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2003-2022 全部
为您找到包含“Enrichment ratio”的内容共2

HAN Zhen,WANG Xiaoyan,SONG Dandan,LI Xinxin

Purpose: This study aimed to (1) observe the effects of rock fragment content on slope erosion processes and eroded sediment selectivity; (2) acquire the effective and ultimate particle size distributions (PSDs) of sediments from slope erosion; and (3) elucidate the influencing factors and characteristics of eroded sediment particles. Materials and methods: The test soil used in this study was collected from Beibei, Xiema in Chongqing, China. We collected six separate soil samples with 0%, 5%, 10%, 20%, 30%, and 40% rock fragments. The experiment were conducted on two parallel 5 m × 1 m × 0.4 m troughs. The rainfall simulation experiments were performed in the State Key Laboratory of Soil Erosion and Dryland Farming in the Loess Plateau. After rainfall, we measured the sediment PSDs using MasterSizer 2000. The PSD data obtained after the sediment was fully dispersed into primary particles labeled the ultimate PSD; whereas those obtained without any dispersion treatment was labeled the effective PSD. Results and discussion: Results revealed that eroded sediment selectivity was represented by clay enrichment. The effective/ultimate ratio of the clay-sized sediments was <1, and this ratio increased as rock fragment contents increased. Silt-sized particles were transported mainly as primary particles because the effective/ultimate ratios of silt-sized particles were closer to 1 than other ratios. The enrichment ratios of sand-sized particles decreased from 0.79 to 0.55 as rock fragment contents increased. The effective/ultimate ratios of sand-sized particles were >1, and this finding suggested that most sand particles, especially those with low rock fragment contents, eroded as aggregates. Clay-, silt-, and sand-sized sediment aggregates were significantly correlated with sediment yield, rock fragment content, and runoff yield strength. Conclusions: The results showed that the runoff coefficient consistently increased as rock fragment contents increased. The soil loss ratio (SLR) and the erosion rate reduced as rock fragment content increased. The relationship between SLR and rock fragment content can be described well in terms of quadratic function. The silt-sized particles were transported mainly as primary particles. The clay-, silt-, and sand-sized sediment aggregates were significantly correlated with rock fragment content.

2017-05-16

Grant (K318009902-1418

National Natural Science Foundation of China(41401298,41571265

Research Fund for the Doctoral Program of Higher Education of China(20130182120015

College of Resources and Environment, Southwest University/Key Laboratory of Eco-environments in Three Gorges Region (Ministry of Education), Southwest University, Chongqing 400716, China,College of Resources and Environment, Southwest University/Key Laboratory of Eco-environments in Three Gorges Region (Ministry of Education), Southwest University, Chongqing 400716, China,State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Northwest A & F University, Yangling 712100, PR China,College of Resources and Environment, Southwest University/Key Laboratory of Eco-environments in Three Gorges Region (Ministry of Education), Southwest University, Chongqing 400716, China

#Agronomy#

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范力,周俊晓,陈志永

2007-10-30

道路沉积物是一种重要的环境介质,其颗粒物积累的潜在毒性对于城市水体是一重要危害,因此,识别道路沉积物重金属的含量及来源就显得尤其重要。分析了采集于南京市工业区、交通区、商业区和住宅区的75个样品中的Pb、Cu、Cr、Zn和Cd 5种重金属,它们在交通区含量最大,Zn、Cu、Cr和Cd含量在商业区、工业区和住宅区有明显差异。通过主成分分析识别道路沉积物中重金属的来源,发现不同功能区的重金属来源有所差别。最后计算了重金属浓度富集率(CER),以评价人类活动对于重金属污染的影响程度。结果表明,有机质是南京城市道路沉积物中重金属的重要载体,人类活动对于该地区重金属污染影响达到中等或中等以上的程度。

河海大学环境科学与工程学院,河海大学环境科学与工程学院,河海大学环境科学与工程学院

#环境科学技术#

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