太湖流域水资源综合规划数模研究--水质模型的建立与率定

太湖流域水资源综合规划数模研究建立了一个覆盖全流域的，包括污染负荷模型、河网湖泊相耦合的水量水质模型的数字流域系统。该系统实现了流域的耦合求解，已在流域水资源规划中发挥了重要的作用。本文建宴了流域水质模型，并在水量模型率定的基础上进行了水质模型的率定。率定结果与实测数据吻合较好，相对误差多在30％之内，一定程度上反映了太湖流域的水质概况。     

奥运湖不同补水方案营养状态趋势分析

规划中的奥运湖位于奥林匹克公园，运行中将采用人工补水方式。为保证未来奥运湖的正常景观生态功能，源水经奥运公园中人工湿地处理后再引入湖中。在规划设计阶段，提出三种补水方案：（1）清河再生水厂出水经湿地处理后入湖，（2）清河河水经湿地处理后入湖，（3）经湿地处理达地表水环境标准中的Ⅳ类水要求后入湖。为了考察不同水源补水方案对奥运湖的水质保障程度，本研究对不同方案下奥运公园湖水质的时间、空间变化过程予以模拟，分析评价奥运湖可能出现的富营养化状况，并对各个补水方案带来的富营养化风险和基本成因予以推断，为奥运湖的设计运行提供技术依据。结果表明，方案3的富营养化风险最小、水质保障程度最高。结合三种补水方案水质特点，推断磷是主要限制因子，所以控制磷的浓度是保证水质安全、降低富营养化风险的重要途径。     

MULTITEMPORAL SCALE HYDROGRAPH PREDICTION USING ARTIFICIAL NEURAL NETWORKS1

Abstract: An artificial neural network (ANN) provides a mathematically flexible structure to identify complex nonlinear relationship between inputs and outputs. A multilayer perceptron ANN technique with an error back propagation algorithm was applied to a multitime-scale prediction of the stage of a hydro-logically closed lake, Devils Lake (DL), and discharge of the Red River of the North at Grand Forks station (RR-GF) in North Dakota. The modeling exercise used 1 year (2002), 5 years (1998–2002), and 27 years (1975–2002) of data for the daily, weekly, and monthly predictions, respectively. The hydrometeorological data (precipitations P_(t), P_(t-1), P_(t-2), P_(t-3), antecedent runoff/lake stage R_(t-1) and air temperature T_(t) were partitioned for training and for testing to predict the current hydro-graph at the selected DL and RR-GF stations. Performance of ANN was evaluated using three combinations of daily datasets (Input I = P_(t)), P_(t-l), P_(t-2), P_(t-3), T_(t) and R_(t-l); Input II = Input-l less P_(t) P_(t-l), P_(t-2), P_(t-3); and Input III = Input-II less T_(t)). Comparison of the model output using Input I data with the observed values showed average testing prediction efficiency (E) of 86 percent for DL basin and 46 percent for RR-GF basin, and higher efficiency for the daily than monthly simulations.     

HOW RIPARIAN ECOSYSTEMS ARE PROTECTED AT LAKE TAHOE1

Riparian ecosystems are designated for special protection from development and disturbance at Lake Tahoe. The Tahoe Regional Planning Agency (TRPA) required protection of Stream Environment Zones (SEZs) in its Regional Plan for the Lake Tahoe Basin in 1987. These zones are identified by the presence of key indicators such as the evidence of surface water flow, riparian vegetation, near‐surface ground water, designated floodplain, and alluvial soils. They are mapped on each potential building site and assigned a setback that is also off limits to building construction. The SEZs are protected to maintain their functions and values, including flood attenuation, water quality enhancement, and wildlife habitat. Strict regulations control use or disturbance of SEZs on public and private property throughout the watershed. The TRPA has set restoration targets to increase the acreage of naturally functioning SEZs in the Tahoe Basin. Many SEZ restoration projects have been designed and implemented, but SEZ restoration targets have not been met. More SEZ restoration projects are being designed and funded each year. Restoration designers would benefit from increased effectiveness monitoring of completed projects and Web‐based dissemination of monitoring results.     

滇池流域环境变迁及环境修复的社会机制

滇池流域人口、经济的高速增长与滇池水面的迅速缩减，使得滇池流域经济社会活动超过了其环境容量；滇池流域洁净地表水的截流与城乡生产、生活污水向滇池的肆意排放，使得滇池缺少源头活水而成为“污水池”。社会机制是修复滇池流域环境的重要方面。因此，本文特建议：增强居民环境意识，推动绿色社团建设，加强社会舆论监督，发动公众自觉参与。     

METHANE FORMATION BY LAKE SEDIMENTS DURING IN VITRO INCUBATION1

ABSTRACT: Renewed (de novo) synthesis of methane gas was shown to occur when samples of lake sediment were dispersed on glass beads and incubated in a helium atmosphere at 23°C. Under the above conditions, sediment samples from hardwater and softwater lakes generated up to 440 nanomoles and 80 nanomoles per ml of sediment per two days, respectively. At the time of collection, sediment samples possessed approximately similar amounts of “native” methane. Nitrate, sulfate, and acetylene were shown to suppress methane synthesis by sediment incubated as described.     

最近10年鄱阳湖区土地利用格局的时空变化

利用1988和1998年4月份的TM遥感数据,采用最大似然法对翻阳湖区的土地利用进行机助分类。把研究区土地利用分成7种类型：林地、灌草坡、水体、湖滩洲地、耕地、城镇用地和裸地。采用空间叠加的方法得到研究区土地利用的转移短阵。结果显示,林地、水体、城镇的面积增加,灌草坡的面积减少。1998年耕地面积比1988年面积减少11．3％,湖滩洲地面积减少42．7％。对不同高程的土地利用变化分析表明,耕地、灌草坡的面积都有所减少;城镇的面积增加,林地的面积增加明显,尤其在丘陵山区。土地利用的变化受到自然和人文因子的双重影响。水体面积增加的主要因于是降水量的增大;林地、灌草坡的变化明显受到政策等因素的影响,湖滩洲地减少的主要原因是水位的升高。     

湖泊沉积物中硫的地球化学循环机制研究

湖泊沉积物中的硫是控制氧化还原体系的重要元素之一。湖泊硫酸盐还原作用主要发生在沉积物表层几厘米范围内,界面硫酸盐还原具有双重环境效应。硫酸盐还原主要形成黄铁矿和有机硫,黄铁矿的生成要受到沉积物中硫酸盐、有机质以及铁氧化物活性的控制。单硫化物不稳定,并且会影响沉积物中重金属的迁移。     

太湖春季水体中的胶体有机碳含量及影响因素分析

在太湖梅梁湾及贡湖湾2个不同生态类型的湖区采集表层水样,利用切向流超滤技术(CFF)分离出所采水样中的胶体有机碳(COC,1kD～1μm),并对其进行定量分析.结果表明,所采水样中的COC浓度为1.79～2.05mg/L,占总溶解有机碳(DOC)的8.11%～22.13%.与其它有关水体相比,太湖水体COC的含量比河流低,但比海洋、海湾及河口等水体高.太湖表层水体COC含量随风浪的增大而减少,其原因可能是风浪增大后表层水中浮游生物减少所致.两湖区COC含量目前尚无显著差异.     

太湖东北部沉积物可溶性氮、磷的季节性变化

通过快速释放实验,研究了太湖东北部营养水平不同的梅梁湾、贡湖湾和胥口湾3个湖区表层沉积物中可溶性氮、磷的季节性变化.结果表明,沉积物总磷(TP)与其释放的可溶性总磷(DTP)在春、夏两季显著相关并且以可溶性有机磷(DOP)为主;春、夏两季DOP与可溶性无机磷(DIP)的形态间转化较秋、冬两季更为活跃.藻型湖区沉积物的总氮(TN)多为夏季减少,而清洁型湖区则为夏季大幅增加;沉积物释放的NH₄⁺-N以夏、冬两季居多,夏季达到最大值;沉积物释放的NO₃^--N夏季大幅度增加,冬季较少.清洁型湖区夏季沉积物的TN及其释放的NH₄⁺-N、NO₃^--N显著高于藻型湖区.