ISOLATING THE RANDOM RAMSTORM COMPONENT FROM BASIN RESPONSE FACTORS IN RAINFALLRUNOFF DATA1

ABSTRACT: Gaged watersheds can provide information as to geomorphic, and geologic influence on the spatial variability of rainfall-runoff relationships. However, correlations between raingages distributed throughout the basin, and stream discharge are influenced by both storm patterns and drainage basin characteristics. Factor analysis has been applied to rainfall-runoff relationship to isolate the storm pattern from a basin response factor. Comparing two periods of time separated by eight years reveals relative stability in the rainfall attenuation (basin response) factor, while storm patterns for the two periods of record are quite disparate.     

An evaluation of selenium concentrations in water, sediment, invertebrates, and fish from the Solomon River Basin

The Solomon River Basin is located in north-central Kansas in an area underlain by marine geologic shales. Selenium is an indigenous constituent of these shales and is readily leached into the surrounding groundwater. Portions of the Basin are irrigated primarily through the pumping of selenium-contaminated groundwater from wells onto fields in agricultural production. Water, sediment, macroinvertebrates, and fish were collected from various sites in the Basin in 1998 and analyzed for selenium. Selenium concentrations were analyzed spatially and temporally and compared to reported selenium toxic effect thresholds for specific ecosystem components: water, sediments, food-chain organisms, and wholebody fish. A selenium aquatic hazard assessment for the Basin was determined based on protocol established by Lemly. Throughout the Basin, water, macroinvertebrate, and whole fish samples exceeded levels suspected of causing reproductive impairment in fish. Population structures of several fish species implied that successful reproduction was occurring; however, the influence of immigration of fish from low-selenium habitats could not be discounted. Site-specific fish reproduction studies are needed to determine the true impact of selenium on fishery resources in the Basin. The U.S. Government’s right to retain a non-exclusive, royalty free license in and to any copyright is acknowledged.     

环境准入门槛设置与指标体系构建实证

根据统筹协调、生态优先、地域差异、管理可行性等原则,从前置性和控制性两个方面,选取包括时序、空间、容量、投资规模、排放总量与强度以及资源、能源消耗标准等要素指标,建立环境准入指标体系;并以江苏省为例,根据指标门槛设置的标准和依据,进行指标门槛的定量测算。初步得到:重点企业最低投资准入、重点区域和重点污染行业环境准入指标测算值,以期为政策制定者提供可资借鉴的依据。     

Odor Control for Land Application of Lime Stabilized Biosolids

Over three million dry metric tons of biosolids produced in the United States are land applied as Class B. Lime stabilization is employed for biosolids treatment at approximately 20% of the wastewater treatment plants because it is a simple and inexpensive process. During lime stabilization, the pH of sewage sludge is raised above 12 for pathogen inactivation and odor reduction. Lime dose and mixing have been found to greatly reduce odor generation from lime stabilized biosolids. A better quality biosolids product is less likely to create public opposition to land application programs. In this study, land application tests using Class B biosolids were conducted in order to determine whether better mixing can reduce odor generation during the land application of lime stabilized biosolids. The mixing quality of a treatment plant’s lime stabilized biosolids was improved by relocating the lime addition point, which prolonged the mixing time and produced a better mixed biosolids product. Based on field observations of land application, the poorly mixed biosolids were more odorous and offensive prior to incorporation. However, once incorporated into the soil, there was no appreciable odor difference between the biosolids. Another land application study was conducted to assess the odor of unincorporated Class A biosolids and compare it with incorporated Class A biosolids with the soil.     

川藏铁路四川段沿线诱发地质灾害降水阈值研究

利用2009—2019年川藏铁路沿线四川段地质灾害数据、国家气象中心逐小时降水量资料,统计了地质灾害与降水的关系,发现研究区89%的滑坡灾害和96.6%的泥石流均发生在汛期,且地质灾害高发路段位于青衣江暴雨区,与四川地区降水时空分布特征相吻合。分析雨型、降雨强度、前期降雨等因子对地质灾害的影响,发现快速激发,中速激发和慢速激发的地质灾害分别约占33.3%、25.9%、40.8%,表明降雨历时并不是影响地质灾害发生的最直接因子,前期降雨的作用不可忽视;结合环境因子对地质灾害进行了分区,基于降雨历时-雨强(I-D)预报模型建立了川藏铁路沿线四川段引发地质灾害的降水阈值分布。利用该降水阈值的分布特征,检验了2019年引发地质灾害的降水量,发现阈值雨量的判别方法较为科学,具有较强的参考价值。     

四溴双酚A和镉复合污染对不同生物体的安全阈值

以赤子爱胜蚓（Eisenia fetida）、斑马鱼（Zebrafish）作为受试生物,进行急性毒性试验,死亡率、超氧化物歧化酶（SOD）、过氧化氢酶（CAT）为效应指标,采用基准剂量（BMD）法推导四溴双酚A （TBBPA）和镉（Cd）单一及联合暴露对不同生物体的安全阈值.结果表明,在本研究的试验剂量范围内,蚯蚓、斑马鱼TBBPA、Cd暴露剂量与死亡率、SOD、CAT活性效应指标存在明显剂量-效应关系.单一暴露下,CAT、SOD活性指标最敏感,蚯蚓和斑马鱼的TBBPA安全阈值分别为0.95,0.44mg/L,Cd安全阈值分别为71.17,0.42mg/L.联合暴露下安全阈值小于单一暴露.蚯蚓、斑马鱼TBBPA安全阈值分别为0.33,0.024mg/L,Cd为6.45,0.176mg/L.     

淮北市煤炭开采对生态系统服务胁迫阈值研究

为揭示煤炭资源型城市煤炭开采对生态系统服务胁迫作用的阈值效应,在构建煤炭开采对生态系统服务胁迫阈值模型的基础上,从土地破坏、地下水资源破坏、大气污染3个维度分析估算了淮北市煤炭开采对生态系统服务的胁迫阈值,并探究了1990~2016年该地区煤炭开采对生态系统服务胁迫作用时序变化规律.结果表明：淮北市煤炭开采对生态系统服务的胁迫作用存在显著的阈值效应,其中,土地破坏、地下水资源破坏、大气污染3大胁迫因子的胁迫阈值分别为1803.19hm²、33253.23×10⁴t和888.81×10⁸m³.1990~2016年淮北市煤炭开采对生态系统服务胁迫作用呈现显著的阶段性特征,其中,1990~2009年该地区煤炭开采所造成的土地破坏、地下水资源破坏、大气污染均未超过阈值范围,生态系统服务运行状况良好;但是在2010年之后,由于该地区煤炭开采造成的地下水资源破坏超出阈值范围,从而导致该地区生态系统服务出现恶化趋势,不过2015年以来恶化趋势有所减缓.因此,该地区必须加快绿色矿区建设,加大生态环境治理力度,着力防范煤炭开采对生态系统服务的胁迫作用超出阈值范围,以保障经济增长与生态环境统筹协调可持续发展.     

基于成本收益理论的宅基地自愿有偿退出有效阈值——以改革试点区宜城市为例

宅基地退出是有效缓解城乡建设用地之间的矛盾、促进乡村振兴的重要手段。在梳理宅基地有偿退出路径的基础上构建宅基地价值补偿体系,按照政府能承受、农户能接受、工作可持续的原则,基于成本收益理论科学测定在不同模式下宅基地自愿有偿退出的有效阈值。结果表明：（1）宅基地退出补偿阈值是农户能接受的最小值和政府能承受的最大值所组成的补偿范围。（2）农户退出宅基地损失的机会成本和退出总成本之和小于最小阈值时农户愿意有偿退出,最大阈值低于宅基地、地上附属设施权利价值和退出总成本之和。（3）“异地改造”模式下,政府处于主导地位,资金来源较少,实际补偿金额接近最小阈值。“一户多宅”模式下,政府和农户诉求相当,补偿金额偏向中位数。“整体搬迁”和“社区化”模式下,农户处于主导地位,政府补偿资金来源较多,实际补偿金额趋向最大阈值。     

Development of a model to simulate soil heavy metals lateral migration quantity based on SWAT in Huanjiang watershed, China

Lateral transportation of soil heavy metals in rainfall events could significantly increase the scope of pollution. Therefore, it is necessary to develop a model with high accuracy to simulate the migration quantity of heavy metals. A model for heavy metal migration simulation was developed based on the SWAT(Soil and Water Assessment Tool) model. This model took into consideration the influence of soil p H value, soil particle size, runoff volume, sediment amount,concentration of water-soluble heavy metals dissolved in runoff and insoluble absorbed to the soil particles. This model was reasonable in Huanjiang watershed, Guangxi Zhuang Autonomous Region, south China, covering an area of 273 km~2. The optimal drainage area threshold was determined by analyzing the effects of watershed subdivision on the simulation results to ensure the simulation accuracy. The main conclusions of this paper were:(1) watershed subdivision could affect simulation migration quantity of heavy metals;(2) the quantity of heavy metals transported by sediment accounted for 97%–99% of the total migration quantity in the study watershed. Therefore, sediment played the most important role in heavy metal migration;(3) the optimal drainage area threshold percentage to ensure high simulation accuracy was determined to be 2.01% of the total watershed;(4) with the optimal threshold percentage, this model could simulate the migration quantity of As, Pb and Cd accurately at the total watershed and subwatershed level. The results of this paper were useful for identifying the key regions with heavy metal migration.     

中国典型城市PM2.5浓度时空演绎规律及影响因素分析

为探讨空气中ρ（PM_2.5）的空间集聚特征和气候、大气成分变量对空气中ρ（PM_2.5）的影响,利用首批纳入PM_2.5监测的74个城市的ρ（PM_2.5）数据计算Moran's I指数,并选取其中38个典型城市进行计量分析.在基于引力模型的空间权重矩阵基础上,构建面板数据SDM（空间面板杜宾模型）.结果表明:ρ（PM₁₀）、ρ（SO₂）、ρ（CO）、ρ（O₃）、RH（relative humidity,相对湿度）与城市ρ（PM_2.5）呈正相关,而T（temperature,温度）和WS（wind speed,风速）与城市ρ（PM_2.5）呈负相关;ρ（PM₁₀）、ρ（CO）、RH是位于前3位影响城市ρ（PM_2.5）的关键性因素,其总效应分别为0.720 1、0.241 7、0.133 9.地理上邻近城市ρ（PM_2.5）具有明显的外部空间溢出效应,即邻近城市ρ（PM_2.5）每增加10百分点,将导致该地区ρ（PM_2.5）增长6.12百分点.300 km左右是保证PM_2.5区域"联防联控"最佳效果的最大门槛距离,超过该门槛距离,区域"联防联控"的力度和效果会随着距离的增加而逐渐减弱;当门槛距离大于500 km时,ρ（PM_2.5）的空间自相关性不显著.气候变量中,RH和ρ（PM_2.5）呈同方向变化,而T、WS与ρ（PM_2.5）呈反方向变化.研究显示,关注单一地区或单一因素（气候或大气成分）均不能有效控制PM_2.5污染,在保持经济稳定增长的前提下,各地治理PM_2.5应从调整产业结构、优化能源结构、完善防控机制等多个维度共同推进,促使经济增长方式早日从"粗放型"向"集约型"转变.