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471.
Quantifying Terrestrial Ecosystem Carbon Dynamics in the Jinsha Watershed, Upper Yangtze, China from 1975 to 2000 总被引:1,自引:0,他引:1
Shuqing Zhao Shuguang Liu Runsheng Yin Zhengpeng Li Yulin Deng Kun Tan Xiangzheng Deng David Rothstein Jiaguo Qi 《Environmental management》2010,45(3):466-475
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. 相似文献
472.
Radiation with UV-B increased the damage to DNA in Scytonema javanicum, a desert-dwelling soil microorganism, and the level of damage varied with the intensity of UV-B radiation and duration of exposure. Production of reactive oxygen species (ROS) also increased because of the radiation. Different exogenous chemicals (ascorbate acid, ASC; N-acetylcysteine, NAC; glyphosate, GPS; and 2-methyl-4-chlorophenoxyacetic acid, MCPA-Na) differed in their effect on the extent of DNA damage and ROS production: whereas NAC and ASC protected the DNA from damage and resulted in reduced ROS production, the herbicides (GPS and MCPA-Na) increased the extent of damage, lowered the rate of photosynthesis, and differed in their effect on ROS production. The chemicals probably have different mechanisms to exercise their effects: NAC and ASC probably function as antioxidant agents or as precursors of other antioxidant molecules that protect the DNA and photosynthetic apparatus directly from the ROS produced as a result of UV-B radiation, and GPS and MCPA-Na probably disrupt the normal metabolism in S. javanicum to induce the leaking of ROS into the photosynthetic electron transfer pathway following UV-B radiation, and thereby damage the DNA. Such mechanisms have serious implications for the use of environment-friendly herbicides, which, because they can destroy DNA, may prove harmful to soil microorganisms. 相似文献
473.
采用水热法制备出LiFePO4催化剂,通过电子显微镜(SEM)、X射线衍射(XRD)和傅立叶红外光谱(FTIR)对其进行表征,并将其作为非均相Fenton催化剂处理亚甲基蓝(MB)染料溶液。实验结果表明,在催化剂用量为4 g/L,H2O2浓度为0.04 mol/L,pH值为3,温度为50℃,反应时间为60 min的条件下,浓度为500 mg/L的亚甲基蓝脱色率达99%。根据实验结果,讨论了LiFePO4作为非均相Fenton催化剂对亚甲基蓝的降解机理。 相似文献
474.
Deng Y Besse-Hoggan P Husson P Sancelme M Delort AM Stepnowski P Paszkiewicz M Gołębiowski M Costa Gomes MF 《Chemosphere》2012,89(3):327-333
Several physico-chemical properties relevant to determine the environmental impact of ionic liquids - aqueous solubility, octanol/water partition coefficient, chromatographically derived lipophilicity and infinite dilution diffusion coefficients in water - were measured in ionic liquids based on pyridinium, ammonium and pyrrolidinium cations with bis(trifluoromethylsulfonyl)imide anions. The influence of the presence of hydroxyl or ester groups in the physico-chemical properties of these liquids was checked. It appeared that the presence of functional oxygenated moieties reduces the lipophilicity of ionic liquids and so decreases the risk of bioaccumulation in environment. 相似文献
475.
Burial of terrestrial and marine organic carbon in Jiaozhou Bay: different responses to urbanization 总被引:3,自引:0,他引:3
Yang Liyang Wu Ying Zhang Jing Liu Sumei Deng Bing 《Regional Environmental Change》2011,11(3):707-714
Organic geochemical proxies (OC, OC/TN, δ13C, and lignin oxidation products) were measured in a 271 cm long sediment core collected from central Jiaozhou Bay, northern
China, to study the response of terrestrial and marine organic carbon burials to the surrounding urbanization. Terrestrial
organic carbon content was constantly low from the bottom of the core to ~150 cm depth, indicating a stable and low level
of terrestrial input before urbanization. Thereafter, it increased up to ~20 cm depth, suggesting that increased human activities
and land-use changes during urbanization likely enhanced the flux of terrestrial organic carbon to the bay. Overall, 5–38%
of the total organic carbon was terrigenous, which was derived from a mixture of woody and non-woody angiosperms and moderately
degraded. Marine organic carbon content did not increase notably during urbanization. It increased from the bottom of the
core to ~180 cm and stayed at high levels until it decreased in the top 20 cm. It was affected by multiple factors, including
grain size and nutrient composition. These results demonstrate the different influences of urbanization on terrestrial and
marine organic carbon cycles and suggest the importance of discriminating between these two organic carbon pools in the reconstruction
of their historical changes. 相似文献
476.
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478.
研究沸石、胶质芽孢杆菌(Bacillus mucilaginosus)、黑曲霉(Aspergillus Niger)、胶质芽孢杆菌与沸石联合以及黑曲霉与沸石联合对模拟废水中Fe3+的吸附等温曲线,分析它们对Fe3+模拟废水的吸附及絮凝作用。结果表明:沸石对Fe3+吸附作用符合Freundlich方程;胶质芽孢杆菌分泌含有—OH和COO-的胞外多糖,对Fe3+具有较好的吸附效果;沸石与胶质芽孢杆菌联合对模拟废水中Fe3+的处理,低浓度以沸石对Fe3+的吸附为主,加入胶质芽孢杆菌絮凝剂使吸附了Fe3+的沸石进行絮凝沉降,吸附等温曲线符合Langmuir吸附等温方程,高浓度两者共同作用使吸附量增加;黑曲霉对Fe3+的吸附符合BET吸附等温方程;沸石与黑曲霉两者共同作用对Fe3+模拟废水吸附等温曲线为直线。通过去除效果对比分析可知:胶质芽孢杆菌既有吸附又有絮凝功能;胶质芽孢杆菌絮凝剂无论是对Fe3+的吸附还是对吸附Fe3+沸石的絮凝都比黑曲霉对Fe3+处理效果好;胶质芽孢杆菌和一些非金属矿物复合处理污染废水是一种无毒、低成本环保的处理方法,本研究将为它们在工程中的应用提供实践依据。 相似文献
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