Dead zones in the coastal oceans have spread exponentially since the 1960s and have serious consequences for ecosystem functioning. The formation of dead zones has been exacerbated by the increase in primary production and consequent worldwide coastal eutrophication fueled by riverine runoff of fertilizers and the burning of fossil fuels. Enhanced primary production results in an accumulation of particulate organic matter, which encourages microbial activity and the consumption of dissolved oxygen in bottom waters. Dead zones have now been reported from more than 400 systems, affecting a total area of more than 245,000 square kilometers, and are probably a key stressor on marine ecosystems.

Supporting Online Material for Spreading Dead Zones and Consequences for Marine Ecosystems

Nitrogen-limited csluaries, shallow coastal waters, and continental shelf ivatcrs cover only 15% of the world’s ocean area, but account for nearly half the global oceanic primary production. This disproportionality is partly attributed to accelerating and geographically expanding anthropogenic N h-lading and eutrophication. Among accelerating N inputs, atmospheric deposition (AD) (as wet- and dryfall) and groundwater (GW) discharge are of considerable and growing importance. AD contributes from 300 to > 1,000 mg N m -2 yr -I lo coastal waters as the biologically available forms NO, , NHJNH,‘, and dissolved organic N. GW-N inputs have not been extensively characterized and quantified but in certain regions may be comparable to 11D. AD and GW can -jointly account from 20 lo >50% of total exogenous, or “new,” N loading and may uniquely mediate coastal eutrophication by bypassing estuarine filters of terrigenous N inputs. Direct AD and offshore GW inputs may impact harmful algal bloom dynamics of coastal and pelagic waters downwind of emissions and downstream of discharges. Example include Norlh American Atlantic coastal waters, the Baltic and North Seas, the western Mediterranean, and the Yellow Sea. Impacts include enhanced N availability and alteration of stoicl-iometric ratios of nutrients (N, P, Si). Trace metal enrichment (e.g. Fe) in AD and GW may interact synergistically with N to stimulate coastal production. Growing urban, industrial, and agricultural AD and GW inputs to coastal and offshore waters may be linked to a purported expansion of harmful algal blooms. Nitrogen limitation characterizes large segments of the world’s oceanic, coastal, and estuarine waters (Dugdale 1967; Ryther and Dunstan 1971; Codispoti 1989). The rate of biologically available nitrogen supply to these waters is a key control of primary production and resultant trophic state (Ryther and Dunstan 197 1; Eppley and Peterson 1979; D’Elia et al. 1986; Nixon 1986, 1988). Biologically available N originates from either endogenous or exogenous sources. Primary production supported by endogenous N is referred to as “regenerated production,” while exogenous production is termed “new” production. In deep (>200 m) oceanic regions away from land masses, much of the primary production is dependent on regenerated ammonium derived from organic matter mineralization. Exceptions include production supported by N, fixation or NO, from upwelled deep water, both of which are considered new N sources. Coastal and estuarine environments are heavily influenced by new N, supplied either naturally by weathering of minerals, decomposition, lightning, and geothermal emissions or anthropogenically. Anthropogenic sources include urban and

https://aslopubs.onlinelibrary.wiley.com/doi/pdf/10.4319/lo.1997.42.5_part_2.1154

Coastal eutrophication and harmful algal blooms : Importance of atmospheric deposition and groundwater as new nitrogen and other nutrient sources

Estuaries are sites of port, industrial, urban and recreational development and also important to many forms of animal life. They often form sinks for sediment and thus for contaminants associated with the sediment which arise from anthropogenic activities in their hinterland and along their shores. These contaminants can adversely affect estuarine ecosystems and are the subject of international agreements on environmental protection. For both of these reasons, it is important to increase our knowledge of the distribution, concentration, controlling influences on, and impacts of, estuarine contamination. Evidence from around the world shows that although estuaries are sinks for contaminants from the terrestrial environment, there is significant transport of marine material up-estuary as bed load sediment whilst fine-grained terrestrial material may be transported seawards in suspension. Major movement of contaminants from estuaries onto the continental shelf probably occurs only during floods and storms and, in general, the impact on shelf seas is relatively minor and confined to the coastal zone. The chief exception to this rule is in the Far East where sediment from major Chinese rivers may be dispersed up to 300 km across the shelf.

Estuaries as Repositories of Historical Contamination and their Impact on Shelf Seas

Kinetics of microbial sulfate reduction in estuarine sediments

Trace-metal partitioning in estuaries: importance of salinity and particle concentration

This preface is being written at a time of exceptional public interest in the North Sea, following media head lines on toxic algal blooms, the mass mortality of common seals, and concern over pollution levels. These headlines may suggest that pollution of the North Sea is a recent event. This is not the case. Although no data are available (methods simply did not exist), it is safe to assume that emission (both into air and water) of heavy metals already started to increase in the 19th cen tury. The growth of cities and introduction of sewer sys tems led to the discharge of raw sewage and sewage sludge. The introduction of man-made (xenobiotic) organ ic chemicals and their subsequent emission into the North Sea commenced before the second world war. The shallower and coastal areas of the North Sea receive the highest concentrations of these pollutants. Not unexpectedly, these areas - some Norwegian fjords, the Dutch coast, the German Bight - show signs of ecosystem deterioration and eutrophication. A certain percentage of the pollutants does not remain in the North Sea but is "exported" to the Atlantic. The North Sea therefore con tributes to the global input of pollutants to the world's oceans. The major part of the pollutants accumulate in the North Sea and are incorporated in the bottom sediments. Although they are "out of sight," they should not be "out of mind.""

Pollution of the North Sea : an assessment

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

W. Salomons

Author Tools

Chat about Author

Papers

Pollution of the North Sea : an assessment