This study investigates single and co-transport behavior of aged (14 and 30 days) poly(methyl methacrylate) nanoparticles (14dPMMANPs, 30dPMMANPs) and florfenicol (FF) in saturated porous media, under varying ionic strengths (IS) and pH values. The results indicate that during the aging process, the carbon-oxygen double bonds in the ester group of PMMANPs were the first to be degraded under simulated sunlight exposure. In single transport experiments, the 14dPMMANPs exhibited higher mass recovery percentage, which can be attributed to their smaller hydrodynamic diameter and higher oxygen-containing functional groups. Interestingly, the oxygenated functional groups exposed on the 14dPMMANPs may provide more cation binding sites, resulting in stronger migration inhibition under Ca2+ conditions compared to Na+ conditions. In contrast, the 30dPMMANPs displayed more negative zeta potential and a lower rate of particle size increase, weakening the inhibitory effect of divalent cations. Under co-transport conditions, FF promoted the migration of 30dPMMANPs in low IS, neutral solutions. Overall, FF reached a new equilibrium between transport inhibition (reduced electrostatic repulsion, increased hydrodynamic diameter of PMMANPs, and additional deposition sites on quartz sand (QS)) and transport promotion (PMMANPs as a carrier and competition for deposition sites on the QS surface). Changes in pH disrupted this equilibrium. Furthermore, the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory, considering surface roughness (SR), provides a good explanation for the breakthrough curves (BTC) of aged PMMANPs during single and co-transport. The surface collapse, inter-particle aggregation, higher SR, and surface inhomogeneity observed in 30dPMMANPs suggest significant chemical heterogeneity, resulting in a lower energy barrier for migration. This study reveals the dynamic relationship between the physicochemical properties and the migration capacity of PMMANPs at different aging stages, demonstrates the dynamic equilibrium of the competition-carrier effect in the co-transport system (FF and PMMANPs), and uncovers the synergistic effect between cation valence and the coordination ability of surface functional groups on nanoplastics, overcoming the limitation of traditional studies that focus only on ionic strength.

This paper studied both carbonated geothermal waters and generic geothermal waters, to better understand deep groundwater circulations in deep fault-basin system in the Heyuan Deep Fault Zone. Uniquely occurring carbonated geothermal waters are not well known in their origin-evolution process, geologic settings of deep ground water systems, and their flow behaviors in response to the unique physicochemical properties. Through deep-borehole data, and field samplings of various isotope and aqueous geochemistry data, we characterized these carbonated and generic geothermal waters, and analyzed water-rock reactions in relevant silicate rocks. Carbonated waters have high contents of HCO3- and dissolved CO2, and enhance their leaching effect in such a way consequently leading to much higher major ion concentrations than non-carbonated thermal waters. According to delta D and delta 18O data, both carbonated waters and non-carbonated waters are of local meteoric origin and recharge from the hilly areas scattering throughout the study area at elevations ranging from 492 to 602 m (masl). The delta 13C results confirm that the high DIC contents in carbonated waters have their deep sources of both mantle and carbonate rock thermal metamorphism genesis. Thermal reservoir temperatures are estimated for water samples, yielding a temperature range of 48.2 to 134.8 degrees C, based on chalcedony and quartz geothermometers. A 3500-m-deep borehole for carbonated water has revealed the relatively low geothermal gradient (2.35 degrees C/100 m) in the carbonated water convergence zone, which is related to the localized depression of the granitic-igneous basement within the study area. Relatively low-temperature environments have formed in localized basement depressions with thick cover of sedimentary rocks, and thus have provided excellent storage condition for deep-derived CO2 rising along deep faults, forming carbonated waters when combined with groundwater systems. The deep crustal groundwater flow was further examined for the crustal thermo-structure, showing the heat flow and temperature distribution in each layer of the crust. The findings and insights could provide further understanding of deep ground water flow systems and deep groundwater circulations. The implications involve effective exploitations and utilizations for carbonated water and non-carbonated thermal water. This study is the first of the kind to study the deep ground water systems including carbonated waters and non-carbonated thermal waters in deep fault-basin systems, in terms of the deep sourcing, ground-water circulation, and thermal structure of the deep crust, and deep groundwater circulation in deep fault settings.

Geothermal systems play a crucial role in understanding Earth’s heat dynamics. The Yunkai Uplift in southern China exemplifies a geothermally rich region characterized by ancient lithologies and high heat flow. This study investigates the geochemical characteristics of geothermal waters in the Yunkai Uplift. Both geothermal and non-thermal water samples were collected along the Xinyi–Lianjiang (XL) Fault Zone and the Cenxi–Luchuan (CL) Fault Zone flanking the core of the Yunkai Mountains. Analytical techniques were applied to examine major ions, trace elements, and dissolved CO2 and H2, as well as isotopic characteristics of O, H, Sr, C, and He in water samples, allowing for an investigation of geothermal reservoir temperatures, circulation depths, and mixing processes. The findings indicate that most geothermal waters are influenced by water–rock interactions primarily dominated by granites. The region’s diverse lithologies, change from ancient Caledonian granites and medium–high-grade metamorphic rocks in the central hinterland (XL Fault Zone) to low-grade metamorphic rocks and sedimentary rocks in the western margin (CL Fault Zone). The chemical compositions of geothermal waters are influenced through mixing contacts between diverse rocks of varying ages, leading to distinct geochemical characteristics. Notably, δ13CCO2 values reveal that while some samples exhibit significant contributions from metamorphic CO2 sources, others are characterized by organic CO2 origins. Regional heat flow results from the upwelling of mantle magma, supplemented by radioactive heat generated from crustal granites. Isotopic evidence from δ2H and δ18O indicates that the geothermal waters originate from atmospheric sources, recharged by precipitation in the northern Yunkai Mountains. After infiltrating to specific depths, meteoric waters are heated to temperatures ranging from about 76.4 °C to 178.5 °C before ascending through the XL and CL Fault Zones under buoyancy forces. During their upward migration, geothermal waters undergo significant mixing with cold groundwater (54–92%) in shallow strata. As part of the western boundary of the Yunkai Uplift, the CL Fault Zone may extend deeper into the crust or even interact with the upper mantle but exhibits weaker hydrothermal activities than the XL Fault Zone. The XL Fault Zone, however, is enriched with highly heat-generating granites, is subjected more to both the thermal and mechanical influences of upwelling mantle magma, resulting in a higher heat flow and tension effect, and is more conducive to the formation of geothermal waters. Our findings underscore the role of geotectonic processes, lithological variation, and fault zone activity in shaping the genesis and evolution of geothermal waters in the Yunkai Uplift.

Aquifers composed of porous granular media are important to human beings because they are capable of storing a large amount of groundwater. Contaminant migration and remediation in subsurface environments are strongly influenced by three-dimensional (3D) microstructures of porous media. In this study, fractal models are developed to investigate contaminant transport and surfactant-enhanced aquifer remediation (SEAR) for the regular tetrahedron microstructure (RTM) and right square pyramid microstructure (RSPM). The relationships of permeability and entry pressure are derived for these two kinds of 3D microstructures of granular porous media. Afterward, the difference in perchloroethylene (PCE) migration and SEAR efficiency between RTM and RSPM is investigated by the numerical simulation based on a synthetic heterogeneous granular aquifer. Results indicate that PCE penetrates faster and spreads farther in RSPM-based aquifers compared with RTM-based aquifers. Further, SEAR in RTM-based aquifers can achieve remediation efficiencies of 66.129%-92.214% with a mean of 84.324%, which is clearly lower than the SEAR efficiency of 70.149%-94.773% (with a mean of 89.122%) in RSPM-based aquifers. Findings are significant for understanding the 3D microstructure of porous media and how the microstructure of porous media affects macroscopic contaminant behaviors and remediation.

The groundwater contamination assessment and prevention regionalization are an important part of groundwater investigation, which is of great significance to groundwater environmental management and contamination control. Although the Guangdong-Hong Kong-Macao Greater Bay Area (GHM Greater Bay Area) has faced significant groundwater contamination since 2020, there's been no investigation into its vulnerability zonation. In this paper, groundwater in a typical area of south China was taken as the research object. We analyzed groundwater contamination risk by considering both the groundwater vulnerability and the load from contamination sources. Using the analytic hierarchy process (AHP) method, we superposed the groundwater risk, function value and contamination status, and realized the quantification and visualization of groundwater contamination prevention regionalization. Based on the DRASTIC model, the zones of low, moderate, high, and very high vulnerability are respectively 14.2 %, 24.28 %, 37.67 %, and 20.45 % of the study area. Results show that the groundwater vulnerability grade in the area is III-IV, which means it is easy to be polluted. The functional value of groundwater in the south-central part of the region is relatively high. Most of the areas with high prevention and control levels are located in plain areas and the Piedmont plain area with an area of 460 km2. The secondary control levels (key protection area) are mainly located in the middle, southwest, and northeast of the plain, with an area of 6944 square kilometers. Consequently, the ideas and contamination prevention zone maps might provide a scientific foundation for long-term planning and management and groundwater conservation in the Guangdong-Hong Kong-Macao Greater Bay Area and peripheral zones.

Due to the extensive use of plastic products and unreasonable disposal, nanoplastics contamination has become one of the important environmental problems that mankind must face. The composition and structure of porous media can determine the complexity and diversity of the transport behavior of nanoplastics. In this study, the influence of diatomite (DIA) on the nanoplastics transport in porous media is investigated by column experiments combined with XDLVO interaction energy and transport model. Results suggest that the recovery rates of unmodified polystyrene nanoparticles (PSNPs) and carboxyl-modified polystyrene nanoparticles (PSNPs-COOH) in the porous media containing DIA decreases compared with that in the pure quartz sand (QS), and the BTCs showed a "blocking" pattern. The presence of DIA inhibits the transport of both PSNPs and PSNPs-COOH, but the inhibition is not significant. This may be because the presence of DIA provides more favorable deposition sites for PSNPs and PSNPs-COOH to some extent. However, since DIA itself carries a certain negative charge, this can only play a role in compressing the double electric layer for PSNPs and PSNPs-COOH with the same negative charge, and cannot destabilize them. The migration capacity of PSNPs and PSNPs-COOH is strongest in the DIA-QS porous media at pH=7, and is weak at pH=9 and pH=5. The inhibition of migration at pH=9 can be attributed to the dissolution of the DIA surface under alkaline conditions and the formation of pore and defect structures, which provide more deposition sites for PSNPs and PSNPs-COOH. The presence of humic acid (HA) leads to an increase in the mobility of PSNPs and PSNPs-COOH, and the mobility is enhanced with HA concentration. The mobility of PSNPs and PSNPs-COOH in DIA-QS decreases with ionic valence and ionic strength, and PSNPs-COOH is more significantly inhibited compared to PSNPs.

With the application of engineered nanomaterials and antibiotics in the fields of medicine, aerospace, new energy and agriculture, the associated contamination is detected widely in soil -groundwater systems. It is of great scientific and practical significance to deeply explore the environmental interface process between nanoparticles and antibiotics for the scientific assessment of environmental fate and ecological environmental risks, as well as the development of new composite pollution control technologies. In this study, the co -transport behaviors of positively charged titanium dioxide nanoparticles (TiO 2 -NPs) and negatively charged levofloxacin (LEV) in quartz sand (QS) are investigated in this study. The results show that TiO 2 -NPs hardly flow out when transported alone in the column because of its positive charge, which creates a strong attraction with the negatively charged quartz sand on the surface. When TiO 2 -NPs co -migrate with LEV in porous media, the presence of LEV promotes the transport of TiO 2 -NPs, while the presence of TiO 2 -NPs inhibits LEV transport. Non-XDLVO interactions based on molecular dynamics (MD) simulations can help explain the observed promotion and inhibition phenomena as well as the correlation between TiO 2 -NPs and LEV. The results indicate that TiO 2 -LEV complexes or aggregates can be formed during the co -transportation process of TiO 2 -NPs and LEV in porous media. As flow velocity increases from 0.204 cm min - 1 to 1.630 cm min - 1 , both the transport capacities of TiO 2 -NPs and LEV are enhanced significantly. Under the condition of high citric acid (CA) concentration (15 mmol L - 1 ), the transport capacity of TiO 2 -NPs is slightly inhibited, while the transport capacity of LEV is enhanced. This study provides new insights into the transport of nanometallic oxides and antibiotics in porous media, which suggests that non-XDLVO interactions should be considered together when assessing the environmental risks and fate of nanometallic oxides and antibiotics in soil -groundwater systems.

The migration behavior of Polymeric Methyl Methacrylate (PMMA) nanoplastics in saturated porous media and unsaturated porous media is investigated under conditions of electrolytes in combination with organic acids. In the saturated porous media, the mass recovery rate of PMMA decreases with ionic strength. The inhibition effect of Ca2+ on PMMA transport is stronger than that of Na+. Under the conditions of the coexistence of electrolytes with humic acid (HA), increasing the concentration of HA does not consistently enhance PMMA migration in porous media. However, citric acid (CA) exerts solely an inhibitory effect on PMMA transport. The orthogonal analysis suggests that Ca2+ concentration is the major factor affecting PMMA transport. Extended DarjaguinLandau-Verwe-Overbeek (XDLVO) interaction energy considering the heterogeneity of HA adsorption on PMMA is calculated to quantify the interactions of PMMA-PMMA and PMMA-quartz sand under different physiochemical conditions. In unsaturated porous media, gravity leads to the creation of dominant channels, and the shear force of water flow in porous media leads to the rapid passage of PMMA through the dominant channels. However, as the water content decreases, the recovery rate of PMMA decreases from 0.99 to 0.71. Significantly, the capillary energy of a colloid retained in a thin film or at the air-water-solid (AWS) interface is several orders of magnitude larger than the XDLVO interaction energy. Findings obtained by this study may improve the current understanding of the environmental fate of nanoplastics in subsurface environments and can provide scientific methods to assess the associated risk of nanoplastics.

Download This Paper Open PDF in Browser Add Paper to My Library Share: Permalink Using these links will ensure access to this page indefinitely Copy URL Copy DOI

This study investigated the influence of groundwater salinity on DNAPL migration and distribution in saturated physically homogeneous and heterogeneous porous media. Interfacial tension (IFT) of PCE/aqueous phase containing NaCl and contact angles through the aqueous phase measured results showed that the contact angle decreased and IFT increased with NaCl concentration, leading to the fact that the wettability of quartz sand can be changed from water-wet to strong water-wet. Three sets of two-dimensional (2-D) sandbox experiments conducted with different salinity showed DNAPL migrated faster in the vertical direction in salinity, yielding decreased residual DNAPL entrapped in the migration path. In addition, the salinity-induced strong water-wet media promoted DNAPL trapping at relatively lower saturation both in the coarse or medium sand, and the volume of PCE entrapped as ganglia increased in the salinity cells. The salinity enhanced the dissolution of PCE from the source zone due to the PCE zone architecture change.

The spill pressure of the contaminant source is an important factor affecting the amount, location, form, and behavior of the dense non-aqueous phase liquids (DNAPLs) that plume in a contaminated subsurface environment. In this study, perchloroethylene (PCE) infiltration, distribution and, remediation via a surfactant-enhanced aquifer remediation (SEAR) technique for a PCE spill event are simulated to evaluate the effects of the spill pressure of the contaminant source on the DNAPLs’ behavior in two-dimensional homogeneous and heterogeneous aquifers. Five scenarios with different spill pressures of contamination sources are considered to perform the simulations. The results indicate that the spill pressure of the contaminant source has an obvious influence on the distribution of DNAPLs and the associated efficiency of remediation in homogeneous and heterogeneous aquifers. As the spill pressure increases, more and more contaminants come into the aquifer and the spread range of contamination becomes wider and wider. Simultaneously, the remediation efficiency of contamination also decreases from 93.49% to 65.90% as the spill pressure increases from 33.0 kPa to 41.0 kPa for a heterogeneous aquifer with 200 realizations. The simulation results in both homogeneous and heterogeneous aquifers show the same influence of the spill pressure of the contaminant source on PCE behaviors in the two-dimensional model. This study indicates that the consideration of the spill pressure of the contaminant sources (such as underground petrol tanks, underground oil storage, underground pipeline, and landfill leakage) is essential for the disposal of contaminant leakage in the subsurface environment. Otherwise, it is impossible to accurately predict the migration and distribution of DNAPLs and determine the efficient scheme for the removal of contaminant spills in groundwater systems.

Geothermal energy is a sustainable renewable energy with great competitive advantages. Studies have shown that hot spring water in geothermal field is characterized by high fluorine content. However, the mechanisms that control fluorine enrichment are still unclear. In this study, 10 hot spring water samples were collected in the northern part of Longchuan County, Guangdong Province, and laboratory tests and hydrochemical analysis were conducted. Hydrogeochemical methods and numerical simulation were used to investigate the fluorine enrichment in hot springs. The results show that the fluorine contents in all hot spring water samples exceed the standard value, with the highest one of 18.27 mg·L−1. The chemical types of hot spring water in the study area are HCO3SO4-Na and HCO3-Na, and the fluorine content is associated with pH, temperature, and Ca2+ values. Mineral dissolution and precipitation, cation exchange, desorption and complexation are the main hydrogeochemical factors affecting fluorine enrichment in hot springs. The hydrothermal cycle process and water-rock interaction in the study area have been quantified by PHREEQC reverse simulation, which further improves our understanding of the enrichment process of fluorine.

Investigation of the change rate for contaminant parameters is important to characterize dense non-aqueous phase liquid (DNAPL) transport and distribution in groundwater systems. In this study, four experiments of perchloroethylene (PCE) migration are conducted in two-dimensional (2D) sandboxes to characterize change rates of PCE saturation (So) and PCE–water interfacial area (AOW) under different conditions of salinity, surface active agent, and heterogeneity. Associated representative elementary volume (REV) of the change rate of So (So rate) and change rate of AOW (AOW rate) is derived over the long-term transport process through light transmission techniques. REV of So rate (SR-REV) and REV of AOW rate (AR-REV) are estimated based on the relative gradient error (εgi). Regression analysis is applied to investigate the regularity, and a model based on a back-propagation (BP) neural network is built to simulate and predict the frequencies of SR-REV and AR-REV. Experimental results indicated the salinity, surface active agent, and heterogeneity are important factors that affect the So rate, AOW rate, SR-REV, and AR-REV of the PCE plume in porous media. The first moment of the PCE plume along the vertical direction is decreased under conditions of high salinity, surface active agent, and heterogeneity, while these factors have different effects on the second moment of the PCE plume. Compared with the salinity and surface active agent, heterogeneity has the greatest effect on the GTP, the distributions of the So rate and AOW rate along the depth, and dM, dI. For SR-REV, the standard deviation is increased by the salinity, surface active agent, and heterogeneity. Simultaneously, the salinity and heterogeneity lead to lower values of the mean value of SR-REV, while the surface active agent increases the mean value of SR-REV. However, the mean and standard deviation of AR-REV have no apparent difference under different experimental conditions. These findings reveal the complexity of PCE transport and scale effect in the groundwater system, which have important significance in improving our understanding of DNAPL transport regularity and promoting associated prediction.

The transport of biochar nano-particles (BCNPs) influenced by complex physicochemical factors is systematically investigated through the transport experiments combined with the interfacial chemistry theory and numerical modeling methods. The two-dimensional (2D) distributions of Derjaguin-Landau-Verwey-Overbeek (DLVO) interaction energy are obtained and a new indicator of DLVO barrier (xi(DB)) is proposed to identify the inflection point related to agglomeration and deposition of BCNPs. Results suggest the mobility of BCNPs in porous media decreases with ionic strength, and the inhibitory effect of divalent cations on BCNPs transport is stronger than that of monovalent cations. However, the mobility of BCNPs is enhanced by the increases in pH and humic acid concentrations. In addition, the higher the concentration of BCNPs, the higher the retention of BCNPs in saturated porous media. The mobility of BCNPs is enhanced under the conditions of high flow velocity. A combined value of DLVO energy barriers is calculated and results suggest the decision coefficient (R-2) decreases with the fraction of DLVO energy barrier of BCNPs-BCNPs, indicating that the interaction between BCNPs and quartz sand (QS) plays a major role in the transport of BCNPs in porous media. Afterward, the continuous values of two-site kinetic transport parameters of BCNPs in porous media as a function of hydrochemical factors can be predicted by the combined value of DLVO energy barriers. Simultaneously, the critical hydrochemical conditions related to BCNPs mobility can be quantitatively determined by a combination of column experiment, DLVO interaction energy and transport model. The critical hydrochemical conditions are IS(Na+)= 29.3-29.4 mM, IS(Ca2+)= 2.50-2.55 mM, pH= 3.36-3.37, HA concentration= 3.68-5.84 mgL-1. The findings are important for understanding the transport behavior and mechanism of BCNPs in porous media, and accurate prediction and assessment of BCNPs transport patterns in soil-groundwater systems.(c) 2023 Institution of Chemical Engineers. Published by Elsevier Ltd. All rights reserved.

碳酸泉以富含游离CO2为特征,主要分布在深大断裂带和地震活动带上.通过针对广东省龙川县3个不同深度的钻孔数据对碳酸地热水的水文地球化学特征进行研究,揭示其水化学组分主要为碳酸盐矿物溶解控制,游离CO2运移过程中强化了水的溶滤作用.Na-K-Mg三角图解和PHREEQC计算表明水-岩作用处于不平衡状态,通过石英温标、玉髓温标及多矿物水-岩平衡估算了地热水的热储温度为60-102℃,循环深度为1692-3548 m.该水化学特征成果可以进一步讨论碳酸泉的形成机理,反映气体在深部地热流和温度剖面中的作用,为研究深部流体对地震的同震响应及地热资源开发提供依据.

In this study, a combination of column experiments, interface chemistry theory and transport model with two-site kinetics was used to systematically investigate the effect of pH on the transport of polystyrene nanoparticles (PSNPs) in porous media. The porous media containing quartz sand (QS) and three kinds of clay minerals (CMs)-kaolinite (KL), illite (IL) and montmorillonite (MT), was used in column experiments to simulate the porous media in the soil-groundwater systems. Experimental results showed that the inhibitory effect of CMs on the transport of PSNPs is weakened as pH increases. The two-dimensional (2D) surface of the DLVO interaction energy (2D-pH-DLVO) was built to calculate the interactions between PSNPs and CMs under different conditions of pH. Results suggested the inflection point of PSNP-QS, PSNP-KL, PSNP-IL and PSNP-MT are 2.42, 3.30, 2.84 and 3.69, respectively. Most importantly, there was a significant correlation between the two-site kinetic parameters related to PSNPs transport and the DLVO energy barrier (DB). The contributions of the interactions of PSNPs-PSNPs and PSNPs-minerals were determined for PSNPs transport in porous media. The critical values of pH related to the migration ability of PSNPs in porous media could be determined by a combination of column experiments, 2D-pH-DLVO and PSNPs transport model. The critical values of pH were 2.95–3.01, 3.22–3.51, 2.98–3.02, 3.31–3.33 for the migration ability of PSNPs in QS, QS + KL, QS + IL and QS + MT porous media, respectively. The stronger migration ability of PSNPs under high pH conditions is attributed to the enhanced deprotonation of the media surface and increased negative surface charge, which increases the electrostatic repulsion between PSNPs and porous media (QS, CMs). Moreover, the agglomeration of PSNPs usually is weaker and the average particle size of agglomerates is smaller under the condition of high pH, thus leading to the stronger migration ability of PSNPs under high pH conditions.

To investigate the effect of microplastics on the transport and retention of antibiotics in subsurface environment, polypropylene (PP) and ciprofloxacin (CIP) are selected as typical microplastic and antibiotic contaminant, respectively. The key factors and main control mechanisms are systematically investigated using a combination of adsorption experiments, column experiments and numerical model. The adsorption experiments indicate the largest adsorption capacity of CIP on PP is 1.03 mg & BULL;g � 1. Simultaneously, the results of column experiments and numerical model suggest that PP can significantly affect the migration behavior and retention of CIP in porous media. CIP mobility is positively correlated to flow velocity, initial concentration of CIP and ionic strength (Na+, Ca2+ and Ba2+). Moreover, compared to monovalent cation (Na+), divalent cations (Ca2+, Ba2+) have a stronger enhancement effect on CIP mobility and a stronger inhibition effect on CIP retention in saturated porous media. The transport of CIP in saturated porous media containing PP is simulated by a single-point kinetic model, and the equations of the transport kinetic parameters of CIP are obtained through regression analysis. The research could help to gain insight into understanding the environmental behavior of antibiotic in the groundwater system, and provide scientific basis for the accurate prediction and assessment of environmental risk caused by microplastic and antibiotic in the groundwater system.

Polyamide (PA) and bisphenol A (BPA) are selected as typical microplastic and endocrine-disrupting chemicals in this study. The adsorption of BPA on the surface of PA and the effect of PA on the transport behavior of BPA in groundwater are systematically investigated using a combination of batch experiments, column experiments and numerical models. The results of scanning electron microscope (SEM) and Fourier transform infrared spectra (FTIR) show that the surface of PA particles is changed significantly after adsorption of BPA. The isothermal adsorption process of BPA can be simulated by the Langmuir model and the Freundlich model. Kinetic adsorption, on the other hand, can be fitted by a quasi-first-order adsorption model, and the adsorption results indicate that the maximum adsorption of BPA on PA reaches 13 mg·g−1. The results of the column experiments suggest that the mass recovery rate of BPA decreases with PA content, and increases with flow velocity, while initial concentration has no apparent influence on BPA transport. In addition, due to the hydrolysis of BPA, the mass recovery rate of BPA does not change with pH under conditions of pH < 10.2 and increases substantially to 94% when pH > 10.2. Moreover, Ca2+ has a significant inhibitory effect on the transport of BPA, while Na+ has no apparent influence on the transport of BPA. The transport process of BPA in porous media is simulated using a single-point kinetic model, and the fitted mathematical relationships for the variation of kinetic parameters with environmental factors are obtained by regression analysis.

以海南岛的琼北地区地热水为研究对象,对研究区的地热水、地下水和地表水水样进行测试分析,运用piper图、δ2H和δ18O图、钠碱指数等方法探究琼北地区高氟地热水的富集规律及分布特征.结果表明,地热水氟浓度均超标,平均值高达14.25 mg·L-1;而地下水和地表水的氟含量未超标,变化范围为0.02-0.44 mg·L-1.沿海地区到内陆地区地热水氟含量呈现逐渐增大的趋势,内陆地区平均含量高达21.69mg·L-1.地热水水化学类型以HCO3-Na为主,温度、pH和地层中的含氟矿物类型对地热水氟的富集具有重要的影响.地下热水补给来源为现代大气降水,并且存在轻微的"氧漂移"现象,受到一定程度的蒸发浓缩的影响.随着文石、方解石的沉淀反应、络合反应形成的络合物以及Na+、K+置换出Ca2+、Mg2+的离子交换反应,地热水中氟浓度不断增大.

Porous media widely exists in natural aquifers, engineering materials (such as materials used to remove contaminants from water) and oil reservoirs, etc. Due to the complexity of particles contained in porous media, the fluid flow and contaminants transport are undoubtedly affected by the particle geometry of porous media. Two kinds of particle geometry models are developed to assess whether the geometry of grain plays an important role on chlorohydrocarbon contaminant transport and bioremediation. Porous medium properties such as tortuosity, permeability and entry pressure are quantified for the two kinds of particle geometries. Meanwhile, a laboratory experiment for perchloroethylene (PCE) transport is performed in a two-dimensional (2D) sandbox to verify permeability and entry pressure derived by different particle geometries. Comparison between geometry models and experimental results indicate rectangular particles (RP) with high & mu; (the ratio of width to length) and ellipse particles (EP) with low & eta; (the ratio of semi-long axis to semi-shorter axis) agree well with the experiment. Moreover, the grains geometry that forms the porous matrix's solid domain applied in the experiment is also identified according to the numerical simulation of PCE migration. Furthermore, two kinds of particle geometries are coupled with UTCHEM, to derive the effects of particle geometry on Trichloroethylene (TCE) transport, redistribution and biodegradation by methanotrophs for a realistic three-dimensional (3D) aquifer application. Results suggest the geometry of grain has a significant influence on the properties of a porous medium. The remediation efficiency became higher when & mu; increased for RP and & eta; decreased for EP. PCE infiltration rate was lowest for RP with high & mu; and EP with low & eta;. Simulation results based on realistic groundwater bioremediation indicated RP with & mu; = 0.9, EP with & eta; = 1.1 and EP with & eta; = 1.3 achieved the highest bioremediation efficiency for TCE contamination.