地下水可溶性污染物迁移的最优估算

对流扩散方程的有限元和有限差方法已经广泛地用来模拟地下水污染物的迁移。由于迁移过程固有的不确定性,模拟方法的不准确性等都会给模型计算带来偏差;另外野外测量的误差也是不可避免的。通过数值模型、量测方程和卡尔曼滤波的结合,作为状态变量的污染物浓度可以优化给出。本文以二维地下水污染物的对流扩散方程为例,应用有限元方法导出卡尔曼滤波的转移矩阵,结果表明,使用滤波技术来估算地下水可溶性污染物浓度的分布比单独使用有限元方法有较大的优越性。     

Toxic responses of different organs following occupational exposure to sub-threshold limit value levels of paving asphalt fumes

The main purpose of this study was to ascertain whether occupational exposure to asphalt fumes, under normal working conditions, is associated with any hepatotoxic, nephrotoxic, or hematotoxic response. This was a cross-sectional study in which 210 subjects (80 exposed and 130 reference subjects) were investigated. Using standard methods, atmospheric concentrations of total particulate and benzene-soluble fractions of asphalt fumes were measured. Additionally, urine and blood samples were taken from subjects for complete blood count, white blood cell differential test, urinalysis, and routine biochemical tests of kidney and liver function. Both groups were similar as far as their demographic variables and smoking habits were concerned. The levels of exposure to total particulate and benzene-soluble fractions were estimated to be 0.9?±?0.2 and 0.32?±?0.09 mg m^?3, respectively (mean?±?SD), both of which being lower than the existing threshold limit values. Statistically, significant associations between exposure to asphalt fumes and changes in most liver and kidney function tests and complete blood count parameters provided circumstantial evidence in favor of the notion that exposure to sub-threshold limit value levels of total particulate and benzene-soluble fractions is associated with early liver and kidney dysfunction as well as hematological disorders.     

Simultaneous monitoring of SARS-CoV-2, bacteria,and fungi in indoor air of hospital: a study on Hajar Hospital in Shahrekord,Iran

The novel SARS-CoV-2 outbreak was declared as pandemic by the World Health Organization (WHO) on March 11, 2020. Understanding the airborne route of SARS-CoV-2 transmission is essential for infection prevention and control. In this study, a total of 107 indoor air samples (45 SARS-CoV-2, 62 bacteria, and fungi) were collected from different wards of the Hajar Hospital in Shahrekord, Iran. Simultaneously, bacterial and fungal samples were also collected from the ambient air of hospital yard. Overall, 6 positive air samples were detected in the infectious 1 and infectious 2 wards, intensive care unit (ICU), computed tomography (CT) scan, respiratory patients’ clinic, and personal protective equipment (PPE) room. Also, airborne bacteria and fungi were simultaneously detected in the various wards of the hospital with concentrations ranging from 14 to 106 CFU m^?3 and 18 to 141 CFU m^?3, respectively. The highest mean concentrations of bacteria and fungi were observed in respiratory patients’ clinics and ICU wards, respectively. Significant correlation (p < 0.05) was found between airborne bacterial concentration and the presence of SARS-CoV-2, while no significant correlation was found between fungi concentration and the virus presence. This study provided an additional evidence about the presence of SARS-CoV-2 in the indoor air of a hospital that admitted COVID-19 patients. Moreover, it was revealed that the monitoring of microbial quality of indoor air in such hospitals is very important, especially during the COVID-19 pandemic, for controlling the nosocomial infections.

     

Geochemical fractionation and pollution assessment of Zn,Cu, and Fe in surface sediments from Shadegan Wildlife Refuge,southwest of Iran

This research focuses on the fractionation and distribution patterns of heavy metals (Zn, Cu, and Fe) in surficial sediments collected from Shadegan Wildlife Refuge, the biggest wetland in southern part of Iran, to provide an overall classification for the sources of metals in the study area using a sequential extraction method. For this purpose, a four-step sequential extraction technique was applied to define the partitioning of the metals into different geochemical phases of the sediment. The results illustrated that the average total level of Zn, Cu, and Fe in surface sediments were 55.20 ± 16.04, 22.86 ± 5.68, and 25,979.01 ± 6917.91 μg/g dw, respectively. On the average, the chemical partitioning of all metals in most stations was in the order of residual >oxidizable-organic > acid-reducible > exchangeable. In the same way, the results of calculated geochemical indices revealed that Cu, Zn, and Fe concentrations are mainly influenced by lithogenic origins. Compared with consensus-based SQGs, Cu was likely to result in occasionally harmful biological effects on the biota.

     

The cut-off point for tympanic temperature as a heat strain index for evaluation of outdoor workers: a field study

Objectives. The aims of this study were (a) to assess the agreement coefficient between tympanic temperatures and the most popular and valid heat stress index, wet bulb globe temperature (WBGT), in outdoor environments; (b) to determine a cut-off point for tympanic temperature as a heat strain index for evaluation of outdoor workers. Methods. 1452 measurements of WBGT index and tympanic temperature were recorded for outdoor workers from nine different climatic regions. Consistency of the WBGT and tympanic temperature were tested. The cut-off point for tympanic temperature in outdoor environments regarding WBGT evaluation was suggested based on obtained sensitivity and specificity from a receiver operating characteristic curve. Results. The results showed that there were numerous situations in which WBGT exceeded the reference value, whilst the measured values of tympanic temperature rarely reached a permissible value for core temperature (38?°C). Therefore, appropriate consistency of results between the heat stress and strain indices was not achieved. Conclusion. The criterion of tympanic temperature equaling 37?°C was suggested as a cut-off point for tympanic temperature as a heat strain index for outdoor environment evaluation.     

Nonlinear molecular based modeling of the flash point for application in inherently safer design

New chemical process design strategies utilizing computer-aided molecular design (CAMD) can provide significant improvements in process safety by designing chemicals with required target properties and the substitution of safer chemicals. An important aspect of this methodology concerns the prediction of properties given the molecular structure. This study utilizes one such emerging method for prediction of a hazardous property, flash point (FP), which is in the center of attention in safety studies. Using such a reliable data set comprising 1651 organic and inorganic chemicals, from 79 diverse material classes, and robust dynamic binary particle swarm optimization for the feature selection step resulted in the most efficient molecular features of the FP investigations. Apart from the simple yet precise five-parameter multivariate model, the FP nonlinear behavior was thoroughly investigated by a novel hybrid of particle swarm optimization and support vector regression. Besides, 195 missing experimental FPs of the DIPPR data set are predicted via the presented procedure.     

CoFe2O4@Methylcelloluse as a New Magnetic Nano Biocomposite for Sonocatalytic Degradation of Reactive Blue 19

Journal of Polymers and the Environment - Reactive Blue 19 (RB19) removal from synthetic textile wastewater was investigated by using a CoFe2O4@methylcellulose (MC) activated with peroxymonosulfate...     

ANALYSIS OF ROCK STRESS AROUND A LIQUID WASTE INJECTION SYSTEM IN ILLINOIS1

: The danger to the environment associated with the injection of liquid industrial wastes into a deep, confined, subsurface rock formation may arise from the transport of the waste laterally or vertically in the formation. The pattern of lateral transport, which can take place as a result of convection as well as dispersion and diffusion, can be determined by an approximate analytical solution to the mass transport equation. Vertical transport may take place through both natural fractures and fractures created by hydrostatic stresses generated around the well during injection. To determine the stresses, we used the finite element method to get a numerical solution of the flow equation. We applied a solution of the flow equation to calculate the stress buildup and decay for the Jones & Laughlin Steel Corporation's injection well near Hennepin in Putnam County, Illinois. According to our computations, the stress buildup due to injection is about 0.16 pounds per square inch per foot - psi - (0.362 Newton per square centimeter per meter), which, added to normal pressure, makes an estimated total stress of 0.60 psi/ft (1.36 Newton/cm²/m). That pressure is insufficient to cause fracturing of the Cambrian Eau Claire aquitard, the confining bed for the disposal zone.     

FIELD MEASUREMENT OF FLOW VELOCITIES,SUSPENDED SOLIDS CONCENTRATIONS,AND TEMPERATURES IN LAKE OKEECHOBEE1

ABSTRACT: This paper presents a field investigation of collecting hydrodynamic and sediment data in Lake Okeechobee with analyses examining mechanisms affecting sediment resuspension in the lake. Lake Okeechobee is a large subtropical lake located in south central Florida. Three‐dimensional flow velocities, suspended solids concentrations (SSC), and temperatures at four locations were measured from January 18 to March 5, 2000. Analyses of these data indicate that wind is the dominant factor in driving flow velocities and therefore transporting suspended solids. Wind direction also affects the SSC, especially in the north central and west littoral areas of the lake. The surface and bottom velocity components frequently flow in opposite directions, forming a stratification of the water column and preventing suspended solids from settling out. This retention of SSC in the water column may have a strong impact on the water quality of Lake Okeechobee. This study provides valuable storm event data and mechanism analyses, which will improve our understanding of the transport of suspended solids, thermal exchanges, and flow patterns within Lake Okeechobee.     

The association between air pollution and cancers: controversial evidence of a systematic review

Environmental Science and Pollution Research - There are inconsistent reports on the association between air pollution and cancers. This systematic review was, therefore, conducted to ascertain the...