ORCID Profile
0000-0001-5846-6071
Current Organisation
Foshan University
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Publisher: Elsevier BV
Date: 04-2018
DOI: 10.1016/J.SCITOTENV.2017.11.159
Abstract: Polybrominated diphenyl ethers (PBDEs) are common pollutants released from electronic waste (e-waste) dismantling and recycling activities. Our city-wide survey of agricultural soils in Qingyuan (40 s ling sites), where e-waste recycling has been active, observed exceedance of PBDEs above background levels (average of 251.9ngg
Publisher: Elsevier BV
Date: 10-2020
Publisher: Elsevier BV
Date: 04-2021
Publisher: Elsevier BV
Date: 09-2016
DOI: 10.1016/J.CHEMOSPHERE.2016.06.030
Abstract: While chelant-enhanced soil washing has been widely studied for metal extraction from contaminated soils, there are concerns about destabilization and leaching of residual metals after remediation. This study integrated 2-h soil washing enhanced by biodegradable ethylenediaminedisuccinic acid (EDDS) and 2-month stabilization using agricultural waste product (soybean stover biochar pyrolyzed at 300 and 700 °C), industrial by-product (coal fly ash (CFA)), and their mixture. After integration with 2-month stabilization, the leachability and mobility of residual metals (Cu, Zn, and Pb) in the field-contaminated soil were significantly reduced, especially for Cu, in comparison with 2-h EDDS washing alone. This suggested that the metals destabilized by EDDS-washing could be immobilized by subsequent stabilization with biochar and CFA. Moreover, when the remediation performance was evaluated for phytoavailability and bioaccessibility, prior EDDS washing helped to achieve a greater reduction in the bioavailable fraction of metals than sole stabilization treatment. This was probably because the weakly-bound metals were first removed by EDDS washing before stabilization. Both in idual and combined applications of biochar and CFA showed comparable effectiveness regardless of the difference in material properties, possibly due to the high level of amendments (150 ton ha(-1)). Based on the mobility and bioaccessibility results, the estimated human health risk (primarily resulting from Pb) could be mitigated to an acceptable level in water consumption pathway or reduced by half in soil ingestion pathway. These results suggest that an integration of EDDS washing with soil stabilization can alleviate post-remediation impacts of residual metals in the treated soil.
Publisher: Elsevier BV
Date: 06-2018
DOI: 10.1016/J.SCITOTENV.2017.12.194
Abstract: To date, no investigation has been carried out to explore the effects of biochars produced at different pyrolysis temperatures on the dynamics of redox potential (E
Publisher: Elsevier BV
Date: 06-2019
DOI: 10.1016/J.ENVINT.2019.03.040
Abstract: Mercury (Hg) is a highly toxic element, which is frequently enriched in flooded soils due to its anthropogenic release. The mobilization of Hg and its species is of ultimate importance since it controls the transfer into the groundwater and plants and finally ends in the food chain, which has large implications on human health. Therefore, the remediation of those contaminated sites is an urgent need to protect humans and the environment. Often, the stabilization of Hg using amendments is a reliable option and biochar is considered a candidate to fulfill this purpose. We tested two different pine cone biochars pyrolyzed at 200 °C or 500 °C, respectively, with a view to decrease the mobilization of total Hg (Hg
Publisher: Elsevier BV
Date: 03-2018
DOI: 10.1016/J.SCITOTENV.2017.10.310
Abstract: In this study, soil washing and stabilization as a two-step soil remediation strategy was performed to remediate Pb- and Cu-contaminated soils from shooting range and railway sites. Ferric nitrate (Fe(NO
Publisher: Springer Science and Business Media LLC
Date: 03-2016
DOI: 10.1007/S10653-016-9808-2
Abstract: Permeable reactive barriers (PRBs) have proved to be a promising passive treatment to control groundwater contamination and associated human health risks. This study explored the potential use of low-cost adsorbents as PRBs media and assessed their longevity and risk mitigation against leaching of acidic rainfall through an e-waste recycling site, of which Cu, Zn, and Pb were the major contaminants. Batch adsorption experiments suggested a higher adsorption capacity of inorganic industrial by-products [acid mine drainage sludge (AMDS) and coal fly ash (CFA)] and carbonaceous recycled products [food waste compost (FWC) and wood-derived biochar] compared to natural inorganic minerals (limestone and apatite). Continuous leaching tests of sand columns with 10 wt% low-cost adsorbents were then conducted to mimic the field situation of acidic rainfall infiltration through e-waste-contaminated soils (collected from Qingyuan, China) by using synthetic precipitation leaching procedure (SPLP) solution. In general, Zn leached out first, followed by Cu, and finally delayed breakthrough of Pb. In the worst-case scenario (e.g., at initial concentrations equal to 50-fold of average SPLP result), the columns with limestone, apatite, AMDS, or biochar were effective for a relatively short period of about 20-40 pore volumes of leaching, after which Cu breakthrough caused non-cancer risk concern and later-stage Pb leaching considerably increased both non-cancer and lifetime cancer risk associated with portable use of contaminated water. In contrast, the columns with CFA or FWC successfully mitigated overall risks to an acceptable level for a prolonged period of 100-200 pore volumes. Therefore, with proper selection of low-cost adsorbents (or their mixture), waste-based PRBs is a technically feasible and economically viable solution to mitigate human health risk due to contaminated groundwater at e-waste recycling sites.
Publisher: Elsevier BV
Date: 2018
DOI: 10.1016/J.ENVPOL.2017.09.040
Abstract: The behaviour of arsenic (As) from geogenic soil exposed to aerobic conditions is critical to predict the impact of As on the environment, which processes remain unresolved. The current study examined the depth profile of As in geologically derived subsoil cores from Hong Kong and investigated the mobilization, plant availability, and bioaccessibility of As in As-contaminated soil at different depths (0-45.8 m). Results indicated significant heterogeneity, with high levels of As in three layers of soil reaching up to 505 mg/kg at a depth of 5 m, 404 mg/kg at a depth of 15 m, and 1510 mg/kg at a depth of 27-32 m. Arsenic in porewater s les was <11.5 μg/L in the study site. X-ray absorption spectroscopy (XAS) indicated that main As species in soil was arsenate (As(V)), as adsorbed fraction to Fe oxides (41-69% on goethite and 0-8% on ferrihydrite) or the mineral form scorodite (30-57%). Sequential extraction procedure demonstrated that 0.5 ± 0.4% of As was exchangeable. Aerobic incubation experiments exhibited that a very small amount (0.14-0.48 mg/kg) of As was desorbed from the soil because of the stable As(V) complex structure on abundant Fe oxides (mainly goethite), where indigenous microbes partly (59 ± 18%) contributed to the release of As comparing with the sterilized control. Furthermore, no As toxicity in the soil was observed with the growth of ryegrass. The bioaccessibility of As was <27% in the surface soil using simplified bioaccessibility extraction test. Our systematic evaluation indicated that As in the geogenic soil profile from Hong Kong is relatively stable exposing to aerobic environment. Nevertheless, children and workers should avoid incidental contact with excavated soil, because high concentration of As was present in the digestive solution (<0.1-268 μg/L).
Publisher: Elsevier BV
Date: 12-2017
DOI: 10.1016/J.SCITOTENV.2017.04.208
Abstract: This study evaluated the feasibility of 2-h chemical-enhanced washing of As-containing soil resulting from geogenic sources in Hong Kong and the fate of As before and after remediation. The soil morphology and As speciation in soil was elucidated by scanning electron microscopy with energy dispersive X-ray spectroscopy, X-ray diffractometer, X-ray photoelectron spectroscopy, and X-ray absorption spectroscopy. Integrated analysis of the results suggests that the As (>90%) resides predominantly as arsenate bound to ferric iron oxides, with a minor contribution (<10%) from an As
Publisher: Elsevier BV
Date: 09-2017
DOI: 10.1016/J.CHEMOSPHERE.2017.05.019
Abstract: Geogenic sources of arsenic (As) have aroused extensive environmental concerns in many countries. This study evaluated the vertical profiles, leaching characteristics, and surface characteristics of As-containing soils in Hong Kong. The results indicated that elevated levels of As (486-1985 mg kg
Publisher: Elsevier BV
Date: 08-2018
DOI: 10.1016/J.CHEMOSPHERE.2018.04.081
Abstract: Chelant-enhanced soil washing, such as EDTA (ethylenediaminetetraacetic acid) and biodegradable EDDS ([S,S]-ethylene-diamine-disuccinic acid), has been widely studied, however, EDTA is persistent under natural conditions while EDDS has a low efficiency for Pb extraction. Therefore, we investigated the efficacy of mixed chelants (EDDS and EDTA mixture at 1:1 M ratio) for the removal of Cu, Zn, and Pb from a field-contaminated soil using various washing schemes (multi-pulse, step-gradient chelant, and continuous washing schemes). Speciation modelling of the target metals, mineral elements, and EDDS/EDTA was performed, while the leachability and bioaccessibility of residual metals in the treated soils were also assessed. Our results suggested that the combined use of EDDS and EDTA reached equivalent extraction efficiency of the target metals as EDTA, i.e., 50% reduction in the dosage of EDTA was made possible. This was accomplished by selective extraction of Cu by EDDS and Pb by EDTA, which was supported by the results of speciation calculation. Multi-pulse washing scheme with intermittent water rinsing steps removed entrapped metal-chelant complexes and free chelants, therefore reducing the leachability and bioaccessibility of residual metals in the treated soils. Step-gradient chelant washing with the maximum dosage of chelants in the first washing step only achieved marginal improvement but undesirably promoted Pb bioaccessibility. Continuous washing for 24 h enhanced metal extraction but promoted mineral dissolution, together with a large amount of uncomplexed chelants and increase in Cu leachability. Thus the combined use of EDDS and EDTA in multi-pulse washing is recommended for further studies.
Publisher: Elsevier BV
Date: 2017
DOI: 10.1016/J.CHEMOSPHERE.2016.09.110
Abstract: To enhance extraction of strongly bound metals from oxide minerals and organic matter, this study examined the sequential use of reductants, oxidants, alkaline solvents and organic acids followed by a biodegradable chelating agent (EDDS, [S,S]-ethylene-diamine-disuccinic-acid) in a two-stage soil washing. The soil was contaminated by Cu, Zn, and Pb at an e-waste recycling site in Qingyuan city, China. In addition to extraction efficiency, this study also examined the fate of residual metals (e.g., leachability, bioaccessibility, and distribution) and the soil quality parameters (i.e., cytotoxicity, enzyme activities, and available nutrients). The reductants (dithionite-citrate-bicarbonate and hydroxylamine hydrochloride) effectively extracted metals by mineral dissolution, but elevated the leachability and bioaccessibility of metals due to the transformation from Fe/Mn oxides to labile fractions. Subsequent EDDS washing was found necessary to mitigate the residual risks. In comparison, prior washing by oxidants (persulphate, hypochlorite, and hydrogen peroxide) was marginally useful because of limited amount of soil organic matter. Prior washing by alkaline solvents (sodium hydroxide and sodium bicarbonate) was also ineffective due to metal precipitation. In contrast, prior washing by low-molecular-weight organic acids (citrate and oxalate) improved the extraction efficiency. Compared to hydroxylamine hydrochloride, citrate and oxalate induced lower cytotoxicity (Microtox) and allowed higher enzyme activities (dehydrogenase, acid phosphatase, and urease) and soil nutrients (available nitrogen and phosphorus), which would facilitate reuse of the treated soil. Therefore, while sequential washing proved to enhance extraction efficacy, the selection of chemical agents besides EDDS should also include the consideration of effects on metal leachability/bioaccessibility and soil quality.
Publisher: Elsevier BV
Date: 2018
DOI: 10.1016/J.SCITOTENV.2017.09.015
Abstract: Remediation of CCA-contaminated soil (Cr, Cu, and As) by biodegradable chelant-enhanced washing (EDDS, S,S-ethylene-diamine-disuccinic-acid) needs further enhancement. This study investigated the effectiveness of coupling with pre-treatment by selective dissolution and post-treatment by soil amendments, respectively. Three groups of reagents (reductants, alkaline solvents, and organic ligands) were adopted in the pre-treatment to dissolve the oxide minerals before EDDS extraction. In the post-treatment, soil amendments (coal fly ash (CFA), acid mine drainage sludge (AMDS), green waste compost (GWC)), and their mixtures) were used for a 2-month stabilization after 2-h EDDS washing. Multi-endpoint evaluation was performed by assessing the chemical state, leachability, mobility, bioaccessibility, and plant-availability of residual metal(loid)s as well as the cytotoxicity, enzyme activities, and available nutrients of the treated soils. Pre-treatment by dithionite-citrate-bicarbonate significantly enhanced extraction efficiency, but also increased the leachability of As and Cr and bioaccessibility of Cr in the treated soils. While sodium hydroxide removed the majority of As without increasing its leachability and bioaccessibility, it increased the cytotoxicity and inhibited the acid phosphatase activity. Post-treatment with AMDS and CFA effectively controlled the mobility and leachability of residual As and Cr after EDDS washing. However, destabilized Cu was only marginally immobilized by GWC due to strong Cu-EDDS complexation. The bioaccessibility and phytoavailability of Cu was primarily reduced by EDDS washing, while those of As and Cr could be attenuated by AMDS and CFA. This study indicates that coupling chemical extraction with subsequent soil amendment plays complementary roles in mitigating effects of residual metal(loid)s and improving environmental quality.
Publisher: Elsevier BV
Date: 02-2020
DOI: 10.1016/J.ENVINT.2019.105376
Abstract: Biochar can reduce the mobility and availability of potentially toxic elements (PTEs) in soils and improve soil properties. However, immobilization efficiencies of biochar can be varied according to environmental conditions, such as pH and redox potential (E
Publisher: Elsevier BV
Date: 08-2018
Publisher: Elsevier BV
Date: 07-2017
DOI: 10.1016/J.CHEMOSPHERE.2017.03.022
Abstract: Biochar has been adopted to control the mobility and phytoavailability of trace elements (TEs) in soils. To date, no attempt has been made to determine the mobility and phytoavailability of arsenic (As) and lead (Pb) in a contaminated soil with biochars as amendments under predefined redox potentials (E
Publisher: Elsevier BV
Date: 08-2018
DOI: 10.1016/J.SCITOTENV.2018.02.247
Abstract: The low-alkalinity stabilization/solidification (S/S) treatment of the soil containing high concentrations of geogenic As by physical encapsulation is considered as a proper management before land development however, the choice of an effective binder and the leaching potential of As remain uncertain. In this study, the influence of S/S binders (cement blended with fuel ash (FA), furnace bottom ash (FBA), or ground granulated blast furnace slag (GGBS)) on the speciation and leaching characteristics of geogenic As was studied. The results of X-ray diffractometer (XRD) and X-ray photoelectron spectroscopy (XPS) showed the reduced amount of calcium silicate hydrate phase and the decrease in oxidation state of As(V)-O on the surface of Fe(III) oxides/hydroxides in the low-alkalinity S/S treated soils. This might be due to the binder incorporation and change in pH conditions, which slightly affected the As-Fe interaction and increased the non-specifically sorbed species of As. Therefore, the S/S treatment increased the leachability and bioaccessibility of geogenic As to varying degree but decreased the phyto-extractable As. The S/S treatment by cement incorporating 25% of class C fly ash (O4C1) could achieve comparable or better performance, while reducing the risk assessment code (RAC) to a greater extent compared to that of using cement only. This study illustrates the effectiveness and limitations of low-alkalinity binders (e.g., O4C1) for geogenic As immobilization and encapsulation, which provides a new insight for determining the appropriate S/S binder in soil remediation.
Publisher: Springer Science and Business Media LLC
Date: 06-10-2017
DOI: 10.1007/S11356-017-0266-X
Abstract: Cement-based stabilization/solidification (S/S) is a practical treatment approach for hazardous waste with anthropogenic As sources however, its applicability for geogenic As-containing soil and the long-term leaching potential remain uncertain. In this study, semi-dynamic leaching test was performed to investigate the influence of S/S binders (cement blended with fuel ash (FA), furnace bottom ash (FBA), or ground granulated blast furnace slag (GGBS)) on the long-term leaching characteristics of geogenic As. The results showed that mineral admixtures with higher Ca content and pozzolanic activity were more effective in reducing the leached As concentrations. Thus, cement blended with FBA was inferior to other binders in suppressing the As leaching, while 20% replacement of ordinary Portland cement by GGBS was considered most feasible for the S/S treatment of As-containing soils. The leachability of geogenic As was suppressed by the encapsulation effect of solidified matrix and interlocking network of hydration products that were supported by scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) results. The long-term leaching of geogenic As from the monolithic s les was diffusion-controlled. Increasing the Ca content in the s les led to a decrease in diffusion coefficient and an increase in feasibility for "controlled utilization" of the S/S-treated soils.
Location: Hong Kong
No related grants have been discovered for Jingzi Beiyuan.