COST‐EFFECTIVE POINT‐NONPOINT TRADING: AN APPLICATION TO THE SUSQUEHANNA RIVER BASIN1

ABSTRACT: Point‐nonpoint trading has been suggested as a relatively efficient approach for reducing nutrient pollution in the Chesapeake Bay and elsewhere. However, relatively little economic research has examined the design of trading programs involving nonpoint sources. The purpose of this paper is to investigate the economics of several fundamental design choices for point‐nonpoint trading programs. The Susquehanna River Basin (SRB) in Pennsylvania as an example, although many of the insights should generally apply to other regions as well.     

TRENDS IN FRESHWATER INFLOW TO SAN FRANCISCO BAY FROM TUE SACRAMENTO-SAN JOAQUIN DELTA1

ABSTRACT: Outflow from the Sacramento-San Joaquin river system (Delta outflow) provides about 90 percent of the freshwater flow to San Francisco Bay. Because this river system also supplies most of the water used in California, some believed that annual freshwater flow to the Bay had declined by as much as 50 to 60 percent as water use increased. Consequently, we studied trends in actual Delta outflow and precipitation for the period 1921 to 1986, which is when Delta outflow data are available. We found that there has been no decrease in the annual Delta outflow over this period. In fact, a statistically significant increase in annual Delta outflow of 87 cfa/yr has occurred during the period 1921 to 1986. One reason that Delta outflow has increased is because precipitation has increased faster than water use. Other contributing factors include increased runoff from land use changes, water imports from other areas, and the redistribution of ground water. In addition, statistically significant seasonal trends in Delta outflow were found. Over the period 1921–1986 Delta outflow decreased in April and May and increased from July through November. Changes in other months were not statistically significant. These seasonal changes result primarily from the operation of upstream flood control and water development projects, which store water in the spring and release it in the summer and fall. These seasonal changes are also influenced by a climatic shift that has decreased spring snowmelt runoff and increased late summer through winter precipitation.     

山东省莱州湾地区海水入侵灾害及其综合防治

本文在分析山东省莱州湾地区海水入侵灾害发生的背景、条件、原因及未来发展趋势的基础上，结合当地防治海水入侵灾害的经验。提出了综合防治海水入侵灾害的措施。向莱州湾地区调黄河水是防治海水入侵的关键；建设防潮堤、防潮闸可以防止海水地表入侵；充分发挥政府的职能是防治海水入侵灾害的基本保证。文中还提出了综合防治海水入侵的其它措施。     

Nutrients Seasonal Variation and Budget in Jiaozhou Bay,China: A 3-Dimensional Physical–Biological Coupled Model Study

A 3-D biological model was developed and coupled to a hydrodynamic model, i.e., Princeton Ocean Model, to simulate the seasonal variation and budget of dissolved inorganic nitrogen, phosphate, and silicate in Jiaozhou Bay. The modeled nutrients distribution pattern is consistent with observation. Silicate, the most important limiting element for phytoplankton growth, is characterized by consumption in spring, increase in summer and autumn, and accumulation in winter, whereas dissolved inorganic nitrogen and phosphorous have increasing trend with low rates in spring, due to excessive river loads. Phytoplankton plays an important role in nutrient renewal by photosynthesis and respiration processes. During an annual cycle, 7.83 × 10³ t N, 0.28 × 10³ t P, and 3.93 × 10³ t Si are transported to the bay’s outer sea, i.e., the Yellow Sea, suggesting that Jiaozhou Bay is a significant source of nutrients for the Yellow Sea. The spatial distribution of nutrients is characterized by vertically homogeneous profiles, with high concentration inside the bay and low concentration toward the bay channel. These features are mainly governed by strong turbulent mixing, fluvial influx, water exchange rate, and Yellow Sea water intrusion. Numerical experiments suggest that the government should pay enough attention to proper layout of sewage drainage.     

深圳湾海域浮游植物的生态特征

根据香港环境保护署2006年1～12月份深圳湾浮游植物的监测数据,分析了深圳湾海域浮游植物的植物群落结构的时空变化特征及浮游植物多样性指数与环境因子的关系.结果表明,2006年在深圳湾海域共鉴定出浮游植物27属34种,主要类群是硅藻,占总种数的52.94%,其次是甲藻,占总种数的29.41%,其他藻类占总种数的17.65%.浮游植物细胞丰度的年波动范围在2.13×106～4.15×106cells/L之间,平均值为2.92×106cells/L,并且在秋季(10月)最高,春季(5月)次之,呈明显的双周期变化特征,平面分布表现为由海湾中部向湾口处递减的格局.浮游植物多样性指数和均匀度偏低,其中多样性指数变化范围在0.76～2.52之间,均匀度范围在0.29～0.74之间,反映出种类间个体数分布欠均匀,群落结构稳定性差,优势种优势度明显.研究海区物种丰度整体水平较低,浮游植物物种丰度指数变化范围在0.57～2.17之间,这与深圳湾海域水质污染严重而导致该海域生态环境恶化有一定关系.研究还表明,营养盐、盐度和溶解氧与浮游植物多样性指数之间呈现显著相关关系.     

胶州湾物质输运模型研究

为了更好地了解胶州湾的水动力特征,应用美国普林斯顿海洋模型研究了胶州湾的潮流特征。计算结果表明,胶州湾的潮流以往复流为特征,涨、落潮最大流均发生在胶州湾口,流速分别为73cm·s^-1和79cm·s^-1左右,潮波系统具有明显的驻波性质。在对胶州湾三维潮流模拟的基础上,建立了一个三维水质模型,并对环胶州湾主要河口陆源所输入的N、P污染物的浓度分布进行了模拟。通过与实测的调查结果进行对比,验证了模式计算的合理性。     

泉州湾重金属污染生态地球化学预警

水中的重金属元素易附着于表面积较大的悬浮颗粒物上而进入水底沉积物中,当外界条件改变时,又会重新释放到水体中而形成二次污染。因此,沉积物是水中重金属污染物的集蚋器,是研究湖泊、河口和港湾污染现状和污染历史的最可靠的采样介质。对接受了漂染、制革等工业废水污染源的福建省泉州湾沉积物和沉积柱进行生态地球化学调查取样,用原子荧光法（AFS）和质谱法（ICP—MS）测试了样品中的重金属元素As、Hg、Pb、Cd、Cr、Cu、Zn、Ni的含量。并进行了沉积柱^210Pb测年分析。通过数学法和增长趋势线法对海湾沉积物和沉积柱中重金属污染分别进行了生态地球化学预警,结果表明：八种重金属元素除Pb外,其它各重金属元素运用两种预警方法所得的顸警结果基本一致,As、Cr、Cu、Ni、Zn五种重金属含量有逐年增大的趋势,未采20～30年内将会对泉州湾生态环境产生巨大负面影响,在沉积过程中,Hg和Cd的含量基本上不变化或出现了负增长。但也对泉州湾生态环境造成一定的影响。     

乳山湾东流区沉积物中氮形态的分布特征

对2003年8月在乳山湾东流区采集的沉积物样品中不同形态N的平面和垂直分布特征进行分析,探讨了这些N的形态分布与贝类养殖之间的关系.结果表明:乳山湾贝类高密度养殖区各形态N含量一般大于低密度养殖区,各形态N在柱样中20 cm以下含量稳定.养殖区TN的平均含量高于非养殖区,但小于其它海区;OSF-N是EF-N的优势形态,其次是IEF-N、IMOF-N和CF-N.非转化态氮约占TN的70%左右.     

湛江湾生态系统服务功能与价值评估

构建了包括4个大类、13个亚类的湛江湾生态系统服务类型体系,采用市场价格法、替代成本法、成果参考法等生态经济评估方法,对湛江湾生态系统服务价值进行了初步定量估算。结果表明,2009年湛江湾生态系统服务总价值约为12.62×108元,平均单位海域生态系统服务价值为467.49×104元/km2,是湛江近海单位海域面积海洋经济总产值的1.31倍。湛江湾生态系统服务的供给服务价值最大,占80.11%;其次为文化服务价值,占15.67%;调节服务价值最小,仅占4.22%。食品供给服务是当前湛江湾生态系统最突出功能,比重占总价值的79.23%,凸显其作为湛江重要水产养殖基地作用。与福建罗源湾和山东桑沟湾相比,湛江湾水产养殖污染对海湾生态系统健康的威胁更大。评估结果同时揭示出湛江湾污染物处理功能价值非常有限,减少陆源污染物的入湾排放是湛江生态海湾型城市建设的关键所在。     

青岛市拥湾发展战略中重大环境制约因素解析

通过筛选"环湾保护拥湾发展"战略中重大环境制约问题,识别出战略实施过程中可能产生的主要环境问题,包括填海造地引起岸线变化、污染物入海总量增加、环湾主要流域及胶州湾水质恶化、海洋湿地及近岸生态系统破坏等,进而反过来分析发展战略可能引起的生态环境变化对拥湾发展战略自身影响,对环湾区域经济发展的制约;寻找破解这些问题的途径、方向。通过有效解析青岛市拥湾发展战略中重大环境制约问题,为拥湾发展战略提供技术支撑,更是环湾保护的切实体现。