Water Pollution W6

Non-marine + marine sewage consequences, biomonitoring

Types of coastal pollution

• microorganisms

• oxygen-depleting substances

• metals (boats, industrial sources)

• hydrocarbons

• nutrients

• thermal

• alien invasive species

• litter + rubbish

• noise

• light

point source nutrient pollution

• domestic sewage effluent

• industrial discharges incl. detergents

• shipping discharges of sewage + wastewater

• fish farms (faecal waste from fish + uneaten fish feed)

diffuse source nutrient pollution

• agricultural runoff

• natural background inputs (rocks weathering, soil leaching, decaying OM)

• atmospheric nitrogen oxides

Algal Blooms (HABs)

• increased nutrient concentrations

• blooms of phytoplankton + other algae produce oxygen in surface waters, then phytoplankton die + sink to seabed

• decomposition of phytoplankton uses up more oxygen

• anoxia in bottom layers

—> makes shellfish unfit for human consumption

—> cause losses in stock through anoxia/asphyxiation

Antarctica

• coliform distributions around research station

• sources: local vertebrate populations, human sewage

• highlighted persistence of sewage pollution + dispersal motoring needs around sewage outflow

E.coli in Devon (2000)

4 cases of poisoning in resort on same day

girl of 8 yrs died

caused by CSO discharges 2km from beach

benefits of recycling sludge to land

• fertiliser - agronomically useful quantities of nutrients

• increases soil quality

• cheaper than mineral fertiliser

• most environmentally sustainable method of disposal

drawbacks of recycling sludge to land

• unsure how much microplastics could be transferred to soil

• diffuse nutrient pollution (fertiliser can lead to excess phosphorus)

Combined Sewer Overflows (CSO)

Transport domestic, industrial, + surface runoff wastewater.

Happens when heavy, prolonged rainfall causes exceedence of system capacity + act as emergency relief system to prevent flooding + backlogs.

CSO regulations

• discharge consents required

• consent regards excess rainfall/snowmelt

• operation + performance monitored as part of EIP

sewage fungus

mass of filamentous bacteria growing in response to organic inputs (sewage), causes oxygen concentrations in water to drop rapidly

General Quality Assessment (GQA)

Old method of measuring water quality by looking at chemistry, biology, and nutrients. Samples of water taken on monthly basis at intervals 5-8km.

chemical: DO, BOD, ammonia

biological: macro invertebrates

nutrient: nitrates, phosphates, Nitrate Vulnerable Zone (NVZ)

Metals properties

• good conductors of heat + electricity

• malleable + ductile

• 16 metals occur in nature in elemental form e.g., gold, silver

• non-biodegradable

slightly elevated metals in natural waters cause:

• histological or morphological changes in tissue

• changes in physiology

• changes in circulation

• changes in biochemistry

• changes in behaviour

• changes in reproduction

tradition water quality indicators

• dissolved oxygen

• pH

• temperature

• salinity

• nutrients e.g., nitrogen, phosphorous

• toxicants, insecticides, herbicides, + metals

habitat indicators

riparian :

• width,

• continuity

• extent of shading

• species composition

in stream:

• measures extent of scouring + bank erosion

• presence of woody debris e,g., fallen trees

biological indicators

freshwater

• macro invertebrates

• benthic algae growth

• fish diversity

estuaries

• less developed

• chlorophyll

coastal embayments

• seagrass condition

• condition of fringing coral reefs

indicator species

May delineate an ecoregion or indicate an env condition.

can be among most sensitive species in a region + act as early warning.

Biomonitors

contain relevant info on the quantitative aspects of the quality of an environment

active bio monitoring

when biomonitors bred in labs are exposed in a standardised form in the field for a define period of time

passive bio monitoring

when organisms already occurring naturally in ecosystem are examined for their actions

advantages of bio monitoring

• indicator organisms act as sensitive early warning system

• provide direct method of studying effects of pollutants in living organisms

• possible to study relationship between concentration of pollutants + effects when both measured at same rate

• can determine species and temporal trends in occurrence and intensity of effects of several pollutants in natural env

• doesn’t depend on electricity for operation

• no expensive equipment

• can be done in remote areas

disadvantages of bio monitoring

• not useful for assessing exposure to substances that exhibit toxic effects at site of first contact where substances are poorly absorbed

• only useful where relationship between waterborne concentrations, internal does and adverse effects is known for specific chemicals

• major limitation is lack of detailed info on fate of industrial chemicals

• most toxicokinetic data available of animal studies extrapolated to humans

• indicator organisms spread over a wide geographical area can cause data interpretation complexities + problems