甘肃省水土保持小流域生态系统建设研究

1991～ 2 0 0 0年甘肃省开展了水土保持小流域生态系统建设研究 ,对全省不同水土流失类型区 10 3条小流域从治理方略、规划设计、生态建设、效益开发、经营管护等方面进行了系统的试验和探索 ,取得了显著成效。平均治理程度由 3 8 86%提高到 77 70 % ;农、林、牧用地比例由基期的 43 17∶12 5 8∶4 5 0调整为 3 8 5 3∶2 9 0 5∶14 19;年人均纯收入由3 82 87元增长到 110 6 3 5元 ;推广应用面积达到了 73 11km2 。     

呼斯太河流域水土保持世行贷款项目效益分析

呼斯太河流域水土保持世行贷款项目实施期为 8年 ( 1994～ 2 0 0 1年 ) ,总投资 85 0 0万元 ,将完成新增治理水土流失面积 2 0 2 7km2 。截至 1999年底 ,6年共完成治理面积 2 3 5km2 ,提前超额完成了任务 ,项目区水土流失治理程度由2 4%提高到 72 9%,土地利用率由 3 2 %提高到 82 0 %,植被覆盖度由 2 5 %提高到 72 %,土地生产力由 1741元 /hm2 增加到 3 75 0元 /hm2 ,人均收入由 62 8元增加到 2 485元 ,已显示出显著的经济、生态、社会效益     

绥棱县水土保持生态修复试点工程及效益综述

绥棱县地处黑龙江省中部,是典型的水蚀水土流失类型区。项目区在3 a内,完成水土保持生态修复面积36 670.36 hm2。占项目区总面积的62.4%,其中水土流失治理面积19 076.86 hm2,水土流失治理程度由原来的1.37%提高到76.23%。每年可蓄水3 735万m3,径流模数由189 200 m3/(km2.a)降至37 398 m3/(km2.a),蓄水效益为62.86%。每年可保土49.9万t,土壤侵蚀模数由2 2 5 0 t/(km2.a)降至6 7 6 t/(km2.a),保土效益为70.02%。项目区内林草植被面积将增至48 681.8 hm2,林草覆盖率由59.57%增至82.84%,林草植被覆盖率提高了23.27%。林草植被迅速恢复,水土流失得到遏制,生态环境明显好转并步入良性循环。农民经济收入不断提高,为实现“二次创业,富民强省”的战略目标起到示范作用。     

广安区治理小流域彰显大效益

1990年以来,四川省广安市广安区各级各部门齐抓共管、协同作战,小流域治理取得可喜成效。目前,全区已初步治理的小流域有12条达到国家治理标准,水土流失面积由治理初的1 019.9 km2降到621 km2,年土壤侵蚀模数由治理初的7 350 t/km2降到3 580 t/km2,项目区农民年人均纯收入由治     

王丈子小流域治理成果探析

经过 3年治理 ,年保水能力达 45 9万m3 ,年土壤侵蚀模数由 5 3 0t/km2 减少到 10 0t/km2 ,水土流失得到基本控制 ,林草郁闭度达 95 %以上 ,人均收入由 816元增加到 2 5 0 0元 ,取得了显著的成效。主要措施是 :( 1)各级领导重视 ,水保组织健全 ;( 2 )科学规划 ,分类实施 ;( 3 )把握特点 ,采取有效治理方法 ;( 4 )积极筹措资金 ,增加投入 ,加快治理步伐。     

黄土丘陵区宁夏西吉县土地利用动态与坡耕地生产力变化

通过资料分析、野外调查和定位试验等方法 ,对半干旱黄土丘陵区宁夏西吉县 15年的土地利用动态及坡耕地生产力变化进行了研究。结果显示 ,1980年西吉县的农、林、牧业用地比例为 8.2∶ 0 .4∶ 1.4 ,由于“三北防护林工程”和世界粮食计划署援助的“2 6 0 5”等项目的实施 ,1987年调整为 4 .6∶ 2 .4∶ 3.0 ,水平梯田面积占农业用地的百分比由 1980年的 1.7%增长到 17.6 % ,1994年继续增加到 38.5 % ;1980年、1987年和 1994年坡耕地的土壤流失量分别为 14 84 ,4 2 2 ,5 5万 t,土壤养分损失折合化肥的总量分别为 6 70 5 16 ,2 30 5 98,16 2 0 5 6 t,分别是当年化肥实际施用总量的 5 96 .5倍、2 7.6倍和 6 .8倍 ;1980年、1987年和 1994年由水土流失造成的坡耕地粮食减产量分别为 90 72 5 ,8870 9,90 4 6 5 t,分别为当年粮食总产量的 93.2 % ,2 8.1% ,16 .8%。     

枳芨壕小流域分类施治措施及成效

地处库布其沙漠边缘丘陵区与风沙区结合部的内蒙古准格尔旗枳芨壕小流域 ,在黄土高原水土保持世行贷款项目支持下 ,在风沙区以防风固沙、开发地下水、恢复植被为主攻方向 ,在丘陵沟壑区以控制水土流失为突破口 ,按照从坡顶到坡面再到沟底的顺序采取造林种草、建设基本农田、修筑库坝工程等综合开发治理措施 ,取得了显著的经济、生态、社会效益 ,水土流失得到控制 ,年均侵蚀模数由 12 0 0 0t/km2 减少为 90 45t/km2 ,生态环境得到改善 ,植被覆盖率由治理前的 2 6 9%提高到现在的 67 5 % ,农民人均纯收入由 64 9元提高到 2 0 60元 ,人均粮食由 3 3 0kg提高到 12 0 0kg。     

南阳市“长治”工程建设成绩斐然

自"长治"工程实施以来,南阳市委、市政府坚持以科学发展观为统领,以建设全国生态示范市为目标,不断创新工作机制,完善建管体制,真抓实干,务求实效,取得了显著的生态、经济和社会效益。项目区植被覆盖率由治理前的13.6%提高到28%,土壤侵蚀模数从治理前的4 100 t/(km2.a)下降至1 100 t/(km2.a),年增拦蓄径流量646.8万m3,年减少土壤侵蚀总量120万t;坡耕地改梯田后粮食产量平均增加1 125 kg/hm2,加上经果林收入,项目区群众经济收入显著提高;"长治"工程与新农村建设相结合,有力地推进了农村精神文明建设和生态文明建设,项目区各县多次受到水利部、财政部和上级有关部门的表彰。     

九华沟流域综合治理开发途径与模式

属干旱半干旱山区的甘肃定西县九华沟流域 ,从上游到下游、从坡面到沟道 ,建成了完整的径流调控体系 ,把导致水土流失的降雨径流变为产业结构调整、侵蚀劣地改造、发展高效农林牧业的有效水资源。通过综合治理、综合开发 ,流域生态环境明显改观 ,治理程度达到 86 3 % ,年土壤侵蚀模数由 5 40 0t/km2 降低到 915t/km2 ,林草覆盖率由 2 4%提高到 5 7 1% ,经济效益稳步增长 ,社会效益显著     

世行贷款昕水河流域水土保持项目建设评价

世行贷款昕水河流域水土保持综合治理项目自 1994年正式启动以来 ,共完成投资 180 3 9 5 7万元 ,治理水土流失面积 3 2 63 9 94hm2 。通过 8年的建设 ,项目区年人均社会总产值由 64 6元上升到 3 884 4元 ,增长 5倍 ;年人均纯收入由 3 91 6元上升到 12 43 81元 ,增长 2 2倍 ;土地利用率由 5 1%提高到 5 6 6%,土地利用结构趋于合理。项目区植被覆盖率由 3 0 6%提高到 3 7 7%,治理度达到 46 1%。     

Accumulation of copper in soils and leaves of tomato plants in greenhouses in Turkey

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.     

Role of selenium in mitigation of cadmium toxicity in pepper grown in hydroponic condition

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.     

红壤区不同肥力水稻土根际硝化作用特征

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。     

自由基在鸡肾病发生中的作用研究

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.     

Occurrence of Sexual Hormones in Sediments of Mangrove in Brazil

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.     

Meta-analysis in the Selection of Groups in Varieties of Citrus

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.     

Effect of iron-quercetin complex on reduction of nitrite in in vitro and in vivo systems

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.     

旱地果园水肥管理模式研究进展

分析了旱地果园水肥管理模式的研究进展和存在问题,指出水肥胁迫尤其是水钾已成为旱区果树高产稳产优质化的主要限制因子。在系统探讨旱地果园水分管理、养分管理、综合管理以及果树叶营养综合诊断施肥标准的基础上,提出了旱地果园的高效水肥管理模式。     

Role of aldehyde oxidase in the hepatic in vitro metabolism of 3-methylindole in pigs

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.     

北京市郊典型农田施肥研究与分析

通过问卷调查形式,对京郊粮田、菜田和果园3种农田施肥现状进行研究.结果表明,菜田和果园化肥施用量较高,氮、磷、钾肥均显著高于粮田.菜田和果园氮肥用量分别为1741.0和1172.8 kg/hm2,分别是粮田氮肥用量的4.5和3.0倍;磷肥用量分别为1375.1和996.4 kg/hm2,分别是粮田磷肥用量的15.5倍和11.2倍;钾肥用量分别为791.3和602.4 kg/hm2,分别是粮田钾肥用量的21.1和16.1倍.另外,3种利用方式的农田氮、磷和钾肥施用比例不同,粮田为75.4%、17.3%和7.3%;果园为42.3%、36.0%和21.7%;而菜田为44.6%、35.2%和20.3%.3种种植类型中均存在氮肥投入过量、钾肥不足的问题.