Nutrients as Pollutants

Major Determinants of Water Qualityand the Impact or Availability of Water Pollutants

OrganismsSolubilityOxygen

pH

Nutrients (N, P)Metals (Hg, Pb, As)

Organic Chemicals (PCBs, Dioxins)

Nutrients: Nitrogen and Phosphorus

Nutrients: Nitrogen and Phosphorus

Both are limiting to primary productivity

Excess amounts can severely alter ecosystems

Availability in the environment is controlled byOxygen

pHOrganisms

Sources: fertilizers, manures, wastewater discharge

Eutrophication

Photosynthetic life

O2

bacteria

Nutrient Additions Nutrient addition increasesprimary productivity (algae)

Sunlight is limited at greater depth

Photoautotrophs die and becomefood for aerobic heterotrophs

Aerobic autotrophs consume O2

Oxygen content in water is reduced

If oxygen is reduced sufficiently,aerobic microbes cannot survive,and anaerobic microbes take over

Nitrogen

Nitrogen

NH4+ and NO3

-

Forms are controlled by organisms

NH4+ is converted to NO3

- by aerobic bacteria

The process is called nitrification

These bacteria, therefore, are controlled by oxygen levels

Nitrifying bacteria do not function well at low pH.

OrganismsOxygen

pH

Dominant Forms: NH4+ and NO3

-

NO3- is more mobile in the environment than NH4

+

_ ___

___

__

Soil particles possessa negative electrical charge

NH4+

NO3-

Leaching to groundOr surface water

Sources: fertilizers, manures, wastewater discharge

Groundwater and Nitrates (NO3-)

Nitrates do not interact significantly with soilmaterial and can move rapidly to groundwater.

3. Areas where the aquifer confining unit is thin are also particularly vulnerable.

What areas are particularly vulnerable?

2. Areas where natural groundwater recharge occurs

1. The unconfined, surficial aquifer

55 – 24 million years ago

Miocene Clays(Hawthorne Formation)

Sandy Materials

The Floridan aquifer is a confined aquifer.The water-bearing unitis permeable limestone.

Low PermeabilityConfining Unit(poor water movement)

Unconfined aquifer isextensive throughoutthe state of Florida

Low permeability rock (confining)

Unconfined Aquifers

Recharge

Thin sandy overburden

Where the Confining Layer is Thin

Groundwater

• residential and commercial septic systems in rural areas• about 300 row crop and vegetable farms• 44 dairies with more than 25,000 animals • 150 poultry operations with more than 38 million birds

Lower Suwannee River Watershed

Nitrates

NO3 Drinking water standard: 10 ppm

Environmental and Health Hazard

Methemoglobinemia

Nitrate is converted to nitrite in infants (pH, organisms)

Nitrite converts iron in the hemoglobin of red blood cells to form methemoglobin which cannot bind oxygen

Adults possess an enzyme that reverses the conversion

Infants possess 60% less of the enzyme

Phosphorus

Phosphorus

Limiting Element to Primary Productivity

ChlorophyllATPPhospholipids

ATP

Additions increase Productivity

Present in Fertilizers, animal wastes, wastewater

Fertility

Only 10-15% of applied fertilizer phosphorous is used by plantsThe rest is bound to soil particles or forms insoluble solids

Most phosphorus is unavailable to plants

This leads to excess application

Plant Availablity and pH

H2PO4- HPO4

-2

pH 3-6 pH 8-11pH 6-8

Optimum pH = 6.5 for plant availability

Most Available

Binding of Phosphorus

Low pH High pH

Aluminum and Iron phosphates

Calcium Phosphates

Formation of Insoluble solidsReaction with soil particles

There is a finite capacity to immobilize phosphorusIf the capacity is exceeded, phosphorus becomes more mobile

Mobile phosphorus can contaminate surface and groundwater

P-impacted

Unimpacted

*

South Florida and Phosphorus

Phosphorus loading to S. Florida Ecosystem

Inputs Northand South ofOkeechobee

Dairy/Beef

Crop production

Sugar, Rice, Veg.700,000 ac

EAA

Crops: Everglades Agricultural Area

Celery 260 200 140 80 20 0 0 0 0

Endive 200 175 150 125 100 75 50 25 0

Escarole 200 175 150 125 100 75 50 25 0

Lettuce (Head) 200 175 150 125 100 75 50 25 0

Radish 100 40 0 0 0 0 0 0 0

Romaine 200 175 150 125 100 75 50 25 0

Sugar Cane 120 100 80 40 20 0 0 0 0

Phosphorus Fertilization (lbs/ac)

Low Soil P V. High Soil P

Based on how much P is already in soils

Phosphorus loading to S. Florida Ecosystem

Agriculture

Overstimulation of primary productivity

Dairy and Beef

Dairy and Beef Kissimmee drainage basin 12,000 km2

In 1521 Ponce de Leon brought horses and cattle to Florida.

No other part of our country had cattle until the Pilgrims brought cattle in the early 1600's

Florida's ranchers now raise the third largest number of cattle of any state east of the Mississippi

(1947)

Phosphorus

Solid Manure: 5.5 g / kg total Phosphorus

One cow can excrete between 40 and 60 g of phosphorus per day

Subject to movement via runoff, stream flow, soil water movement, and groundwater movement

Cattle and Dairy

Okeechobee, Highlands, and Glades Counties: 328,000 head (19% of total)

Okeechobee County is ranked number one for all cattle in the state

The Kissimmee river alone contributes about 20% of the phosphorus flowing intoLake Okeechobee

The Lower Kissimmee River Basin is among largest sources of external phosphorus loading to Lake Okeechobee

Kissimmee – Okeechobee - Everglades

Okeechobee, in turn, is a sourceof phosphorus to the Everglades

urban

Surface Water Improvement Management Act: SWIM

SWIM Plan priority basins

Mandated phosphorus load level of 397 tons/yr

Clean Water act: 154.3 tons per year

DEP: 140 tons per year

Lake

Target level of 40 ppbin Lake Okeechobee

urban

The Dairy Rule (1987) creating lagoons to capture and contain dairy waste

Dairy Buy-Out Program to facilitate removal of animals from dairies not able to comply

Works of the District Rule permits are required for all discharges into waterways

Implement Best Management Practices (BMPs) buffer areas around places animals congregate, eliminating phosphorus fertilization near tributaries to the lake, reducingphosphorus imports in animal feeds, reducing animal density

Some Strategies

19 of 45 Dairies Remain

Phosphorus concentrations in the Lake remain at about 117 ppb

2007: 146 ton reduction of P entering Okeechobee

The target level is 40 ppb.

From a baseline of 433 tons/yr

Internal Loading

Decomposition of submerged aquatic vegetationreleasing phosphorus back into the water column

Dissolution of Iron and Aluminum compounds in sediments which bind and store phosphorus.

Two Sources

Phosphorus and Iron

Phosphorus has a strong affinity for iron

FePO4

Solid Precipitate

Readily incorporates into bottom sediments

Internal Loading

Fe3+ high oxygen Fe2+ low oxygen

Iron Exists in Two Different Forms Depending on Oxygen Content

Forms insoluble solids with Phosphate Phosphorus compounds become soluble

Fe3+ + PO43- = FePO4

solid

Internal Loading

Dissolved phosphorus combines with oxidized iron (Fe3+) to create an insoluble compound that becomes buried in lake sediments.

If oxygen contents are reduced (anoxic bottom sediments) theFe3+ converts to Fe2+ which solubilizes the compound returning P to water.

P released by sediments is taken up by photosynthetic algae faster than it can be returned to the sediments

Fe3+ + PO43- = Fe(PO4)

solid

(PO4)Fe to water2+

Fe3+ high oxygen Fe2+ low oxygen

3-

Simplified:

RECOMMENDATION – Control Internal Phosphorus Loading.

Phosphorus-rich mud sediments need to be removed from the lake to the maximum extent that is practical, in order to reduce internal phosphorus loading. Unless this internal loading is substantially reduced, it may take as long as 100 years for the lake to respond to watershed phosphorus control programs.

Lake Okeechobee Action PlanDeveloped by the Lake Okeechobee Issue Team

December 6, 1999

Next: Arsenic, Fluoride, Mercury

Chemical PollutantsMetals and Non-metals

Lead found in blood sample from 1 of 10 Washingtonians

Arsenic found in urine samples from 4 of 10 Washingtonians

Mercury found in hair samples from 10 of 10 Washingtonians

Mercury, Arsenic, and Lead

Common Health Effects

Lead

behavioral problemshigh blood pressure, anemiakidney damagememory and learning difficultiesmiscarriage, decreased sperm productionreduced IQ

Mercury

blindness and deafness brain damagedigestive problemskidney damagelack of coordinationcognitive degeneration

Arsenic

breathing problemsdeath if exposed to high levelsdecreased intelligenceknown human carcinogen: lung and skin cancernausea, diarrhea, vomitingperipheral nervous system problems

Mercury Nitrate

Symptoms included tremors, emotional instability, insomnia, dementia and hallucinations

Wonderland

Natural Groundwater Contaminants

Fluoride and Arsenic

water tables falling by 20 feet per year

21 million backyard tube wells

Failure of 246 surface water quality projects

$600 electric pumps (1% of GDP)

India

95 %

What do you do when your water table falls?

Deeper Wells and Fluoride

Naturally occurring element in Granitewhich dissolves into the groundwater

Water near the surface is generally unaffected

Lowering water tables = deeper wells

Deep wells can penetrate granite with high fluoride levels

Fluoride in water can be a cumulative poison

What’s the obvious question?

Intentional Fluoridation of Water in the U.S.

Fluoridation became an official policy of the U.S. Public Health Service in 1951.

By 1960 water fluoridation had become widely used in the U.S. reaching about 50 million people.

By 2006, 69.2% of the U.S. population on public water systems were receiving fluoridated water.

How does it work?

Tooth enamel is made of a mineral called hydroxyapatite

Ca5(PO4)3OH

Hydroxyapatite is subject to dissolution by acids (H+)

Fluoridation changes the chemical composition ofhydroxyapatite to a crystal less subject to acid dissolution

Bacteria in the mouth create acids (H+)

Ca5(PO4)3

Sodium fluorosilicate (Na2SiF6)

Sodium fluoride (NaF)

NaF Na+ + F-

OH

Ingestion of fluoridated water increases the F- concentration in saliva

F- replaces OH in hydroxyapatite making fluoroapatite

F-

Fluoroapatite is less soluble in acid than hydroxyapatite

Fluoride concentrationsIn U.S. tap water

0.5 – 1.0 mg/L

Lower values in warm climates

1.6 to 6.6 mg/day

Colorado Brown Stain

Dental Fluorosis

Intake:

Permissible fluoride limit in India is 1.2 mg/L

Fluoride levels between 5-25 mg/L have been found

Fluoride levels > 1.5 mg/L

9 mg/day to 12 mg/day

Fluorosis has risen from 1 million to 25 million and threatens 60 million people in India.

Skeletal Fluorosis

Intake

Fluoride levels > 10 mg/L

*

Groundwater and Arsenic

Arsenic is Naturally Occurring

occurs primarily in association with sulfur-containing minerals

Mobilization of arsenic in the environment arises from anthropogenic activities related to mining and ore processing,

metallurgy, agriculture, wood preservation, and industry.

Natural waters, in general, contain low levels of total arsenic

Inorganic Forms of Arsenic

AsO4-3AsO3

-3

Arsenite Arsenate

Low Oxygen High Oxygen

Arsenite is more toxic than arsenate, interfering withenzyme activities which catalyze metabolic reactions

Arsenite compounds are also more mobile in the environment

Both arsenate and arsenite are chronic accumulative toxins

“The World’s Largest Mass Poisoning”

Bangladesh and W. India

ranked among the world's 10 poorest countries

Bangladesh Prior to 1970s

One of the highest infant mortality rates in the worldPrincipally due to waterborne disease.

Ineffective water and sewage systemsPeriodic monsoons and floods

cholera, dysentery

water-borne pathogens

Deaths Due to Surface water contamination: 250,000/yr

Deaths Due to Surface water contamination: 250,000/yr

The Solution: Tap groundwater resources• easy• inexpensive• available

First 1 million wells were sunk with aid from

World GovernmentsUNICEF

World Bank

12 million hand-operated tube wellsdeliver water to over 80% of the rural village population

Infant mortality and diarrheal illness reduced by 50%

Accumulation ofthick mudsin the floodplainsand deltas

Floodplain and Delta of theGanges and Brahmaputra Rivers.

Floodplain: area paralleling a river that is periodically inundated

Deltas are formed from the deposition of sediment carried by the river as the flow leaves the mouth of the river

Himalayas

Ganges-Brahmaputra Delta

Wells in Floodplain and Delta Sediments

Water Bearing Muds

Natural erosion ofarsenic to water-bearing units.

Well depths between 20m and 100 m

Majority of wells > 50 ppb arsenic Some wells contain 500 - 1000 ppb

WHO/U.S limit: 10 ppbBangladesh limit: 50 ppb

Delta and Floodplain Regions

Exposure Estimates

Above 10 ppb: 57 million peopleAbove 50 ppb: 35 million people

Early Symptoms:Skin lesions and thickeningStrong skin pigmentation

Accumulative Toxin

Long-term Exposurebreathing problems

death if exposed to high levelslung and skin cancer

peripheral nervous system

2003 Studies

83 million people

Bihar: 40% wells contaminated

Red River Delta

11 million people

First wells sunk7 years ago

Next: Mercury

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