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251.
Xiaoliang Lu Qianlai Zhuang 《Mitigation and Adaptation Strategies for Global Change》2010,15(5):467-487
The Midwest of the United States includes 12 states and accounts for about a quarter of the total United State land area.
In recent years, there is an increasing interest in knowing the biomass potential and carbon balance over this region for
the past and the future. In this study, we use the Terrestrial Ecosystem Model (TEM) to evaluate these quantities in the region
from 1948 to 2099. We first parameterize the model with field data of major crops, including corn (Zea mays), soybean (Glycine max), and wheat (Triticum spp); then the model is applied to the region for the historical period (1948–2000). Next, we evaluate the simulated forestry
biomass with forest inventory data, the agricultural net primary production (NPP) with agricultural statistics data, and the
regional NPP with a satellite-based product at the regional scale. Our results show that the simulated annual NPP for the
Midwest increased by 1.75% per year and the whole Midwest terrestrial ecosystem acted as a carbon sink during 1948–2005. During
the 21st century, vegetation and soil carbon fluxes and pools show an increase trend with a great inter-annual variability.
The ecosystems serve as a carbon sink under future climate scenarios. NPP in the Midwest will increase and net ecosystem production
(NEP) will also increase and show an even larger interannual variability. This study provides the information of the biomass
and NEP at a state- level in the Midwest, which will be valuable for the region stakeholders to better manage their land for
the purpose of increasing carbon sequestration on the one hand and meeting the increasing demand of biomass on the other. 相似文献
252.
城市河流沉积物镉污染的潜在生态风险评价——以重庆市清水溪为例 总被引:1,自引:0,他引:1
针对目前河流污染问题的严重性,采用Hakanson潜在生态风险指数法,通过分析清水溪流域18个采样点沉积物中典型重金属污染物镉的含量,定量确定了清水溪沉积物中重金属镉的污染程度和潜在生态风险程度。结果表明:清水溪流域镉污染非常严重,上游比下游污染严重,而且在新桥到高滩岩段受到重金属镉的高强度污染,对周围环境存在着极高的镉生态风险。在清水溪干流采样点沉积物中镉的质量浓度范围在0.38~1.48mg·kg^-1之间,平均值0.85mg·kg^-1,各支流沉积物中镉的质量浓度范围为0.51~1.08mg·kg^-1。对于清水溪各支流镉的污染程度与潜在生态风险程度由高到低的排序为杨家沟〉金竹沟〉芭蕉沟〉关井沟〉石碾盘沟。 相似文献
253.
Qianlai Zhuang Tonglin Zhang Jingfeng Xiao Tianxiang Luo 《Mitigation and Adaptation Strategies for Global Change》2009,14(1):85-99
Net primary production (NPP) of terrestrial ecosystems provides food, fiber, construction materials, and energy to humans.
Its demand is likely to increase substantially in this century due to rising population and biofuel uses. Assessing national
forest NPP is of importance to best use forest resources in China. To date, most estimates of NPP are based on process-based
ecosystem modeling, forestry inventory, and satellite observations. There are little efforts in using spatial statistical
approaches while large datasets of in-situ observed NPP are available for Chinese forest ecosystems. Here we use the surveyed
forest NPP and ecological data at 1,266 sites, the data of satellite forest coverage, and the information of climate and topography
to estimate Chinese forest NPP and their associated uncertainties with two geospatial statistical approaches. We estimate
that the Chinese forest and woodland ecosystems have total NPP of 1,325 ± 102 and 1,258 ± 186 Tg C year−1 in 1.57 million km2 forests with a regression method and a kriging method, respectively. These estimates are higher than the satellite-based
estimate of 1,034 Tg C year−1 and almost double the estimate of 778 Tg C year−1 using a process-based terrestrial ecosystem model. Cross-validation suggests that the estimates with the kriging method are
more accurate. Our developed geospatial statistical models could be alternative tools to provide national-level NPP estimates
to better use Chinese forest resources. 相似文献
254.
Analysis of bacterial community in bulking sludge using culture-dependent and -independent approaches 总被引:1,自引:0,他引:1
Decai Jin Ping Wang Zhihui Bai Xinxin Wang Hong Peng Rong Qi Zhisheng Yu Guoqiang Zhuang 《环境科学学报(英文版)》2011,23(11):1880-1887
Combination of 16S rRNA gene clone library and cultivation for assessing of bacterial diversity of the microflora in bulking sludge was evaluated in the study. 相似文献
255.
本文作者主要研究了腐殖酸对聚乙烯吡咯烷酮包覆的纳米银颗粒(polyvinylpyrrolidone-coated AgNPs)毒性的影响,受试生物涵盖了水生系统不同的营养级别,包括藻类(Raphidocelis subcapitata)、水蚤类(Chydorus sphaericus)以及淡水鱼类(Danio rerio)。结果显示,腐殖酸可降低AgNPs对本研究中所有水生生物的毒性,并具有明显的剂量效应关系。原因为:1)腐殖酸使AgNPs表面带有更多负电荷,这阻碍了AgNPs与藻细胞的接触,使毒性降低;2)腐殖酸抑制了AgNPs中Ag+的溶出,而本研究显示自由Ag+的毒性高于团聚的纳米银颗粒。
精选自Zhuang Wang, Joris T.K. Quik, Lan Song, Evert-Jan Van Den Brandhof, Marja Wouterse and Willie J.G.M. Peijnenburg. Humic substances alleviate the aquatic toxicity of polyvinylpyrrolidone-coated silver nanoparticles to organisms of different trophic levels. Environmental Toxicology and Chemistry: Volume 34, Issue 6, pages 1239–1245, June 2015.
DOI: 10.1002/etc.2936
详情请见http://onlinelibrary.wiley.com/doi/10.1002/etc.2936/full 相似文献
256.
257.
Nitrogen removal and simultaneous nitrification and denitrification in a fluidized bed step-feed process 总被引:2,自引:0,他引:2
For urban wastewater treatment, we conducted a novel four-stage step-feed wastewater treatment system combined with a fluidized bed laboratory experiment to investigate chemical oxygen demand (COD), NH4+-N, and total nitrogen (TN) removal performance. The removal rates of COD, NH4+-N and TN were 88.2%, 95.7%, and 86.4% with effluent concentrations of COD, NH4+-N and TN less than 50, 8, and 10 mg/L, respectively. Biomass and bacterial activities were also measured, with results showing more nitrobacteria in the activated sludge than in the biofilm; however, bacterial activity of the biofilm biomass and the activated sludge were similar. Nitrogen concentrations during the process were also detected, with simultaneous nitrification and denitrification found to be obvious. 相似文献
258.
A real-time fluorescent quantitative immuno-polymerase chain reaction (RT-IPCR) assay was developed for the detection of non-dioxin-like polychlorinated biphenyl (PCB) congener in soil samples. Based on the construction of 3,4-dichlorinated biphenyl (IUPAC PCB12) hapten and its immunogen, the specific polyclonal antibodies (pAbs) to PCB12 was obtained and used to develop a direct competitive RT-IPCR assay. Using the optimized assay, a standard curve for PCB12 was prepared. The linear range for the determination of PCB12 was from 10.0 to 1.0 × 106 fg/mL with a correlation coefficient of 0.98 and a detection limit of 1.53 fg/mL. The RT-IPCR assays were tested for their cross-reactivity profiles using four selected congeners and four Aroclor products. The results for the soil samples correlated with the concentrations of PCBs obtained by gas chromatography/mass spectrometry. This highly specific, sensitive, and robust assay can be applied to on-site tests of PCBs and serve as a model for other pollutant immunoassays. 相似文献
259.
Haoshu Wang Yong Qin Liqing Xin Changxun Zhao Zhuang Ma Jian Hu Weixiang Wu 《Frontiers of Environmental Science & Engineering》2023,17(4):47
260.
溪洛渡坝区下游癞子沟泥石流发育特征及堵江可能性分析 总被引:1,自引:1,他引:0
在野外详细调查、测绘的基础上,研究了癞子沟泥石流的特性,分析了泥石流堵江的可能性。研究结果表明,癞子沟是一条老泥石流沟,泥石流的性质为过渡—粘性,容重为1.8~2.2 t/m3,规模属大—特大型。通过计算和分析,癞子沟泥石流在区域性降雨条件下,不会堵断金沙江,但是在局地暴雨条件下,可能堵断金沙江。如果在200年一遇泥石流堵断的情况下,堵河的高度达20.11 m;500年一遇时,堵河的高度达30.39 m。堵江后不但会淹没大坝尾水出水口,而且导致沟口右岸的癞子沟碴场失稳,形成灾害链。 相似文献