Establishment of permit limits for mill effluent

Various governmental regulatory agencies are responsible for establishing regulations on the discharge of chlorinated organic compounds from pulp and paper mills. The procedures for setting permit limits are the basic topic of this article. Different methods of determining permit limits are set forth and discussed in a number of references, including documents of the Environmental Protection Agency. This paper discusses in detail the application of one particular methodology—the lognormal model approach. In this paper we utilize a real data set and include the necessary calculations required to set up permit limits. The basic tenets of the permit process are such that if limits are set too low, operators who are in full regulatory compliance will still be frequently cited, and if limits are set too high, operators who are not in compliance will seldom if ever be cited. Thus there is a great need for these effluent limits to be determined with great care, both to protect the environment receiving the wastewater and the industry producing the wastewater.     

Development of novel combustion risk index for flammable liquids based on unsupervised clustering algorithms

Current liquid flammability classification mainly relies on flash point and its risk is largely dependent on consequence and probability. However, combustions of liquefied marine fuels have their uniqueness, leading to a less consistent with the common classification. This work aims at classifying flammable liquids in compression ignition engines for further safety evaluation. Besides liquid flammability characteristics, flame propagation and aerosol formulation are considered. Two unsupervised machine learning clustering algorithms, k-means and spectral clustering, are applied to the collected liquid compounds database. To consider both cluster cohesion and separation, the global mean silhouette value is used to find the optimal number of clusters and to evaluate the clustering performance. The results show that the spectral clustering outperforms k-means on classifying the risk ratings for all proposed models, while the clustering accuracy of the optimal model has been doubled by employing spectral clustering algorithm. Moreover, principal component analysis and star coordinate diagrams are presented to visualize high dimensional data to 2-D graphs. Finally, the overall liquid safety performance is evaluated by a novel combustion risk index via the weight values determined by the information entropy approach. This index can be used to explore inherently safer fuels in the process industries.     

Climate variability,water levels,and fish catch in the Upper East Region of Ghana

The aim of the research was to investigate the effects of climate variability on selected water bodies in the Upper East Region of Ghana using time series decomposition and simple linear regression analyses. Data on temperature and rainfall (1960–2015), annual total fish catch (1996–2016), and the recorded water levels (1987–2015) of a major reservoir, the Tono, were used. Time series decomposition analyses were performed on the rainfall, temperature, and water level data to identify their trends. While temperature was increasing, rainfall was decreasing and resulted in a decrease in the water level in the Tono Reservoir. The decreasing water level in the reservoir made fish catch easier, which led to overfishing. Out of the other 39 dugouts studied, 8 (21%) were silted. Also, rainfall was decreasing at 4.4% per decade and minimum and maximum temperatures were increasing at 2.5% and 0.03% per decade, respectively. The minimum, maximum, and mean water levels of the Tono Reservoir were 3.7, 8.0, and 4.9 meters (m), respectively. The water level of the Tono Reservoir was decreasing by ?0.08 m per year. It is concluded that the water level in the Tono Reservoir was continually decreasing as a result of decreasing rainfall and increasing maximum and minimum temperatures. To maintain a much more stable microclimate and decrease the siltation rate of the reservoirs, farmers are advised to stop farming along the banks of water bodies and avoid clearing vegetation. Fishermen are also encouraged to adopt fish farming in enclosed areas within the reservoir to meet the growing protein demands in the Upper East Region of Ghana.     

导致上西里西亚工业区儿童血铅水平升高环境和社会经济因素研究

本文集中在横向分析近期波兰儿童铅暴露和铅暴露增加背后的社会经济因素。在上西里西亚工业区,铅是分布最广泛的有毒重金属之一。儿童血铅水平升高关系儿童幸福,不断引起严重关切。本研究涉及在1999 - 2013年间,上西里西亚地区3岁到18岁的4 882名儿童。记录了每一个孩子血液中铅的浓度。孩子的父母被要求回答关于儿童接触铅的环境和家庭社会经济条件的问卷调查。铅暴露增加的因素包括：父母受教育程度较低,父母失业、父母的职业铅暴,家庭的贫穷社会经济地位,在家吸烟,生活在建筑物底层,食用本地种植的蔬菜和水果,在污染环境中长期进行户外活动和男性性别。铅的环境暴露仍然是导致上西里西亚地区儿童慢性铅中毒的主要因素。与儿童血铅浓度关系最大的社会经济因素是儿童父母的低教育水平。
精选自Wojciech Pelc, Natalia Pawlas, Micha? Dobrakowski, S?awomir Kasperczyk. Environmental and socioeconomic factors contributing to elevated blood lead levels in children from industrial area of Upper Silesia. Environmental Toxicology and Chemistry: Volume 35, Issue 10, pages 2597–2603, October 2016. DOI: 10.1002/etc.3429
详情请见http://onlinelibrary.wiley.com/doi/10.1002/etc.3429/full
     

基于健康风险的场地土壤修复限值分析

以某有机污染场地为研究对象,综合选择USEPA、ASTM和VROM等认可程度较高的健康风险评价方法,结合我国的人群特点和场地特征修正风险评估参数,对该场地污染土壤进行健康风险分析。监测结果表明,土壤中苯、苯并(a)芘和苯并(a)蒽3种有机污染物分别超过了其风险筛选值。通过口腔摄入、皮肤接触和呼吸吸入污染物3种暴露途径计算健康风险,污染土壤对人体产生的叠加致癌风险概率CR和非致癌危害HQ分别达到了9.59×10-5和15.46,会对该场地上的居民产生较大健康危害。根据CR和HQ的可接受风险水平10-6和1,将土壤中苯并(a)芘和苯并(a)蒽的修复目标值确定为0.033 mg/kg和0.33 mg/kg。     

基于多指标约束的隧道集中排烟量设计模型

利用经典羽流模型计算烟气生成量来设计隧道集中排烟系统的排烟量存在设计量偏小的问题。从火灾烟气控制效果出发,选取排烟效率、烟气蔓延范围、烟气流动速度、人员疏散微环境4个指标,提出一套隧道集中排烟系统的评价指标,构建基于多指标约束的隧道集中排烟量设计模型。通过FDS 5.0对某越江隧道火灾时的各评价指标参数值进行模拟计算,得到该隧道集中排烟系统在20MW火灾时的最适排烟量为140～150 m3/s。研究表明,利用多指标约束的排烟量设计模型可提高隧道集中系统排烟量设计的准确性。     

滤膜对环境空气中砷测定的影响及改进

依据《环境空气和废气 颗粒物中砷、硒、铋、锑的测定 原子荧光法》（HJ 1133—2020）的要求,对采集环境空气中砷的9种滤膜的本底值、回收率、检出限、精密度和准确度进行了实验对比。根据实验各项性能指标及成本考虑,建议选择尼龙、硝酸纤维或混合纤维3种国产有机滤膜,其购买方便、价格较低,方法检出限均为0.2 ng/m³,精密度和准确度均能满足环境空气中砷的测定要求。     

Five Hundred Years of Hydrological Drought in the Upper Colorado River Basin1

Abstract: This article evaluates drought scenarios of the Upper Colorado River basin (UCRB) considering multiple drought variables for the past 500 years and positions the current drought in terms of the magnitude and frequency. Drought characteristics were developed considering water‐year data of UCRB’s streamflow, and basin‐wide averages of the Palmer Hydrological Drought Index (PHDI) and the Palmer Z Index. Streamflow and drought indices were reconstructed for the last 500 years using a principal component regression model based on tree‐ring data. The reconstructed streamflow showed higher variability as compared with reconstructed PHDI and reconstructed Palmer Z Index. The magnitude and severity of all droughts were obtained for the last 500 years for historical and reconstructed drought variables and ranked accordingly. The frequency of the current drought was obtained by considering two different drought frequency statistical approaches and three different methods of determining the beginning and end of the drought period (annual, 5‐year moving, and ten year moving average). It was concluded that the current drought is the worst in the observed record period (1923‐2004), but 6th to 14th largest in terms of magnitude and 1st to 12th considering severity in the past 500 years. Similarly, the current drought has a return period ranging from 37 to 103 years based on how the drought period was determined. It was concluded that if the 10‐year moving average is used for defining the drought period, the current drought appears less severe in terms of magnitude and severity in the last 500 years compared with the results using 1‐ and 5‐year averages.     

基于健康风险评价的职业接触限值合理性分析

根据国家卫生部颁布GBZ2.1-2007《工作场所有害因素职业接触限值化学有害因素》,选取苯、甲苯、硝基苯及二硝基甲苯作为评级因子,运用健康风险评价的方法,计算出在其接触浓度限值下的致癌风险值和非致癌风险指数,根据计算结果评价职业接触限值的合理性。评价结果表明:GBZ2.1-2007中的苯、甲苯、硝基苯及二硝基甲苯的接触限值是不合理的,长期暴露于该浓度限值下将会对人体健康产生不利影响。     

CLIMATE VARIABILITY AND FLOOD FREQUENCY ESTIMATION FOR THE UPPER MISSISSIPPI AND LOWER MISSOURI RIVERS1

ABSTRACT: This paper considers the distribution of flood flows in the Upper Mississippi, Lower Missouri, and Illinois Rivers and their relationship to climatic indices. Global climate patterns including El Niño/Southern Oscillation, the Pacific Decadal Oscillation, and the North Atlantic Oscillation explained very little of the variations in flow peaks. However, large and statistically significant upward trends were found in many gauge records along the Upper Mississippi and Missouri Rivers: at Hermann on the Missouri River above the confluence with the Mississippi (p = 2 percent), at Hannibal on the Mississippi River (p < 0.1 percent), at Meredosia on the Illinois River (p = 0.7 percent), and at St. Louis on the Mississippi below the confluence of all three rivers (p = 1 percent). This challenges the traditional assumption that flood series are independent and identically distributed random variables and suggests that flood risk changes over time.