Phosphorus Nutrient Essential for plant growth Metabolism ADP to ATP DNA & RNA Fertilizers and Detergents Biological productivity & water quality

Forms of Phosphorus Phosphorus occurs naturally in rocks Weathering releases phosphate ions (PO 4 -3 ) Inorganic Orthophosphates Polyphosphates (Metaphosphates) Organic phosphate

Forms of Phosphorus Orthophosphates Readily available to the biological community Typically found in low concentrations in unpolluted waters H 3 PO 4 H 2 PO 4 - HPO 4 2- PO 4 3-

Forms of Phosphorus Polyphosphates Molecularly dehydrated forms of orthophosphates Used in detergents and treating boiler waters In water, they are transformed to orthophosphates and available for plant uptake

Forms of Phosphorus Organic Phosphate bound or tied up in plant tissue, waste solids, or other organic material When decomposed thru bacterial action, phosphate released and returned to environment

Imp. of Phosphorus Key element for plants and animals Limiting nutrient Too much = eutrophication Relationship between C, N and P C:N:P Ratio 106:16:1

Imp. of Phosphorus Critical Level of Inorganic Phosphorus: mg/L

Phosphate Cycle

Human Impacts Commercial synthetic fertilizers Apatite mining Aurora Phosphate Mine, NC Polyphosphates are used in boilers

Human Impacts Waste Water Treatment Average person releases 1.5 g/day Prior to the development of detergents: Inorganic 2-3 mg/L Organic 0.5 – 1 mg/L EPA: Sewage effluent should not contain > 1 mg/L Unpolluted waters usually < 0.1 mg/L

Human Impacts Heavy-duty synthetic detergents Contain polyphosphates 12-13% phosphorus Domestic wastewater 2-3x inorganic P due to detergents

Methods Gravimetric, volumetric and colorimetric Organic and polyphosphates have to be converted to orthophosphate for measurement