedent conditions: ~30%; modified NSE: ~0.4). It was also found that the method accurately estimated surface runoff at high rainfall intensity (e.g., PBIAS < 15%); however, at low rainfall intensity, the CN method repeatedly underestimated surface runoff (e.g., PBIAS > 60%). This was possibly due to low infiltrability and valley bottom saturated areas typical of many tropical soils, indicating that there is scope for further improvements in the parameterization/representation of tropical soils in the CN method for runoff estimation, to capture low rainfall‐intensity events. In this study the retention parameter was linked to the soil moisture content, which seems to be an appropriate approach to account for antecedent wetness conditions in the tropics.     

Low dose effects and non-monotonic dose responses for endocrine active chemicals: Science to practice workshop: Workshop summary

A workshop was held in Berlin September 12–14th 2012 to assess the state of the science of the data supporting low dose effects and non-monotonic dose responses (“low dose hypothesis”) for chemicals with endocrine activity (endocrine disrupting chemicals or EDCs). This workshop consisted of lectures to present the current state of the science of EDC action and also the risk assessment process. These lectures were followed by breakout sessions to integrate scientists from various backgrounds to discuss in an open and unbiased manner the data supporting the “low dose hypothesis”. While no consensus was reached the robust discussions were helpful to inform both basic scientists and risk assessors on all the issues. There were a number of important ideas developed to help continue the discussion and improve communication over the next few years.     

旅游资源竞争力与旅游收入关系实证分析——以安徽省17地市为例

在构建旅游资源竞争力评价指标体系的基础上，运用位序得分法对安徽省17个地市的旅游资源竞争力进行了评价，同时借助两轴折线图、散点图及拟合曲线等工具对17个地市旅游资源竞争力与旅游收入关系进行了实证分析。结果表明，安徽省绝大多数地市旅游业发展仍依赖于旅游资源；少数地市旅游资源竞争力与旅游收入出现偏离，成为非旅游资源依赖性城市。从资源属性来看，综合类旅游资源与旅游收入的相关性最大，其次为自然类旅游资源，人文类的相关性最小。     

鄱阳湖典型洲滩湿地土壤质地与水分特征参数研究

频繁干湿交替增强了鄱阳湖洲滩土壤水对湿地系统的动态调节作用。以鄱阳湖吴城国家自然保护区的一个典型洲滩湿地为研究区,调查分析了土壤质地沿高程梯度的分布特征,确定了不同土壤质地的水分特征参数,并阐述了土壤质地与其水分特征参数的空间异质性。结果发现:该洲滩湿地主要分布砂土、粉壤土和粘土三种类型。水平断面方向上,粒径较粗的砂土和粉壤土主要分布在高位滩地,而粒径相对较细的粘土主要分布在近湖区开阔水面的低位滩地;土壤剖面方向上,土壤质地呈现出固有分层特性。van Genuchten模型应用于鄱阳湖洲滩湿地土壤水分特征曲线拟合,证实了该模型在鄱阳湖洲滩湿地的适用性。模型结果表明土壤残余含水率θr变化约9%~19%,饱和含水率θs变化约42%~57%,土壤进气值的倒数α约0.01 cm~(–1),水分特征曲线形状参数n介于1.11~4.65之间。土壤含水率变化对van Genuchten模型中参数α和n较为敏感,而对θr和θs的敏感性相对较弱。研究成果可为后续该区域以及全湖区湿地生态水文模型的构建和发展提供背景信息和参数资料。     

Effect of culture time on the growth curve and power performance in a microbial fuel cell at a fixed amount of liquid culture

The microbial fuel cell uses the microorganism biochemistry to carry on the energy conversion. Concerning the experimental precision, the colony culture would be replaced by a fixed amount of liquid culture for Microbial fuel cell of Escherichia coli. The anode and cathode chambers whose each volume is 100 mL were utilized, the effective surface area of proton exchange membrane Nafion-117 is about 9 cm². In addition, the electrode area of carbon cloth is 20 cm². Three kinds of Escherichia coli, named as BCRC No. 10322, 10675 and 51534, respectively, would be selected. Results show that the electricity performance of Escherichia coli of BCRC No.51534 is better than the other microorganism studied because of having a larger open circuit voltage of 1.01 V and limiting current 22 mA, the maximum power density of 1342 mW/m^2, and average working power density of 295 mW/m² would be produced. These results would be useful to improve the performance of microbial fuel cell.