Enantioselective effects of herbicide imazapyr on Arabidopsis thaliana

The enantioselective toxicity of chiral herbicides in the environment is of increasing concern. To investigate the enantioselective effects of the chiral herbicide imazapyr on target organisms, we exposed Arabidopsis thaliana to imazapyr enantiomers and racemate. The results show that imazapyr was enantioselectively toxic to A. thaliana. The total chlorophyll content in A. thaliana was affected more by (+)-imazapyr than (±)-imazapyr and (?)-imazapyr. Concentrations of proline and malondialdehyde reflected a toxic effect in the order of (+)-imazapyr > (±)-imazapyr > (?)-imazapyr at every concentration. Acetolactate synthase (ALS) activity was inhibited more by (+)-imazapyr than (±)-imazapyr or (?)-imazapyr. At 100 mg L^?1 of imazapyr, ALS activity was 78%, 43%, and 19% with (?)-, (±)-, and (+)-imazapyr, respectively. The results suggest the significant enantioselective toxicity of imazapyr in A. thaliana for greater toxicity with (+)-imazapyr than (±)-imazapyr and (?)-imazapyr, which suggests that (+)-imazapyr has more herbicidal effect.     

The effect of fiscal decentralization,environmental regulation,and economic development on haze pollution: empirical evidence for 270 Chinese cities during 2007–2016

The current discourse addresses fiscal issues, financial decentralization, and environmental quality and significantly affects economic development and sustainability. This investigation aims to address the research gap in fiscal decentralization and haze pollution for innovation and sustainable growth. This study uses the annual data of 270 Chinese cities from 2007 to 2016 for comprehensive analysis and employs spatial regression methods. The key findings imply that haze pollution in neighbouring cities causes further ecological issues. While the environmental regulations of China tend to have negative impacts on pollution, fiscal decentralization was found to be a key contributor to environmental pollution in Chinese cities. Overall, the study supports the validity of the pollution refuge hypothesis in China. Lastly, the conclusions allow us to conclude that China might need micro-level reforms regarding fiscal decentralization, environmental tax laws, and encouragement of cleaner production technologies.

     

Environmental Issues for the Chinese Strong Aromatic Liquor Industry: an Assessment for the Brewing System

Environmental assessments are often performed for industries due to a lot of issues produced in the processes. However, few studies are reported for environmental assessment of Chinese liquor production. A lot of material consumptions in Chinese liquor industries often bring about serious environmental pollution. Thus, Chinese strong aromatic liquor (CSAL) is taken as a representative for the environmental issues assessment of Chinese liquor industry in view of cleaner production (CP). The assessment is performed for the brewing system of CSAL including three main phases: crude liquor brewing, crude liquor blending, and steam production, which addresses resource and energy consumptions and environmental impacts. The results indicate that, according to the standards of Ministry of Environmental Protection of China, the consumptions of materials and energy are acceptable while the water consumption is higher than the requirement. Moreover, the discharge of chemical oxygen demand (COD) in the brewing phase is above the standard requirement and contributes much to eutrophication. The total environmental impacts in the blending phase are less than those in the brewing and steam production phases. In detail, in the brewing phase, high concentration of volatile organic compounds in the wastewater results in the odor threshold values and photochemical ozone creation. In the blending phase, the main environmental impact is eutrophication owing to the wastewater. In the steam production phase, the most and least significant impacts are global warming and soot emission, respectively, wherein waste gas emission is dominated. Cost analysis reveals that when the water consumption and COD discharge meet the requirements according to the CP option, there are plenty of economic and environmental benefits for the CSAL industry. The results confirm that the reform strategies for the Chinese liquor enterprise should be performed to decrease the water consumption, promote the utilization efficiency of water, improve recycle and reuse of by-products, reduce the pollutant discharge, and enhance waste treatment efficiency.     

Persulfate oxidation of trichloroethylene with and without iron activation in porous media

In situ chemical oxidation with persulfate anion (S2O82*) is a viable technique for remediation of groundwater contaminants such as trichloroethylene (TCE). An accelerated reaction using S2O82* to destroy TCE can be achieved via chemical activation with ferrous ion to generate sulfate radicals (SO4*)(E degrees =2.6 V). The column study presented here simulates persulfate oxidation of TCE in porous media (glass beads and a sandy soil). Initial experiments were conducted to investigate persulfate transport in the absence of TCE in the column. The persulfate flushing exhibited a longer residence time and revealed a moderate persulfate interaction with soils. In TCE treatment experiments, the results indicate that the water or persulfate solution would push dissolved TCE from the column. Therefore, the effluent TCE concentration gradually increased to a maximum when about one pore volume was replaced with the flushing solution in the column. The presence of Fe2+ concentration within the column caused a quick drop in effluent TCE concentration and more TCE degradation was observed. When a TCE solution was flushing through the soil column, breakthrough of TCE concentration in the effluent was relatively slow. In contrast, when the soil column was flushed with a mixed solution of persulfate and TCE, persulfate appeared to preferentially oxidize soil oxidizable matter rather than TCE during transport. Hence, persulfate oxidation of soil organics may possibly reduce the interaction between TCE and soil (e.g., adsorption) and facilitate the transport of TCE through soil columns resulting in faster breakthrough.     

XANES study of Cr sorbed by a kitchen waste compost from water

A kitchen waste compost was used to sorb Cr for various times from water containing either Cr(NO3)3 or CrO3 in different concentrations. Scanning electron microscopy (SEM) results show that the composts have been partially oxidized by Cr(VI) during the sorption experiments. X-ray absorption near edge structure (XANES) simulation suggests that about 54.1-61.0% Cr sorbed on the compost is in form of organic Cr(III) through ionic exchange process with the rest being existent as Cr(NO3)3 in the Cr(III) sorption case; no Cr(OH)3 is observed or expected because the solution pH after sorption experiments is or= 5.94. Moreover, organic Cr(III) represents about 51.7-69.0% of the total sorbed Cr, and the rest (6.1-28.5%) is Cr(VI).     

Effect of humic substance on thermal treatment of chromium(VI)-containing latosol soil

Latosol soils contaminated with chromium(VI) [Cr(VI)], which is hazardous, can be recycled as raw materials for porcelain and construction sectors if a proper thermal stabilization process is implemented. This study investigates how thermal treatment affects Cr behavior during the sintering of latosol and deorganic latosol samples; both samples are artificially contaminated with CrO3. Approaches including X-ray absorption spectroscopy, scanning electron microscopy, N2-based Brunauer Emmett Teller surface analyzer, thermogravimetric analyzer/differential scanning calorimeter, and the toxicity characteristic leaching procedure promulgated by Taiwan Environmental Protection Administration are used in this study. After drying the Cr(VI)-contaminated latosol (i.e., containing 37,120 mg of Cr/kg sample) at 105 degrees C, approximately 80% of the doped CrO3 is chemically reduced to Cr(OH)3 by a humic substance naturally existing in the soil. In contrast, in the organics-free CrO3-contaminated latosol dried at 105 degrees C, only 9% of the doped CrO3 is reduced to Cr(OH)3. Heating the samples at 500 and 1100 degrees C transforms hazardous Cr(VI) into Cr(III) that is negligibly toxic; Cr2O3, which is insoluble, is detected as the most abundant Cr species. Moreover, formation of Cr2SiOs, which is suggested to relate to low Cr leaching, is only detected in the sample heated at 1100 degrees C. Surface morphology, surface area, and thermogravimetric analyzer/differential scanning calorimeter results demonstrate that thermal treatment at 1100 degrees C can incur considerable soil sintering/ melting if the humic substance in the soil has been heated off previously. Finally, Cr concentrations in the toxicity characteristic leaching procedure leachates collected from the samples thermally treated at 1100 degrees C for 4 hr are < or =0.21 mg of Cr L(-1) that are much less than the Taiwan Environmental Protection Administration regulatory limit (<5 mg of Cr L(-1)); consequently, these two samples are nonhazardous, and they have the potential for resource recycling. Conversely, Cr concentrations in the leachates from all 500 degrees C and 105 degrees C samples are in the 25.6-1279 mg L(-1) range.     

Spatio-Temporal Variability of Soil Respiration of Forest Ecosystems in China: Influencing Factors and Evaluation Model

Understanding the influencing factors of the spatio-temporal variability of soil respiration (R _s) across different ecosystems as well as the evaluation model of R _s is critical to the accurate prediction of future changes in carbon exchange between ecosystems and the atmosphere. R _s data from 50 different forest ecosystems in China were summarized and the influences of environmental variables on the spatio-temporal variability of R _s were analyzed. The results showed that both the mean annual air temperature and precipitation were weakly correlated with annual R _s, but strongly with soil carbon turnover rate. R _s at a reference temperature of 0°C was only significantly and positively correlated with soil organic carbon (SOC) density at a depth of 20 cm. We tested a global-scale R _s model which predicted monthly mean R _s (R _s,monthly) from air temperature and precipitation. Both the original model and the reparameterized model poorly explained the monthly variability of R _s and failed to capture the inter-site variability of R _s. However, the residual of R _s,monthly was strongly correlated with SOC density. Thus, a modified empirical model (TPS model) was proposed, which included SOC density as an additional predictor of R _s. The TPS model explained monthly and inter-site variability of R _s for 56% and 25%, respectively. Moreover, the simulated annual R _s of TPS model was significantly correlated with the measured value. The TPS model driven by three variables easy to be obtained provides a new tool for R _s prediction, although a site-specific calibration is needed for using at a different region.     

Molecular study of concentrated copper pollutant with a compost

Humic substance in compost contains various organic functional groups that can sorb metal ions through ionic force. This study used thermal treatment technology to concentrate copper in the heated residues while destroying the humic substance of copper-sorbed kitchen compost. Scanning electron microscopy (SEM) results show that copper clusters were formed in the heated residues. Information from both X-ray diffraction (XRD) patterns and Cu K-edge X-ray absorption spectroscopy (XAS) spectrum indicates that about 30% of the doped Cu(II) was chemically reduced to Cu(I) and Cu(0) when the sample was heated at 500 and 900 degrees C for 2h. The XAS results indicate that after 500 degrees C thermal treatment, the loaded Cu(NO(3))(2) was transformed into CuO (ca. 54%), Cu (ca. 18%), Cu(OH)(2) (ca. 15%), and Cu(2)O (ca.13%). Heating at 900 degrees C caused more transformation into elemental Cu probably due to more release of oxygen.     

Temperature dependence of nickel stabilization in inorganic oxide matrices

Scanning electron microscopy, X-ray diffractometry, X-ray absorption spectroscopy, and other means are used to investigate the effect of thermal treatment temperature, 105-1100 degrees C, on the immobilization of nickel (Ni) by the inorganic oxides of latosol. Ni is more firmly immobilized by the latosol with increasing temperature. Spectral analyses indicate that a shoulder toward the edge-jump appears in the spectra of X-ray absorption near-edge structure for the samples heated at 900 and 1100 degrees C. Moreover, the intensity of the main peak at the edge increases with higher temperature; this information indicates the distortion of the divalent nickel [Ni(II)] environment in the samples heated at 900 and 1100 degrees C. Nevertheless, the distortion is absent from the samples heated at 105 and 500 degrees C. The fact of the distortion of the Ni(II) environment suggests the occurrence of a chemical reaction between the Ni compound and the inorganic matrices of the latosol soil during the heating process at 900 and 1100 degrees C. In addition, the extended X-ray absorption fine structure results correspond well to the X-ray absorption near-edge structure results; the former are supportive of the occurrence of a distorted Ni(II) environment in the samples heated at 900 and 1100 degrees C. The wet-chemistry results show that the samples heated at 900-1100 degrees C leach less Ni than the 105-500 degrees C samples do. The change of the Ni environment is related to the observation that less Ni is leached from the samples heated at 900-1100 degrees C. Furthermore, the pore closing phenomenon is observed only in the 1100 degrees C sample; this phenomenon corresponds with the fact that the 1100 degrees C sample leaches less Ni than the 900 degrees C sample does.     

Temperature Dependence of Nickel Stabilization in Inorganic Oxide Matrices

Abstract

Scanning electron microscopy, X‐ray diffractometry, X‐ray absorption spectroscopy, and other means are used to investigate the effect of thermal treatment temperature, 105–1100 °C, on the immobilization of nickel (Ni) by the inorganic oxides of latosol. Ni is more firmly immobilized by the latosol with increasing temperature. Spectral analyses indicate that a shoulder toward the edge‐jump appears in the spectra of X‐ray absorption near‐edge structure for the samples heated at 900 and 1100 °C. Moreover, the intensity of the main peak at the edge increases with higher temperature; this information indicates the distortion of the divalent nickel [Ni(II)] environment in the samples heated at 900 and 1100 °C. Nevertheless, the distortion is absent from the samples heated at 105 and 500 °C. The fact of the distortion of the Ni(II) environment suggests the occurrence of a chemical reaction between the Ni compound and the inorganic matrices of the latosol soil during the heating process at 900 and 1100 °C. In addition, the extended X‐ray absorption fine structure results correspond well to the X‐ray absorption near‐edge structure results; the former are supportive of the occurrence of a distorted Ni(II) environment in the samples heated at 900 and 1100 °C. The wet‐chemistry results show that the samples heated at 900–1100 °C leach less Ni than the 105–500 °C samples do. The change of the Ni environment is related to the observation that less Ni is leached from the samples heated at 900–1100 °C. Furthermore, the pore closing phenomenon is observed only in the 1100 °C sample; this phenomenon corresponds with the fact that the 1100 °C sample leaches less Ni than the 900 °C sample does.