宁夏水土流失的成因分析与防治措施的探讨

宁夏是一个干旱、风沙、盐碱、荒漠化都比较严重的省区,水土流失较为严重,生态环境脆弱,严重制约了地区经济建设和社会发展。根据实际调查和有关资料查证,分析了宁夏水土流失的原因,探讨了该区水土流失的防治与保护措施。     

滩涂围垦区的水土流失及其治理

江苏滩涂为粉砂质沉积物组成,有机质含量低,结构性差,抗蚀能力弱.为了解滩涂围垦区的水土流失特征及其治理途径,依据多年对该区的调查、观测资料,分析了该区水土流失的特征降雨是该区水土流失的最主要外营力,水蚀是该区水土流失的主要形式;粉砂土抗剪强度小,该区的重力侵蚀总是与水蚀相伴而生;风蚀是滩涂新垦区在缺乏植被保护的情况下造成水土流失的主要原因之一;提出了该区水土流失的治理途径科学规划,合理确定改良利用方向;采取生物措施,改善生态环境,建立人工生态系统;进行必要的工程措施,提高沟河路渠抗蚀能力;精心护理,合理耕作,提高盐土抗蚀能力.可为滩涂围垦区的水土保持及土地的综合开发利用提供依据,对该区经济的可持续发展有重要意义.     

西藏输变电工程水土流失特点及防治措施分析

西藏自治区生态环境脆弱,自我修复能力差,一旦遭到破坏将很难恢复。西藏输变电工程在该区复杂环境的影响下,具有不同于其他地区输变电工程的建设特点,通过对西藏输变电工程水土流失特点进行分析,针对各防治区不同的水土流失特点提出有针对性的水土保持措施,旨在达到减少水土流失、保护生态环境的目的。     

浙江临安市水土流失现状及生态修复对策

临安市由于土地利用方式不合理以及开发建设项目等原因造成水土流失严重、生态环境恶化。全市水土流失总面积为467.7 km²,以中度土壤侵蚀为主。水土流失主要发生在林地,面积占水土流失总面积的79.50%,尤以山核桃林为主。本文在介绍临安市水土流失现状特点、危害及成因的基础上,提出了该区进行水土保持生态修复的对策,特别是山核桃林下水土流失防治措施,以期促进当地经济与生态环境建设可持续发展。     

陕北黄土高原森林群落物种多样性分析

晋陕蒙能源基地榆神府矿区,煤炭资源丰富,是我国重要的能源重化工基地。由于地处鄂尔多斯盆地东北部的黄土丘陵区和毛乌素沙地,自然条件恶劣,生态环境十分脆弱,水土流失是该区主要环境地质问题之一,而煤炭资源的大规模开发,必将加剧水土流失和环境恶化。根据1987年、1992年和1999年3期TM卫星遥感影像解译成果,在地理信息系统空间数据库功能的支持下,应用层次分析法,评价了该区水土流失现状,初步揭示了水土流失影响因素和发展规律。结合调查成果,研究了矿山开发等对水土流失的影响,并进行了初步预测评价,为该区环境保护和水土流失的防治提供了依据。     

鲁中南低山丘陵区水土流失原因及治理措施

鲁中南低山丘陵区由于山高坡陡,冲蚀切割强烈,为山东省水土流失最严重的地区。阐述了鲁中南低山丘陵区水土流失的现状及危害,分析了其形成的原因。该区通过建立工程、生物、农业措施紧密结合的防护体系,有效地控制水土流失,改善生态环境,取得了显著的生态效益、社会效益和经济效益。     

浅谈黑土区的水土流失及其综合治理措施

黑土,因其肥力很高,自古以来就有“土中之王”、“谷物粮仓”之美誉.黑土区是我国重要的商品粮基地,多年来,为我国提供了大量粮食,对我国社会主义建设作出了重要贡献.长期以来,由于水土资源的不合理利用,粗放经营,导致水土流失严重,土壤肥力下降,地力减退,生态环境恶化.本文分析了这一地区水土流失、生态恶化的同时,提出了防治该区水土流失的综合措施.     

自动化监测系统在水土流失观测中的引进与应用

由于土壤侵蚀使土壤退化及土地生产力下降,甚至威胁人类生产生活的生态环境.多年来土壤侵蚀规律研究一直是自然科学领域研究的关键性技术.20世纪50年代初,黄委会在黄土丘陵沟壑区第1副区设立了小流域土壤侵蚀不同类型的因子观测站网、径流小区等,采集获得60 a多的原始观测资料.长期以来一直为人工观测,成果资料多为降雨-径流-泥沙的特征点源数据,而每次降雨侵蚀是一个连续的自然过程,人工监测由于其因子对位性、监测数据的连续性和系统性较差,造成研究成果只局限于土壤侵蚀影响的单因子或部分因子研究成果,严重影响该区水土流失系统模型的开发.为了进一步提升水土流失规律研究的水平,寻找土壤侵蚀客观真实的自然数据规律,加快该区水土流失模型开发,在该区引进了现代自动化的水土流失监测系统,经过2 a的监测实践和成果数据的比测分析,不仅节约了大量的人、才物资源,而且获取得了客观真实、精度较高和连续动态的水土流失过程数据,对该区水土流失规律研究将起到积极的推动作用.     

三峡库区坡耕地运用生物埂治理水土流失技术的研究

阐述了三峡库区耕地构成及其水土流失成因,研究了该区坡耕地运用生物埂治理水土流失技术,并提出该区减少水土流失、防止农业面源污染的对策与措施     

豫南大别山区水土流失现状和防治对策

豫南大别山区是河南省重要的木材基地和粮食区, 面积近200万ha。由于自然条件和社会因素的作用, 水土流失严重。本文调查分析了该区水土流失的现状、问题和防治措施, 为搞好该区水土保持和发展生产献计献策。     

贵州草海耕地土壤与农作物中DDTs和HCHs残留及污染特征

采集草海流域周边成熟期整株农作物及土壤样品,分析测试其中DDTs和HCHs的含量,对比研究了土壤和作物中DDTs和HCHs污染水平及其在作物中富集能力。结果表明：研究区域土壤中HCHs和DDTs残留检出率均为100％,残留范围分别为0．06～16．66μg·kg^-1和0．08-39．77μg·kg^-1,土壤中HCHs和DDTs的残留量均小于国家土壤环境质量一级标准;三种农作物中DDTs、HCHs及∑（DDTs,HCHs）残留量差异显著,HCHs含量最高的是玉米,DDTs和（DDTs,HCHs）最高的是马铃薯;三种农作物中HCHs和DDTs残留的风险系数均为1．1,属于低度风险,农作物中DDTs、HCHs及∑（DDTs,HCHs）的安全指数IFSc均小于1,DDTs和HCHs残留量对三种农作物安全影响的风险是可以接受的。     

陇陕片预警减灾工作的成效与做法

自 1991年长江上游水土保持重点防治区滑坡、泥石流预警系统运作以来 ,陇南陕南片成功预报和处理滑坡、泥石流险情 10 3处 ,保护人口 11 6 8万 ,避免经济和财产损失 11879 6 5万元 ,取得了良好的社会效益。主要做法及经验是 :依靠各级政府 ,健全预警网络 ;广泛深入宣传 ,增强防灾意识 ;健全管理制度 ,落实岗位职责 ;强化技术培训 ,提高业务技能 ;加强检查指导 ,现场解决问题 ;及时调查险情 ,做好技术服务 ;预防治理结合 ,注重减灾实效。     

Changes in yield and gas exchange parameters in Festulolium and alfalfa grown in pure sowing and in mixture under drought stress

Crop performance and yield are the results of genotypic expression as modulated by continuous interaction with the environment. Among environmental factors, water is globally one of the most limiting for crop production. Water resources in the world are steadily diminishing and in many areas, including Poland, more frequent periods of drought are being observed. The aim of the study was to compare the yields and gas exchange parameters of Festulolium hybrid (Festulolium braunii (K. Richt) A. Camus) and alfalfa (Medicago?×?varia T. Martyn) under different levels of soil moisture (well-watered conditions and drought stress) and cultivation method (pure stand and mixture). The study has shown that all the measured parameters were affected by drought stress. Net photosynthetic rate, transpiration rate, stomatal conductance and dry mass yield were significantly lower under drought stress than under well-watered conditions in all treatment types. Alfalfa grown in a pure sowing showed the strongest reaction to stress, while hybrid Festulolium grown in mixture showed the weakest. It was also found that under stress, grass assimilated CO₂ and evaporated water much more intensively in mixture cultivation than in pure sowing. Higher water use efficiency (WUE) was observed in alfalfa and Festulolium growing in mixture only in the first year of the study.     

Cadmium Effects in Sunflower: Membrane Permeability and Changes in Catalase and Peroxidase Activity in Leaves and Calluses

Mechanisms preventing oxidative burst in cells exposed to high metal concentrations are crucial for cell survival. In this report, sunflower (Helianthus annuus L.) was used as a model species to investigate: (a) how cadmium (Cd) affects plant defense pathways (in particular, those involved in preventing oxidative stress), and (b) whether antioxidative enzymes of plants and of in vitro cell culture (calluses) have similar responses to Cd exposure. For this experiment, plants (grown hydroponically on Long Ashton medium) and calluses (grown on Murashige and Skoog medium) were exposed for three weeks to different Cd concentrations (0, 5, 50, and 500 μ M). Solute and electrolyte leakage increased significantly with the increase in Cd concentration in the external medium and in exposed leaves, and less in exposed calluses. Cadmium exposure also reduced significantly soluble protein contents in both leaves and calluses. The activities of catalase and peroxidase decreased significantly in 50 and 500 μ M-exposed leaves compared with the control, but increased in 5 μ M-exposed calluses, decreasing in the calluses exposed 500 μ M Cd. The decrease in antioxidative enzymes activities is congruent with the decrease in membrane integrity and suggests that calluses develop antioxidant mechanisms that respond better to Cd stress than do leaves. On average, 100% of plants exposed for 21 d to 500 μ M and 95% of plants exposed for 45 d to 50 μ M Cd were dead. After 45 d, only 53% of 50 μ M-exposed calluses had died. These surviving calluses were maintained on 50 μ M for six months. Six-month-old exposed calluses had higher activities of peroxidase and catalase when compared with control calluses, as well as lower membrane degradation. These data show that calluses are more tolerant than plants to Cd exposure, and that antioxidant mechanisms under Cd exposure may differ between the two cell systems and vary with time.     

肯尼亚和中国农业资源投入与农业单产水平变化

当前,肯尼亚和中国在生产足够粮食以保障粮食安全方面都面临着严峻的挑战。尤其是对于肯尼亚而言,因为其2100年预测的人口将达到2018年的1.4倍,且其粮食生产在过去并没有大幅度的改善。而中国近些年粮食生产能力显著提高。本文系统分析了肯尼亚和中国农业资源投入、种植业和畜牧业单产水平的历史变化,以及农业资源投入与产量之间的关系,为肯尼亚粮食危机和消灭贫困提供更多的理论支撑。研究结果表明,在20世纪60年代,肯尼亚耕地、草地和降水等自然资源人均占有量比中国高2~3倍,且人均食物能量和蛋白质供应显著高于中国。当前,肯尼亚人均资源拥有量仍高出中国约30%,但是其人均食品供应和粮食自给率却远低于中国平均水平。这是由于与肯尼亚相比,中国在种植业和畜牧业长期持续的投入,大幅度地增加了种植业和畜牧业能量或蛋白质单产水平。1961-2017年,中国和肯尼亚作物蛋白的平均单产分别增加282%和44%。中国的数据表明,种植业和畜牧业单产水平与肥料、精饲料、机械和农药的投入具有显著正相关性;农牧业生产结构对单产水平的变化影响也很大,如种植业中蔬菜和水果播种面积占比,畜牧业中单胃动物饲养占比等。总的来说,农业资源投入和农业结构对生产力的提高都有很大的影响,这可能是肯尼亚提高农业生产力的潜在选择。     

Fungal abundance and diversity in earthworm casts and in uningested soil

Earthworm casts and adjacent uningested soil from 30 different locations were compared to determine the abundance and diversity of fungal species. The casts contained larger fungal populations (g^-1 dry soil weight) and numbers of fungal species than the soil. Variations in these parameters between casts and soil were statistically significant (P=0.05). Fungal populations and the number of fungal species in casts and soil also varied significantly (P=0.05) between samples from different locations. A total of 27 fungal species were recorded from the casts and soil. Indices of dominance (0.084 casts; 0.14 soil) and general diversity (2.53 casts; 2.02 soil) demonstrated that the casts displayed more diverse fungal flora than the soil. The diversity of fungal species increased in earthworm casts after passing through the earthworm gut.     

云南省开展水土保持的做法与成效

云南省各级党政领导重视和支持水土保持 ,积极出台有关法规、政策 ,为搞好水土保持工作提供了保障。治理中坚持高起点要求 ,有力地推动了水保产业化建设。适应市场经济要求 ,大力发展水土保持专业户、重点户 ,调动社会各方面力量参与水土流失治理开发。介绍了具体的做法、成效及今后做好水保工作的思路。     

1,4-Dimethoxyglucobrassicin in Barbarea and 4-hydroxyglucobrassicin in Arabidopsis and Brassica

A novel indole glucosinolate, 1,4-dimethoxyglucobrassicin (1,4-dimethoxyindol-3-ylmethylglucosinolate), was isolated as the desulfo derivative from roots of the P-type of Barbarea vulgaris ssp. arcuata, and its structure was determined by spectroscopy including 2D NMR spectroscopy. 4-Hydroxyglucobrassicin (4-hydroxyindol-3-ylmethylglucosinolate) was isolated as the desulfo derivative from green siliques (fruits) of Arabidopsis thaliana and identified by comparison of its (1)H NMR spectrum with the spectrum of the known desulfoglucosinolate from Brassica napus. The delayed elution of desulfo indole glucosinolates from the DEAE Sephadex column used in sample preparation was examined, and the diode-array UV spectra of desulfo indole glucosinolates were measured, to ensure a reliable determination of 1,4-dimethoxyglucobrassicin and 4-hydroxyglucobrassicin with the existing analysis method based on the HPLC of desulfoglucosinolates. 1,4-Dimethoxyglucobrassicin was not detected in 10 other Arabidopsis, Brassica, and Barbarea species, indicating an evolutionarily recent mutation in the indole glucosinolate biosynthesis in B. vulgaris ssp. arcuata type P.     

Aorta and liver changes in rats fed cholesterol-containing and raw vegetable-supplemented diets: experiments in vitro and in vivo

The aim of this investigation was to compare the liver and aorta changes in rats fed cholesterol-containing diets and the possible improvement when diets would be supplemented with frequently used raw vegetables. The phenolic compounds of three vegetables in methanol-water (1:1) fraction were characterized using electrospray ionization mass spectra (ESI-MS). Results showed that the content of polyphenols, flavonoids, quercetin, flavanols, tannins, and ascorbic acid varied for garlic and white and red onions ranging from 6.68 to 18.08 mg GAE/g DW, 490.4-701.0 μg CE/g DW, 281.2-1100.0 μg, 32.40-41.30 μg CE/g DW, 2.88-3.12 mg CE/g DW, 1.87-2.33 mg AA/g DW, 1388.2-1442.3 μg CGE/g DW, respectively. The radical scavenging capacities (μM TE/g DW) for the same investigated vegetables for ABTS, FRAP, CUPRAC, and DPPH assays ranged from 48.78 to 92.42, 9.41-28.56, 3.06-10.41, and 6.49-23.42, respectively. Good correlations were observed between the phenolic contents and the radical scavenging capacities of the vegetables. The interaction between BSA and quercetin, BSA and garlic and onions extracts was measured by 3-dimensional fluorescence (3D-FL) and Fourier transform infrared (FT-IR) spectroscopy. The highest polyphenol content was found in methanol/water fraction of onions and garlic; therefore, for the investigation of in vitro interactions with BSA only polyphenols of this fraction were used. For in vivo studies, 30 male Wistar rats were divided into 5 groups each of 6 and named Control, Chol, Chol/Garlic, Chol/OnionRed, and Chol/OnionWhite. During 6 weeks, the rats of all 5 groups were fed a basal diet (BD). The rats of the Control group were fed the BD only. The BD of the Chol group was supplemented with 10 g/kg of nonoxidized cholesterol (NOC). Each of the other three groups was supplemented with 10 g/kg of NOC and 500 mg of raw fresh garlic, 500 mg of raw fresh red onion, and 500 mg of raw fresh white onion on 1 kg of body weight for Chol/Garlic, Chol/OnionRed, and Chol/OnionWhite diet groups, respectively. In order to detect the changes in the liver and aorta, a histological procedure was applied, and the liver enzymes were determined and compared. It was found that the main changes vs the Control group were in the liver of rats fed the cholesterol-containing diet without vegetable supplementation. Significantly less histological changes in the liver and lower level of liver enzymes vs those of the Chol group were detected in rats of the Chol/Garlic group (P < 0.05). The interaction between the polyphenol extract of garlic and BSA in vitro showed its strong ability comparable with that of quercetin to quench the intrinsic fluorescence of BSA. In conclusion, all studied vegetables showed protective effects, but raw garlic supplemented with cholesterol-containing diets significantly prevented the aorta and liver damages of rats.