华北地区粮食生产与水供应情势分析

华北地区是我国重要的粮食生产基地,其粮食产量在全国粮食总产中的比重由1949年的22%上升到1998年的29.6%。灌溉是保证该区粮食高产稳产的重要保证。华北地区目前用水处于严重紧张状态,1997年人均综合用水量为315m3,农业是用水大户,工农业用水比为1∶5,水资源供需的主要矛盾在农业。华北地区水资源利用率高达98.5%,整体供水潜力所剩无几;随着工业和城镇的发展,农业用水分额将继续减少;同时,受频繁的旱涝灾害、日益严重的水污染和大面积的地下水位下降的影响,农业供水保证率将进一步降低。分析指出,若无连续丰水年和外调水源的补给,要继续保证或发展本区的粮食生产规模,本区的农业用水情势有恶化之势,急需研究并制定出解决本区粮食生产和水资源供给不足矛盾的办法。     

作为厌氧发酵原料的水分选有机垃圾特性分析

对水分选有机垃圾（WSOFMSW）的固体有机部分（SOF）和气浮污泥部分（AFS）进行采样,分析它们的成分及生化特性,并在此基础上进行小试规模（30L）的厌氧发酵产甲烷实验.结果表明：SOF的惰性部分为18%,可降解部分（挥发性固体）为72%,其中,碳水化合物、蛋白质和脂肪分别为40.4%、21.8%和9.8%;AFS的惰性部分为2%,可降解部分为82.4%,其中,碳水化合物、蛋白质和脂肪分别为53.5%、19.2%和9.7%.SOF的金属含量比AFS高,主要金属元素为Ca、Fe、Al、K、Na和Mg.在重金属中,Zn、Mn、Ni、Hg和Cr的含量超过堆肥产品的限制值.WSOFMSW在标准温度和压力（0 ℃ 和1.013×105 Pa ,文中以STP表示）下的理论产甲烷能力为484 m3 ·t-1(以VS计),实验甲烷产率为273 m3 ·t-1,中试甲烷产率为245 m3 ·t-1,每吨湿WSOFMSW产甲烷32 m3.水分选有机垃圾在厌氧消化过程中不会发生重金属、挥发性脂肪酸和氨氮抑制,但是厌氧消化启动时间较长,需要20 d.     

Effects of air pollution on rice yield in the Pakistan Punjab

A study using open-top chambers ventilated with ambient or charcoal filtered air in the vicinity of Lahore, Pakistan demonstrated reductions of 42% and 37% in the grain yield of two cultivars of rice (Oryza sativa L.). This yield reduction was primarily due to the reduction in mean panicle number per plant, although significant effects of filtration on 1000 grain weight and the number of filled grains per panicle were also detected. The 6-h daily mean O(3) concentrations were only 10-20 nl litre(-1) during the monsoon season, but increased to 30-55 nl litre(-1) later in the growing season, while the mean NO(2) concentration during the experiment was 12 nl litre(-1). On the basis of experience in North America and Japan, the reductions in yield in the present study are substantially greater than might be predicted. The reasons for this discrepancy are discussed, together with the implications for effects on rice yield in other regions of south and south-east Asia.     

生态足迹方法在中国应用的案例初探

生态足迹方法通过估算维持人类生存的自然资源消费量和同化人类产生的废弃物所需要的生态性生产空间面积大小,并与给定人口区域的生态承载力进行比较,衡量区域的可持续发展状况。本文介绍了生态足迹模型的理论依据和计算方法,从模型方法应用范围,计算所需资料和模型自身三方面分析了生态足迹方法在我国应用中存在的问题和方法本身的不足。详细分析和比较了生态足迹方法在我国不同省市及地区的应用案例,结果表明,经济比较发达地区很大程度上需要通过地区贸易从不发达地区输入生态足迹,因而加重了不发达地区的生态负担。     

不同容重的泥石流淤积厚度计算方法研究

泥石流的淤积厚度是泥石流灾害评估和防治的最重要的参数之一,但迄今还没有较好的方法计算不同容重的泥石流淤积厚度。本文通过研究泥石流屈服应力的特点,提出了用地区参数和泥石流体积浓度来计算泥石流屈服应力,进而计算泥石流淤积厚度的方法。采用本文方法计算已发生泥石流地区不同容重泥石流的淤积厚度,可以很好地应用于泥石流灾害评估和防治。     

SOLUBLE SUGAR COMPOSITION OF POND‐CYPRESS: A POTENTIAL HYDROECOLOGICAL INDICATOR OF GROUND WATER PERTURBATIONS1

ABSTRACT: Pond‐cypress, a deciduous conifer, is a dominant canopy species in depressional wetlands of the southeastern Coastal Plain (SCP). Extensive premature decline and death of pond‐cypress trees in central Florida have been attributed to hydroperiod alterations due to excessive withdrawals of ground water from the Floridan aquifer. One factor identified in the decline process is basal decay, which may be related to the presence of Botryosphaeria rhodina and Fusarium species (nonaggressive, facultative fungal pathogens). These fungi have been cultured from sapwood tissue of declining pond‐cypress associated with ground water mining, but not from pond‐cypress away from ground water mimng areas. In this experiment, differences in soluble (nonstructural) carbohydrate composition of branch tips were evaluated for one‐and two‐year old, nursery‐grown (unsheltered) pond‐cypress, following a year of growth under treatment conditions (control, fungal inoculation, water stress, and fungal inoculation plus water stress) in a growth chamber. Results from two methods of wet chemical analysis were compared (trimethylsilyl methylglycoside‐Method A, and alditol acetate ‐ Method B). Three pentoses (arabinose, rhamnose, and xylose) and three hexoses (galactose, glucose, and mannose) were identified in branch tips from both age classes. A fourth hexose (fucose) also was identified in samples from the younger trees. The acidic sugar, galacturonic acid, was identified in both age classes using Method A. Results suggest that prolonged water stress is correlated with greater relative concentrations of the neutral soluble sugars rhamnose (P = 0.02), xylose (P = 0.02), and galactose (P = 0.02), in addition to the acidic sugar galacturonic acid (P = 0.01), for Method A, and arabinose (P = 0.02) for Method B. These results also suggest that in the absence of water stress, the fungal pathogen B. rhodina does not penetrate to the sapwood of the trees, and that inoculation with this fungal pathogen is not correlated with differences in relative concentrations of nonstructural, soluble carbohydrates, based on Method A analysis. Empirical evidence suggests that pond‐cypress trees in depressional wetlands respond similarly to anthropogenic perturbations of ground water, but not to natural periods of drought in the absence of such perturbations. Therefore, pond‐cypress appear to be integrators of groundwater perturbations. Greater concentrations of the soluble sugars identified in this study in pond‐cypress branch tips may be hydroecological indicators of such anthropogenic perturbations as unsustainable yield from the regional aquifer and adverse impacts from aquifer storage and recovery (ASR) activities in the SCP.     

土工建筑物地震永久滑移变形计算方法研究进展评述

在地震动作用下,土石坝等土工建筑物与地基将产生不可恢复的瞬时失稳滑移或永久变形。从国内外发展现状及所取得的主要研究进展和近期发展动向等角度,对土工建筑物地震永久滑移变形的各种简化计算方法进行了系统的综述和总结,进而对各种分析方法及其适用条件进行了评述,最后对今后关于这一专题所应开展的研究提出了建议。     

控释掺混肥对麦玉轮作体系作物产量和温室气体排放的影响

为探究控释掺混肥一次性施肥对华北平原麦玉（冬小麦和夏玉米）轮作体系作物产量和温室气体排放的影响,于2020~2022年在德州市现代农业科技园区开展田间试验.冬小麦和夏玉米均设不施氮对照（CK）、农户习惯施氮（FFP）、优化施氮（OPT）、CRU1（包膜尿素与普通尿素在冬小麦和夏玉米上的掺混比例分别为5∶5和3∶7）、CRU2（包膜尿素与普通尿素在冬小麦和夏玉米上的掺混比例分别为7∶3和5∶5）共5个处理.对比分析了不同处理的作物产量、氮肥利用效率、施肥经济效益和温室气体排放的差异.结果表明,施氮可显著提高麦玉轮作系统单季和周年作物产量（P<0.05）.与FFP相比,CRU1和CRU2处理的夏玉米、冬小麦和周年产量分别提高了0.4%~5.6%、-5.4%~4.1%和-1.1%~3.9%（P>0.05）;氮肥吸收利用率、氮肥农学利用率和氮肥偏生产力分别提高了-8.6%~43.4%、2.05~6.24 kg·kg^-1和4.24~10.13 kg·kg^-1;周年净收益提高了0.2%~6.3%.施氮显著增加了麦玉轮作体系的土壤N₂O和CO₂的周年排放（P<0.05）,但对CH₄周年排放没有影响（第1年FFP处理除外）.CRU1和CRU2处理的土壤N₂O周年排放总量较FFP处理显著降低了23.4%~30.2%（P<0.05）.施氮显著增加了麦玉轮作体系的周年全球增温潜势（GWP）（P<0.05）,但各施氮处理通过提高作物产量降低了温室气体排放强度.与FFP相比,CRU1和CRU2处理的周年GWP降低了9.6%~11.5%（P<0.05）,周年温室气体排放强度（GHGI）降低了11.2%~13.8%（P>0.05）.综上所述,一次性减量施用控释掺混肥在减少氮肥和人工投入、提高作物产量、经济效益和降低温室气体排放方面具有积极作用,是促进华北平原粮食作物清洁生产的有效氮肥管理措施.     

Recent Changes of Sediment Yield in the Upper Yangtze, China

/ Reservoir sedimentation is one of the many environmental problems associated with the Three Gorges Project in China. The rate and characteristics of sedimentation that directly affect the operating life of the reservoir are closely related to soil erosion and sediment transport dynamics in the upstream catchment and to the ability to manage the throughput of sediment-laden waters. The recent changes in sediment yield were examined using gauging data from 187 stations of varying sizes from less than 100 km2 to larger than 1,000,000 km2 in the Upper Yangtze basin between 1956 and 1987. Whereas many previous studies have concentrated on the trends in the main channel of the Yangtze, the distributed pattern of changes across the whole catchment is complex. Results from time series analysis indicate ten stations, mainly located in the Dadu and Wu tributaries (with a total incremental catchment area of 78,963 km2) have shown increasing trajectories of sediment yield, and six stations, located in the upper Jialing and Tuo tributaries (with a total incremental area of 27,816 km2) have experienced decreasing trajectories. By dividing the time series into three components, it is possible to map significant decadal changes in sediment yields that can be related to phases of deforestation and the construction of water conservancy projects. Most of the observed decreases in sediment yield are associated with large reservoir schemes on tributary rivers. The lack of evidence for increasing sediment input to the Three Gorges area masks a considerable variation in sediment conveyance and storage within the Upper Yangtze catchment.KEY WORDS: Sediment yield; Reservoir sedimentation; Three Gorges Project; Time series analysis; China     

白盆珠水库库区坡面径流侵蚀规律初步研究

在对白盆珠水库库区开展水土流失实地调查的基础上,选择库区典型的侵蚀地貌类型与植被类型进行降雨-径流-产沙规律的初步研究.通过6个径流小区试验对比,分析了在不同植被条件下产流、产沙的差异,结果表明缺乏地表草本植被的纯飞播造林的水土保持效益十分有限;库区降雨径流产沙是白盆珠水库淤积的重要来源.