Soil-water System Research Articles

Numerical Simulation of Plant–microbial Remediation for Petroleum-polluted Soil

ABSTRACTThis paper presents a numerical analysis of the migration and transformation mechanism of petroleum hydrocarbons (PHs) pollutants in soil. The mathematical model of the solute migration and plant–microbial remediation for PH polluted soil was established. The model was verified by field experimental data. Then, the software Hydrus-1D was employed to simulate the processes of diffusion, adsorption, desorption, microbial degradation, and plant adsorption of PHs in the soil–water system. The process of plant–microbial remediation for PH-contaminated soil was also simulated. The space-time change of PHs in soil was obtained, and the fate and remediation efficiency of PHs in soil were revealed in different remediation conditions. The results indicated that the Hydrus-1D model can adequately simulate the process of plant–microbial remediation. Plant–microbial remediation appears to be more efficient than the application of bacteria or Suaeda salsa. The majority of PH pollutants are degraded in the upper soil levels. For long-chain petro-alkane-contaminated soil, plant–microbial remediation is a more efficient method. A suitable moisture level in soil is important for improving the bioremediation effect of plant–microbial remediation technology.

Catalyzed hydrogen peroxide combined with CO2 sparging for the treatment of contaminated groundwater

In this work we propose and investigate an innovative groundwater remediation option based on the combination of catalyzed hydrogen peroxide (H2O2) with CO2 sparging. The effectiveness of this new process was evaluated by carrying out lab-scale tests on a soil–water system spiked with Methyl Tertiary Butyl Ether (MtBE). The results achieved with the combined process, evaluated in terms of H2O2 lifetime and MtBE residual concentration in the liquid phase, were then compared with those obtained using H2O2 only or amended with KH2PO4 as stabilizing agent. The experimental results showed that the combined H2O2–CO2 process has basically two beneficial effects. On the one hand, fluxing CO2 into the oxidizing solution can lead to a pH decrease to acidic values that enhance the H2O2 stability. Indeed, from the results obtained in the stability tests carried out, it was observed that the hydrogen peroxide lifetime in the combined H2O2–CO2 process proved to be longer than the one achieved in the tests carried out with H2O2 only, although slightly lower than the one achieved using KH2PO4 as stabilizing agent. On the other hand, it was observed that with respect to a traditional chemical oxidation application, the CO2 sparging can further enhance the overall effectiveness of the process as a result of contaminant stripping by CO2. Indeed, the residual MtBE concentration observed after application of the combined H2O2–CO2 process was slightly lower than the ones obtained using H2O2 only or comparable to the one achieved using H2O2 amended with KH2PO4. Overall, these results showed that the combined H2O2–CO2 process could represent a promising alternative to traditional formulations, avoiding the use of chemical amendments, while leading to comparable residual contaminant’s concentration.

The role of sorption and biodegradation in the removal of acetaminophen, carbamazepine, caffeine, naproxen and sulfamethoxazole during soil contact: A kinetics study

In countries like Spain, where water is a limited resource, reusing effluents from wastewater treatment plants may imply the introduction of incompletely eliminated pollutants into the environment. Therefore, this work identified the role of sorption and biodegradation in attenuating pharmaceutical compounds (acetaminophen, carbamazepine, caffeine, naproxen and sulfamethoxazole) in natural soil. It also determined which sorption and removal (“sorption+biodegradation”) kinetics models describe the behaviour of these substances in the water-soil system. Presence of potential transformation products (TPs) as a result of pharmaceuticals biodegradation was also studied. To this end, serial batch-type experiments were performed with a soil:water ratio of 1:4 and an initial pharmaceutical concentration of 100μgL−1. Despite results are dependent on soil characteristics, they revealed that, for those substances with a higher affinity to the soil used (loamy sand), sorption seems to play a key role during the first 48h of contact with soil, and gives way to biodegradation afterwards. The sorption of the pharmaceuticals studied follows a pseudo second-order kinetics. Caffeine and sulfamethoxazole displayed the fastest initial sorption velocities (h=2055 and h=228μgkg−1h−1, respectively). The removal kinetics experiments, satisfactorily simulated by the first-order kinetics model, indicated the presence of potential microbial adaptation to degradation. Indeed, half-lives decreased from 1.6- to 11.7-fold with respect to initial values. The microbial capacity to degrade sulfamethoxazole could be a matter of concern if bacteria have developed resistance to this antibiotic. Caffeine, acetaminophen and sulfamethoxazole were mitigated to a greater extent, whereas the removal of naproxen and carbamazepine was more limited. The appearance of epoxy-carbamazepine and N4-acetyl-sulfamethoxazole as possible TPs of carbamazepine and sulfamethoxazole, respectively, indicated that biodegradation was incomplete and showed the capacity of soil microbes to transform these substances.

Effect of biochar on migration and biodegradation of 4-n-nonylphenol (NP) during river-based groundwater recharge with reclaimed water

To investigate how biochar affects coupled migration-biodegradation of NP, a lab-scale column was set up to simulate the recharge process. The filler media of the two columns was mainly composed of silty clay (SC) and biochar amendment silty clay (BCSC). The results showed that the attenuation effect of NP in the BCSC system was 3.3% higher than that in the SC system. The attenuation rate constants of NP in the SC and BCSC systems were 0.20 and 0.24 m−1, respectively, which followed first-order kinetics. The two turning points of NP concentration with depth in the leachate were 0.15 and 0.45 m as a result of fast sorption and biodegradation, respectively. The primary metabolites were not the only hydroxylated 4-nonyl-4-hydroxycyclohexa-2,5-dienone and 4-hydroxyphenyl-nonanoic-acid; detached branched alkyl moieties were also produced during the biotransformation process. The accumulation of NP in the soil was higher in BCSC soils than in the SC system. The bacterial community in the upper layer was more diverse than in the bottom layer, which was related to oxygen concentrations in the water-soil system. Five known bacterial classes (Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, Sphingobacteria, and Bacilli) and 15 known bacterial genera (six major genera: Methylobacillus, Azotobacterium, Sphingomonas, Pseudomonas, Bacillus, and Hyphomicrobium) were considered to be NP-degradation-associated bacteria. The bacterial community diversity and percentage of NP-degradation-associated bacteria in the BCSC system were marginally greater than those in the SC system. The higher bacterial diversity and adsorption capacity in the BCSC system were able to mitigate the migration of NP into groundwater.

Removal of 2-ClBP from soil–water system using activated carbon supported nanoscale zerovalent iron

We explored the feasibility and removal mechanism of removing 2-chlorobiphenyl (2-ClBP) from soil–water system using granular activated carbon (GAC) impregnated with nanoscale zerovalent iron (reactive activated carbon or RAC). The RAC samples were successfully synthesized by the liquid precipitation method. The mesoporous GAC based RAC with low iron content (1.32%) exhibited higher 2-ClBP removal efficiency (54.6%) in the water phase. The result of Langmuir–Hinshelwood kinetic model implied that the different molecular structures between 2-ClBP and trichloroethylene (TCE) resulted in more difference in dechlorination reaction rates on RAC than adsorption capacities. Compared to removing 2-ClBP in the water phase, RAC removed the 2-ClBP more slowly in the soil phase due to the significant external mass transfer resistance. However, in the soil phase, a better removal capacity of RAC was observed than its base GAC because the chemical dechlorination played a more important role in total removal process for 2-ClBP. This important result verified the effectiveness of RAC for removing 2-ClBP in the soil phase. Although reducing the total RAC removal rate of 2-ClBP, soil organic matter (SOM), especially the soft carbon, also served as an electron transfer medium to promote the dechlorination of 2-ClBP in the long term.

Fate and transport of the β-adrenergic agonist ractopamine hydrochloride in soil–water systems

The feed additive ractopamine hydrochloride was fortified at four concentrations into batch vials containing soils that differed in both biological activity and organic matter (OM). Sampling of the liquid layer for 14days demonstrated that ractopamine rapidly dissipated from the liquid layer. Less than 20% of the fortified dose remained in the liquid layer after 4hr, and recoveries of dosed ractopamine ranged from 8 to 18% in the liquid layer at 336hr. Sorption to soil was the major fate for ractopamine in soil:water systems, i.e., 42%–51% of the dose at 14days. The major portion of the sorbed fraction was comprised of non-extractables; a smaller fraction of the sorbed dose was extracted into water and acetone, portions which would be potentially mobile in the environment. Partitioning coefficients for all soils suggested strong sorption of ractopamine to soil which is governed by hydrophobic interactions and cation exchange complexes within the soil OM. Ractopamine degradation was observed, but to mostly non-polar compounds which had a higher potential than ractopamine to sorb to soil. The formation of volatiles was also suggested. Therefore, despite rapid and extensive soil sorption, these studies indicated a portion of ractopamine, present in manures used to fertilize soils, may be mobile in the environment via water-borne events.

Migration and biodegradation of BDE-99 in different river-based natural groundwater recharge modes with treated municipal wastewater

Abstract Pentabromodiphenyl ether is one of the most abundant flame retardant additives detected in treated municipal wastewater, river water and sediments in China. When using treated municipal wastewater for recharging river-based natural groundwater, polybrominated diphenyl ether (PBDE) pollution might be a potential threat to underground aquifers. Lab-scale column experiments simulating recharge were conducted to investigate the migration and biodegradation of 2,2′,4,4′5-pentabromodiphenylether (BDE-99) under different recharge modes. Three recharge columns were operated in continual sterilization recharge (CSR), continual recharge (CR), and wetting and drying alternative recharge (WDAR). The results showed that the attenuation effect of the BDE-99 was in the order of CR > WDAR > CSR, whereas the intermediate products of PBDE biodegradation were in the order of WDAR > CR > CSR. The attenuation rate constants of BED-99 in the CSR, CR and WDAR systems were 0.105, 0.139 and 0.127 m−1, respectively, which followed first-order kinetics. The primary debrominated metabolites were BDE-15, -28, -47 in the CR system, whereas high-brominated diphenyl ethers (BDE-153, -154, -183) and isomers of BDE-99 (BDE-100) were also produced during the biotransformation process in the WDAR system. The accumulation amount of BDE-99 was higher in WDAR soils than in the CR system, whereas the intermediate product concentration of PBDEs and OH-PBDEs were in reverse order. According to the high-throughput sequencing, the bacterial community in the upper layer was more diverse than in the bottom layer, which was related to the oxygen concentrations, BDE-99 and its halogenated intermediate concentrations in the water-soil system. The dominant groups were found to be proteobacteria, Acidobateria, and Firmcutes, including Gammaproteobacteria, Betaproteobacteria, Alphaproteobacteria, Acidobateria-6, and Clostridia, suggesting that these microbes might play an important role in BDE-99 and intermediate metabolite degradation. The findings of this study provide an understanding of PBDE accumulation in natural groundwater recharge areas under different recharging operation modes and can facilitate the prediction of the fate of PBDEs in underground aquifers.

Reduction and persulfate oxidation of nitro explosives in contaminated soils using Fe-bearing materials.

The oxidative and reductive transformation of nitro explosives in contaminated soils with Fe-bearing materials and persulfate (S2O8(2-)) was examined via batch experiments. Zero-valent cast iron [Fe(0)], steel dust from a steel manufacturing plant, and FeS rapidly reduced 2,4,6-trinitrotoluene (TNT) and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) in soil under anaerobic conditions as long as a sufficient amount of water was present. The Fe-bearing materials also effectively activated persulfate to enhance the oxidative transformation of TNT and RDX in soil-water systems. Kinetically, reductive and oxidative transformations removed more than 90% of the explosives from a soil-water system within 5 h under the given conditions. Pseudo-first-order rates in the range of 0.7-23.4 h(-1) were observed. By increasing the concentration of persulfate or Fe-bearing materials, the oxidative transformation could be promoted. Treated soils via redox reactions using the Fe-bearing materials did not show significant toxicity, except for the case of TNT-contaminated soils oxidized by FeS-assisted persulfate. Considering the kinetics of explosive degradation and the toxicity of treated wastewaters and soils, Fe(0) or steel dust-assisted persulfate oxidation may be a safe option as an ex situ remediation process for the treatment of explosive-contaminated soils.

A Thermomechanical Transport Approach and Application in Soil-Water System of Polluted Mining Areas considering the Three-Phase Coupling

The thermomechanical transport approach includes the process of diffusing or the condition of being diffused, absorption/desorption, swell/shrink, equilibrium/nonequilibrium, and thermomechanical transport of contaminant in three phases of polluted mining soil which are discussed. The thermomechanical transport model of the contaminants transport in polluted soil is established, and its basic equations are given. Based on that, the distribution regularities of the contaminant seepage in water-soil system are discussed in detail and the sensitivities of parameters are analyzed. The study shows that the parameter has important influence on the contamination distribution and transportation in polluted soil-water system. The influence degree is also related to the action of seepage force directly.

Mowing with invasive machinery can affect chemistry and trophic state of rheophilous mire

Vegetation management in the form of mowing or grazing is usually the obvious prescription for the protection of open wetlands facing the threat of secondary plant succession. This study assessed and quantified the response of the chemistry of a rheophilous mire to oxygen shortages caused by the decomposition of organic matter forced into the floodwater/surface water by the caterpillars of mowing machinery. We hypothesized that the addition of readily available carbon in the form of cut biomass would affect the redox conditions of the soil–water system and consequently enhance P mobilization from soil storage. The laboratory experiment demonstrated that the input of biomass produced favorable conditions (mean Eh<−250mV) for the release of the redox-sensitive fraction of P. The net P release generated a flux of P from the soil to the water column, reaching more than 200μmolm−2day−1. The changes in the soluble reactive phosphorus (SRP) concentration coincided with those in Fe(II)aq; however, a significant relationship was found for only a few of the microcosms under analysis. The intensive release of P increased the SRP concentration in floodwater overlying the soil column to 3.6μmolL−1, which was one order of magnitude higher than under the initial experiment conditions and the concentration expected in the field. We conclude that mowing using invasive machinery can destroy the fragile state of dynamic equilibrium that is responsible for low P availability and may consequently affect the oligotrophy of the ecosystem.

Application of column tests and electrical resistivity methods for leachate transport monitoring

Abstract Development of the human civilization leads to the pollution of environment. One of the contamination which are a real threat to soil and groundwater are leachates from landfills. In this paper the solute transport through soil was considered. For this purpose, the laboratory column tests of chlorides tracer and leachates transport on two soil samples have been carried out. Furthermore, the electrical resistivity method was applied as auxiliary tool to follow the movements of solute through the soil column what allowed to compare between the results obtained with column test method and electrical resistivity measurements. Breakthrough curves obtained by conductivity and resistivity methods represents similar trends which leads to the conclusion about the suitability of electrical resistivity methods for contamination transport monitoring in soil-water systems.

Assessment of sorption of 137Cs and 90Cr in model soil-water systems

The paper has investigated sorption of 137Cs and 90Sr on natural clayey minerals—montmorrilonite of the Cherkassy and kaolinite of Hlukhovets deposits and their modified forms by means of precipitation of hydroxides of Fe(III) an humic acids with fraction of total mass 5%. It has been found that both for natural minerals and for their modified forms the most effective sorption of radionuclides from aqueous solutions is observed in a broad area of the pH characteristic of natural soil media. An increase of the sorption value of radionuclides occurs in the series: M < M-GK < M-Fe. A similar relationship is observed also for kaolinite samples. We have determined the impact on the sorption of 137Cs and 90Sr of cations-macrocomponents—Na+ and Ca2+ characteristic of natural water media.

Sorption characteristics and factors affecting the adsorption behavior of bisphenol A and 17β-estradiol/ethinyl estradiol in river- and farmland-based artificial groundwater recharge with reclaimed water

Endocrine-disrupting chemicals (EDCs) in river- and farmland-based natural groundwater recharge using reclaimed municipal wastewater pose a major threat to groundwater-based drinking water supplies in Beijing, China. The sorption characteristics of three selected typical EDCs, bisphenol A (BPA), 17β-estradiol (E2), and ethinyl estradiol (EE2) were investigated in river sediment– and farmland soil–water systems to simulate the sorption process and the factors influencing sorption during reclaimed water recharge. The results showed that the two-compartment first-order model fitted the kinetics of sorption very well (R2 > 0.99). The fast sorption rates for E2 and EE2 onto soil were higher than those onto sediment, while the rate was different for BPA. The partitioning and π–π bonds might be a relatively more important mechanism for the sorption of BPA onto sediment, while surface adsorption contributed significantly to E2 and EE2 sorption onto soil. The fast sorption rate was negatively correlated to the △G values in all adsorption media. The average removal rate (η) of the three EDCs was in the order η(BPA) < η(17β−E2) < η(EE2) and soil < sediment which showed that E2 was easily adsorbed onto sediment, while BPA was more mobile in the farmland-based artificial groundwater recharge system. The absolute free energy values of ΔG were less than 40 kJ/mol, indicating that the adsorption process consisted primarily of physical sorption. With an increase in pH value, the adsorption capacity and partition coefficient clearly decreased, especially when the pH value was higher than the pKa values of the EDCs. The amounts of BPA, E2, and EE2 that were adsorbed increased with an increase in ionic strength, especially for the E2 and EE2, because the amount of ion exchange and polar sorption would increase. However, these values decreased with an increase in temperature. These results could be useful for predicting a potential pathway for removal and the ecological risks of EDCs when using reclaimed municipal wastewater for aquifer recharge.

Thallium occurrence and partitioning in soils and sediments affected by mining activities in Madrid province (Spain)

Thallium (Tl) and its compounds are toxic to biota even at low concentrations but little is known about Tl concentration and speciation in soils. An understanding of the source, mobility, and dispersion of Tl is necessary to evaluate the environmental impact of Tl pollution cases. In this paper, we examine the Tl source and dispersion in two areas affected by abandoned mine facilities whose residues remain dumped on-site affecting to soils and sediments of natural water courses near Madrid city (Spain). Total Tl contents and partitioning in soil solid phases as determined by means of a sequential extraction procedure were also examined in soils along the riverbeds of an ephemeral and a permanent streams collecting water runoff and drainage from the mines wastes. Lastly, electronic microscopy and cathodoluminescence probe are used as a suitable technique for Tl elemental detection on thallium-bearing phases. Tl was found mainly bound to quartz and alumino-phyllosilicates in both rocks and examined soils. Besides, Tl was also frequently found associated to organic particles and diatom frustules in all samples from both mine scenarios. These biogenic silicates may regulate the transfer of Tl into the soil-water system.

Application of Low-Cost Adsorbents for Pesticide Removal

Pesticides released from agricultural practices are an important class of pollutants due to their reported toxicity even at trace levels. Therefore, pesticides removal is an increasing concern. Among various treatment methods, adsorption is supposed as the best one due to its inexpensiveness, universal nature and ease of operation. This review highlights and provides an overview of the use of cheap and non-pollutant materials as an viable alternative for pesticide and their metabolite adsorption process and removal technology. However, there is a lack of data on field scale application for testing of adsorption units using single biosorbents and their combinations to recover pesticides from soil-water system. This work describes a global assessment of the equilibrium modeling of biosorption processes as well as the structural, chemical and morphological modification and activation of biosorbents.

The study of adsorption mechanism of mixed pesticides prometryne-acetochlor in the soil–water system

This article reported adsorption mechanism of mixed pesticides Prometryne-Acetochlor (PA) in soil. Thermodynamics and adsorption isotherms were used to preliminarily evaluate adsorption force, and IR and XRD were used to characterize adsorption characteristics between Prometryne/Acetochlor (PA) and soil, The result shows that adsorption isotherms is F-type, adsorptive heat are 9.57 kJ/mol and −93.83 kJ/mol of prometryne and acetochlor respectively. Hydrogen bonds also had been confirmed by IR and XRD analysis. The results can provide a theoretical support to the use of mixed pesticides agents.

Migration and biotransformation of three selected endocrine disrupting chemicals in different river-based aquifers media recharge with reclaimed water

When using reclaimed water for the river-based artificial groundwater recharge, endocrine disrupting chemicals (EDCs) pollution is believed to be a potential threat to the drinking water supplies in Beijing, China. Lab-scale column experiments simulating recharge were conducted to study the migration and transformation of three selected EDCs, namely ethinylestradiol (EE2), 4-n-Nonylphenol (NP) and bisphenol A (BPA). The filler media of the two columns mainly consisted of fine sand (FS) in the middle section and less-permeable silty clay (SC) in the southern section, all representative soil vadose zone media from Chaobai river in Beijing. The results showed that the attenuation effect of EDCs was in the order of NP > EE2 > BPA and all of them followed a first-order kinetics, while the migration capacity was in the reverse order. The residual EDCs in different depths of SC were much higher than those in FS, suggesting that the SC soil has a significantly higher adsorption capacity. The attenuation effect of NP and BPA by unit mass was better in FS than that in SC, indicating that the biodegradation was the main attenuation mechanism. The bacterial biomass and community diversity decreased with depth in SC, while the changes in FS were unobvious. According to the DGGE fingerprints, the bacterial community in the middle layer was more diverse than in the upper layer, which was related to the EDCs concentrations and transformation products in the water-soil system. The dominant group was found to be proteobacteria, including Alphaproteobacteria, Betaproteobacteria and Gammaproteobacteria, suggesting that these microbes might play an important role in EDC transformation. The described process provides a potential pathway for improving the removal of EDCs.

Multivariate analysis of heavy metal leaching from urban soils following simulated acid rain

Heavy metal pollution in urban soils and its effect on urban ecological environment and human health are of increasing concern. In this study, a leaching experiment was conducted to assess the effect of simulated acid rain (SAR) on the migration of Cd, Pb, Cu, and Zn and their transformation and speciation in nine natural urban soils from Guangzhou, China, combined with two-dimensional hierarchical cluster analysis (2-D HCA) heat map and principal component analysis (PCA). The maximum concentrations of Zn and Cu in leachates were lower than Grade III of Chinese Environmental Quality Standards for Ground and Surface water, although being seriously contaminated with Zn (up to 19,570mg/kg) and Cu (322.4), thereby suggesting that Zn and Cu leached from urban soils receiving SAR pose little risk of water pollution. However, the maximum concentrations of Pb and Cd in leachates exceeded Grade III and V of the standards, respectively. The proportions of metals in the non-residual fractions were generally decreased after the leaching test for S(oil)5 (with high concentrations of metals in leachate), representing the decreased contamination risk in the soil–water system. A similar trend was observed for S(oil)6 (with low concentrations of metals in leachate) in terms of Zn and Cu, whereas the proportions of Cd and Pb in the non-residual fractions of S6 increased after leaching. Significantly positive relationships were observed between the concentration of heavy metal in leachate and all fractions of heavy metal, as well as the total concentration of soil heavy metals. In terms of Zn, Cd, and Pb, there were negative relationships between the concentration of heavy metal in leachate and clay and silt, respectively, while the inverse relationships were observed for Cu. The release of heavy metals from soil was strongly associated with their fractions and such soil properties as pH, soil texture, and organic matter.

Abiotic soil changes induced by engineered nanomaterials: A critical review

A large number of research papers on the fate of engineered nanomaterials (ENMs) in the soil–water system have appeared in recent years, focusing on ENM transport, persistence and toxicological impact. It is clear from these publications that soil is a major sink for ENMs, and that only a small portion degrades or is mobilized further into groundwater. However, to date, very few studies have examined the impact of ENMs on the natural soil–subsurface matrix and its properties. Moreover, it is now well accepted that chemical contaminants are capable of changing soil properties either by inducing direct chemical or physical changes, or through indirect changes by, e.g., influencing biological activity that in turn modifies soil properties. Here, we review studies on the deposition, retention, and accumulation of ENMs in soil, indicative of the extent to which soil acts as a major sink of ENMs. We then examine evidence of how these retained particles lead to modification of surface properties, which are manifested by changes in the sorption capacity of soil for other (organic and inorganic) solutes, and by surface charges and composition different than the natural surfaces. Finally, we demonstrate how this results in physical and hydrological changes to soil properties, including hydraulic conductivity, swelling capacity and wettability. The overall picture revealed in this critical review sheds light on a perspective that has received little attention thus far. These aspects of soil change, due to exposure and subsequent accumulation of ENMs, may ultimately prove to be one of the most important impacts of ENM releases to the environment.

Adsorption and biodegradation of three selected endocrine disrupting chemicals in river-based artificial groundwater recharge with reclaimed municipal wastewater

Endocrine disrupting chemical (EDC) pollution in river-based artificial groundwater recharge using reclaimed municipal wastewater poses a potential threat to groundwater-based drinking water supplies in Beijing, China. Lab-scale leaching column experiments simulating recharge were conducted to study the adsorption, biodegradation, and transport characteristics of three selected EDCs: 17β-estradiol (E2), 17α-ethinylestradiol (EE2) and bisphenol A (BPA). The three recharge columns were operated under the conditions of continual sterilization recharge (CSR), continual recharge (CR), and wetting and drying alternative recharge (WDAR). The results showed that the attenuation effect of the EDCs was in the order of WDAR>CR>CSR system and E2>EE2>BPA, which followed first-order kinetics. The EDC attenuation rate constants were 0.0783, 0.0505, and 0.0479m−1 for E2, EE2 and BPA in the CR system, respectively. The removal rates of E2, EE2, and BPA in the CR system were 98%, 96% and 92%, which mainly depended on biodegradation and were affected by water temperature. In the CR system, the concentrations of BPA, EE2, and E2 in soil were 4, 6 and 10 times higher than in the WDAR system, respectively. According to the DGGE fingerprints, the bacterial community in the bottom layer was more diverse than in the upper layer, which was related to the EDC concentrations in the water-soil system. The dominant group was found to be proteobacteria, including Betaproteobacteria and Alphaproteobacteria, suggesting that these microbes might play an important role in EDC degradation.