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81.
The Xiangxi River is the first middling tributary of the Changjiang River near the Three Gorges Dam. The River is subject
to phosphorus pollution mainly from industrial wastewater. As the water quality of the Xiangxi River could directly influence
the water quality of the Three Gorges Reservoir, the research on phosphorus levels and its change in the sediment profile
of the Xiangxi River could provide useful information in the dynamic changes in the system, thereby offering options for mitigative
measures. Water and sediment samples from lower reaches of Xiangxi River were collected and the different forms of phosphorus
in sediments of the Xiangxi River were studied. The concentrations of total phosphorus in sediment ranged from 757.67 to 1438.54 mg/kg.
Inorganic phosphorus concentrations ranged from 684.63 to 1055.58 mg/kg. Phosphorus contamination was serious in some parts
of the Xiangxi River. With an average concentration of 635.17 mg/kg, calcium-bound phosphorus is the main form among different
inorganic phosphorus forms. Labile phosphorus and iron/aluminum-bound phosphorus measured 3.40, 0.05and 35.28 mg/kg, respectively.
The mobilization potential of phosphorus of sediments was studied through adsorption and release experiments. The equilibrium
concentration of phosphorus adsorption and release was around 0.1 mg/L. The initial concentrations of phosphorus in the overlying
water and the sediments have obvious effect on phosphorus mobilization potential. In addition, the release rate of phosphorus
in sediment increased with water depth. 相似文献
82.
当前我国地理基础教育领域正在进行着一场意义深远的课程改革。在这场改革中,推进信息技术与地理教学的整合成为其中的重要内容。地理教师应该也必须掌握将信息技术与地理教学进行整合的技能,从而实现地理教育的目标。本文就信息技术与地理教学整合的意义、原则以及整合中应注意的一些问题作论述。 相似文献
83.
A short reply to discussion by Chanson. 相似文献
84.
85.
Paul Augustinus Michael Reid Sofia Andersson Yanbin Deng Mark Horrocks 《Journal of Paleolimnology》2006,35(4):789-805
Frozen sediment cores from Lake Pupuke in Auckland City, New Zealand, contain a high resolution decadal to annual scale record
of changing lake paleoenvironments and geochemistry that reflects changing landuse and hydrology in the catchment over the
past c. 190 years. A reliable chronology is available from AMS 14C and 210Pb dating of the sediments, with the timing of the older part of the record supported by the first appearance of pollen of
introduced Pinus and Plantago lanceolata associated with European settlement of Auckland in the early 1840s. Diatom stratigraphy, sediment elemental and carbon isotope
geochemistry reflect changes in sediment sources and lake conditions commensurate with European development of the Lake Pupuke
catchment, in particular enhanced algal productivity controlled by the influx of nutrients after c. 1920 AD. Attempts to prevent
nuisance algal blooms in 1933, 1934 and 1939 using CuSO4 addition produced Cu spikes in the sediment that allowed confirmation of the accuracy of the 210Pb chronology. Hence, the elemental and isotopic composition of the Lake Pupuke sediments reflect the timing of significant
anthropogenic activities, rather than climatic variations, that have occurred within the watershed over the past c. 190 years.
The comparison of records of land use change in the catchment with the multi-proxy record of changes in the sediments usually
allowed unambiguous identification of the signatures of change and their causes. 相似文献
86.
针对空间数据存储的特点,结合网格和虚拟SAN技术的优势,提出了基于虚拟SAN的网格GIS数据存储解决方案.旨在解决网格GIS环境下的数据存储问题。 相似文献
87.
88.
在Geolord-AT空三加密软件中对数码航片进行框标定向的前期处理,创建带有框标的数码航片或者直接创建内定向的*.kb文件,使数码航片顺利按要求通过内定向。 相似文献
89.
本文提出了人为土的工程概念,从其成因的角度给出了人为土明确的科学定义,归纳和总结了人为土的基本特征,为人为土的工程分类体系建立、合理评价、工程利用和环境整治提供科学依据。 相似文献
90.