Response of three paleo-primary production proxy measures to development of an urban estuary

In this study we present a novel comparison of three proxy indicators of paleoproductivity, pigments, biogenic silica (BSi), and cysts of autotrophic dinoflagellates measured in cored sediments from New Bedford Harbor, Massachusetts. In addition to detailed historical reports we use palynological signals of land clearance, changes in the ratio of centric and pennate diatoms, sedimentary organic carbon and stable carbon isotopes to constrain our interpretations. Our study spans the period from prior to European settlement to approximately 1977, during which watersheds were cleared, port development occurred and much of the coastal property became industrialized. The combined effects of nutrient loading from watershed clearance and urban sewage on the estuarine ecosystem shifted not only levels of primary production, but also the nature of the production. Our proxies show that when European colonists first arrived the estuarine production was benthic-dominated, but eventually became pelagic-dominated. Importance of water column production (by diatoms and dinoflagellates) rapidly increased as soil nitrogen was released following forest clearance. Stabilization in rates of forest clearance is reflected as a decline in production. However, population increases in the urbanizing watershed brought new sources of nutrients through direct sewage discharge, apparently again stimulating primary production. We assume that early 20th century changes in sewage discharge and introduction of heavy metals into Harbor waters caused a temporary reduction in primary production. The introduction of a new sewer outfall near the core site and changes in estuarine hydrography due to construction of a hurricane barrier across the mouth of the harbor are reflected by renewed water column production, but decreases in the population of diatoms and dinoflagellates. Fossil pigments suggest renewed water column production in the latest years recorded by our sediment core.     

A Case History of Ozone System Supplier Prequalification and Equipment Procurement

To facilitate a fast track implementation of ozone facilities at two of its water treatment plants, the East Bay Municipal Utility District prepurchased ozone equipment during the design phase of the project to reduce total design and construction time and enable a more cost-effective design. Several steps were taken to assure an orderly bidding process to minimize the potential for protests and project delays. These steps included prequalification of ozone equipment suppliers, a mandatory pre-bid conference, and a requirement for a detailed technical proposal prior to contract award. Ultimately, this process withstood legal challenge. Because of the prepurchase of the ozone equipment, the contract documents provide careful attention to interfaces between the equipment supplier and the installing contractor, including shipping, handling, storage before installation, physical connections, and performance testing after installation.     

淤泥质海岸挖槽回淤预测的沉积动力学途径：以杭州湾试挖槽为例

在淤泥质河口、海岸地区，港池和航道开挖后，挖槽内外经历着冲淤交替过程，在挖槽中由于水流作用的弱化，使得槽内淤积增加而冲刷减少，并随槽内深度增加而产生净淤积（即回淤）。挖槽回淤的沉积动力学途径，是建立在对冲淤机理分析和冲淤过程的合理概化基础上，可以构造半经验的回淤预报公式，也可为冲淤数学模型提供合理的结构和参数，关键是采用水动力强度指标，即水流及波浪引起的底部切应力τ（或摩阻流速Ｕ）来界定冲淤发生的条件和衡量冲淤发生的规模；此外还必需分析和表达挖槽工程区域水体含沙量的时空分布；工程区沉积物的平面及柱状分布及其物理力学指标、沉速、淤积切力、冲刷切力、固结过程、流变参数等的实验测定。本文以杭州湾试挖槽工程为实例，通过沉积动力学各项参数的取得，进行东槽、西槽两个试挖槽回淤预报的数值计算，取得了与实际观测相一致的结果，从而论证了挖槽回淤预报过程中进行沉积动力学途径研究的重要性和必要性。     

大亚湾核电站18个月换料大破口失水事故的计算分析

大亚湾核电站18个月换料的设计中，堆芯焓升因子和功率峰值因子有了较大的提高，通过采用DRM分析方法和CATHARE程序对LBLOCA事故进行了较为全面的计算、分析和论证，得出了在18个月换料运行方式下，堆芯的包壳温度等参数仍然满足验收准则的结论。在此基础上重新建立了LOCA包络限制线。     

大亚湾核电站两个机组反应堆第四循环堆芯换料设计

简要介绍了大亚湾核电站换料设计的基本原理和内容，以及两个机组第四循环换料设计的主要结果，并与测量值作了比较，计算结果表明，两个机组的换为设计满足了安全性能准则和经济性要求，测量结果表明，理论预测值与实测值符合良好。     

渤海湾盆地滩海地区油气勘探前景

渤海湾盆地滩海地区经过详查,其中1.4万km~2是前景很大的地区,分别是下辽河、黄骅、济阳、渤中四个含油气坳陷的延伸区,具有与陆上油区相类似的有利石油地质条件。构造发育的延续性决定了滩海地区主力生油层为沙三段和东营组下段,东营组和明化镇—馆陶组是主要储油层。滩海地区油气藏类型多样,其中披覆背斜、逆牵引背斜和古潜山油气藏所占石油地质储量比例较大。目前地球物理勘探已发现30多个有利构造区带,总体勘探程度很低,勘探潜力很大。     

Blowouts in coastal foredunes

Foredune blowouts within many embayments along the south coast of South Africa are traditionally believed to be caused by human activities and the result of onshore winds reducing vegetation cover and developing landward migrating patches of bare sand. These bare areas are not blowouts sensu strictu, however, and are more likely the elongated horns of barchan dunes formed across the direction of the dominant winds. Blowouts of this type have been present on the foreshore of Algoa Bay for more than 100 years and long before present-day human pressures could be the possible causal factor. They are not likely to present major management problems provided buildings are not constructed within them or closely behind them. Where necessary, vegetation cover should be maintained either by keeping people out of the dunes or by implementing revegetation options. Some mechanical sand relocation may occasionally be a helpful short-term management solution.     

Distribution and Abundance of Larval Fish in the Nearshore Waters of Western Lake Huron

Ichthyoplankton was collected at 17 nearshore (bottom depth ≥5 m but ≤10 m) sites in western Lake Huron during 1973–75 with a 0.5-m net of 351-micron mesh towed at 99 m/min. Larvae of rainbow smelt (Osmerus mordax) dominated late spring and early summer catches and larvae of alewives (Alosa pseudoharengus) the midsummer catches. Larval yellow perch (Perca flavescens) were caught in early summer but were rarely the dominant species. The time of spawning and hatching, and thus occurrence of larvae, differed between areas but was less variable for alewives than for yellow perch. The appearance of larvae in Saginaw Bay was followed successively by their appearance in southern, central, and northern Lake Huron. Rainbow smelt were most abundant in northern Lake Huron and yellow perch and alewives in inner Saginaw Bay. Densities of either rainbow smelt or alewives occasionally exceeded 1/m³, whereas those of yellow perch never exceeded 0.1/m³. Abundance of alewives was usually highest 1 to 3 m beneath the surface and that of rainbow smelt 2 to at least 6 m beneath the surface. Important nursery areas of rainbow smelt were in bays and off irregular coastlines and those of yellow perch were in bays. All nearshore waters seemed equally important as nursery areas of alewives.     

大亚湾核电厂全厂失电的后果及应急措施

本文介绍了大亚湾核是厂全厂失电后的现象，后果以及采取的应急措施（包括技术措施及事故处理程序）。最后简单介绍了核电厂全厂失电后的剩余风险指标分析计算方法及结果。