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黄土高原地区水土保持淤地坝规划概述 总被引：2，自引：0，他引：2
黄土高原地区淤地坝建设范围涉及 3 9条支流 (片 ) ,总土地面积 42 .6万km2 ,水土流失面积 2 7.2万km2 。按照规划 ,到 2 0 10年 ,建设淤地坝 6万座 ,其中骨干坝 1万座 ;到 2 0 15年 ,建设淤地坝 10 .7万座 ,其中骨干坝 1.7万座 ;到 2 0 2 0年 ,建设淤地坝 16.3万座 ,其中骨干坝 3万座。工程完成后 ,工程实施区水土流失综合治理程度达到 80 % ,可减少入黄泥沙 4亿t ,拦截泥沙能力达到 40 0亿t ,新增坝地面积达到 5 0万hm2 ,促进退耕面积可达 2 2 0万hm2 、封育保护面积可达40 0万hm2 。 相似文献
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淤地坝是陕北黄土丘陵沟壑区控制水土流失和建设高产农田的有效措施。文中论述了坝系规划及坝地利用模式、淤地坝的经济效益和坝系的减水减沙效益。有关建坝的设计标准、建坝密度和投资回收年限等几个主要问题也予以讨论。 相似文献
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陕北淤地坝建设现状调查分析 总被引：1，自引：0，他引：1
淤地坝建设在陕北有着悠久的历史，截至１９８９年底止，共建成淤地坝３１７９７座，其中有骨干工程５８座，大型８３６座，中型５６００座，小型２５３０３座，总库容３９４９２８万ｍ３，已拦泥２９８１０９万ｍ３，共可淤地４９３８６ｈｍ２，已淤地４３２８９ｈｍ２，坝地利用率６９．８％。大中型和骨干工程控制流域面积１７５６２．５７ｋｍ２，占全区水土流失面积的２６．７％。由于缺乏合理的规划设计、施工质量低、运行年限超过设计淤积年限等原因，有７５．８％的淤地坝成为病险坝。应加强淤地坝建设的科学研究，加强管护、抓紧整修加固配套。 相似文献
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截至 2 0 0 2年底 ,陕西省共建成各类淤地坝 3 75 77座 ,其中骨干坝 3 73座 ,大型坝 793座。据对陕北榆林、延安两市的 3 2 5 98座淤地坝调查 ,采用集体统管分户使用形式管理的有 185 5 3座 ,采取承包、租赁、股份制、拍卖等形式改制的有 14 0 45座。介绍了各种改制形式 ,并进行了评价。以新建坝不再给国家增加负担 ,努力实现以坝养坝、滚动发展为淤地坝建设的总目标 ,提出了淤地坝运行管理改革思路 相似文献
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陕北千沟万壑,适宜修造淤地坝,每平方公里可建坝地2.3～3.5hm~2。经多年努力,已建成淤地坝3.4万座,拦泥20多亿t,淤成坝地5.38万hm~2,年产粮食1.6亿kg,减少了入黄泥沙,提高了群众生活水平。但现有淤地坝存在坝系布设不合理、工程不配套、大部库容已淤满、防洪标准低和部分坝地盐碱化等问题。为此,提出加高配套淤地坝、布设控制性的骨干工程等对策,并分析了陕北坝地建设的发展前景。 相似文献
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《山西水土保持科技》2007,(1):35
2007年,我省将突出抓好以淤地坝建设为重点的水土保持工作。一是按照全省淤地坝工程建设规划,2007年开工并建成淤地坝2 000座,增加坝滩地1.7万hm2;二是依托国家水土保持重点工程项目建设,完成水土流失综合治理面积36万hm2,实施生态修复面积73.3万hm2,确保水土流失年治理度达到3 相似文献
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截至2006年底,黄河水土保持生态工程西宁、互助项目区共完成水土流失治理面积263.9 km2,建成骨干坝29座、中小型淤地坝211座,修建谷坊341座、沟头防护120处,13条小流域坝系已建成淤地坝152座,其中骨干坝28座、中型淤地坝44座、小型淤地坝80座,共实施生态修复面积7 539 km2,为减少入黄泥沙、改善局部生态环境和农牧民的生产生活条件、调整农业生产结构、加快山区脱贫致富、促进当地经济社会的可持续发展做出了重要贡献。介绍了青海黄河水土保持生态工程建设的具体成效及经验。 相似文献
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Appropriate compost standards are being considered in Canada. Five aspects of compost safety and quality are being evaluated; probably the most controversial aspect is the standards for metals in compost. In order to assist in the development of appropriate standards, the authors began an extensive research project in October, 1993 to determine the bioavailability of metals from compost and compost-metal mixtures. Swiss chard was grown in compost-amended soils or compost in a growth room using five treatments of increasing percentages of compost in the media (0, 25 percent, 50 percent, 75 percent, 100 percent compost (v/v)). A Truro loamy sand and a race-track manure-biosolids compost (RTM-biosolids) supplemented with a high metal biosolids were used in a completely randomized design with five replicates. Dry matter yield, metal content in plant tissue, and total metal uptake were evaluated as well as the total and DTPA-extractable metal content in the compost-soil mixes. The results of this and five other experiments conducted by the authors will help determine whether the suggested limits for As, Cd, Co, Cr, Cu, Hg, Mo, Ni, Pb, Se and Zn in composts are appropriate. 相似文献
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《Communications in Soil Science and Plant Analysis》2012,43(4):291-301
Abstract The seasonal patterns of foliage nutrient concentrations and contents were monitored for two growing seasons in an 11‐year—old Pinus el1iottii stand. In the first growing season after needle initiation, N, P, K, Mg, and Zn concentrations decreased, but this was followed by an increase in the fall and winter months. Another drop in concentration of all elements, except P, occurred in the second growing season. Decreases in total contents indicated that this drop was a result of translocation to other tissues. In contrast to the mobile elements, the concentration and fascicle contents of Ca, Mn, and Al increased with aging of the needles. Between‐tree variability was least for N, P, and Zn and the N, K, Mg, Mn, and Zn in the current foliage had consistently lower variation than that in the 1‐year‐old foliage. Between‐tree variation for K was lower in the winter than the spring. For pine foliage, recommended sampling period for N, P, Mg, and Zn is mid to late summer and for the other elements it is late fall to late winter. There are several sources of variation that influence the level of nutrients in tree foliage. The most important of these, apart from the tree nutrient status, are seasonal fluctuations, variation between trees, and age of needles . Smaller sources of variation are associated with position of the needles within the crown, diurnal changes, year to year variation, and analytical errors1,2. These variables must be studied in order to develop suitable sampling techniques and in Pinus this has been undertaken for P. banksiana 1, P. taeda 3, P. strobus 4, P. resinosa 4, P. sylvestris 5, and P. radiata 6,7. However, foliage sampling has not been studied in detail for slash pine (Pinus elliottii Englem var. elliottii) and earlier studies with other pines have been largely confined to temperate or cool climates. This study reports the variation in elemental concentrations with season, age of foliage, and between slash pine trees growing in a subtropical climate in Florida. 相似文献
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A Gimeno 《Journal of the Association of Official Analytical Chemists》1979,62(3):579-585
A general method is described for determining 16 mycotoxins in mixed feeds and other food products used in the manufacture of these feedstuffs. The mycotoxins are extracted and cleaned up by extracting with solvents of different pH. Thin layer chromatography is used to separate the toxins; toxins are then quantitated by the limit detection method. The minimum detectable concentration of mycotoxins in various products is: aflatoxin B1 or G1, 4--5 micrograms/kg; ochratoxin A or ethyl ester A 140--145 micrograms/kg; citrinin 600--750 micrograms/kg; zearalenone, 410--500 micrograms/kg; sterigmatocystin, 140--145 micrograms/kg; diacetoxyscirpenol, 2400--2600 micrograms/kg; T-2 toxin, 800--950 micrograms/kg; patulin, 750--800 micrograms/kg; penitrem A 14,000--14,500 micrograms/kg; penicillic acid 3400--3650 micrograms/kg. 相似文献
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B S Kaphalia R Takroo S Mehrotra U Nigam T D Seth 《Journal of the Association of Official Analytical Chemists》1990,73(4):509-512
A total of 244 samples of cereals (wheat flour, rice, and maize), pulses (arhar, moong, gram, lentil, and black gram), spices (turmeric, chili, coriander, and black pepper), vegetables (potato, onion, spinach, cabbage, brinjal, and tomato), fruits (mango, guava, apple, and grape), milk, butter, Deshi ghee, and edible oils (vegetable, mustard, groundnut, and sesame) collected from different cities of Northern Province (Utter Pradesh) were analyzed by gas liquid chromatography for the presence of organochlorine pesticide residues. Residues of hexachlorocyclohexane (HCH) and 2,2-bis(p-chlorophenyl)-1,1,1-trichloroethane (DDT) were detected in about 85% of the total samples of cereals, spices, milk, butter, Deshi ghee, and edible oils analyzed in the present study. However, the residue levels were either very small (less than 0.06 ppm) or not detected at all in pulses, vegetables, and fruits as compared with very high concentrations in wheat flour (4.42 and 0.12 ppm), butter (1.19 and 4.85 ppm), mustard oil (1.26 and 2.42 ppm), Deshi ghee (1.10 and 3.84 ppm), vegetable oil (1.02 and 0.59 ppm), groundnut oil (0.51 and 1.49 ppm), and chili (0.48 and 1.92 ppm). The levels of HCH and DDT residues detected in rice, maize, turmeric, corlander, black pepper, and all the vegetables and fruits were also lower than those found in wheat flour, oil, and fat samples analyzed in the present study. These findings suggest that a restricted and controlled use of such persistent pesticides may be useful for decreasing their contamination levels in different food items. 相似文献
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《Communications in Soil Science and Plant Analysis》2012,43(9):751-756
Abstract The phytotoxicity of five nonessential elements (Co, V, Ti, Ag, Cr) to higher plants was studied in solution culture experiments with bush beans (Phaseolus vulgaris L. C.V. Improved Tendergreen). All, but in varying degrees, tended to concentrate in roots with a decreasing gradient to stems and leaves. Cobalt was one of the more mobile of the five trace metals. Its toxicity was expressed as severe chlorosis; 43 (with 10‐5 M) and 142 (with 10‐4 M) μg Co/g dry weight in leaves resulted in severe chlorosis. Vanadium as 10‐4 M vanadate resulted in smaller plants but not in chlorosis. Leaf, stem, and root V, respectively, were 13, 8, and 881 μg/g dry weight. Titanium was somewhat mobile with considerable yield decrease at 10‐4 M; leaf, stem, and root Ti concentrations, respectively, were 202, 48, and 2420 μg/g. Symptoms were chlorosis, necrotic spots on leaves, and stunting. Silver was very lethal at 10‐4 M AgNO3; at 10‐5 M yields were greatly decreased, but plants were grown without symptoms. Leaf, stem, and root concentrations of Ag for this treatment, respectively, were 5.8, 5.1, and 1760 μg/g dry weight. Plants grown with 10‐5 N Cr2O7 were decreased in yield by about 25% with or without EDTA (ethylenediamine tetraacetic acid) while the same level of Cr2(SO4)3 was essentially without effect. For the two salts, the leaf, stem, root concentrations for Cr, respectively were 2.2 and 1.3, 0.7 and 0. 7, and 140 and 104 μg/g. Most of the trace metals studied here had interactions in the uptake and/or distribution of other elements. 相似文献
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Nigel J.H. Smith 《Biological conservation》1981,19(3):177-187
Amazonia, the world's largest tropical rain forest, is often assumed to be a virtually untouched wilderness. The region is often referred to as a demographic void; there is on average only about one person per sq. km. Yet in response to international market forces, the hand of man has penetrated deep into the imposing forests. Since colonial times, wildlife, particularly along rivers, has been exploited on a large-scale basis for commercial purposes. This paper focuses on the effects of the trade on some aquatic animals. 相似文献
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Rababah TM Hettiarachchy NS Horax R 《Journal of agricultural and food chemistry》2004,52(16):5183-5186
The total phenolics and antioxidant activities of fenugreek, green tea, black tea, grape seed, ginger, rosemary, gotu kola, and ginkgo extracts, vitamin E, and tert-butylhydroquinone, were determined. Grape seed and green tea were analyzed for their phenolic constituents using high-performance liquid chromatography. The total phenolics of the plant extracts, determined by the Folin-Ciocalteu method, ranged from 24.8 to 92.5 mg of chlorogenic acid equivalent/g dry material. The antioxidant activities of methanolic extracts determined by conjugated diene measurement of methyl linoleate were 3.4-86.3%. The antioxidant activity of the extracts using chicken fat by an oxidative stability instrument (4.6-10.2 h of induction time) followed a similar trend in antioxidant activity as determined by the Folin-Ciocalteu method. Seven phenolics in grape seed and green tea extracts were identified that ranged from 15.38 to 1158.49 and 18.3 to 1087.02 mg/100 g of extract, respectively. Plant extracts such as green tea and grape seed extracts can be used to retard lipid oxidation in a variety of food products. 相似文献
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Fixation of Si, Mg, Fe, Al, Mn, Cr, Ni and Co in saprolite and laterite above serpentinite - Gebe Island, Indonesia The fixation of various major and trace elements has been studied in a saprolite/laterite profile above serpentinized peridotite. Sequential extraction of < 63 μm fraction shows different types of element fixation in soil: adsorption on mineral surfaces (1), fixation to Mn-oxides (2), bonding to poorly and better crystallized Fe-oxides (3). In the laterite, most of the extractable Si-, Al-, Cr- and Ni-contents are bound to goethitic Fe-hydroxide. The saprolite has considerable amounts of secondary quartz which has been formed during ageing of amorphous silica modifications. Their precipitation is favoured by high Si adsorption capacity of poorly crystallized Fe-hydroxide. In saprolite and laterite Co is bound to Mn-oxides. It can readily be extracted from pure Mn-oxides. In contrast, the intimate association of Mn-oxides to goethite reduces the rate of easily extractable Mn and Co in middle and upper zones of the laterite. 相似文献
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