Pollution in Coastal and Shelf Seas: An Overview Huge topic; 766,000 hits on Google! An overview of key points, Some of more important topics in more detail (* ) Case study of Black Sea. What is pollution (UN version)? “Marine pollution is the introduction by humans into the marine environment, directly or indirectly, of substances or energy that can lead to deleterious effects on e.g. biological systems, human health, fisheries, or reduce the quality of the environment for use by the leisure industry”

Types of pollutants- major categories Sewage discharges (high organic carbon, plus other materials) Nutrients* (at high levels) Metals* Hydrocarbons/oil* Chlorinated compounds, and other synthetic organics (endocrine disrupters, herbicides, unknown organics etc.) Plastics/garbage Radio-nuclides (power/reprocessing plants- Cs-137, Sb-125, Chernobyl Cs-134) Heat (power stations; impact on species composition & > bacterial respiration)

Some pollutants may be naturally present However, Human activity often has enhanced releases, e.g. Metals released from mine spoil Eutrophication may enhance occurrence of toxin release from HABs, (Harmful Algal Blooms) Natural oil seeps

Origins of pollutants: Domestic effluents Industrial effluents [direct (outfalls) and indirect (e.g. via atmosphere)] Ship origin (sinking tankers, washing tanks, anti-fouling agents etc)

Impact of pollutants Function of toxicity Sub-lethal effects- pressure on species Bio-accumulation through food web Control of Marine Pollution requires knowledge of: Pathways by which pollutants reach the coastal and shelf seas Rates of inputs and dispersal of pollutants Forms in which pollutants occur and how they behave in marine systems

Note that as the coastal and Shelf seas systems are open to inputs from land and atmospheric source, controlling pollution here is synonymous with controlling Global Pollution! It is clear that knowledge of relevant marine physics, biology, chemistry and geology/sedimentology are all needed to provide an interdisciplinary view of pollution.

From Simpson, 1994

Nutrients in coastal waters Referring to N, P and Si, as essential nutrients for phytoplankton growth Major input through rivers, although atmosphere can be important for N (ammonia, nitrate) Human impact principally through use of fertilisers and detergents Recent estimates of impact of human activities on P fluxes = 2.4 X pre-human

Nitrate in the southern North Sea 1989, µM

Phytoplankton, organic carbon inputs, bacteria and oxygen demand (highly simplified!) oxygen Low or no oxygen: Eutrophic conditions produces Oxidation provides energy respiration Humans algae bacteria N P CO2 Dead organic matter supplies Sewage/C inputs

Increase in biomass, on dying high bacterial respiration and oxygen reduction = Eutrophication Impact in terms of fish mortality, red-tide incidence etc. Particularly important when no or limited mixing with oxygenated waters Major impact in restricted exchange environments (e.g. Baltic Sea) Can be large-scale impact – e.g. Gulf of Mexico Controls include reduced use of fertilisers, ban on P based detergents

Oxygen minimum zone (shaded) that develops annually in response to nutrient and other inputs to the Gulf of Mexico

Metals as Pollutants in the coastal zone Example of metals released from mining in Spain Mining since Roman times, of Iberian pyrite belt in Andalucia Build up of mine tailings- residue after most metals removed from sulphide ores, but still high metal content Sulphides oxidised in air- products sulphate and acid! Very low pH waters

Tailing dams typically contain acid (pH2) waters and sulphide sludge Background source of Zn and other heavy metals to S Spanish coastal waters Zn signal can be followed for very long distances and into Mediterranean Sea Los Frailes mine spill, April 1998, released circa 6 x 106 m3 sludge and water released into Guadiamar river Concern over damaging Doñana Park (UNESCO world biosphere reserve) 1.5 m thick layer of sludge covered 4000-5000 Ha of flood plain but was diverted from park

Image showing grey layer of metal laden sludge deposited on the flood plain of the Guadiamar. (c/o Dr E. Achterberg)

Main rivers draining mining areas Manganese Strait of Gibraltar Copper

Oil pollution Crude oil formed from organic remains of dead organisms over geologic time-scales. Thousands of organic compounds may be present 50-98% of compounds hydrocarbons (C and H only)

Oil introduced into marine environment through variety of routes: Major incidents- sinking tankers- most Washing out tanks at sea (now banned) Land based inputs

Fate of Crude oil spilt on seawater: Fate and behaviour of spilt crude oil will depend on composition (origin) As oil is hydrophobic and < dense that water, will form thin layer at interface with atmosphere 100-200L of oil will cover 1 km2 to about 0.1 µm- thicker if major spill Film moves with wind and tides

Examples of legislation to reduce pollution: Tri- butyl Tin (TBT) Major impact on certain molluscs Impact on oyster growth (deformed shells; reduced growth) Now banned, even on larger vessels

Banning of “over the side” dumping of garbage at sea (1988)