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Grade-Tonnage, Ore Value-Tonnage, andenrichment ratio-Tonnage Models forResource Assessment

Journal of China University of Geosciences 2001年第1期12卷 45-53页

作者： Shoji Tetsuya Department of Environment Systems, The University of Tokyo, Tokyo 113-0033, Japan Department of Environment Systems The University of Tokyo

According to grade-tonnage diagrams of nickel and zinc deposits, their critical grades are 0.4 % and 3. 4 %, respectively, and hence the former resources can be considered optimistic and the latter pessimistic. The grade-tonnage diagram of gold deposits is convex downwards suggesting that the critical grade is 1 X 10-6 in the low-grade part. The ore value (OV)-tonnage diagram of all deposits In the world consists of three parts: high, middle and low vain f classes. The enrichment ratio (ER)-tonnage diagram of all deposits in the world ho consists of three parts: high, middle and low ratio *** quality categories defined by ER and OV are characterized by some keywords indicating deposit types as follows: category RH (high ER-high OV: 0. 7 %) by 'unconformity' and 'Mississippi Val-ley', category HM (high ER-middle: OV: 0.7 %) by 'vein', category ML (middle ER-low OV: 0 %) by 'sandstone', 'stockwork' and' dissemination', category LM by 'orthomagmatic',' laterite',komatiite and ' chemical', and category LL by 'porphyry', 'dissemination' and 'placer'. Category MM is not characterized by any keyword. If the commodities of a deposit are defined by both the enrichment ratio and the ore value, the defined commodities are relatively coincident for gold and nickel,but different for copper, silver and zinc, and greatly different for molybdenum and lead. Deposits containing lead and/or zinc are complimentary. If the commodity Ph+Zn is applied, most lead or zinc deposits are classified as Ph+Zu by both definitions. Accessory metals are commonly expected for deposits of kuroko-type zinc, epithermal silver, massive sulfide-type zinc and volcanogenic zinc, but uncommon for deposits of orthomagmatic chromium, chemically precipitated copper and sandstone-type uranium.

关键词： grade ore value enrichment ratio tonnage mineral resources deposit model.

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Difference in Organic Carbon Contents and Distributions in Particle-size Fractions between Soil and Sediment on the Southern Loess Plateau, China

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Journal of Mountain Science 2014年第3期11卷 717-726页

作者： LI Guang-lu PANG Xiao-ming College of Resources and Environment Northwest A&F University Tianshui Soil and Water Conservation Experiment Station of YRCC

The purpose of this study was to assess the effect of long-term cultivation and water erosion on the soil organic carbon （OC） in particle-size fractions. The study site is located at Nihegou Watershed in the Southern Loess Plateau, China. The soil at this site is loess with loose and silty structure, and contains macropores. The results showed that the OC concentrations in sediments and in the particle-size fractions of sediments were higher than those in soils and in the particle-size fractions of soils. The OC concentration was highest in the clay particles and was lowest in the sand particles. Clay particles possessed higher OC enrichment ability than silt and sand particles. The proportions of OC in the silt fractions of soil and sediment were the highest （mean value of 53.87% and 58.48%, respectively）, and the total proportion of OC in the clay and silt fractions accounted for 96% and 98% of the total OC in the soil and sediment, respectively. The loss of OC was highest in silt particles, with an average value of 0.16 Mg ha^-1 y^-1, and was lowest in the sand （0.003 Mg ha^-1 y^-l）. This result suggests that the fine particle-size fraction in the removed sediment may be an important indicator to assess soil OC losses.

关键词： Soil organic carbon Loess Plateau enrichment ratio Water erosion Particle fraction

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Effects of soil conservation practices on soil erosion and the size selectivity of eroded sediment on cultivated slopes

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Journal of Mountain Science 2021年第5期18卷 1222-1234页

作者： XU Lu ZHANG Dan PROSHAD Ram CHEN Yu-lan HUANG Tian-fang UGURLU Aysenur Institute of Mountain Hazards and Environment Chinese Academy of SciencesChengdu 610041China University of Chinese Academy of Sciences Beijing 100049China Liangshan Company of Sichuan Provincial Tobacco Co. Xichang 615000China Chengdu Institute of Biology Chinese Academy of SciencesChengdu 610041China

Soil conservation practices can greatly affect the soil erosion process,but limited information is available about its influence on the particle size distribution(PSD)of eroded sediment,especially under natural *** this study,the runoff,sediment yields,and effective/ultimate PSD were measured under two conventional tillage practices,downhill ridge tillage(DT)and plat tillage(PT)and three soil conservation practices,contour ridge tillage(CT),mulching with downhill ridge tillage(MDT),and mulching with contour ridge tillage(MCT)during 21 natural rainfall events in the lower Jinsha *** results showed that(1)soil conservation practices had a significant effect on soil *** conventional tillage of DT caused highest runoff depth(0.58 to 29.13 mm)and sediment yield(0.01 to 3.19 t hm^(-2)).Compared with DT,the annual runoff depths and sediment yields of CT,MDT and MCT decreased by 12.24%-49.75%and 40.79%-88.30%,respectively.(2)Soil conservation practices can reduce the decomposition of aggregates in *** ratios of effective and ultimate particle size(E/U)of siltand sand-sized particles of DT and PT plots were close to 1,indicating that they were transported as primary particles,however,values lower/greater than 1 subject to CT,MDT and MCT plots indicated they were transported as *** ratios of E/U of claysized particles were all less than 1 independently of tillage practices.(3)The sediments of soil conservation practices were more selective than those of conventional tillage *** CT,MDT and MCT plots,the average enrichment ratios(ERs)of clay,silt and sand were 1.99,1.93 and 0.42,respectively,with enrichment of clay and silt and depletion of sand in ***,the compositions of the eroded sediments of DT and PT plots were similar to that of the original *** findings support the use of both effective and ultimate particle size distributions for studying the size selectivity of eroded sediment,and provide a scien

关键词： Natural rainfall Runoff and sediment yield Soil particle size distribution enrichment ratio Purple soil

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Soil and onsite nutrient conservation potential of aromatic grasses at field scale under a shifting cultivated,degraded catchment in Eastern Ghats,India

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International Journal of Sediment Research 2018年第3期33卷 340-350页

作者： Partha Pratim Adhikary Hunsur Chikkanarasimhaiah Hombegowda Dhananjay Barman Madegowda Madhu ICAR-Indian Institute of Soil and Water Conservation Research Centre ICAR-Central Research Institute for Jute and Allied Fibres

Land degradation due to soil erosion is a global problem, especially on cultivated hill slopes. Economically important aromatic grasses can protect degraded hill slopes more effectively than field crops, but little information is available on their performance. This study quantifies runoff, sediment yield,enrichment ratios of soil and nutrients, and sediment-associated organic carbon and nutrients losses under three aromatic grass species: citronella(Cymbopogon nardus), lemon(Cymbopogon flexuosus), and palmarosa(Cymbopogon martini), compared with a traditional field crop, finger millet(Eleusine coracana)grown at three land slopes(4%, 8%, and 12%). It was observed that the degree of slope and type of grass both significantly influenced runoff generation. Runoff and sediment yield(SY) were significantly higher at 12% slope than at 8% and 4% slopes. Relation between rainfall and runoff were significant for all the grass species(p enrichment of clay, silt, sand, soil organic carbon(SOC), available nitrogen(N), phosphorus(P) and potassium(K) in the sediment were not significantly different between slopes but differed significantly between aromatic grasses and finger millet. Sediment associated nutrient load varied inversely with SY mainly because of the nutrient dissolution effect of high runoff volume. Annual loss of SOC and nutrients varied from 84.7-156.8 kg ha-1y-1for SOC, 4.38-9.18 kg ha-1y-1for available N, 0.35-0.75 kg ha-1y-1for available P, and 2.22-5.22 kg ha-1y-1for available K, with the lowest values for citronella and highest for finger millet. The study found that the aromatic grasses have greater environmental conservation values than finger millet on steep degrade

关键词： Aromatic grass enrichment ratio Nutrient loss Runoff Sediment yield

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黄土溅蚀过程中土壤有效粒径分布和富集/损耗的临界粒径

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地理学报:英文版 2023年第10期33卷 2113-2130页

作者：齐小倩程西科刘俊娥周正朝王宁申楠马春艳王占礼 School of Geography and Tourism Shaanxi Normal UniversityXi’an 710119China State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau Institute of Soil and Water ConservationNorthwest A&F UniversityYangling 712100ShaanxiChina Yulin University Shaanxi Key Laboratory of Ecological Restoration in Shaanbei Mining AreaYulin 719000ShaanxiChina

Effective soil particle size composition can more realistically reflect the particle size sorting process of *** reveal the individual contributions of rainfall intensity and slope to splash erosion,and to distinguish the enrichment ratio of each size and the critical size in splash,loessial soil collected on the Loess Plateau in May 2019 was tested under different rainfall intensities(60,84,108,132,156 mm h^(-1))and slopes(0°,5°,10°,15°,20°).The results demonstrated that 99%of splash mass was concentrated in 0–0.4 *** intensity was the major factor for splash according to the raindrop generation mode by rainfall simulator *** contributions of rainfall intensity to splash erosion were 82.72%and 93.24%,respectively in upslope and downslope *** mass percentages of effective clay and effective silt were positively correlated with rainfall intensity,while the mass percentages of effective very fine sand and effective fine sand were negatively correlated with rainfall *** to effective very fine sand,the mass percentages of effective clay significantly decreased with increasing *** intensity had significant effects on enrichment ratios,positively for effective clay and effective silt and negatively for effective very fine sand and effective fine *** critical effective particle size in splash for loessial soil was 50μm.

关键词： splash erosion loessial soil effective soil particles splash distance enrichment ratio

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Distribution of Soil-Bound Lead Arising from Rainfall-Runoff Events at Impact Berm of a Military Shooting Range

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Journal of Environmental Protection 2016年第5期7卷 623-634页

作者： Effiong Ukorebi Etim Department of Chemistry University of Ibadan Ibadan Nigeria

Surface runoff from rainfall event is an important indicator of metal mobility in soil, which may enhance non-point source contamination of soil. This study is designed to assess the mobility of soil-bound lead through simulated rainfall runoff experiment and its spatial distribution within the vicinity of a berm at a major military shooting range. Contamination was more significant at the impact area of berm, indicating threefold increase in Pb (17,500 ± 3811 μg/g) within a space of ten years. However, the non-impact area (459 ± 147 μg/g) was less contaminated. Other metals (Cu, Cd, Cr, Ni and Zn) analyzed were about background levels except for Cu at impact area. The enrichment ratio of Pb in runoff sediments was mostly high for the 0.43 mm sediment fractions independent of rainfall condition. Principal component analysis (PCA) biplot showed strong correlation between spatial distributions of metals around the vicinity of the berm (farmlands behind the berm) with concentrations on the impact berm soil. Surface runoff simulated on impact area soil had high concentrations of Pb (40.4 - 65.6 μg/mL) which could further lead to enrichment of soil-Pb levels within the vicinity of the berm. Decontamination measure is therefore required to minimize extensive contamination of surrounding soils of the impact berm due to rainfall runoff events.

关键词： Lead Soil Contamination enrichment ratio Sediment Shooting Range

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The enrichments of organic matter and total nitrogen in sediment as affected by relavant factors

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Journal of Geographical Sciences 2004年第4期14卷 495-502页

作者：张兴昌郑纪勇李世清 State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau Institute of Soil and Water ConservationNorthwest Sci-tech University of Agriculture and ForestryYangling 712100China

Serious soil erosion has already resulted in degradation of the Loess Plateau of China. Soil erosion is commonly accompanied by extensive soil nutrient loss. Because of enrichment processes,sediment nutrient content is often higher than that of natural soil. The objective of this study is to determine the enrichments of organic matter and total nitrogen in sediment in hilly and gully loess areas on the Loess Plateau of China. Measurements of enrichment ratios (ER) of organic matter (EROM) and total nitrogen (ERTN) in sediment as affected by rainfall, slope gradient, tillage, and fertilization were made in the field under natural rainfall conditions. The results showed that the enrichment of clay in sediment resulted in the enrichment of organic matter (OM) and total nitrogen (TN) in sediment. The averages of sediment clay ER, EROM and ERTN for the various slope gradients were 1.77, 2.09 and 1.61, respectively. The soil erosive module was negatively correlated with EROM and ERTN. Our results indicate that measures to reduce soil erosion, i.e. reducing rainfall erosivity, decreasing soil slope gradient, decreasing fertilizer use, and using level trenches, may increase EROM and ERTN. Both quantity and quality of sediment yield should be considered when implementing erosion control measures.

关键词： sediment organic matter total nitrogen enrichment ratio

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