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1.
[目的]揭示三峡库区弃渣场土壤侵蚀规律,为该地区弃渣场的土壤侵蚀治理提供依据。[方法]通过现场搭建径流小区并采用人工模拟降雨的方法进行研究。[结果]降雨量同侵蚀量存在极显著的线性关系;降雨强度同渣场产流时间呈极显著的幂函数关系,同径流含沙率呈极显著的指数函数关系;渣场表层较高的细砾石含量,一定程度上可以减少溅蚀与面蚀量,但在强降雨或持续降雨条件下会促进坡面沟蚀的发育;渣场侵蚀具有一定季节分布,非雨季时,渣场侵蚀以面蚀与轻微沟蚀为主,坡面主要发育为细沟与浅沟,侵蚀量较少;雨季时,渣场坡面浅沟迅速转化为切沟,泥沙流失严重。[结论]研究区渣场侵蚀具有一定的季节性,渣场施工时应根据气候特征适当调配,主动避开雨季,并在雨季前完成渣场的水土保护设置;采取相应防护措施抑制或减缓雨季沟蚀的发育是研究区渣场水土保持防护的重点。 相似文献
2.
水电站建设项目弃渣场岩土侵蚀研究 总被引：8，自引：0，他引：8
弃渣场是水电站建设项目水土流失最敏感的部位之一,弃渣堆积过程破环了原有岩土结构、地形和植被,且堆积坡度大,稳定性差,岩土侵蚀程度剧烈,岩土侵蚀类型多样。以金沙江上游金安桥大型水电站工程弃渣场为例,通过定位观测和调查,对其土壤侵蚀形式及成因进行了分析,测算了弃渣场不同部位的土壤侵蚀模数。结果显示,弃渣场不同部位存在溅蚀、面蚀、沟蚀、沉陷、陷穴、岩土泻溜、滑塌、滑坡等侵蚀形式;弃渣场不同部位无截排水措施的开挖边坡细沟侵蚀带、弃渣堆积平台和运渣道路不均匀面蚀带、有截排水措施和无截排水措施的弃渣堆积边坡水力-重力侵蚀带,其岩土侵蚀模数是原地貌平均侵蚀模数的73、124、186和887倍,而修建截排水措施后弃渣堆积坡面的侵蚀模数是无措施的弃渣堆积坡面的1/7.2倍。 相似文献
3.
为探讨公路弃土场边坡沟蚀发生发展规律,以湖北沪蓉西高速公路(宜长段)为例,从弃土场沟蚀发育特征、发生发展规律和与沟间侵蚀的关系3方面对弃土场沟蚀规律进行探讨.结果表明,弃土场边坡沟蚀与降雨有密切的关系,沟蚀在坡面土壤侵蚀量占的比重越来越大;弃土场坡面沟蚀发展呈加剧发展趋势,随着观测时间的变化,细沟侵蚀在整个坡面土壤侵蚀量中占的比重越来越小,而相对浅沟侵蚀和切沟侵蚀所占的比重越来越大. 相似文献
4.
以长江中上游典型侵蚀性土壤紫色土为研究对象,采用变坡限定性细沟土槽,研究不同流量、坡度和沟长情况下,紫色土细沟侵蚀特征,并量化了细沟侵蚀参数。结果表明:细沟侵蚀受水流水力特征、土壤性质和坡面影响,随着水流含沙量的增大,细沟侵蚀速率呈现减小趋势;流量越大,坡度越陡,细沟水流的剥蚀率越大,造成细沟侵蚀速率也越大。在5L/min的小流量下,细沟侵蚀速率受剥蚀率限制与含沙量没有出现线性关系,15,25L/min流量下,细沟侵蚀速率与含沙量呈线性相关。侵蚀速率在细沟开始处最大,随沟长的增大,水流能量消耗于挟带泥沙而迅速减小,相关性分析得到侵蚀速率与沟长呈指数递减,相关系数R2变化于0.45~0.98之间。通过回归分析得到试验条件下,紫色土细沟土壤可蚀性均值为0.005 3s/m,临界剪切力均值为2.92Pa。研究结果对于坡面土壤侵蚀物理模型的建立和推广应用提供数据支撑,为紫色土坡面侵蚀研究提供借鉴。 相似文献
5.
褐土与棕壤坡耕地细沟侵蚀发生的阶段性水沙变化 总被引：3，自引：0，他引：3
为深入探究辽西低山丘陵区坡耕地土壤侵蚀机理,以该区的典型土壤类型褐土和棕壤为研究对象,采用室内人工降雨模拟试验,研究3种坡度(5°,10°,15°)和3种降雨强度(40,60,80 mm/h)下细沟侵蚀发生的阶段性水沙变化过程。结果表明:褐土与棕壤坡面侵蚀过程可划分为3个阶段,即细沟侵蚀之前阶段、跌坎发育阶段和细沟侵蚀快速发育阶段;细沟侵蚀之前的面蚀阶段,同一坡度条件下,褐土与棕壤随雨强的增加,坡面流速呈增大趋势,而在同一雨强条件下,坡度对流速的影响并无明显规律;细沟侵蚀阶段,当坡度一定条件下,褐土与棕壤细沟内、细沟间的流速随雨强的增加而增大,当雨强一定时,褐土与棕壤随坡度的增加细沟间流速增加;细沟侵蚀阶段流速表现为细沟内流速坡面流速细沟间流速;细沟侵蚀快速发育阶段2种土壤产生的径流量占总径流量的80%以上,土壤侵蚀量占总侵蚀量均在70%以上,且棕壤对总体侵蚀量的贡献更稳定,更易发生细沟侵蚀。整场降雨的侵蚀方式是面蚀向细沟侵蚀的转变,坡面一旦发生侵蚀,细沟侵蚀对坡面总侵蚀的贡献更大。 相似文献
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通过组合不同坡度(10°,15°,20°,25°)、不同坡长(5,10 m)、不同降雨强度(1.5,2 mm/min)的室内纯净水模拟降雨试验,对坡面细沟侵蚀发生过程进行阶段划分,并探索分析各阶段影响因素及其效应.试验结果显示,细沟侵蚀可以分为面蚀、细沟雏形、细沟发育和细沟调整4个阶段;面蚀阶段的坡面平均含沙量随着坡度的增大呈增大的趋势,降雨强度在此阶段对坡面侵蚀速率影响较坡度影响明显;细沟发育阶段坡面侵蚀产沙比例占总侵蚀比例最大,坡面总侵蚀量与细沟发育阶段最大15 min侵蚀量之间呈线性关系. 相似文献
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沪蓉西高速公路弃土场渣体侵蚀特征——以宜(昌)至长(阳)段为例 总被引：2，自引：0，他引：2
随着我国高速公路的迅速发展，由此形成的水土流失已成为突出的环境问题。为探讨高速公路建设期间弃土场渣体侵蚀规律，在沪蓉西高速公路宜长段Ⅰ标区弃土场布设观测小区进行定位观测和分析研究。结果表明：（1）降雨量与弃土场渣体侵蚀量呈显著的正相关关系。在不考虑影响坡面渣体侵蚀其它因素前提下，随降雨量的增大，渣体侵蚀量逐渐加大。（2）研究区堆渣体沟蚀发生严重，局部坡面渣体侵蚀量高达92848t／km^2。调查发现沟深下切深度基本在40cm以内，受坡面汇水面积影响，从坡上到坡脚，堆渣侵蚀量逐渐加大。 相似文献
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坡度对坡面土壤矿质氮素水蚀流失负荷的影响 总被引：4，自引：0，他引：4
坡度是影响坡面水土流失和土壤养分流失过程的重要因素。室内模拟降雨试验表明,当坡长一定时,不仅土壤侵蚀量存在一个“侵蚀临界坡度”,土壤矿质氮流失量随坡度变化也存在一个“养分流失临界坡度”。试验测定这2个临界坡度均在15°～20°之间。土壤矿质氮地表流失以随地表径流流失为主,约占总流失量的99%。坡面矿质氮总流失量的96%为硝态氮,硝态氮对径流中矿质氮总量的贡献率明显高于在侵蚀泥沙中的贡献率。采取一定的截流措施是控制坡面矿质氮流失的关键。 相似文献
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基于水动力学的紫色土区植物篱控制面源污染的临界带间距确定 总被引：3，自引：1，他引：3
为了分析确定紫色土区植物篱控制面源污染合适的带间距,该研究基于坡面水流动力学,利用四川省遂宁市水土保持试验站多年观测资料,分析了紫色土区新银合欢植物篱带间距对10°、15°农耕地面源污染的控制机理。结果表明：紫色土区在天然降雨条件下,为保证植物篱带间距能有效地控制篱带间的土壤流失,坡面发生细沟侵蚀时的径流流速应不大于颗粒粒径<0.02 mm土粒的起动流速。通过对坡面细沟发育过程推导表明,紫色土区坡度为10°、15°的坡面布设植物篱时带间距最大分别应为13.73、9.00 m。当坡面开始产生细沟侵蚀时的径流流速与颗粒粒径<0.02 mm土粒的起动流速刚好处于临界状态时,10°、15°坡面产生细沟侵蚀的最小径流流速分别为0.183、0.190 m/s。坡面表土养分流失主要是通过土壤颗粒流失的,植物篱控制坡面土壤颗粒的流失对控制农业面源污染具有重要意义。 相似文献
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M. Kaplan 《Journal of plant nutrition》2013,36(2):237-244
Copper (Cu)‐containing fertilizers, fungicides, and bactericides has been used extensively in the greenhouses in the Antalya province in recent decades with the use of such materials tending to increase year by year. The level of DTPA‐extractable Cu was determined in 210 soils (0–20 and 20–40 cm depth) and 105 leaf samples obtained from 105 tomato greenhouses. The DTPA‐extractable Cu contents of the soils taken from the 0–20 depth ranged between 0.76 and 88.03 mg kg‐1 (mean 7.79 mg kg‐1). The percentage of soils containing DTPA‐extractable Cu greater than the critical toxicity level (20 mg kg‐1) was 8.1. The Cu content of tomato leaf samples ranged between 2.4 and 1,490 mg kg‐1 (mean 166.5 mg kg‐1). The Cu concentration in leaf samples was very high due to the intensive use of foliar applied Cu‐containing chemicals. As a consequence, 24.8% of the leaf tomato samples analyzed contained over 200 mg Cu kg‐1, the maximum accepted tolerance level. Therefore, it may be necessary to reduce the use of Cu‐containing pesticides and fertilizers, or at least reduce the amount of Cu‐containing fertilizers being used in those greenhouses where Cu‐containing pesticides have been or are being used. 相似文献
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Leila Shekari Maryam Mozafariyan Mirza Hasanuzzaman Farshad Sadeghi 《Journal of plant nutrition》2017,40(6):761-772
Selenium (Se) is an essential element for humans but is not considered as essential for plants. However, its beneficial role in improving plant growth and stress tolerances is well established. In order to study the role of Se in cadmium (Cd) toxicity in pepper (Capsicum frutescens cv. Suryankhi Cluster), this experiment was carried out in greenhouse conditions. Treatments comprised Cd [0, 0.25, and 0.5 mM cadmium chloride (CdCl2)] and Se [0, 3, and 7 µM sodium selenite (Na2SeO3)] with three replications. The result showed that Cd decreased chlorophyll a, chlorophyll b, and carotenoids, whereas Se supplementation diminished Cd toxicity on photosynthetic pigment. Selenium at 7 µM significantly increased the leaf area in the plants grown at 0.25 mM Cd. The application of Se at 3 µM with 0.25 mM Cd and Se at 3 µM and Se at 7 µM with 0.5 mM Cd increased the activity of catalase (CAT). Selenium at 7 µM decreased the proline content of pepper leaves exposed to Cd at 0.5 mM (30%). Selenium significantly enhanced the antioxidant activity of leaves, which was diminished by Cd toxicity. In general, Se has a beneficial effect on plant growth and is an antioxidant enzyme of pepper cv. Suryankhi Cluster under Cd stress and non-stress conditions. 相似文献
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红壤区不同肥力水稻土根际硝化作用特征 总被引：3，自引：1，他引：2
通过根际培养箱(三室)——速冻切片技术研究了红壤地区高、低两种肥力下水稻苗期根表、根际和土体土壤矿质态氮含量和硝化强度,以及水稻生长、氮素积累的差异。结果表明,肥力水平对水稻根表和根际土壤铵态氮(NH4+-N)含量无显著影响,但高肥力显著提高土体土壤NH4+-N含量,以及根表、根际和土体土壤硝态氮(NO3--N)含量及硝化强度。两种肥力水稻土硝化强度最大值均出现在距根表2 mm处,分别为0.20和0.31μmol kg-1 h-1。土体土壤硝化强度随距根表距离增加而降低,低肥力土壤在距根表10～40mm处时硝化强度接近本底值,而高肥力土壤在距根表20～40 mm处时接近本底值。与不种水稻的CK相比,种植水稻显著提高根际土壤硝化强度。高肥力能显著改善水稻生长,增加植株氮素积累量,尤其显著促进根系生长及通气组织发育。由于红壤稻田肥力水平的差异造成水稻根际硝化强度以及水稻吸收NO3-的差异,导致高肥条件下水稻显示出更强的生长势和氮素吸收利用能力。因此,合理提高红壤稻田肥力水平对改善红壤区水稻根际土壤硝化作用及水稻氮素营养具有重要意义。 相似文献
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自由基在鸡肾病发生中的作用研究 总被引：2，自引：2，他引：0
肾病即急性肾小管坏死.鸡肾病在养鸡生产中极为常见,尤其近年来,鸡肾病的发生日益增多,由于其发生机制不清楚,临床治疗鸡肾病的依据不足,致使治疗效果不佳,为此,提出本研究以探讨鸡肾病的发生机制,为本病防治提供理论依据. 相似文献
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Sandro Froehner Karina Scurupa Machado Elisa Stefen Marcelo Nolasco 《Water, air, and soil pollution》2011,219(1-4):591-599
The presence of sexual hormones (female estrogens) was assessed in sediments of a mangrove located in the urban region of southern Brazil. The estrogens are involved in human sexual reproduction. They act as the chemical messengers, and they are classified as natural and synthetic. The estrogens inputs in the environment are from treated and untreated sewage. The presence of estrogens in sewage is excretion from the female due to natural production and use of contraceptives (synthetic estrogens). With the indiscriminate release of sewage into the environment, estrogens can be found in rivers, lakes, and even in oceans. In this work, the presence of estrone (E1), 17-??-estradiol (E2), and 17-??-ethynilestradiol (EE2) in eight sedimentary stations in Itacorubi mangrove located on Santa Catarina Island, south Brazil, was investigated. Historically, the Itacorubi mangrove has been impacted by anthropogenic activities because the mangrove is inserted in the urban area of the Florianopolis. The estrogen EE2, used as contraceptive, had the highest concentration in mangrove sediment, 129.75?±?3.89 ng/g. E2 was also found, with its concentration ranging from 0.90?±?0.03 to 39.77?±?1.19 ng/g. Following the mechanism, under aerobic or anaerobic conditions, E2 will first be oxidized to E1, which is further oxidized to unknown metabolites and finally to CO2 and water (mineralized). EE2 is oxidized to unknown metabolites and also finally mineralized. Theoretically, under anaerobic conditions, EE2 can be reduced to E1 even in environments such as mangrove which is essentially anaerobic. 相似文献
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《Communications in Soil Science and Plant Analysis》2012,43(15):1948-1959
Brazil is the largest producer of oranges (Citrus sinensis) in the world. The nutrient management of tree orchards is designed from experiments with a limited number of varieties. This knowledge is transferred to other varieties by diagnosing tissue nutrient composition and tree demand. Compositional data analysis has been first applied to tissue analysis of agricultural crops using centered log ratios with compositional nutrient diagnosis (CND-clr). The isometric log ratio (ilr) transformation is a new approach based on binary nutrient ratios and the principle of orthogonality (CND-ilr). We analyzed eleven nutrients: nitrogen (N), sulfur (S), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), boron (B), copper (Cu), zinc (Zn), manganese (Mn), and iron (Fe) in leaf tissue samples across 108 commercial plots (thirty-one grow Valencia, twenty-two Hamlim, twenty Pera, and thirty-five Natal). Nutrients were partitioned between macro- and micronutrients as well as anionic and cationic species. The effect size of varieties over Valencia was quantified by the mean and standard deviation of ilr values across ilr coordinates. Specific varietal nutrient profiles and ilr norms were defined. The nutrient profile of orange varieties could be classified into homogeneous groups to take advantage of fertilizer trials conducted on varieties of the same group. The Aitchison distance and a perturbation vector could be instrumental for diagnostic purposes and nutrient management. 相似文献
17.
Ohnishi H Iwanaga S Kawazoe K Ishizawa K Orino S Tomita S Tsuchiya K Kanematsu Y Harada N Mori K Tsuchihashi T Ishikawa Y Tamaki T 《Journal of agricultural and food chemistry》2008,56(21):10092-10098
This study investigated whether reducing agents such as quercetin and iron(II) facilitate formation of nitric oxide (NO) gas from orally ingested nitrite in an vivo study. When 3 mg/kg Na (15)NO2 was orally administered to rats with or without iron(II) or quercetin, Hb (15)NO, which is indicative of systemic (15)NO, was detected in the blood, with the maximum blood concentration of Hb (15)NO at 15 min after nitrite or nitrite plus quercetin treatment, whereas after administration of nitrite plus iron(II) or nitrite plus iron(II) and quercetin, the time was shortened to 10 min. Interestingly, iron(II), quercetin, or iron(II) plus quercetin did not affect the total amount of Hb (15)NO generated from orally administered Na (15)NO2. However, the systemic nitrite concentration was significantly decreased in the presence of iron(II) or iron(II) plus quercetin. These results may indicate that iron(II) is critical to the generation of NO gas from nitrite, whereas quercetin contributed little under the in vivo experimental conditions. 相似文献
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Role of aldehyde oxidase in the hepatic in vitro metabolism of 3-methylindole in pigs 总被引：2，自引：0，他引：2
The metabolism of 3-hydroxy-3-methylindolenine (HMI), a recently discovered metabolite of 3-methylindole (3MI, skatole) produced by porcine liver microsomes, was investigated in vitro using porcine liver cytosol. HMI was rapidly metabolized to a single product, 3-hydroxy-3-methyloxindole (HMOI), by porcine cytosol. By the use of the selective inhibitors menadione and quinacrine, it was shown that the enzyme responsible for the oxidation of HMI into HMOI was aldehyde oxidase (AO; aldehyde:oxygen oxidoreductase, EC 1.2.3.1). The activity of AO in the conversion of HMI to HMOI was measured in a population of pigs (n = 30) with a wide range of 3MI levels in back fat (0.07-0.30 mg/kg). AO activity was found to be negatively correlated (r = -0.70; P < 0.001) with the level of 3MI in fat. The results of the present study suggest that AO plays an important role in the metabolism of 3MI in the pig and that its catalytic activity is related to an adequate 3MI clearance. 相似文献
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东北黑土土壤磷的纬向分异 总被引：8，自引：0，他引：8
以中国东北的中纬度黑土区为样带,研究了有机磷浓度与有机质、全氮浓度的关系;全磷、有机磷、无机磷及有机磷和无机磷的比率与纬度分布的关系。结果表明,有机磷和有机质、全氮浓度具有良好的相关性,它们之间的相关系数分别为0.90和0.92,呈极显著正相关(P<0.01)。全磷、有机磷、无机磷、Po/Pi在纬度上都存在不同程度的分异规律,即随着纬度的升高,其浓度或比率均有逐渐升高的趋势;其相关系数分别为0.68、0.77、0.26和0.60,相关分析表明,这些纬向分异规律都达极显著水平(P<0.01)。除了无机磷的纬向分异原因尚不明确之外,其他纬向分异的原因可能是由于黑土南北样带气候热量上的差异和人类活动的影响所致,从而造成南北样带之间有机质的矿化程度和速率产生差异。 相似文献