The use of environmental integrative indicators to assess seabed disturbance in estuaries and coasts: Application to the Humber Estuary, UK

The coastal zone is subject to many and varied changes resulting from human activities and natural processes. Existing or emerging agreements and legislation acknowledge the relevance of indicators for monitoring these. In the UK, following a series of recent workshops, potential indicators of nearshore disturbance have been identified and grouped into three broad indices: 'Coastline Morphological Change', 'Resource Use Change' and 'Environmental Quality and its Perception'. The present study developed these indicators further and tested their use by applying them to 18 sections in the Humber Estuary, Eastern England. The results obtained reflect the current knowledge of the state of the Humber environment and show the potential of integrative indicators but indicate that further studies are required to assess the relative importance of the indicators and their value in reflecting the ability of the ecosystems to sustain natural habitats and populations at a good conservation status.     

太湖地区农业源污染核算研究进展

太湖地区水体污染严重,控制太湖污染、改善太湖水质,对发挥太湖的综合服务功能,促进全流域经济可持续发展和社会稳定具有重要的战略意义.充分把握和核算太湖地区农业源污染排放量、入河量及其时空分布是落实太湖地区污染物科学减排从而进一步改善太湖水质的基础.本研究总结和概述了太湖地区农业源污染现有的核算方法、产排污参数、控制途径等,结合太湖地区农业源污染构成、排放与布局的复杂情况,提出综合运用各种核算研究方法,充分考虑各污染来源,确定农业源污染的产污量、排污量和入河量,并通过建立分期、分区、细分类型的农业源污染排放、入河参数,为科学确定农业源污染减排指标以及制定减排措施提供依据.     

Latitude versus Depth Simulations of Ecodynamics and Dissolved Gas Chemistry Relationships in the Central Pacific

Nutrient ecology and trace gas processing are intimately coupled in the surface ocean and participate in key linkages through the Earth biogeochemical system. We have added water column photochemistry for volatile sulfur and organic compounds to large scale nutrient cycle modules, in order to create a one dimensional, open ocean ecochemistry simulator. Phyto- and zooplankton, recyclers and biological waste products are represented through N and Fe densities. Dimethyl sulfide, carbonyl sulfide and the methyl halides are tracked individually along with certain precursors and nonmethane hydrocarbons. The model is applied along the 180 degree meridian in the Northern Hemisphere. Ecodynamics are validated against satellite ocean color maps. Biological/photochemical production terms are then iterated upon to match measured distributions for the trace gases. Data are most complete for dimethyl sulfide. Major patterns in its climatology are captured within individual ecological provinces. However, at the basin scale reduced sulfur release must be varied over almost an order of magnitude because the mechanism developed contains only one plant taxon. Based on sparser data, first order rate constants are estimated for phytoplanktonic exudation of the methyl halides. Parameters are also established for photolytic injection of carbonyl sulfide and propylene from the dissolved organics. Ocean general circulation models and interactive ocean-atmosphere transport simulations are discussed as frameworks for future application.     

The effect of metal complexation on hydrogen sulfide transport across the sea-air interface

Hydrogen sulfide dissolved in surface seawater is distributed into free forms which include the volatile neutral H₂S and its conjugate anions, and also into a set of involatile metal complexes. Calculation of the sulfide fraction capable of supporting sea-air flux is sensitive to large uncertainties in complexation equilibrium relationships, both for the sulfides themselves, and for organic ligands competing with them to coordinate dissolved copper. Saturation can be achieved relative to the troposphere if metal interactions are minimized, or if strong sulfide binders are titrated.     

A survey of the unusual motions in M17 with a Fabry-Perot monochromator

The results of the most extensive survey ever undertaken of the profiles of the [Oiii] line over M17 are presented. These were obtained with an optically-contacted, pressure-scanned, single-etalon Fabry-Perot monochromator used on the 74-in. Radcliffe reflector. Some very unusual velocity features have been revealed. Several regions were found to be emitting lines split by motions of 20 km s^?1 whereas others produce lines with three or more separate velocity components which stretch up to ?70 km s^?1 from the mean radial velocity of the nebula. Some speculative explanations for these motions are offered.     

Linear free energy techniques for estimation of metal sulfide complexation constants

Unknown sulfide complex formation constants have been estimated through linear free energy comparisons of known values with sulfide solubility products, and with reactions of the model ligand dithizone. Results of the two techniques are in agreement for complexes of the +2 metals with two sulfide ligands. Data are currently insufficient to establish a slope for free energy lines relating single ligand +2 complexes. Alternative methods for deducing single ligand formation include interpolation across oxidation states and correlation of bisulfide formation constants with the analogous hydroxide values. By linear free estimates, several trace metals speciate predominantly as sulfide complexes over the bisulfide concentration ranges calculated from carbonyl sulfide hydrolysis in the mixed layer. Recent preliminary measurements of total dissolved sulfide confirm this result for Cu, and perhaps also Hg.     

Transitional waters: A new approach, semantics or just muddying the waters?

Estuarine, Coastal and Shelf Science has throughout its history considered a diverse range of habitats including estuaries and fjords, brackish water and lagoons, as well as coastal marine systems. Its articles have reflected recent trends and developments within the estuarine and coastal fields and this includes the changing use of well-accepted terms. The term “transitional waters” first came to prominence in 2000 with the publication of the Water Framework Directive of the European Communities [European Communities, 2000. Directive 2000/60/EC of the European Parliament and of the Council of 23 October 2000 establishing a framework for Community action in the field of water policy. Official Journal of the European Communities 43 (L327), 75 pp.], where “transitional waters” are defined as “bodies of surface water in the vicinity of river mouths which are partially saline in character as a result of their proximity to coastal waters but which are substantially influenced by freshwater flows”. The inclusion of the term transitional waters in our own aims and scope reflects the evolution of language in this subject area, encompassing tidal estuaries and non-tidal brackish water lagoons. This article reflects on some of the difficulties posed by the use of the term and its attempts to be inclusive by incorporating fjords, fjards, river mouths, deltas, rias and lagoons as well as the more classical estuaries. It also discusses the problems of including in the term river mouths discharging either into predominantly brackish areas such as the Baltic Sea, or into freshwater-poor areas bordering the Mediterranean.     

Mats of Beggiatoa bacteria reveal that organic pollution from lumber mills inhibits growth of Zostera marina

The objectives of this study were to determine the distribution and abundance of Zostera marina (eelgrass) in relation to the distribution of the mat forming bacteria Beggiatoa spp., and the levels of sulfide and organic material (wood waste) in the sediment. Underwater videography and intertidal surveys were used to map the distribution and abundance of Z. marina beds and Beggiatoa in the nearshore area of Commencement Bay, WA (USA), a location that has a long history of sawmill activity. Zostera marina occurred from the intertidal to ?6 m mean lower low water (MLLW) on sandy substrates in areas with low levels of sulfide (<50 μm ) and organic material (<5 % total volatile solids). Areas with high sulfide levels (>200 μm ) occurred where there were significant amounts of organic material in the sediments, which was found to be wood waste that had been discarded from sawmills. Zostera marina was absent from the intertidal and occurred at lower densities in areas with high sulfide levels. In contrast, mats of Beggiatoa were only found in areas where the sulfide levels were >1000 μm and there were significant deposits of wood. Thus, the negative correlation between the distribution and abundance of Z. marina and Beggiatoa suggests that the presence of Beggiatoa mats could be used as a biological indicator of inhibiting levels of hydrogen sulfide in the marine environment.     

Topographic effects on the wind‐driven ocean circulation

Abstract

This is a study of the influence of bottom topography of an ocean basin on the wind‐driven, barotropic ocean circulation. A detailed investigation is made of the role of vorticity transfer to the ocean bottom in the presence of varying topography. It is shown that the wind‐driven gyre over the topography of the North Atlantic has a transport in the western part of the basin only half of that obtained in an ocean of constant depth.