黑龙江省近40年洪涝旱灾害及未来减灾对策

洪涝旱灾害是黑龙江省的主要自然灾害。本文提出了黑龙江省洪涝旱灾害指标;分析了1949～1990年洪涝旱灾害的时空分布特性;提出理论损失新概念,较系统地估算洪涝旱灾害造成的实际损失和理论损失;探讨防灾减灾对策。     

缓控释肥深施对黏性土壤麦田氮素去向的影响

黏性土壤严重影响土壤水肥运移.采取适宜的农艺措施优化土壤无机氮分布,减少该类型土壤的氮素损失是农业绿色可持续发展的关键.为明确缓控释肥种肥深施对黏性土壤麦田氮素损失的影响,选择常规化肥(CN)和缓控释肥(RCU)这2种类型肥料,采用撒播撒施(B)和机械化条播深施(D),研究了缓控释肥种肥深施对黏性土壤小麦产量、季节麦田氮素径流流失、氨挥发和N₂O排放的影响;并分析了其耕层土壤的无机氮时空分布特征.结果表明,相同肥料类型下,D处理的小麦产量显著高于B处理;而相同施肥方式下,RCU处理的产量显著高于CN处理.D-RCU处理的小麦产量最高,达6.97 t·hm^-2.季节径流和氨挥发氮损失量高于N₂O形态的氮损失,且不同损失途径对肥料类型和施肥方式的响应不同.肥料类型和径流发生时间是麦田径流氮素流失的主要影响因素.受监测年份降雨年型分配影响,RCU处理的季节径流氮素流失量(20.35 kg·hm^-2)较CN处理(10.49 kg·hm^-2)显著增加.生育后期是麦田氨挥发损失的主要时期,...     

长江上游的水环境问题与对策

本文论述了长江上游是长江流域生态环境危机的关键地区,每年排入的工业污水和生活污水达38亿m~3,水污染十分严重。该地区水源涵养林遭受破坏、水土流失严重、自然灾害频繁、生态环境恶化的形势十分严峻,森林植被的破坏是造成这种危机的主要原因。文章提出了营造上游水源涵养林、控制水土流失、治理工业污染和流域统一管理的防治措施。     

烟气循环流化床（CFB-FGD）干法脱硫优化调整

本文分析了烟气循环流化床工艺的运行调节原理,针对电厂自身的特点,对吸收塔进出口烟温差及床层压降参数进行调整,提高了烟气循环流化床系统运行的经济性.最后根据此实践提出了系统运行中优化调整的可行性.     

氮肥形态对坡耕地雨季土壤养分流失的影响

为了明确氮肥形态对土壤养分流失通量及途径的影响,采用随机区组试验设计,利用模拟径流小区观测的方法,研究在地膜覆盖与不覆盖情况下氮肥形态对坡耕地雨季土壤养分流失通量及途径的影响。研究结果表明：壤中流氮、磷和钾的流失量分别占总径流流失量的71.30%、6.36%和8.85%,说明磷和钾流失的主要途径是地表径流,而氮流失的主要途径是壤中流,地膜覆盖降低酰胺态氮肥和缓控释肥处理氮素流失量,其中酰胺态氮肥处理地膜覆盖较不覆盖壤中流氮流失浓度和径流氮素流失量分别降低40.40%和29.32%。在无覆盖条件下,各处理径流氮素流失顺序表现为：酰胺态氮肥〉铵态氮肥〉缓控释肥〉硝态氮肥,施用硝态氮肥氮素流失量最低,较施用酰胺态氮肥氮素流失少40.86%。在地膜覆盖条件下,各处理径流中氮素流失顺序表现为：铵态氮肥〉酰胺态氮肥〉硝态氮肥〉缓控释肥,施用缓控释肥氮素流失量最低,较施用铵态氮肥氮素流失少59.60%。结果表明在四川紫色丘陵区为了有效控制水土养分流失,在肥料形态的选择上,以无覆盖条件下施用硝态氮肥较好,以地膜覆盖条件下施用缓控释肥较好。     

陕西省自然灾害损失年景和评价指标的研究

应用模糊数学系统聚类方法对陕西1949～1990年自然灾害造成的人口死亡、房屋倒塌和农田成灾面积进行了聚类分析,划分出相似成灾年份及相应损失指标,同时通过总损失价值计算进行了逐年损失等级划分,建立了各级等级标准和灾害年景序列。     

Effect of grazing on plant attributes and hydrological properties in the sloping lands of the East African highlands

Extending livestock grazing to the steep slopes has led to unstable grazing systems in the East African Highlands, and new solutions and approaches are needed to ameliorate the current situation. This work was aimed at studying the effect of livestock grazing on plant attributes and hydrological properties. The study was conducted from 1996 to 2000 at the International Livestock Research Institute at Debre Ziet Research Station. Two sites were selected: one at 0–4% slope, and the other at 4–8% slope. The treatments were: (1) no grazing (control); (2) light grazing, 0.6 animal unit months per hectare (aum/ha); (3) moderate grazing, 1.8 aum/ha; (4) heavy grazing, 3.0 aum/ha; (5) very heavy grazing, 4.2 aum/ha; (6) initially plowed and continuously very heavily grazed, 4.2 aum/ha. The result showed that species richness, infiltration rate, bare ground, and soil loss significantly varied with grazing pressure. Species richness was higher in grazed plots compared to nongrazed plots. Biomass yield improved on heavily grazed plots as cow dung accumulated over years. Cynodon dactylon plant species persisted with livestock grazing pressure in both sites. Infiltration rate improved and soil erosion declined in all treatments after the first year.     

Natural factors and human modifications contributing to marsh loss in Louisiana's Mississippi River Deltaic Plain

Natural factors and human modifications contribute to the estimated annual loss of 10,200 ha of coastal land in the Mississippi River Deltaic Plain Region of south Louisiana. This paper combines information on regional geology and human-induced habitat alterations to evaluate the relative importance of human and natural factors to marsh loss. Data on marsh area and habitat type for 139 7.5-min quadrangles were calculated from maps based on aerial photographs from 1955/56 and 1978, and data on regional geology obtained from published maps were used to construct multivariate model relating initial marsh area, change in urban and agricultural area, change in canal and spoil area, canal area in 1978, depth of sediment overlying the Prairie terrace, and subdelta age to marsh loss. The model indicated that between 25.0% and 39.0% of the marsh loss that occurred during the 23-year period was related to canal and spoil construction, and between 9.5% and 12.7% was related to urban and agricultural development. These are minimal estimates of loss because they do not include many secondary effects (for example, canal orientation, saltwater intrusion, and eutrophication) that can also result in indirect loss. Depth of sediment, initial marsh area, delta lobe age by 1978 canal and spoil area interaction, and indirect effects not included in the model accounted for remaining marsh loss.     

QUANTITATIVE EVALUATION OF SEDIMENT DELIVERY RATIOS1

Ability to adequately estimate sediment yield is an important step in dealing effectively with soil erosion problems. Predictions of sediment yield made using the Universal Soil Loss Equation (USLE) with different forms of sediment delivery ratio (SDR) are compared with those made by Modified USLE (MUSLE) and a fundamentally derived Erosion-Deposition Model (EDM). The USLE and USLE with SDR are poor predictors of sediment yield for individual storms compared to the MUSLE and EDM. Although MUSLE gave better results than USLE it showed somewhat more scatter of data points than the recently developed EDM.     

经济植物复层栽培对三峡库区水土保持和移民经济的作用

三峡库区森林覆盖率低，水土流失严重。三峡工程兴建后，由于大量耕地被淹，移民后靠，库区的生态环境与移民经济之间的矛盾将会更加突出。本文提出了经济植物复层栽培方法，对其在减少库区水土流失、改善库区生态环境和解决库区移民经济方面的作用作了全面的论述。经济植物复层栽培是解决三峡库区生态环境和移民经济的基本途径，采用扩大种植农作物的方法来解决三峡库区移民经济问题将会加剧水土流失，使生态环境更加恶化。