Search

Abstract: More than 70% of primary energy production and consumption in China is occupied by coal. The exploitation quantity has been about 35 billion tons since 1949, over 95% of which is by underground mining. In 2008, the coal production has reached 2.72 billion tons. Long-time and intensive mining has caused spatiotemporal cumulative effects on soil, water, air environment, and ecosystem, which include ground subsidence, hydrodynamics change, land use change, soil pollution, air pollution, and ecosystem evolution etc. In this study, the cumulative sources, paths, and main performances of the environmental cumulative effects on underground coal mining region are analyzed. Moreover, the existence of synergistic effects among all environmental factors is pointed out, with some suggestions proposed for future research. [Copyright &y& Elsevier]

Abstract: Transmission Electron Microscope (TEM) was used to investigate the damage of wheat seedlings by cadmium and the distribution of Cd2+ in different parts of wheat seedlings was discussed. Experiments show that Cd is more mobile than other metals and the pollution damages the root tip cells. In addition, lots of abnormal symptoms were observed, including cell-wall thinning and cell deforming, cytoplasm and organelle swelling or even becoming vacuolization, nuclear membrane becoming disrupted and square cells being formed. The damage of Cd2+ on wheat leaves was less serious than that of root tips. Cd pollution may promote cell cleavage, resulting in swelling and disturbance of the layered structure of chloroplast, leading mitochondrion to swelling or even becoming round. The dense electron particles exist in ektexine, extracellular matrix, vacuolar of root cells as polluted by low concentration of Cd and exist outer the wall and inside the cytoplasm of leaves cells as polluted by different levels of Cd. [Copyright &y& Elsevier]

The illegal use and low biodegradability of psychoactive substances has led to their introduction to the natural water environment, causing potential harm to ecosystems and human health. This paper compared the reaction kinetics and degradation mechanisms of ketamine (KET) and methamphetamine (METH) by UV/H2O2. Results indicated that the degradation of KET and METH using UV or H2O2 alone was negligible. UV/H2O2 had a strong synergizing effect, which could effectively remove 99% of KET and METH (100 μg/L) within 120 and 60 min, respectively. Their degradation was fully consistent with pseudo-first-order reaction kinetics (R2 > 0.99). Based on competition kinetics, the rate constants of the hydroxyl radical with KET and METH were calculated to be 4.43 × 109 and 7.91 × 109 M−1·s−1, respectively. The apparent rate constants of KET and METH increased respectively from 0.001 to 0.027 and 0.049 min−1 with the initial H2O2 dosage ranging from 0 to 1000 μM at pH 7. Their degradation was significantly inhibited by HCO3−, Cl−, NO3− and humic acid, with Cl− having relatively little effect on the degradation of KET. Ultraperformance liquid chromatography with tandem mass spectrometry was used to identify the reaction intermediates, based on which the possible degradation pathways were proposed. These promising results clearly demonstrated the potential of the UV/H2O2 process for the effective removal of KET and METH from contaminated wastewater. [ABSTRACT FROM AUTHOR]

The water-sediment regulation scheme (WSRS) in the Yellow River has been adjusted annually to maintain the optimal capacity of the Xiaolangdi Reservoir via the scouring of deposits downstream before the rainy season. The high-intensity sediment scouring in a short time has given rise to elevated dissolved inorganic carbon (DIC) exportation; however, the source of the DIC is still unclear. Here, we hypothesized that sediment scouring released porewater DIC into the river water, increasing the riverine DIC concentration and enhancing CO 2 outgassing during the adjustment of the WSRS. To test this hypothesis, we used the isotopic composition of the DIC (δ13C DIC) to constrain the sources and transformations of the DIC. River water samples were collected below the Xiaolangdi Reservoir dam before, during, and after the adjustment of the WSRS. In these three stages, the pH of the river water decreased from 8.2 to 8.0 and then increased to 8.4; and the DIC concentrations increased from 185.30 to 216.37 mg L−1, and then decreased to 199.93 mg L−1. The δ 13C DIC values decreased from −7.01 to −11.53‰ and then increased to −6.82‰; and the partial pressure of the CO 2 increased from 5.21 × 10−3 to 35.30 × 10−3 atm, and then decreased to 3.40 × 10−3 atm. The increase in the DIC concentrations with negative δ 13C DIC values during the adjustment of the WSRS resulted from the release of porewater DIC due to the sediment scouring, which was derived from the anaerobic oxidation of organic matter in the permeable sediment environment. More broadly, the sedimentary organic carbon-derived DIC released into the ocean would counteract CO 2 drawdown via the burial of organic carbon in the geological timescales. [Display omitted] • Artificial sediment scouring increased DIC concentrations and flux during the WSRS. • Riverine δ 13C DIC values were negative during the WSRS. • DO concentrations were as low as 1.6 mg/L, and d -excess values increased to 9‰ during the WSRS. • Porewater mixing has resulted in negative δ 13C DIC values and increased DIC concentrations. [ABSTRACT FROM AUTHOR]