The Contribution of Marsh Zones to Water Quality in Dutch Shallow Lakes: A Modeling Study

Many lakes have experienced a transition from a clear into a turbid state without macrophyte growth due to eutrophication. There are several measures by which nitrogen (N) and phosphorus (P) concentrations in the surface water can be reduced. We used the shallow lake model PCLake to evaluate the effects of three measures (reducing external nutrient loading, increasing relative marsh area, and increasing exchange rate between open water and marsh) on water quality improvement. Furthermore, the contribution of different retention processes was calculated. Settling and burial contributed more to nutrient retention than denitrification. The model runs for a typical shallow lake in The Netherlands showed that after increasing relative marsh area to 50%, total phosphorous (TP) concentration in the surface water was lower than the Maximum Admissible Risk (MAR, a Dutch government water quality standard) level, in contrast to total nitrogen (TN) concentration. The MAR levels could also be achieved by reducing N and P load. However, reduction of nutrient concentrations to MAR levels did not result in a clear lake state with submerged vegetation. Only a combination of a more drastic reduction of the present nutrient loading, in combination with a relatively large marsh cover (approximately 50%) would lead to such a clear state. We therefore concluded that littoral marsh areas can make a small but significant contribution to lake recovery.     

矿区铁路安全管理信息系统的研究

针对我国矿区铁路运输安全管理落后的现状,分析矿区铁路运输安全管理的主要特点,设计了矿区铁路安全管理信息系统的总体结构。以徐沛铁路运输系统为例,基于B/S模式开发了徐沛铁路安全管理信息系统,实现了对职工的安全培训考核、职工安全档案管理、运输事故信息的录入与统计分析、各类安全文档的管理、技术措施的审批和安全直通车的功能。该系统已在徐沛铁路运输安全管理中得到成功应用,也可应用于其他矿区铁路安全管理。     

羊角月芽藻摄取磷形态的动力学研究

将湖水中的磷分成总溶解磷,溶解反应磷,总反应磷、溶解的水解性磷,溶解的光解性磷。研究其在羊角月芽过程中的变化。     

新建住宅小区噪声验收监测方法初探

住宅小区噪声监测是近年来房地产验收过程中的重要环节,围绕新建住宅小区噪声验收监测方法、评价标准、布点原则等方面进行初步探讨,并根据某住宅小区噪声验收监测实例,提出了相应的建议。     

射阳湖浮游动物群落结构特征及其与环境因子相关性研究

2016—2017年对射阳湖开展浮游动物群落结构和水质指标逐月监测。结果表明,射阳湖共鉴定出浮游动物61种,其中原生动物、轮虫、枝角类和桡足类分别为25种、24种、7种和5种。浮游动物种类数呈现春夏季多于秋冬季的变化趋势。浮游动物优势种数量较多、分布广,群落结构相对复杂且稳定。运用Shannon-Wiener指数、均匀度指数和B/T指数对射阳湖水质作评价,结果表明,该湖处于轻度—中度污染状态,生物学指标评价法与常规水质评价结果一致。浮游动物群落结构与水质指标相关性分析表明,水温、透明度、Chl-a和DO是影响射阳湖浮游动物群落结构的主要水质指标。     

镧改性膨润土对底泥内源磷控制效果

以商业化的锁磷材料—镧改性膨润土(Phoslock?)为对象,研究了Phoslock?对磷的吸附动力学和等温线,同时研究了材料对上覆水体以及底泥内源磷释放的控制效果.结果表明,Phoslock?对磷的吸附可以用Langmuir模型拟合,相关性达到0.96,模型计算磷的最大吸附量为10.4mgP/g,且磷吸附符合拟一级和...     

加快攀西-六盘水地区优势资源的开发

攀西-六盘水地区水能、矿产资源丰富,是建设我国能源、原材料生产的重要基地,也是长江上游资源开发和生态保护区的重要组成部分。本文在分析加快开发该区优势资源的有利条件和不利因素的基础上,提出了开发建设的总体目际和思路,突出水能和矿产资源优势,加强对农业和林业的开发,力争到21世纪中叶使该区建成我国重要的能源、原材料生产基地,从根本上改变该区文通闭塞、经济、文化落后的面貌,在主要经济、技术指标上赶上全国的平均先进水平。     

REVIEW OF A SEVENTEEN-YEAR CHLOROPHYLL RECORD AS IT PERTAINS TO THE TROPIIIC STATUS OF LAKE OKEECHOBEE,FLORIDA, USA1

ABSTRACT: A 17-year record of chlorophyll a at eight limnetic sampling stations was used to evaluate putative changes in the trophic status of Lake Okeechobee, a shallow polymictic lake located in the subtropical environment of South Florida. Significant spatial differences were observed in the temporal patterns and variability of chlorophyll a concentrations. The highest chlorophyll a values were found in the northern and northwestern regions of the lake. The center of the lake, subject to high levels of non-algal suspended solids, exhibited relatively low chlorophyll a values and coefficient of variation. The lowest chlorophyll a values were observed at the southernmost sampling station in the lake. This was also the station that showed a significant upward trend in annual mean chlorophyll a values over the 17-year period of record. Examination of the relationship between chlorophyll a and three key environmental variables (i.e., total phosphorus concentration, phosphorus loading, and lake stage) revealed significant correlations at two out of the eight stations. The overall results of this study indicate that spatial and temporal disparities in the distribution and dynamics of chlorophyll a in Lake Okeechobee mandate more temporally and spatially intense approaches to the evaluation of trophic state than used in previous studies.     

PHOSPHORUS MANAGEMENT TO PROTECT LAKE WATER QUALITY1

ABSTRACT: The Hallett Quarry gravel pit lakes are an active sand and gravel extraction operation located 0.4 km north of the City of Ames, Iowa. During periods of drought, these lakes serve as a supplemental water supply for Ames. A modified version of the Vollenweider input-output model was used to predict future water quality under various watershed land use, drainage, and lake configurations. The dominant factor controlling the future water quality of the lakes was found to be the nutrient input. It is recommended that a management plan to protect the future water quality should be oriented towards reducing the sources of phosphorus to the lakes.     

COMPARATIVE WATER CHEMISTRY OF FOUR LAKES IN ROCKY MOUNTAIN NATIONAL PARK1

ABSTRACT: The inorganic chemistry of two pairs of lakes in Rocky Mountain National Park was studied to determine reasons for their similarities and differences. The pairs were located on differing geologic units. It was expected that weathering from the different types of parent material would cause differing cation concentrations between the pairs. This was verified by dissimilar concentrations of those cations which are products of primary weathering. Unexpected was a significant difference in anion concentrations between members of one pair having the same bedrock geology. This difference has been attributed to the presence of a wet sedge meadow above one of the lakes which serves as a biological filter for anions, particularly nitrate and sulfate. It is shown that small scale drainage characteristics which can alter regional atmospheric contributions are important contributors to lake chemistry.