三江平原旱田耕作对湿地土壤理化性质的累积影响初探

在中国科学院三江平原湿地生态试验站综合实验场,对不同耕作年限的湿地土壤(0~20 cm)进行环境累积效应分析。结果表明,随着开垦时间的增加,土壤的理化性质发生渐变,物理性质方面,土壤容重和比重逐渐增大,而孔隙度和田间持水量逐年减少;化学性质方面,土壤pH值随开垦时间的增加而增加,有机质和其他养分则随开垦时间的增加而逐年降低。弃耕后土壤性质有所恢复。土壤性质在开垦初期变化较明显,而后逐渐变缓。     

近10 a来松嫩平原湿地研究的回顾与展望

松嫩平原是中国内陆湿地集中分布区之一。该区湿地类型有沼泽、湖泊、盐沼和稻田,此外还有水库和少量泥炭地。概述了该区湿地的研究现状,并指出目前研究热点。重点探讨了未来本区湿地的研究趋势,主要体现在湿地生态系统结构、功能和过程研究,湿地的区域生态功能评价,湿地污染及其治理,退化湿地恢复和重建,湿地多样性与湿地保护,湿地资源综合利用,湿地对全球变化响应和全球变化对湿地影响,湿地-草地-盐碱地转换机制和过程和驱动力等方面。     

应用ISSR标记分析三江平原狭叶甜茅不同种群的遗传多样性

以三江平原狭叶甜茅(Glyceriaspiculosa)为研究对象,选取3个不同群落类型:狭叶甜茅优势种群落、狭叶甜茅和毛苔草(Carexlasiocarpa)为共建种的群落以及狭叶甜茅为主要伴生种的群落,共45个材料进行了ISSR分子标记分析。结果从41个引物中筛选出7个有效引物,扩增出80条清晰条带,平均每个引物扩增了11.4条带,其中70个位点是多态的,总的多态位点比率为87.5%,表明被测材料间ISSR标记多态性较高。利用Popgen(version1.32)软件分析了扩增结果,并得到了狭叶甜茅不同群落类型的遗传距离、遗传一致度、Nei和Shannon信息指数等遗传特征。结果表明,对于一个物种来说,当地理距离太近不能成为影响其遗传多样性水平的因素时,其构成的种群在群落中的地位将是影响遗传多样性水平的主要因素之一。     

早涝碱咸综合治理与生态环境良性循环

华北平原东部淡水资源短缺，旱涝碱成灾害限制了农业生产的可持续发展。海河的治理，解决了排洪排涝排咸出路。春季开发利用地下水包括微咸水和半咸水抗旱灌溉。夏季利用伏雨洗盐排咸，增大降雨入渗，减少径流流失，防治渍涝灾害，把降雨转化为地下水资源。秋冬引蓄河水，回灌地下水补源。以土壤与潜水的地层空间作为调节大气降水、土壤水、地下水、地表水的地下水库，以调控地下水埋深在临界动态为指标，最大限度地把时空分布不均的天然降雨转化为可持续利用的水资源。地表水地下水联合运用，促使水资源采补平衡，降雨灌溉淋洗脱盐强于干旱蒸发积盐过程，地下水淡化强于矿化过程。实现旱涝碱咸综合治理，水土资源可持续利用，经济社会可持续发展，生态环境良性循环。     

松嫩平原内陆盐碱湿地的类型特征及分布规律

内陆盐碱湿地是湿地的重要组成部分,其类型、特征及分布规律的研究十分薄弱。松嫩平原是世界上内陆盐碱湿地发育的典型地区之一。本文参考国内外湿地分类标准,结合松嫩平原的特点,建立了内陆盐碱湿地的分类体系,将该区的盐碱湿地划分为2个湿地类,6个湿地型,13个湿地亚型,描述了各类型的主要特征,并阐述了松嫩平原内陆盐碱湿地的分布规律。这对我国的湿地分类系统是一个重要的补充,对进一步实施内陆盐碱湿地的保护、恢复和重建,促进松嫩平原社会经济和环境的可持续发展都具有重要意义。     

Late Pleistocene–Holocene hydrologic changes in the interfluve areas of the central Ganga Plain, India

Abandoned channel belts, ponds and point bar deposits of palaeochannels in the interfluve regions of the central Ganga Plain suggest changes in the morphohydrologic conditions during the Latest Pleistocene–Holocene. Stratigraphy of these ponds comprises channel sand at the base overlain by shell-bearing clayey silt. The contact of the two facies marks the phase when channels converted into standing water bodies. Point bar deposits of some palaeochannels are overlain by oxidised aeolian sand, indicating that the channel abandonment possibly occurred due to the desiccation and aridity in the region.Optically stimulated luminescence (OSL) chronometry of the pond sediments suggests that the deposition of the basal channel sand started before 13 ka and continued up to 8 ka. The ponds formed around 8–6 ka when the channel activity ceased. Evidence from the point bar deposits also indicates that the fluvial activity in the region ended sometime during 7–5 ka. This was followed by aeolian aggradation. The present study thus suggests that the hydrologic conditions in the Gangetic plains, i.e. initiation of channels and their abandonment, formation of microgeomorphologic features such as ponds and their eventual siltation, were controlled largely by climatic changes (i.e. monsoon changes) supported by tectonic activity. For the past 2 ka, increasing human and related agricultural activity has substantially accentuated the natural siltation rate of ponds.     

平原水库饮用水水质净化的有效途径

针对地表饮用水水源地蓄水后水质发生变化的情况，结合平原水库工程管理和水源保护工作的实践，分析了地表饮用水水源地产生富营养化的原因及危害，阐述了生物净化水质的机理，提出了利用生物净化水质技术，通过对生物种群结构和生物量的科学调控，消耗水体中的营养物质，达到既能充分利用营养资源，又可净化水质，改善水体环境的理想效果，为地表饮水水源地的水质净化找到了有效途径和方法。     

PELIMINARY ANALYSES FOR CROP WATER CONSUMPTION BY USING LYSIMETER

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Evolution of Quaternary groundwater system in North China Plain

The Quaternary groundwater system in the North China Plain is formed mainly through the terrestrial water flow action on the united geological and tectonic backgrounds. The analysis of groundwater dynamic field, simulation of groundwater geochemistry, and the¹⁴C dating and extraction of isotope information have provided more evidence for recognizing and assessing the evolution of groundwater circulation system and studying the past global changes. The exploitation and utilization of groundwater on a large scale and overexploitation have given rise to the decline of regional groundwater level, change of flow field, decrease of water resources and downward movement of saline water body. The water environment has entered a new evolution stage in which it is intensely disturbed by the mankind’s activities. Project supported by the National Natural Science Foundation of China.     

Inferring the mass fraction of floc-deposited mud: application to fine-grained turbidites

Fine sediment deposition in the ocean is complicated by the cohesive nature of muds and their tendency to flocculate. The result is disaggregated inorganic grain size (DIGS) distributions of bottom sediment that are influenced by single‐grain and floc deposition. This study outlines a parametric model that characterizes bottom sediment DIGS distributions. Modelled parameters are then used to infer depositional conditions that account for the regional variation in the grain sizes deposited by turbidity currents on the Laurentian Fan–Sohm Abyssal Plain, offshore south‐eastern Canada. Results indicate that, on the channellized Laurentian Fan, the mass fraction of floc‐deposited mud increases only slightly downslope. The small evolution in this fraction arises because sediment concentration and turbulent energy are associated in turbidity currents. On the Sohm Abyssal Plain, however, the mass fraction of floc‐deposited mud decreases, probably as a result of lower sediment concentration at this source‐distal site. Estimates of the mass fraction of mud deposited as flocs suggest that floc deposition is the dominant mode by which sediment is lost from suspension, although single‐grain deposition contributes more to the depositional flux in proximal areas where high energy breaks flocs and in distal areas where low sediment concentration limits floc formation. It is concluded that, throughout the dispersal system, changes in the fraction of flocculated mud deposited from turbidity currents reflect changes in sediment concentration and energy downslope.