Eutrophication Flashcards
(28 cards)
What does oligotrophic mean?
Low nutrient status aquatic environment.
What does eutrophic mean?
Nutrient rich.
What does mesotrophic mean?
Intermediate level of nutrients/productivity.
What is eutrophication?
The enrichment of the environment with nutrients and associated production of undesirable effects.
What is an undesirable disturbance?
A perturbation of a marine ecosystem that appreciably degrades the health or threatens the sustainable human use of that ecosystem.
What is nutrient pollution?
Excess amounts of nitrogen and phosphorus in aquatic systems.
What are the stages of eutrophication?
1) Increase in plant nutrient concentration
2) Increase in nutrient concentration and an increase in plant (algal) production
3) Increase in nutrient concentration and an increase in algal production leading to:
- Changes in species composition
- Abnormal blooms of algae
- Toxic algal species
- Deoxygenation
- Adverse effects on fish and invertebrates
- Changes in structure of benthic communities.
What is an illegal dry spill?
Untreated wastewater spills straight out into rivers and seas when there is no rain.
What is normal operation in sewage systems?
System functionally normal as wastewater flows smoothly through the system to the sewage treatment plant.
What is a legal spill?
Water companies can spill untreated wastewater under certain conditions, such as heavy or prolonged rainfall.
What is preliminary treatment?
Screening large objects, maceration and grit removal. Iron bars 5-10cm spacing, removes wood, paper, bottles.
What is primary treatment in sewage processing?
Suspended solids separated out as sludge.
What is secondary (biological) treatment?
Dissolved and colloidal organics are oxidised in presence of micro-organisms.
What is tertiary treatment?
Used when high quality effluent is required. It may involve removal of further BOD, bacteria, suspended solids, toxic compounds and nutrients.
How is sewage discharge recorded?
Monitored using water level sensors which detect releases at designated points. Allows untreated sewage into the environment. Sensors measure the start of overflow and the end which gives us a duration. Only ~80% is monitored 12/24 method.
Describe the process of spill counting for sewage discharge.
Spill counting starts when the first discharge occurs. A discharge occurs when the sewer level exceeds the threshold level. Any discharge(s) in the first 12-hour block is counted as 1 spill. Any discharge(s) in the next and subsequent 24-hour blocks are each counted as 1 additional spill per block. Counting continues until there is a 24-hour block with no discharge. For the next discharge after the 24-hour block with no discharge, the 12 hour and 24-hour block spill counting sequence begins again.
What are the characteristics of a balanced marine ecosystem?
A pelagic food chain which effectively couples production to consumption and minimises the potential for excess decomposition.
Natural species composition of plankton and benthic organisms.
If appropriate, a natural distribution of submerged aquatic vegetation.
What is an oxygen minimum zone (OMZ)?
A region in the ocean where dissolved oxygen concentration is significantly lower than in the surrounding waters at intermediate depths.
What are possible catchment solutions?
Water-friendly Agricultural Practices, Urban Runoff & Sewage Management, Wetland Restoration, Community Engagement, Real-time Monitoring.
What are water-friendly agricultural practices?
Work with farmers, install livestock fencing, reduce use and safe handling of pesticides, soil testing, tree planting and buffer zones.
What is wetland restoration?
Establish buffer zone, natural filter pollutants, provide habitats.
What is community engagement in catchment solutions?
Inspire locals, motivate water-friendly practices and behaviours, empower to become custodians of river health and advocate protection.
What is real-time monitoring?
Open access data to increase rapid response to pollution, protects ecosystems and public health.
What is Contamination vs. Pollution
Contamination: Presence of a substance where it doesn’t belong (not necessarily harmful).
Example: Natural arsenic in groundwater.
Pollution: Contamination causing adverse effects.
Example: Oil spills harming marine life.
