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Prediction of selenium uptake by pak choi in several agricultural soils based on diffusive gradients in thin-films technique and single extraction Texto completo
2020
Peng, Qin | Wang, Dan | Wang, Mengke | Zhou, Fei | Yang, Wenxiao | Liu, Yongxian | Liang, Dongli
The accurate assessment of soil selenium (Se) bioavailability is crucial for Se biofortification in Se-deficient areas and risk assessment in selenosis areas. However, a universally accepted approach to evaluate Se bioavailability in soil is currently lacking. This research investigated Se bioavailability in six soils treated with selenite (Se(IV)) or selenate (Se(VI)) by comparing diffusive gradients in thin-films (DGT) technique and chemical extraction methods through pot experiments. A bioindicator method was used to evaluate Se concentrations in pak choi and compare the results with the Se concentration measured by other methods. Results showed that chemical extraction methods presented different extraction efficiencies for available Se over a range of soil types, and the same extraction method had various extraction efficiencies for different Se species in the same soil. DGT measured Se concentrations (CDGT−Se) for Se(VI) treatment were 2.3–34.1 times of those for Se(IV) treatment. KH2PO4–K2HPO4 and AB-DTPA extractable Se could predict the bioavailability of soil Se, but they were disturbed by soil properties. HAc extraction was unsuitable for evaluating Se bioavailability in different Se(IV)-treated soils. By contrast, DGT technique was preferable for predicting plant uptake of Se(IV) over chemical extraction methods. Although DGT technique was independent of soil properties, KH2PO4–K2HPO4 extraction provided the best fitting regression equation for Se(VI) when it was dependent on soil organic matter. Thus, KH2PO4–K2HPO4 extraction may be preferred to assess Se(VI) bioavailability in different soil types on a large scale.
Mostrar más [+] Menos [-]Modelling Hg mobility in podzols: Role of soil components and environmental implications Texto completo
2020
Gómez-Armesto, Antía | Martínez Cortizas, Antonio | Ferro-Vázquez, Cruz | Méndez-López, Melissa | Arias-Estévez, Manuel | Nóvoa-Muñoz, Juan Carlos
A high-resolution soil sampling has been applied to two forest podzols (ACB-I and ACB-II) from SW Europe in order to investigate the soil components and processes influencing the content, accumulation and vertical distribution of Hg. Total Hg contents (THg) were 28.0 and 23.6 μg kg⁻¹ in A horizons of ACB-I and ACB-II, then they strongly decreased in the E horizons and peaked in the Bhs horizons of both soils (55.3 and 63.0 μg kg⁻¹). THg decreased again in BwC horizons to 17.0 and 39.8 μg kg⁻¹. The Bhs horizons accounted for 46 and 38% of the total Hg stored (ACB-I and ACB-II, respectively). Principal component analysis (PCA) and principal components regression (PCR), i.e. using the extracted components as predictors, allowed to distinguish the soil components that accounted for Hg accumulation in each horizon. The obtained model accurately predicted accumulated Hg (R² = 0.845) through four principal components (PCs). In A horizons, Hg distribution was controlled by fresh soil organic matter (PC4), whereas in E horizons the negative values of all PCs were consistent with the absence of components able to retain Hg and the corresponding very low THg concentrations. Maximum THg contents in Bhs horizons coincided with the highest peaks of reactive Fe and Al compounds (PC1 and PC2) and secondary crystalline minerals (PC3) in both soils. The THg distribution in the deepest horizons (Bw and BwC) seemed to be influenced by other pedogenetic processes than those operating in the upper part of the profile (A, E and Bhs horizons). Our findings confirm the importance of soils in the global Hg cycling, as they exhibit significant Hg pools in horizons below the uppermost O and A horizons, preventing its mobilization to other environmental compartments.
Mostrar más [+] Menos [-]Redox reactions between chromium(VI) and hydroquinone: Alternative pathways for polymerization of organic molecules Texto completo
2020
Tzou, Yu-Min | Chen, Kai-Yue | Cheng, Ching-Yun | Lee, Way-Zen | Teah, Heng Yi | Liu, Yu-Ting
Chromium (VI) reduction by organic compounds is one of the major pathways to alleviate the toxicity and mobility of Cr(VI) in the environment. However, oxidative products of organic molecules receive less scientific concerns. In this study, hydroquinone (H₂Q) was used as a representative organic compound to determine the redox reactions with Cr(VI) and the concomitant oxidative products. Spectroscopic analyses showed that Cr(III) hydroxides dominated the precipitates produced during redox reactions of Cr(VI) and H₂Q. For the separated filtrates, the acidification induced the oxidative polymerization of organic molecules, accompanied with the complexation with Cr(III). The aromatic domains dominated the chemical structures of the black and fluffy organic polymers, which was different to the natural humic acids due to the shortage of aliphatic chains. Results of linear combination fitting (LCF) for Cr K-edge X-ray absorption near edge structure (XANES) spectra demonstrated that up to 90.4% of Cr inventory in precipitates derived after the acidification of filtrates was Cr(III) complexed with humic-like polymers, suggesting that Cr(III) possibly acted as a linkage among organic molecules during the polymerization processes of H₂Q. This study demonstrated that Cr(VI) may lead to the polymerization of organic molecules in an acidic solution, and thus, it could raise scientific awareness that the oxidative decomposition of organic molecules may not be the only pathway while interacting with the strong oxidant of Cr(VI).
Mostrar más [+] Menos [-]Development and environmental implication of pedotransfer functions of Cd desorption rate coefficients in historically polluted soils Texto completo
2020
Lin, Zhongbing | Zou, Xingying | Zhang, Renduo | Nguyen, Christophe | Huang, Jiesheng | Wang, Kang | Wu, Jingwei | Huang, Shuang
Development and environmental implication of pedotransfer functions of Cd desorption rate coefficients in historically polluted soils Texto completo
2020
Lin, Zhongbing | Zou, Xingying | Zhang, Renduo | Nguyen, Christophe | Huang, Jiesheng | Wang, Kang | Wu, Jingwei | Huang, Shuang
The desorption rate is an important factor determining cadmium (Cd) ecotoxicity and pollution remediation in soils. The pedotransfer functions (PTFs) of desorption rate coefficients of fresh Cd in soils have been developed in literature. We hypothesized that the aging of Cd pollution would alter Cd desorption process. Taking historically polluted soils as the object, this study aimed at testing the hypothesis and developing new PTFs of desorption rate coefficients for historical Cd. 15 d batch extraction experiments and 13 kinetic models were employed to define Cd desorption rate coefficients in 27 historically polluted soil samples. Compared with fresh Cd, the desorption rate coefficients of historical Cd were lower, and the break time of biphasic desorption processes was retarded to 3 d (4320 min). Different with the usual models for fresh Cd desorption (e.g. parabolic diffusion and two constant rate models), the best models to mimic the historical Cd desorption processes were the pseudo first order, logarithmic, Elovich, and simple Elovich models. The rate-limiting step controlling Cd desorption was changed from the intraparticle diffusion to the interface reaction with aging of pollution. New PTFs of desorption rate coefficients of historical Cd were established (R² ≥ 0.71). Cd desorption rate coefficients increased with organic matter and clay contents, but decreased with oxalate extractable Fe content, solution pH, cation exchange capacity, and silt content. The key soil properties influencing desorption rate coefficients were not altered by the aging of pollution. The developed PTFs could guide us to adjusting the ecotoxicity and pollution remediation of Cd in historically polluted field soils.
Mostrar más [+] Menos [-]Development and environmental implication of pedotransfer functions of Cd desorption rate coefficients in historically polluted soils Texto completo
2020
Lin, Zhongbing | Zou, Xingying | Zhang, Renduo | Nguyen, Christophe | Huang, Jiesheng | Wang, Kang | Wu, Jingwei | Huang, Shuang | State Key Laboratory of Water Resources and Hydropower Engineering Science ; Wuhan University [China] | Sun Yat-sen University [Guangzhou] (SYSU) | Interactions Sol Plante Atmosphère (UMR ISPA) ; Ecole Nationale Supérieure des Sciences Agronomiques de Bordeaux-Aquitaine (Bordeaux Sciences Agro)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)
International audience | The desorption rate is an important factor determining cadmium (Cd) ecotoxicity and pollution remediation in soils. The pedotransfer functions (PTFs) of desorption rate coefficients of fresh Cd in soils have been developed in literature. We hypothesized that the aging of Cd pollution would alter Cd desorption process. Taking historically polluted soils as the object, this study aimed at testing the hypothesis and developing new PTFs of desorption rate coefficients for historical Cd. 15 d batch extraction experiments and 13 kinetic models were employed to define Cd desorption rate coefficients in 27 historically polluted soil samples. Compared with fresh Cd, the desorption rate coefficients of historical Cd were lower, and the break time of biphasic desorption processes was retarded to 3 d (4320 min). Different with the usual models for fresh Cd desorption (e.g. parabolic diffusion and two constant rate models), the best models to mimic the historical Cd desorption processes were the pseudo first order, logarithmic, Elovich, and simple Elovich models. The rate-limiting step controlling Cd desorption was changed from the intraparticle diffusion to the interface reaction with aging of pollution. New PTFs of desorption rate coefficients of historical Cd were established (R2 ≥ 0.71). Cd desorption rate coefficients increased with organic matter and clay contents, but decreased with oxalate extractable Fe content, solution pH, cation exchange capacity, and silt content. The key soil properties influencing desorption rate coefficients were not altered by the aging of pollution. The developed PTFs could guide us to adjusting the ecotoxicity and pollution remediation of Cd in historically polluted field soils.
Mostrar más [+] Menos [-]Detection of oil pollution impacts on vegetation using multifrequency SAR, multispectral images with fuzzy forest and random forest methods Texto completo
2020
Ozigis, Mohammed S. | Kaduk, Jorg D. | Jarvis, Claire H. | da Conceição Bispo, Polyanna | Balzter, Heiko
Oil pollution harms terrestrial ecosystems. There is an urgent requirement to improve on existing methods for detecting, mapping and establishing the precise extent of oil-impacted and oil-free vegetation. This is needed to quantify existing spill extents, formulate effective remediation strategies and to enable effective pipeline monitoring strategies to identify leakages at an early stage. An effective oil spill detection algorithm based on optical image spectral responses can benefit immensely from the inclusion of multi-frequency Synthetic Aperture Radar (SAR) data, especially when the effect of multi-collinearity is sufficiently reduced. This study compared the Fuzzy Forest (FF) and Random Forest (RF) methods in detecting and mapping oil-impacted vegetation from a post spill multispectral optical sentinel 2 image and multifrequency C and X Band Sentinel – 1, COSMO Skymed and TanDEM-X SAR images. FF and RF classifiers were employed to discriminate oil-spill impacted and oil-free vegetation in a study area in Nigeria. Fuzzy Forest uses specific functions for the selection and use of uncorrelated variables in the classification process to yield an improved result. This method proved an efficient variable selection technique addressing the effects of high dimensionality and multi-collinearity, as the optimization and use of different SAR and optical image variables generated more accurate results than the RF algorithm in densely vegetated areas. An Overall Accuracy (OA) of 75% was obtained for the dense (Tree Cover Area) vegetation, while cropland and grassland areas had 59.4% and 65% OA respectively. However, RF performed better in Cropland areas with OA = 75% when SAR-optical image variables were used for classification, while both methods performed equally well in Grassland areas with OA = 65%. Similarly, significant backscatter differences (P < 0.005) were observed in the C-Band backscatter sample mean of polluted and oil-free TCA, while strong linear associations existed between LAI and backscatter in grassland and TCA. This study demonstrates that SAR based monitoring of petroleum hydrocarbon impacts on vegetation is feasible and has high potential for establishing oil-impacted areas and oil pipeline monitoring.
Mostrar más [+] Menos [-]Polycyclic aromatic compounds (PACs) in the Canadian environment: A review of sampling techniques, strategies and instrumentation Texto completo
2020
Ahad, Jason M.E. | Macdonald, Robie W. | Parrott, Joanne L. | Yang, Zeyu | Zhang, Yifeng | Siddique, Tariq | Kuznetsova, Alsu | Rauert, Cassandra | Galarneau, Elisabeth | Studabaker, William B. | Evans, Marlene | McMaster, Mark E. | Shang, Dayue
A wide variety of sampling techniques and strategies are needed to analyze polycyclic aromatic compounds (PACs) and interpret their distributions in various environmental media (i.e., air, water, snow, soils, sediments, peat and biological material). In this review, we provide a summary of commonly employed sampling methods and strategies, as well as a discussion of routine and innovative approaches used to quantify and characterize PACs in frequently targeted environmental samples, with specific examples and applications in Canadian investigations. The pros and cons of different analytical techniques, including gas chromatography – flame ionization detection (GC-FID), GC low-resolution mass spectrometry (GC-LRMS), high performance liquid chromatography (HPLC) with ultraviolet, fluorescence or MS detection, GC high-resolution MS (GC-HRMS) and compound-specific stable (δ¹³C, δ²H) and radiocarbon (Δ¹⁴C) isotope analysis are considered. Using as an example research carried out in Canada’s Athabasca oil sands region (AOSR), where alkylated polycyclic aromatic hydrocarbons and sulfur-containing dibenzothiophenes are frequently targeted, the need to move beyond the standard list of sixteen EPA priority PAHs and for adoption of an AOSR bitumen PAC reference standard are highlighted.
Mostrar más [+] Menos [-]Health risks associated with the polycyclic aromatic hydrocarbons in indoor dust collected from houses in Kuwait Texto completo
2020
Al-Harbi, Meshari | Alhajri, Ibrahim | Whalen, Joann K.
Polycyclic aromatic hydrocarbons (PAHs) are a byproduct of combustion processes. They are common pollutants in oil-producing countries because fossil fuel processing generates PAHs that associate with dust. Airborne particles containing PAHs are transported into houses during dust storms, which are common in the arid oil-producing countries, and consequently the children and adults in the household are exposed to PAHs in indoor house dust. The goal of this study was to present a systematic survey of PAHs in indoor house dust in Kuwait. The PAHs concentrations and composition of indoor house dust was determined, along with their probable source and the potential carcinogenic risks. Total PAHs concentrations (ƩPAH) were, on average (±standard deviation) 1112 ± 347 μg/kg and ranged from 450 to 2242 μg/kg. Heavier congeners (4–6 ring PAHs) represented 61% of the ƩPAH. Petroleum combustion and traffic emissions were the major source of PAHs, based on the isomeric ratios of PAHs in indoor house dust. The incremental lifetime cancer risks (ILCRs) of exposure to PAHs in indoor house dust was 2.23 × 10⁻³ (95% CI: 1.99 × 10⁻³ – 2.48 × 10⁻³) for children and 2.15 × 10⁻³ (95% CI: 1.94 × 10⁻³ – 2.37 × 10⁻³) for adults, exceeding the US EPA safe limit of 1 × 10⁻⁶. Therefore, exposure to PAHs present in indoor house dust increases the cancer risk for children and adults in Kuwait.
Mostrar más [+] Menos [-]Effects of ketoprofen on rice seedlings: Insights from photosynthesis, antioxidative stress, gene expression patterns, and integrated biomarker response analysis Texto completo
2020
Wang, Huan | Jin, Mingkang | Xu, Linglin | Xi, Hao | Wang, Binhui | Du, Shaoting | Liu, Huijun | Wen, Yuezhong
Pharmacologically active compounds found in reclaimed wastewater irrigation or animal manure fertilizers pose potential risks for agriculture. The mechanism underlying the effects of ketoprofen on rice (Oryza sativa L.) seedlings was investigated. The results showed that low concentrations (0.5 mg L⁻¹) of ketoprofen slightly stimulate growth of rice seedlings, while high concentrations can significantly inhibit growth by reducing biomass and causing damage to roots. Ketoprofen affects photosynthetic pigment content (Chla, Chlb, and carotenoids) and chlorophyll synthesis gene (HEMA, HEMG, CHLD, CHLG, CHLM, and CAO) expression. Fluorescence parameters such as minimum fluorescence (F₀), maximum fluorescence (Fₘ), variable fluorescence (Fᵥ), potential photosynthetic capacity (Fᵥ/F₀), maximum quantum efficiency of PSII photochemistry (Fᵥ/Fₘ), electron transfer rate (ETR), and Y(II), Y(NPQ), Y(NO) values were affected, showing photosynthetic electron transfer was blocked. Active oxygen radical (O₂•−and H₂O₂), malondialdehyde and proline content increased. Superoxide dismutase, catalase and ascorbate peroxidase activities, glutathione content and antioxidant-related gene (FSD1, MSD1, CSD1, CSD2, CAT1, CAT2, CAT3, APX1, APX2) expression were induced. Higher integrated biomarker response values of eight oxidative stress response indexes were obtained at higher ketoprofen concentrations. Ultrastructure observation showed that ketoprofen causes cell structure damage, chloroplast swelling, increase in starch granules, and reduction in organelles. This study provides some suggested toxicological mechanisms and biological response indicators in rice due to stress from pharmacologically active compounds.
Mostrar más [+] Menos [-]Contribution of aquatic products consumption to total human exposure to PAHs in Eastern China: The source matters Texto completo
2020
Wang, Qian | Chu, Lanlan | Peng, Fei | Li, Juan-Ying | Chen, Hongjie | Jin, Ling
Demand for aquatic products surges, due to the increasing concerns on high-quality nutrition and food security. Eastern China is the leading area in contributing significantly to both production and consumption of aquatic products from inland aquaculture, coastal fishing, and distant-water fishing. It is imperative to comprehensively assess the dietary risks of common chemical hazards, such as polycyclic aromatic hydrocarbons (PAHs) in aquatic products of these supply origins, and the contribution of aquatic product consumption to total human exposure. The observed body loads of total PAHs in the coastal aquatic products varied significantly, indicating an unstable food quality from the east coast of China. In the meantime, benzo[a]pyrene equivalent concentrations (BaPₑq) exhibited the highest level in the aquatic products from inland farm ponds. High BaPₑq, along with high consumption of inland aquaculture products, led to higher corresponding cumulative carcinogenic risks (ILCRs) than the other two kinds of products, which further indicate that the origins and consumption rates of the aquatic products do matter. Furthermore, it is confirmed that the consumption of aquatic products is an important contributor to the total daily exposure to PAHs, especially for children and pregnant women. Finally, it is necessary to apply practical remediation in aquaculture farm ponds to provide high-quality products, especially for the population groups of children and pregnant women, and alleviate the exposure and risk due to the PAHs in aquatic products.
Mostrar más [+] Menos [-]Applying fungicide on earthworms: Biochemical effects of Eisenia fetida exposed to fluoxastrobin in three natural soils Texto completo
2020
Zhang, Cheng | Zhou, Tongtong | Du, Zhongkun | Juhasz, Albert | Zhu, Lusheng | Wang, Jun | Wang, Jinhua | Li, Bing
Fluoxastrobin is one of the most widely used strobilurin fungicides, however, application of the fungicides may result in soil residues leading to environmental damage including oxidative stress and damage to sentinel organisms (i.e. earthworms). While this has been demonstrated in artificial soil, the biochemical response of Eisenia fetida exposed to fluoxastrobin in natural soils is unclear. This study utilized three typical natural soils (fluvo-aquic soils, red clay, and black soils) to evaluate the biochemical response of Eisenia fetida exposed to fluoxastrobin (0.1, 1.0, 2.5 mg/kg) including the production of reactive oxygen species, impact on three enzyme activities, lipid peroxidation, and 8-hydroxydeoxyguanosine after a 4-week exposure. The effects of fluoxastrobin on Eisenia fetida in different soils were assessed using an integrated biomarker response (IBR). The findings may be possible to state that the toxic effects of fluoxastrobin in artificial cannot exactly represent that in natural soils. Specifically, the fluoxastrobin subchronic toxicity was highest in red clay and lowest in black soil among the three natural soils. Furthermore, the 8-OHdG content was more sensitive to fluoxastrobin in all six environmental indicators of the present study.
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