Characterization of mercury species in brown and white rice (Oryza sativa L.) grown in water-saving paddies

In China, total Hg (Hg_T) and methylmercury (MeHg) were quantified in rice grain grown in three sites using water-saving rice cultivation methods, and in one Hg-contaminated site, where rice was grown under flooded conditions. Polished white rice concentrations of Hg_T (water-saving: 3.3 ± 1.6 ng/g; flooded: 110 ± 9.2 ng/g) and MeHg (water-saving 1.3 ± 0.56 ng/g; flooded: 12 ± 2.4 ng/g) were positively correlated with root-soil Hg_T and MeHg contents (Hg_T: r² = 0.97, MeHg: r² = 0.87, p < 0.05 for both), which suggested a portion of Hg species in rice grain was derived from the soil, and translocation of Hg species from soil to rice grain was independent of irrigation practices and Hg levels, although other factors may be important. Concentrations of Hg_T and other trace elements were significantly higher in unmilled brown rice (p < 0.05), while MeHg content was similar (p > 0.20), indicating MeHg infiltrated the endosperm (i.e., white rice) more efficiently than inorganic Hg(II).     

不同温度对SBR腐殖活性污泥系统运行效能的影响

在10～22℃范围内,通过实验考察了温度对腐殖土间歇式活性污泥处理(SBR)系统的运行特性的影响.实验结果表明,降低温度对SBR腐殖活性污泥系统去除COD影响不大,当温度降至10℃时,COD去除率仍可达到80%以上;在22～14℃范围内,SBR腐殖活性污泥系统对NH+4-N和TN的去除影响不大,温度降至10℃时,NH+...     

氧化节杆菌对铜溶液的吸附特性

以氧化节杆菌为吸附剂,处理Cu（NO3）2、CuSO4和CuCl2溶液,研究菌体对Cu2＋和NO3-的吸附效果,以及NO 3-、SO42-和Cl-对Cu2＋吸附的影响。结果表明氧化节杆菌对Cu2＋和NO 3-的吸附具有选择性。Cu2＋的吸附效果理想,0.1 g/L菌体在10 min时,对2 mg/L Cu2＋的吸附率达...     

Photocatalytic inactivation of Escherichia coli by natural sphalerite suspension: effect of spectrum, wavelength and intensity of visible light

The photocatalytic disinfection of Escherichia coli K-12 is investigated by the natural sphalerite (NS) under different spectra, wavelengths and intensities of visible light (VL) emitted by light-emitting-diode lamp (LED). The spectrum effect of VL on disinfection efficiency is studied by using white LED, fluorescent tube (FT) and xenon lamp (XE), which indicates that the “discreted peak spectrum” of FT is more effective to inactivate bacteria than “continuous spectrum” of LED and XE. Besides, the photocatalytic disinfection of bacteria is compared under different single spectrum (blue, green, yellow and red color) LEDs. The results show that the most effective wavelength ranges of VL for photocatalytic disinfection with the NS are 440-490 and 570-620 nm. Furthermore, a positive relationship is obtained between the disinfection efficiency and the VL intensity. The experiment shows that NS can completely inactivate 10⁷ cfu mL⁻¹E. coli K-12 within 8 h irradiation by white LED with the intensity of 200 mW cm⁻² at pH 8. Moreover, the destruction process of the cell wall and the cell membrane are directly observed by TEM. Finally, no bacterial colony can be detected within a 96 h regrowth test of inactivated bacteria, which reveals that the VL-photocatalytic disinfection leads to an irreversible damage to the bacterial cells.     

Development of a novel mathematical model using a group contribution method for prediction of ionic liquid toxicities

A new mathematical model has been developed that expresses the toxicities (EC₅₀ values) of a wide variety of ionic liquids (ILs) towards the freshwater flea Daphnia magna by means of a quantitative structure-activity relationship (QSAR). The data were analyzed using summed contributions from the cations, their alkyl substituents and anions. The model employed multiple linear regression analysis with polynomial model using the MATLAB software. The model predicted IL toxicities with R² = 0.974 and standard error of estimate of 0.028. This model affords a practical, cost-effective and convenient alternative to experimental ecotoxicological assessment of many ILs.     

China’s Primary Programs of Terrestrial Ecosystem Restoration: Initiation, Implementation, and Challenges

China has undertaken several major programs of terrestrial ecosystem restoration (ERPs) in recent years, including the Natural Forest Protection Program (NFPP) and the Sloping Land Conversion Program (SLCP). There have been reports on the implementation of these programs, their preliminary impacts, and the problems encountered in carrying them out; a great deal has been learned from these studies. Nonetheless, China’s ERPs are not limited to the NFPP and the SLCP. Because a complete documentation and a timely update of these major efforts are still missing from the literature, it is difficult to gauge the scope of these programs and the scale of their impacts. In addition, a more thorough and critical analysis of both the general ERP policy and the specific technical measures used in implementing the ERPs remains urgently needed. The purpose of this article is to tackle these tasks. Overall, with the huge government investments in the ERPs, tremendous progress has been made in implementing them. To complete them successfully and to fundamentally improve the targeted ecosystems, however, it is essential for China to have a more balanced and comprehensive approach to ecological restoration. This approach must include: adopting better planning and management practices; strengthening the governance of program implementation; emphasizing the active engagement of local people; establishing an independent, competent monitoring network; and conducting adequate assessments of program effectiveness and impact.     

Quantifying the Effect of Ecological Restoration on Soil Erosion in China’s Loess Plateau Region: An Application of the MMF Approach

Land degradation due to erosion is one of the most serious environmental problems in China. To reduce land degradation, the government has taken a number of conservation and restoration measures, including the Sloping Land Conversion Program (SLCP), which was launched in 1999. A logical question is whether these measures have reduced soil erosion at the regional level. The objective of this article is to answer this question by assessing soil erosion dynamics in the Zuli River basin in the Loess Plateau of China from 1999 to 2006. The MMF (Morgan, Morgan and Finney) model was used to simulate changes in runoff and soil erosion over the period of time during which ecological restoration projects were implemented. Some model variables were derived from remotely sensed images to provide improved land surface representation. With an overall accuracy rate of 0.67, our simulations show that increased ground vegetation cover, especially in forestlands and grasslands, has reduced soil erosion by 38.8% on average from 1999 to 2006. During the same time period, however, the change in rainfall pattern has caused a 13.1% ± 4.3% increase in soil erosion, resulting in a net 25.7% ± 8.5% reduction in soil erosion. This suggests that China’s various ecological restoration efforts have been effective in reducing soil loss.     

Quantifying Terrestrial Ecosystem Carbon Dynamics in the Jinsha Watershed, Upper Yangtze, China from 1975 to 2000

Quantifying the spatial and temporal dynamics of carbon stocks in terrestrial ecosystems and carbon fluxes between the terrestrial biosphere and the atmosphere is critical to our understanding of regional patterns of carbon budgets. Here we use the General Ensemble biogeochemical Modeling System to simulate the terrestrial ecosystem carbon dynamics in the Jinsha watershed of China’s upper Yangtze basin from 1975 to 2000, based on unique combinations of spatial and temporal dynamics of major driving forces, such as climate, soil properties, nitrogen deposition, and land use and land cover changes. Our analysis demonstrates that the Jinsha watershed ecosystems acted as a carbon sink during the period of 1975–2000, with an average rate of 0.36 Mg/ha/yr, primarily resulting from regional climate variation and local land use and land cover change. Vegetation biomass accumulation accounted for 90.6% of the sink, while soil organic carbon loss before 1992 led to a lower net gain of carbon in the watershed, and after that soils became a small sink. Ecosystem carbon sink/source patterns showed a high degree of spatial heterogeneity. Carbon sinks were associated with forest areas without disturbances, whereas carbon sources were primarily caused by stand-replacing disturbances. It is critical to adequately represent the detailed fast-changing dynamics of land use activities in regional biogeochemical models to determine the spatial and temporal evolution of regional carbon sink/source patterns.     

满度漂移对红外分光光度法测定废水中石油类物质的影响

红外分光光度法是测废水中石油类物质的国家标准分析方法,但仪器在使用过程中,满度会发生变化。满度的漂移对实验数据准确性的影响很大,尤其是低浓度水样。本文讨论了红外分光光度法测定水体中石油类物质满度对实验数据的影响。     

Occurrence of monoethylmercury in the Florida Everglades: Identification and verification

A few studies have reported the occurrence of monoethylmercury (CH₃CH₂Hg⁺) in the natural environment, but further verification is needed due to the lack of direct evidence and/or uncertainty in analytical procedures. Various analytical techniques were employed to verify the occurrence of CH₃CH₂Hg⁺ in soil of the Florida Everglades. The identity of CH₃CH₂Hg⁺ in Everglades soil was clarified, for the first time, by GC/MS. The employment of the recently developed aqueous phenylation-purge-and-trap-GC coupled with ICPMS confirmed that the detected CH₃CH₂Hg⁺ was not a misidentification of CH₃SHg⁺. Stable isotope-tracer experiments further indicated that the detected CH₃CH₂Hg⁺ indeed originated from Everglades soil and was not an analytical artifact. All these evidence clearly confirmed the occurrence of CH₃CH₂Hg⁺ in Everglades soil, presumably as a consequence of ethylation occurring in this wetland. The prevalence of CH₃CH₂Hg⁺ in Everglades soil suggests that ethylation could play an important role in the biogeochemical cycling of Hg.