Pressure - Nutrients

Sources of nutrients:

• Nutrients enter wetlands from diffuse catchment (via over-land surface flow (local watershed), in flood waters (overbank flow) or groundwater) or directly from urban and agricultural land use or point sources
• Nutrients can be dissolved in the water or bound to sediments
• Plants and algae can act as nutrient sinks as they remove nutrients from the water column/groundwater
• Nitrogen from Sewage Treatment Plants (STP) has an increased delta¹⁵ N signature which can be traced through the food chain
• Nutrients are cycled naturally within the system with nitrogen (N² gas) lost through denitrification
• Clearing of wetland, fringing zone or catchment vegetation, or vegetation loss through poor fire management, can result in increased run-off due to bare ground or decreased nutrient removal from the incoming waters
• Agricultural activities can increase nutrient loads through fertiliser run-off or erosion (nutrients bound to sediments)
• Dense fauna populations (e.g. bird colonies, feral pigs) and livestock can increase nutrient loads directly to wetlands through faeces and urine
• Numerous land-use activities, such as feedlots, N-fixing crops, golf courses, aquaculture, mining, forestry, housing (septic tank leakage), can be sources of nutrients to wetland