State of the Bay Report 2010-Final - Anchor Environmental
State of the Bay Report 2010-Final - Anchor Environmental
State of the Bay Report 2010-Final - Anchor Environmental
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<strong>Anchor</strong> <strong>Environmental</strong><br />
3 BACKGROUND TO ENVIRONMENTAL MONITORING AND<br />
WATER QUALITY MANAGEMENT<br />
3.1 Introduction<br />
Pollution is defined by <strong>the</strong> United Nations Convention on <strong>the</strong> Law <strong>of</strong> <strong>the</strong> Sea as ‘<strong>the</strong><br />
introduction by man, directly or indirectly, <strong>of</strong> substances or energy into <strong>the</strong> marine environment,<br />
including estuaries, which results in such deleterious effects as harm to living resources and marine<br />
life, hazards to human health, hindrance to marine activities, including fishing and o<strong>the</strong>r legitimate<br />
uses <strong>of</strong> <strong>the</strong> sea, impairment <strong>of</strong> quality for use <strong>of</strong> <strong>the</strong> sea water and reduction <strong>of</strong> amenities’. A wide<br />
variety <strong>of</strong> pollutants are generated by man, many <strong>of</strong> which are discharged to <strong>the</strong> environment in one<br />
form or ano<strong>the</strong>r. Pollutants or contaminants can broadly be grouped into five different types: trace<br />
metals, hydrocarbons, organochlorines, radionuclides, and nutrients. Certain metals, normally<br />
found in very low concentrations in <strong>the</strong> environment (hence referred to as trace metals) are highly<br />
toxic to aquatic organisms. These include for example Mercury, Cadmium, Arsenic, Lead, Chromium,<br />
Zinc and Copper. These metals occur naturally in <strong>the</strong> earth’s crust, but mining <strong>of</strong> metals by man is<br />
increasing <strong>the</strong> rate at which <strong>the</strong>se are being mobilised which is enormously over that achieved by<br />
geological wea<strong>the</strong>ring. Many <strong>of</strong> <strong>the</strong>se metals are also used as catalysts in industrial processes and<br />
are discharged to <strong>the</strong> environment toge<strong>the</strong>r with industrial effluent and waste water. Hydrocarbons<br />
discharged to <strong>the</strong> marine environment include mostly oil (crude oil and bunker oil) and various types<br />
<strong>of</strong> fuel (diesel and petrol). Sources <strong>of</strong> hydrocarbons include spills from tankers, o<strong>the</strong>r vessels,<br />
refineries, storage tanks, and various industrial and domestic sources. Hydrocarbons are lethal to<br />
most marine organisms due to <strong>the</strong>ir toxicity, but particularly to marine mammals and birds due to<br />
<strong>the</strong>ir propensity to float on <strong>the</strong> surface <strong>of</strong> <strong>the</strong> water where <strong>the</strong>y come into contact with seabirds and<br />
marine mammals. Organochlorines do not occur naturally in <strong>the</strong> environment, and are<br />
manufactured entirely by man. A wide variety <strong>of</strong> <strong>the</strong>se chemicals exists, <strong>the</strong> most commonly known<br />
ones being plastics (e.g. polyvinylchloride or PVC), solvents and insecticides (e.g. DDT). Most<br />
organochlorines are toxic to marine life and have a propensity to accumulate up <strong>the</strong> food chain.<br />
Nutrients are derived from a number <strong>of</strong> sources, <strong>the</strong> major one being sewage, industrial effluent,<br />
and agricultural run<strong>of</strong>f. They are <strong>of</strong> concern owing to <strong>the</strong> vast quantities discharged to <strong>the</strong><br />
environment each year which has <strong>the</strong> propensity to cause eutrophication <strong>of</strong> coastal and inland<br />
waters. Eutrophication in turn can result in proliferation <strong>of</strong> algae, phytoplankton (red tide) blooms,<br />
and deoxygenation <strong>of</strong> <strong>the</strong> water (black tides).<br />
It is important to monitor both <strong>the</strong> concentration <strong>of</strong> <strong>the</strong>se contaminants in <strong>the</strong> environment<br />
and <strong>the</strong>ir effects on biota such that negative effects on <strong>the</strong> environment can be detected at an early<br />
stage before <strong>the</strong>y begin to pose a major risk to environmental and/or human health.<br />
3.2 Mechanisms for monitoring contaminants and <strong>the</strong>ir effects on <strong>the</strong><br />
environment<br />
The effects <strong>of</strong> pollutants on <strong>the</strong> environment can be detected in a variety <strong>of</strong> ways as can <strong>the</strong><br />
concentrations <strong>of</strong> <strong>the</strong> pollutants <strong>the</strong>mselves in <strong>the</strong> environment. Three principal ways exists for<br />
assessing <strong>the</strong> concentration <strong>of</strong> pollutants in aquatic ecosystems - through <strong>the</strong> analysis <strong>of</strong> pollutant<br />
concentrations in <strong>the</strong> water itself, in sediments or in living organisms. Each has <strong>the</strong>ir advantages and<br />
disadvantages. For example, <strong>the</strong> analysis <strong>of</strong> pollutant concentrations in water samples is <strong>of</strong>ten<br />
problematic owing to <strong>the</strong> fact that even at concentrations lethal to living organisms, <strong>the</strong>y are<br />
difficult to detect without highly sophisticated sampling and analytical techniques. Pollutant<br />
concentrations in natural waters may vary with factors such as season, state <strong>of</strong> <strong>the</strong> tide, currents,<br />
extent <strong>of</strong> freshwater run<strong>of</strong>f, sampling depth, and <strong>the</strong> intermittent flow <strong>of</strong> industrial effluents, which<br />
<strong>State</strong> <strong>of</strong> <strong>the</strong> <strong>Bay</strong> <strong>2010</strong>: Saldanha <strong>Bay</strong> and Langebaan Lagoon 36