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Membrane technology is widely regarded as one of the most promising technologies for wastewater treatment and reclamation in the 21st century. However, membrane fouling significantly limits its applicability and productivity. In recent decades, research on the membrane fouling has been one of the hottest spots in the field of membrane technology. In particular, recent advances in thermodynamics have substantially widened people’s perspectives on the intrinsic mechanisms of membrane fouling. Formulation of fouling mitigation strategies and fabrication of anti-fouling membranes have both benefited substantially from those studies. In the present review, a summary of the recent results on the thermodynamic mechanisms associated with the critical adhesion and filtration processes during membrane fouling is provided. Firstly, the importance of thermodynamics in membrane fouling is comprehensively assessed. Secondly, the quantitative methods and general factors involved in thermodynamic fouling mechanisms are critically reviewed. Based on the aforementioned information, a brief discussion is presented on the potential applications of thermodynamic fouling mechanisms for membrane fouling control. Finally, prospects for further research on thermodynamic mechanisms underlying membrane fouling are presented. Overall, the present review offers comprehensive and in-depth information on the thermodynamic mechanisms associated with complex fouling behaviors, which will further facilitate research and development in membrane technology. [ABSTRACT FROM AUTHOR]

The effects of climate change and anthropogenic activities on the concentration of heavy metal in maize were quantitatively characterized in this study to help us better understand the complex interactions among the groundwater, vadose, plant, and atmosphere layers in the critical zone. We hypothesized that climate change and groundwater resource exploitation firstly affected the shallow groundwater level, and then the groundwater table fluctuation (GTF) impacted the concentration of heavy metal in maize through the critical zone (CZ) structure and parameters. To test our hypothesis, we collected 960 soil and 288 maize samples from the Luan River catchment in the North China Plain. The Groundwater Modeling System software was used to describe the effects of precipitation and groundwater resource exploitation on the groundwater table, and then, the structural equation method was employed to characterize the quantitative effects of GTF, precipitation, and air temperature on the concentration of heavy metal in maize. The results indicate that the influence coefficients of the effects of climate change and anthropogenic activities on the concentrations of Fe, Mn, Cr As, Pb, and Sr were 0.1595, 0.088, 0.0042, − 0.0092, 0.2219, and 0.0493 in the north plain, respectively, and 0.0256, 0.0151, 0.0816, − 0.2264, 0.1125, and − 0.0106 in the south plain of the study region, respectively. Since the human health risks of metals were mainly attributed to Fe, Mn, and Cr in the Luan River catchment, increasing the groundwater resource exploitation volume is an effective way to decrease the Fe, Mn, and Cr contents in maize by decreasing the shallow groundwater table. [ABSTRACT FROM AUTHOR]

This study was performed in order to establish new parameters to recognize the depositional microfacies using grain size distribution (GSD) data from laser diffraction analysis. A total of 938 samples were collected from five sedimentary microfacies, and 18 characteristic parameters of these samples were developed by statistical analysis, fractal theory, fingerprint methods, and variogram function. The samples were divided into a training data set and testing data set. The training data set was used to establish a discriminative database with five depositional microfacies; the testing data set was used to verify whether these characteristic parameters can identify their depositional microfacies according to the discriminative database. Out of the 50 samples in the testing data set, 47 samples were correctly recognized within their depositional environment and only three samples of point bar were shared with natural levee using the random forest (RF) method. The analysis results indicate the fine grain size and general characteristic of GSD have more significant influences on depositional environment classification than other parameters. The flood plain and fan-between depression environments had the most similar hydrodynamic conditions among the five considered depositional microfacies. Therefore, the 18 characteristic parameters of GSD are useful tools to identify depositional microfacies for hydrogeological parameter studies. [ABSTRACT FROM AUTHOR]

Traditional chemical methods have mainly focused on the variation and transportation of elements in the aquifer layer. The primary goal of this paper was to establish a spatial distribution model of chemical elements in the critical zone (CZ). The effects of anthropogenic activities (AA) and CZ structure on these models are quantitatively described. To this aim, 200 sediment and pore water samples were collected from ten drills in two profiles and analyzed for 16 variables. The most important influencing factors were identified from CZ structure parameters, and the effects of AA and CZ structure on chemical variables in the CZ were quantitatively characterized. Distribution models of the influences of AA and CZ structure were established for these two profiles. The correlation coefficient of the clay fraction content was greater than the other parameters, which was negative with total dissolved solids (TDS) and the arsenic of pore water and was positive with the arsenic in sediments. The distribution model of chemical variables was divided into three components: CZ1, CZ2, and A-A, which represent the effects of the first and second most important influencing factors and AA. The distribution models of chemical variables and their A-A part had the strongest similarity. The clay fraction content was more important than the other CZ structure parameters. It can inhibit the TDS and arsenic of pore water migration, resulting in greater arsenic ion adsorption on the sediment. AA is a triggering factor for chemical variables transportation, and CZ structure has an amplification effect on AA. According to characterize the spatial distribution of chemical variables in sediment and pore water within the CZ, the effects of AA and CZ structure can be quantitatively described, providing a rapid and effective technique for ecological environmental protection. [ABSTRACT FROM AUTHOR]