Water Pollution

Big Idea  The LARGER the population GROWS the greater the pollution will FLOW and the negative effects we’ll KNOW.

Point Source Pollution vs. Nonpoint Source Pollution What’s the difference?

Point Source Pollution  comes from a specific source, like a pipe  factories, industry, municipal treatment plants  can be monitored and controlled by a permit system

What is nonpoint source pollution ?  Nonpoint Source (NPS) Pollution is pollution associated with stormwater or runoff  NPS pollution cannot be traced to a direct discharge point such as a wastewater treatment facility

Examples of NPS  oil & grease from cars  fertilizers  animal waste  grass clippings  septic systems  sewage & cleaners from boats  household cleaning products  litter

Pollutant Transport Mechanisms NPS pollutants build up on land surfaces during dry weather  Atmospheric deposition  Fertilizer applications  Animal waste  Automotive exhaust/fluid leaks Pollutants are washed off land surfaces during precipitation events (stormwater runoff) Stormwater runoff will flow to lakes and streams

Point or Non-Point Source?  Eroding soil from construction sites  Leachate from landfill  Overflowing hog lagoon  Pesticides  Septic tank leak  Storm water run-off from city streets

Point or Non-Point Source?  Eroding soil from construction sites NON-POINT  Leachate from landfillPOINT  Overflowing hog lagoonPOINT  PesticidesNON-POINT  Septic tank leakPOINT  Storm water run-off from city streets NON-POINT

Pollutant build-up and wash off are affected by land use.  Imperviousness increases runoff  Land use changes impact build up

Linking Land Use to Water Quality More Imperviousness = More Water

What is impervious cover?  roads, rooftops, parking lots, and other hard surfaces that do not allow stormwater to soak into the ground  “predominant American vegetation”

Impervious Cover provides a surface for accumulation of pollutants leads to increased polluted runoff and flooding inhibits recharge of groundwater

Impact of Nonpoint Source Pollution  fish and wildlife  recreational water activities  commercial fishing  tourism  drinking water quality

Pollutants Found in Runoff Sediment Soil particles transported from their source Biochemical Oxygen Demand (BOD) ● Oxygen depleting material  Leaves  Organic material Toxics ● Pesticides  Herbicides  Fungicides  Insecticides ● Metals (naturally occurring in soil, automotive emissions/ tires)  Lead  Zinc  Mercury ● Petroleum Hydrocarbons (automotive exhaust and fuel/oil) Debris Litter and illegal dumping Nutrients ● Various types of materials that become dissolved and suspended in water (commonly found in fertilizer and plant material):  Nitrogen (N)  Phosphorus (P) Bacteria/ Pathogens Originating from: ● Pets ● Waterfowl ● Failing septic systems Thermal Stress Heated runoff, removal of streamside vegetation

Potential Sources of Pollutants Found in Residential Areas  Nutrients: Fertilizers and septic systems  Pathogens: Pet waste and septic systems  Sediment: Construction, road sand, soil erosion  Toxic: Pesticides, household products  Debris: Litter and illegal dumping  Thermal: heated runoff, removal of streamside vegetation

Pollutants from Agriculture  Sediment  Nutrients  Pathogens  Pesticides

Why are these pollutants important?  Sediment reduces light penetration in stream, clogs gills of fish and aquatic invertebrates.  Nutrients act as fertilizer for algae & aquatic plants which can cause highly varying dissolved oxygen levels. At low DO levels, the aquatic life has the potential to be harmed.  Toxics can impact life and contaminate drinking water supplies.  Bacteria/Pathogens are an indicator of possible viruses present in the system.

Inefficient Irrigation  Worldwide, the amount of land under irrigation has been increasing.  Whether from aquifers or surface bodies of water, the majority of the freshwater we use for irrigation is lost before it ever reaches the crops. Figure 14-15

Inefficient Irrigation  Inefficient “flood and furrow” irrigation, in which fields are liberally flooded with water that may evaporate from shallow standing pools, accounts for 90% of irrigation worldwide.  Over-irrigation leads to waterlogging and salinization, which affects 1/5 of farmland today and reduces world farming income by $11 billion.  Unfortunately, huge amounts of groundwater are being used up for little gain; because of the dry climate and inefficient irrigation methods. Flood and Furrow Irrigation

We Can Cut Water Waste in Irrigation  Flood irrigation Wasteful  Center pivot, low pressure sprinkler  Low-energy, precision application sprinklers  Drip or trickle irrigation, microirrigation Costly; less water waste

Fig , p. 335 Center pivot (efficiency 80% with low-pressure sprinkler and 90–95% with LEPA sprinkler) Drip irrigation (efficiency 90–95%) Water usually pumped from underground and sprayed from mobile boom with sprinklers. Gravity flow (efficiency 60% and 80% with surge valves) Above- or below-ground pipes or tubes deliver water to individual plant roots. Water usually comes from an aqueduct system or a nearby river.

Solutions: Reducing Irrigation Water Waste

Eutrophication  Most nutrients in water come from organic matter (leaves, waste, etc.)  Nutrients are an essential part of any aquatic ecosystem, but when slow-moving waters contain too much, they are eutrophic.

Eutrophication  Eutrophication= build-up of organic matter in water causing algal blooms  Outcomes: Decreased sunlight Decaying matter uses oxygen Suffocation/Fish Kills 

Artificial Eutrophication  Humans act as a catalyst by adding excess nutrients to the soil  Main culprits= phosphates from fertilizers and cleaning agents  Human activity can also cause thermal pollution

POLLUTION OF GROUNDWATER  It can take hundreds to thousand of years for contaminated groundwater to cleanse itself of degradable wastes. Nondegradable wastes (toxic lead, arsenic, flouride) are there permanently. Slowly degradable wastes (such as DDT) are there for decades. Groundwater has low flow rates, few bacteria, & cold temps - all slow down recovery time Avg. recycling time for groundwater = 1400 years

Fig. 21-8, p. 502 Aquifer Water well Migrating vapor phase Contaminant plume moves with the groundwater Free gasoline dissolves in groundwater (dissolved phase) Groundwater flow Water table Gasoline leakage plume (liquid phase) Leaking tank Bedrock

Surface water vs. Groundwater Which is generally more polluted? ~ Surface Water Which is harder to clean up? ~ Groundwater

Groundwater pollution sticks around...  Very cold, no bacterial breakdown  Very slow water movement: recharge can take 100’s or 1000’s of years  Pollutants can stick to rocks in aquifer and pollute new water

What Pollutes Groundwater?

Sources of Groundwater pollution...  landfills  leaky underground storage tanks  mines  septic tanks  hazardous waste - deep well injection  any pollutant in runoff that percolates

Laws  Clean Water Act – surface water 1972 – make water swimmable and fishable by regulating point sources 1977 and 1987 – storm water runoff Section 404 – requires permit for draining, dredging, filling wetlands  Mitigation banking  Safe Drinking Water Act (1974) – monitors levels of contaminants in groundwater