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61.
岩体裂隙面的形貌特征直接影响其渗流特性,为了分析二者的相关关系,采用劈裂法制备了单裂隙砂岩试样,进行了裂隙面扫描分析和渗流试验,基于分形维数在定量表达不规则曲线形貌特征方面的优势,提出了考虑裂隙面形貌各向异性特征的分形维数计算方法。研究结果表明:(1)基于矩阵理论的裂隙面综合分形维数,相当于用矩阵网格去覆盖整个裂隙面,可以较好地反映裂隙面的整体形貌特征;(2)裂隙面的形貌特征对其渗流特性影响显著,随着裂隙面综合分形维数逐渐增大,裂隙岩体的渗透系数逐渐减小,而且侧向应力越大,渗透系数的减小趋势越明显;(3)分析建立了裂隙岩样渗透系数kf与裂隙面综合分形维数■的相关关系,验证分析表明,该公式计算得到的裂隙岩样渗透系数与试验结果吻合较好。相关研究成果可为裂隙岩体渗流特性分析提供参考。 相似文献
63.
将传统的碳排放因子法与人口权重分配法相结合,估算了2015年中国2 170个县域的碳排放量,并将县域分为高/低碳排放量-高/低碳排放强度的4种类型。分析表明:(1)县域的平均碳排放量为1 287×103 t,但差异较大,空间分布上整体呈现东高西低;81.58%的县域的碳排放强度在0.01~1.05t/万元,空间分布上呈现西部及西北高、东部及东南低。(2)低碳排放量-低碳排放强度类县域数量最多(占45.81%),在全国除东南沿海区域均有分布;高碳排放量-低碳排放强度类县域分布在中国部分华北地区及东部、东南沿海地区,中部也有少量分布;高碳排放量-高碳排放强度类县域主要分布在东北三省;低碳排放量-高碳排放强度类县域主要分布在中国西北的西藏自治区、新疆维吾尔自治区和青海省,同时山西省境内也有较多分布。(3)整体看,中低收入、处于发展提速的中西部县域发展仍需预留一定的碳排放空间;对于高收入的东部县域,则要提出更高的减排要求。 相似文献
64.
为确定亚硝酸对聚磷菌好氧吸磷的抑制作用,利用批量实验研究了在不同pH下不同浓度的亚硝态氮对聚磷菌好氧吸磷过程的影响.实验结果表明,亚硝酸对聚磷菌好氧吸磷具有更直接的影响;亚硝酸质量浓度达到0.001 00 mg/L时,聚磷菌好氧吸磷即会受到50%的抑制.聚磷菌受到较低浓度的亚硝酸抑制时,其在无亚硝酸存在的环境中好氧吸磷能力基本能恢复. 相似文献
65.
Evaluation of spatial-temporal variations and trends in surface water quality across a rural-suburban-urban interface 总被引:1,自引:0,他引:1
Kun Mei Lingling Liao Yuanli Zhu Ping Lu Zhenfeng Wang Randy A. Dahlgren Minghua Zhang 《Environmental science and pollution research international》2014,21(13):8036-8051
Water quality degradation is often a severe consequence of rapid economic expansion in developing countries. Methods to assess spatial-temporal patterns and trends in water quality are essential for guiding adaptive management efforts aimed at water quality remediation. Temporal and spatial patterns of surface water quality were investigated for 54 monitoring sites in the Wen-Rui Tang River watershed of eastern China to identify such patterns in water quality occurring across a rural-suburban-urban interface. Twenty physical and chemical water quality parameters were analyzed in surface waters collected once every 4–8 weeks from 2000 to 2010. Temporal and spatial variations among water quality parameters were assessed between seasons (wet/dry) and among major land use zones (urban/suburban/rural). Factor analysis was used to identify parameters that were important in assessing seasonal and spatial variations in water quality. Results revealed that parameters related to organic pollutants (dissolved oxygen (DO), chemical oxygen demand (manganese) (CODMn), and 5-day biochemical oxygen demand (BOD5)), nutrients (ammonia nitrogen (NH4 +-N), total nitrogen (TN), total phosphorus (TP)), and salt concentration (electrical conductivity (EC)) were the most important parameters contributing to water quality variation. Collectively, they explained 70.9 % of the total variance. A trend study using the seasonal Kendall test revealed reductions in CODMn, BOD5, NH4 +-N, petrol, V-phen, and EC concentrations over the 11-year study period. Cluster analysis was employed to evaluate variation among 14 sampling sites representative of dominant land use categories and indicated three, three, and four clusters based on organic, nutrient, and salt water quality characteristics, respectively. Factors that are typically responsible for water quality degradation (including population, topography, and land use) showed no strong correlation with water quality trends implying considerable point source inputs in the watershed. The results of this study help inform ongoing water quality remediation efforts by documenting trends in water quality across various land use zones. 相似文献
66.
Spatial and temporal variations of nitrous oxide flux between coastal marsh and the atmosphere in the Yellow River estuary of China 总被引:1,自引:0,他引:1
Zhigao Sun Lingling Wang Xiaojie Mou Huanhuan Jiang Wanlong Sun 《Environmental science and pollution research international》2014,21(1):419-433
To investigate the spatial and seasonal variations of nitrous oxide (N2O) fluxes and understand the key controlling factors, we explored N2O fluxes and environmental variables in high marsh (HM), middle marsh (MM), low marsh (LM), and mudflat (MF) in the Yellow River estuary throughout a year. Fluxes of N2O differed significantly between sampling periods as well as between sampling positions. During all times of day and the seasons measured, N2O fluxes ranged from ?0.0051 to 0.0805 mg N2O m?2 h?1, and high N2O emissions occurred during spring (0.0278 mg N2O m?2 h?1) and winter (0.0139 mg N2O m?2 h?1) while low fluxes were observed during summer (0.0065 mg N2O m?2 h?1) and autumn (0.0060 mg N2O m?2 h?1). The annual average N2O flux from the intertidal zone was 0.0117 mg N2O m?2 h?1, and the cumulative N2O emission throughout a year was 113.03 mg N2O m?2, indicating that coastal marsh acted as N2O source. Over all seasons, N2O fluxes from the four marshes were significantly different (p?<?0.05), in the order of HM (0.0256?±?0.0040 mg N2O m?2 h?1)?>?MF (0.0107?±?0.0027 mg N2O m?2 h?1)?>?LM (0.0073?±?0.0020 mg N2O m?2 h?1)?>?MM (0.0026?±?0.0011 mg N2O m?2 h?1). Temporal variations of N2O emissions were related to the vegetations (Suaeda salsa, Phragmites australis, and Tamarix chinensis) and the limited C and mineral N in soils during summer and autumn and the frequent freeze/thaw cycles in soils during spring and winter, while spatial variations were mainly affected by tidal fluctuation and plant composition at spatial scale. This study indicated the importance of seasonal N2O contributions (particularly during non-growing season) to the estimation of local N2O inventory, and highlighted both the large spatial variation of N2O fluxes across the coastal marsh (CV?=?158.31 %) and the potential effect of exogenous nitrogen loading to the Yellow River estuary on N2O emission should be considered before the annual or local N2O inventory was evaluated accurately. 相似文献
67.
Arsenic levels and speciation in the total suspended particles (TSPs) were quantitatively determined by high performance liquid chromatography on-line coupled with hydride generation atomic fluorescence spectrometry in Beijing, China from February 2009 to March 2011. The high TSP levels fluctuated between 0.07 and 0.79 mg m−3, with a mean level of 0.32 ± 0.17 mg m−3. The total arsenic concentrations ranged from 0.03 to 0.31 μg m−3 (mean: 0.13 ± 0.06 μg m−3) in Beijing‘s air. The concentrations of As(III) and As(V) ranged from 0.73 to 20 ng m−3 (mean: 4.7 ± 3.6 ng m−3) and from 14 to 2.5 × 102 ng m−3 (mean: 67 ± 35 ng m−3), respectively. As levels and speciation demonstrated relative higher levels in spring and autumn and lower values in summer and winter. As(V) accounted for 81-99% of the extractable species in the TSP samples which showed that As(V) was the major fraction of the extractable As. Organoarsenic species, monomethylarsonate (MMA) and dimethylarsinate (DMA) were not found in all samples. Higher values of enrichment factors demonstrated that arsenic in TSP mainly come from anthropogenic sources. High As and its species levels in air and respiratory exposure (0.30-0.84 μg d−1) attributed to higher excess cancer risk ((4.2 ± 2.0) × 10−4) for people in Beijing. 相似文献
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