东北黑土区水土流失治理措施及主要问题探讨

东北黑土地是世界三大黑土区之一.由于自然因素及人为原因,黑土层在逐年减少,黑土区的保护和治理已刻不容缓.近年来,全国坡耕地水土流失综合治理试点等工程相继实施,黑土区水土保持工作已经全面展开.对目前东北黑土区水土流失治理措施体系以及对其中存在的一些问题进行了总结和探讨.同时指出：技术是基础,政策是保障,管理是根本,为东北黑土区进一步的保护和治理提供参考.     

漫川漫岗黑土区水土流失综合治理范式

漫川漫岗黑土区是我国东北商品粮主产区和黑土坡耕地最集中的地方,也是坡耕地水土流失最严重的地区。根据漫川漫岗黑土区水土流失规律和特点,在已有水土流失治理模式的基础上,通过总结该区水土流失综合调控机制,凝练基于粮食安全的黑土区长坡缓坡水土流失综合治理范式,并对形成的水土流失综合治理范式体系的结构进行解析,对其推广应用效益进行分析,以补充和完善黑土区水土流失综合调控理论。结果表明:1)漫川漫岗黑土区水土流失治理应以坡耕地水土流失控制为主,水土流失综合治理调控主要由地表径流调控、沟道侵蚀调控和土地生产力调控3部分构成;2)基于粮食安全的黑土区长坡缓坡水土流失综合治理范式,以生态安全保障和粮食安全保障2大体系为支撑,系统结构主要包括水土流失立体防护体系结构和生态农业技术体系结构及二者之间的耦合;3)该范式可为促进东北漫川漫岗黑土区生态、社会和经济更协调发展提供科学参考和实践样板。     

东北黑土区水土流失综合防治技术体系

东北黑土区土层每年正以0.3~1.0cm的速度流失,40~50 a后大部分黑土层将流失殆尽,根据东北黑土区水土流失现状和防治分区划分,松辽流域确定了水土流失严重的漫川漫岗区、低山丘陵沟壑区、农牧交错区水土流失综合治理技术体系。     

东北黑土区水土流失综合治理试点工程取得明显成效

东北黑土区是世界仅有的三大黑十区之一,也是我国重要的商品粮基地,破誉为“北大仓”。东北黑土区有水土流失面积27.59万km^2,占土地总面积的26.79％。2003年,水利部启动了东北黑土区水土流失综合治理试点工程。试点工程实施期3年,累计中央投入1.2亿元,初步治理水七流失面积1804km^2,项目区水十流失治理程度达到81％。     

漫岗丘陵黑土侵蚀区建立水土保持型生态农业模式的探讨

东北漫岗丘陵黑土侵蚀区,水土流失比较严重,导致地力衰退、生态经济恶化。拜泉县从综合治理水土流失入手,实行生物与工程结合,治理与开发同步,在不同类型区创立了岗坡洼综合治理开发、农林牧协调发展、基塘农业、庭院生态经济良性循环四种水土保持型生态农业模式,取得了良好的生态效益和经济效益,为漫岗丘陵黑土侵蚀区的治理开发,展现出资源永续利用、经济持续发展的美好前景。     

彰武县黑土区治理试点工程进展及今后任务

"东北黑土区水土流失综合防治试点工程"项目在彰武县实施后,初步遏制了彰武县黑土区内土壤性状进一步恶化的趋势,粮食产量有所增加。但存在农民水土保持意识淡薄,生态效益与经济效益矛盾等问题。为此建议:多部门协作,采用先进技术恢复黑土生存条件;转变经营方式,降低农业比重;建立现代农业制度,巩固治理成果。进一步加大投入和宣传力度,增强农民参与意识,使黑土区的生态环境得到保护,实现经济的可持续发展。     

东北黑土区水土流失重点治理区农耕地侵蚀现状及潜在危险程度分析

东北黑土区水土流失问题正日益受到社会各界的瞩目，随着《东北黑土区水土流失综合防治试点工程》的启动实施，黑土区土壤侵蚀关键性指标的确定已从基础研究层面提升到保障该区科学治理的战略高度。通过对黑土区重点治理区坡耕地侵蚀现状和潜在危险程度的分析评价，以期为相关区域的水土保持综合治理提供可资借鉴的技术依据。     

东北典型黑土区小流域水土流失综合防治体系

针对东北黑土区土地资源不断流失和退化问题,总结东北黑土区小流域综合防治经验,对保护黑土资源和保障国家粮食生产安全是非常必要的。基于典型黑土区具有代表性的通双小流域近50a水土流失治理实践和数据,探讨和分析小流域水土流失防治措施体系结构及其综合效益。在此基础上,系统分析了小流域从坡顶到沟道的三道防线立体防护体系的原理和效益:岗顶第一道防线减少溅蚀,削弱并拦截上坡来水来沙,涵养水源,改善土壤质量;坡耕地第二道防线截短坡长,减缓径流流速和侵蚀动能;坡底第三道防线主要采用植物跌水固沟保土,抑制侵蚀发展,恢复土地资源。该三道防线是适合典型漫川漫岗水力侵蚀区水土保持综合治理的模式体系。通过水土流失治理,通双小流域森林覆盖度显著增加,生态环境得到有效改善,小流域由强侵蚀区改善为微侵蚀区,侵蚀模数由6 600t/(km2.a)降低为300t/(km2.a),且土壤质量得到明显改善,粮食产量由1979年的1 200kg/hm2增加至1995年的3 465kg/hm2,年人均收入由1985年的1 100元上升至2005年的2 700元。最后对黑土区和黄土区典型小流域综合治理模式进行了对比分析,为典型黑土漫川漫岗水力侵蚀区小流域水土流失综合防治和流域可持续发展提供借鉴和样板。     

东北黑土区水土流失综合治理成效

东北黑土区严重的水土流失,直接影响着该区生态环境安全与农业生产的可持续性.为了解决这一难题,多年来东北黑土区实施了一系列水土流失治理工程,在黑土地保护和黑土资源持续利用方面做出了重要贡献.在梳理东北黑土区国家水土保持重点工程实施情况基础上,分别从土壤侵蚀强度、林草面积、粮食产量及群众满意度变化等方面阐述了黑土地综合治理...     

加强领导 明确重点 全力搞好东北黑土区水土流失综合防治试点

在党中央、国务院的高度重视下 ,东北黑土区的水土流失防治试点工程正式启动。东北黑土区是我国重要的商品粮基地 ,然而由于多年来的自然侵蚀和人为过度开垦 ,黑土区水土流失问题日趋严重 ,现状水土流失面积已达2 7 5 9万km2 ,占黑土区总面积的 2 7 1% ,据初步测算 ,黑土区仅侵蚀沟吞噬的耕地 ,每年就损失粮食高达 40多亿kg。因此 ,有关方面要提高认识 ,明确重点 ,创新机制 ,加强领导 ,全力搞好试点工程 ,加快黑土区水土流失防治工作的步伐     

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.