Final Exam ENVR Science

Invasive Species

non-native, introduced species that

cause ecological harm by destroying habitat or

reducing/eliminating native species through competition,

predation, or infection

EXAMPLES: Blue Catfish, Northern Snakehead

Invasive Solutions

Prevention: stop non-native introductions in the 1st place

through law, education (e.g., clean boats/equipment

between uses in different water bodies, regulating bilge

discharge in ships)

 Eradication: For example, the USDA successfully

eradicated Nutria (which destroy marshes in Chesapeake

Bay) in MD.

 Management: Keep invasive populations under control to

minimize damage. Example: encouraging fishing/collecting

of invasives

Types of Overexploitation

Overcollecting: primarily ornamental plants (e.g., orchids), medicinal plants

(e.g., American ginseng), and birds, fish & amphibians for the pet trade

 Overhunting: primarily mammals and reptiles for food, trophies (e.g., skins,

horns/antlers), & traditional medicine

Overfishing

The first 2 require vigorous crackdowns on illegal domestic and international

wildlife trade (i.e., enforcement of CITES – Convention on International Trade

in Endangered Species

Overfishing

Fish and other resources in the open ocean are vulnerable to

overuse because no private or governmental entity owns them

(Tragedy of the Commons)

Over 1/4 of global fish species are currently overfished

Populations of many large predatory fish (e.g., tuna, marlin) have declined by 90%

since the 1950s

Commercial Fishing Techniques

Drift Nets – long floating nets

(up to 40 mi) that

indiscriminately entangle

anything swimming by (banned

in most countries)

Longlines – long floating lines

(up to 80 mi) with thousands of

baited hooks

Trawl Bag – large, weighted

net bag dragged along ocean

bottom for shrimp and bottom

fish

Purse Seine Net – long net

used to encircle target fish &

trap them

Bycatch

Approximately 25% of all marine animals caught by commerical fishing fleets are bycatch

Solutions to overfishing

• Increase the amount and area of marine protected areas (where

harvesting is significantly restricted or forbidden). Currently less

than 10% of the ocean is protected. Many suggest closer to 30% is

needed.

• Ban or limit fishing in international waters.

• Encourage tight regulations & enforcement of fishing practices

within each country’s exclusive economic zone (marine areas

within 200 miles of a nation’s coast) and provide developing nations

resources to enforce these to prevent local and international ships

from stealing their fish

Aquaculture

Farming of fish industry, ½ of all fish consumed globally are from aquaculture

Downsides to Aquaculture

• Feces and missed food particles

pollute surrounding waters

• Large crowded populations increase

risk of disease transmission.

• Parasites, bacteria or viruses released

into surrounding water, killing wild fish

• Many farmed species are

carnivorous, requiring harvesting

even more wild fish (it takes 5lb of

wild caught fish to make 1lb of farmed

Sea bass)

• Antibiotics administered to fish

increase antibiotic resistance

• Coastal marshes and mangroves

may be destroyed to create facilities

Aquaculture Land Footprint

Open Ocean Aquaculture is best as it has lowest land footprint. However, aquaculture of certain species (Catfish, Salmon, Trout) Has much lower land footprint.

Bivalves have almost no land footprint

Distribution of Water

Water is a solvent (a fluid in

which other substances, called

solutes, dissolve). Seawater, for

example, is water containing

small amounts of salts and other

solutes

Only 0.5% of water on earth is freshwater readily available to humans

Water is a solvent (a fluid in

which other substances, called

solutes, dissolve). Seawater, for

example, is water containing

small amounts of salts and other

solutes

Watersheds

Surface water = remains on the surface as lakes, rivers, etc.

 Runoff = over land movement of water that eventually makes its way

into surface waterbodies

 Watershed (drainage basin) = land area that delivers water into a

given surface waterbody

Groundwater

Groundwater = water under the earth’s surface stored in aquifers

Recharge area = region of land where water penetrates the surface

and fills an aquifer

Aquifer = underground caverns and porous layers of sand, gravel and

rock in which groundwater is stored. 2 types:

Unconfined aquifer = has no layer of impermeable rock above the

aquifer so it is recharged by precipitation directly above

Confined aquifer = covered by impermeable rock. Recharged over

a small area where there is a gap in the impermeable rock for water

to seep through

Water table = the top (upper limit) of a body of groundwater. It is

equivalent to the surface of a lake in that it is the top of that collection

of water. The water table may be close to the ground surface, or far

below

Flooding

Flooding

• Floodplain = area bordering a river that periodically floods. The

boundaries of the floodplain are often designated by how

frequently they are likely to be flooded (e.g., a 100 year

floodplain historically floods once every 100 years or so).

• People often colonize floodplains because they have rich soil for

farming (from the periodic deposition of sediment during flood

events) and the availability of water nearby. Since this places

them in danger of floods, they often build dams to control the

amount of water flow or levees to contain overflowing water

Levees

Levees are raised embankments constructed along riverbanks to reduce flooding.

• Eliminates wetland habitat

• Levees should be spread further apart to allow wetland formation and some flooding of

floodplains during floods.

Desalination

Desalinization = removal of salt from ocean or brackish water. 2

methods:

Distillation - salt water is heated and evaporated, and water

vapor is condensed into freshwater

Reverse Osmosis - involves forcing salt water through a

membrane permeable to water, but not salt and many other

solutes

Desalination is more expensive and energy intensive than other water sources

Extraction of Groundwater

• Water is extracted from aquifers via wells.

• - If water is drawn out faster than it is recharged by rain, the water

table drops and eventually the well must be drilled deeper.

• This is even more problematic in confined aquifers because it may

take thousands of years to replenish what is being removed

because it has a small recharge area

Aquifer Depletion in the US

• When groundwater is

removed more rapidly

than it is replenished by

rain, the water table

drops and available

water is depleted

• This is occurring at

modest levels across

Delmarva (due to

agriculture and

municipal use) and in

prime ag lands

elsewhere, such as the

Great Plains (Ogallala

Aquifer)

Groundwater flows like a slow-moving river and may connect with nearby

surface water bodies. Where water flows out of an aquifer to a surface water

body, it is called a spring.

Water Footprint

Water footprint (WF) measures the annual volume of freshwater

used by countries, individuals etc., broken down into:

Green WF – direct use of rainwater

Blue WF – drawn from surface or ground water

Gray WF – water polluted

Roughly 3/4 of our global water footprint is for meat production,

beef being worst (112 liters/g protein), pork next (57 l/g), and

chicken/eggs/milk the best (29-34 l/g

Humans currently appropriate half of all surface/groundwater

and continues to grow.

Aral Sea

The Aral Sea use to be the World’s 4th largest lake. Water diversion from

rivers feeding the lake for agriculture has reduced it’s area by 90%, leaving a

desert in its wake and high salinity water, devastating fish populations and the

associated fish industry (which formerly employed 40,000 people)

International Water Issues

• In some parts of the world, water resource use is complicated by the fact that

water bodies may span multiple countries. If countries upstream divert too

much water or pollute it, this can lead to conflict with downstream countries.

• Ex.: The Colorado River supplies water to large population centers and

agricultural lands in several US states. As a result of the 49 dams and

massive water diversion, the river regularly fails to reach the sea. This has

destroyed the Colorado River Delta ecosystem in Mexico

Solving the water issue

• Many ag lands use large amounts of water distributed on the

surface where much is lost through evaporation.

• Drip Irrigation (microirrigation) - administering water through

pipes, often underground directly to roots. This dramatically

reduces evaporation (yielding 40-60% reduction in water use)

and salt accumulation in arid/semi-arid areas’

• Where water is still administered

along the surface, leveling the land

reduces water use because you

don’t have high spots requiring extra

water to compensate for runoff to

low spots, and low spots don’t get

drenched.

Personal Water Conservation

• Install low-flow shower heads/faucets (use

about 1/3rd as much water)

• Install low-flush toilets (use ~1/3rd as much

  water)

• Don’t let faucet run while shaving or washing your

face, hands, car, dishes when not actively using it.

• Use the dishwasher (full load ideally) instead of

washing by hand.

• Install rain barrel to use rainwater for watering

garden/lawn.

• Most importantly, reduce farmed meat

consumption, especially beef & pork

Water Pollution Source Types

• Point Source Pollution = water pollution that can be traced to a

specific point of origin (e.g., sewage or industrial effluent pipe)

• Non-point Source Pollution = pollutants that enter bodies of

  water over large areas rather than being concentrated at a

  single point of entry (e.g., agricultural or urban runoff). May be

  diffuse but effect is often very large

Types of Water Pollution

Water pollution = any change to water that adversely affects

the health of humans or other organisms. Major categories:

1. Radioactive

2. Thermal

3. Physical

4. Chemical

5. Nutrient

a) Sewage

b) Agriculture

Radioactive Substances

• Contain atoms of unstable isotopes that spontaneously

emit radiation, increasing risk of cancer and other

ailments. Potential sources of exposure include mining

and processing but also nuclear, medical and research

facilities.

• Solution is to tightly regulate the above.

Thermal Pollution

Thermal pollution = heated water produced during industrial

processes is released into waterways. Warm water holds less oxygen

than cold water. Warmer water and lower oxygen can be a major

stressor to cold water adapted fish, altering species composition in

favor of warm water adapted species. Solution is to regulate warm

water discharge.

Physical Pollution

Physical Pollution = excessive sediments or other suspended solids like

plastics in the water. Limit light penetration for photosynthesis, bury benthic

environments, & harm wildlife (e.g., entanglement in fishing gear)

Sediment pollution is most often caused by runoff/erosion of cropland

and overgrazed land, but also clearcut forests, & construction sites.

Plastics primarily come from discarded fishing debris but also municipal

runoff in developing nations with inadequate garbage collection

Physical Pollution Solutions

Sediment pollution: use best management practices that limit runoff

from ag land (vegetated buffers, no overgrazing), construction sites

(use silt fences), & clearcuts (limit on slopes & along water bodies)

Plastics: Have and enforce laws against littering and maintain strong

garbage collection & recycling infrastructure. Most importantly,

identify strategies for reducing commercial fishing debris

pollution.

Chemical Pollution

Synthetic Organic Compounds = include pharmaceuticals, gasoline

additives, industrial chemicals like pesticides, etc. Most at risk are

aquatic/semiaquatic species (e.g., fish, amphibians) in nearby waterways,

particularly to pesticides containing endocrine disruptors that can lead to

sterility, birth defects, etc

Inorganic Chemicals = contaminants that contain elements other than

carbon. These do not degrade as easily as organic compounds. Examples:

• Lead - interferes with the development of the nervous system, thus most

dangerous for children. Found in old paint.

• Mercury - damages kidneys, cardiovascular and nervous systems.

Released from old coal-fired power plants and medical/municipal waste

incineration. Bioaccumulates in muscle and biomagnifies (higher

concentrations higher in food chain - top predators like t

Bioaccumulation + Biomagnification

Persistence – a variety of toxins,

including some pesticides, persist in

the environment, impacting species

long after they are applied

Bioaccumulation – some also

buildup in the tissues of organisms,

affecting the animals that eat them

Biomagnification – Increase

concentration of toxic chemicals in

tissues of organisms at high trophic

levels … making it dangerous to eat

top predators in environments

where this is a problem

Chemical Pollution Solutions

Industrial: Most US industries recover toxins before they go into the

waste stream. The field of Green Chemistry seeks to identify ways

to minimize environmental impacts of industrial processes by

reducing chemical wastes, more effectively breaking down chemical

waste, and finding less toxic alternatives. For agriculture, minimizing

use of pesticides (e.g., integrated pest management), use of

vegetated buffers along stream edges and ditches, and identifying

lower risk pesticides can reduce collateral damage.

 Municipal: Ensure stormwater runoff and municipal wastewater

undergo significant water treatment before discharge into water

bodies.

Sewage

Sewage = wastewater from personal human use (e.g., toilets)

• When released into water bodies untreated, causes 2 problems:

• Eutrophication

• Disease-causing agents = infectious bacteria, viruses, or

other parasites released from feces into water

Oligotrophic Water Bodies

Oligotrophic water bodies =

low turbidity (cloudiness), low

nutrients (e.g., nitrogen,

phosphorous), support small

populations of species adapted

to these conditions (e.g.,

sturgeon, small mouth bass,

lake trout)

Naturally Eutrophic Water Bodies

Eutrophic water bodies =

generally slow-flowing stream,

lake or estuary enriched by

nutrients. High turbidity

(cloudiness due to high

concentrations of suspended

solids), nutrients, and algal

growth. Low dissolved oxygen.

Species adapted to these

conditions (e.g., catfish, carp)

Eutrophication

Eutrophication = human-caused enrichment/fertilization of a
body of water by introducing high levels nutrients (e.g., nitrogen
and/or phosphorus). This leads to increased algae growth.
When the algae die, they sink to the bottom and bacteria
decompose them. This uses up large amounts of oxygen,
decreasing the Dissolved Oxygen (DO) in the water. If DO gets
low enough, aquatic plants and animals cannot survive.
One measure of the eutrophication risk of sewage is its
Biological Oxygen Demand (BOD) – the amount of oxygen
needed by microorganisms to decompose biological wastes.
The greater the BOD, the more DO will decrease

Disease Causing Agents

Many infectious organisms have a fecal-oral mode of

transmission where they disperse from an infected individual

into water through their feces and infect new individuals through

drinking water. Common examples:

• Bacterial – Cholera (diarrhea, vomiting)

• Protozoan – Amoebic dysentery (severe diarrhea)

• Flatworm – Schistosomiasis (severe diarrhea, weakness)

• Monitored by testing water for presence of E. coli with a fecal

coliform test. Why E. coli?

• Because E. coli is generally not found in nature except via

feces. More E. coli = more feces = higher probability of

pathogenic organisms (including some strains of E. coli )

Municipal Sewage Treatment

Primary treatment = allows solids to settle out as sludge.

Remaining fluid and suspended particles moved to 2nd stage.

• Secondary treatment = aeration to help bacteria decompose

suspended organic material; additional sludge settles out and is

removed. Fluid moved on to next phase.

• Tertiary treatment = use of microfiltration or constructed

lagoons to remove additional phosphorus and nitrogen. Most

sewage not treated with tertiary treatment

• Disinfection = effluent chlorinated or exposed to UV radiation to

kill microbes.

• Sewage Sludge = solids remaining after primary and secondary

sewage treatment has been completed. Taken to landfill, used

as fertilizer, or incinerated

Municipal Sewage Treatment cont.

• Good sewage treatment plant with tertiary treatment can sometimes release

water that is cleaner than the river it is releasing into (as in the case of the

Wicomico River)

Combined Sewage System

When it rains on city surfaces, the runoff is transported

by storm drains. These either empty directly into nearby

waterways or into combined sewer systems.

• Combined sewer systems = pipes that convey both

sewage and storm water runoff to a sewage treatment

plant. The advantage of this is that runoff can be treated

before release into water. The downside is that heavy

storms can overwhelm treatment plant capacity, causing

combined sewer overflow in which storm water and

raw sewage enter waterways untreated.

Septic Tank

Used for homes not connected to municipal Sewage

• Solids settle on bottom as sludge, oils rise to top and broken down by bacteria, then water flows out to drain field

Water Pollution in other countires

25% of people globally lack proper access to adequate sanitation systems, in many develooping nations, sewage is dumped directly into rivers.

Worldwide, more than 9000 people die daily from waterborne illness

agriculture and water pollution

Agriculture is leading source of water pollution in the United States, the majority of which is meat/animal production

Pollution is due to runoff of Animal manure, sediments, fertilizers, and pesticides

Meat is responsible for 100% of manure pollution and 70% of cropland pollution

Gulf of America Dead Zones

The Mississippi River watershed spans much of the US, mostly in areas of prime farmland. As a result, it accumulates large amounts of nutrients from farms, resulting in a Dead Zone the size of New Jersey off the coast of Louisiana

Meat

In the US, livestock produce

roughly 13 times as much feces

as the entire human population. NONE OF WHICH IS PROCESSED BY SEWAGE TREATMENT PLANTS - Contains pharmaceuticals and anti-biotic resistant bacteria

CAFO

Concentrated Animal Feeding Operations

(Factory Farms)

• Waste Lagoons from these farms can spill into neighboring waterways during periods of heavy rain

Chlorine Dilemma

• chlorine byproducts are linked to

numerous cancers, miscarriages and birth defects. Peru

stopped chlorinating municipal water, resulting in a huge

cholera epidemic infecting 300,000 people & killing at least

3,500. The US EPA struck a middle ground by lowering

maximum chlorine levels but still using it.

Fluoridation

growing evidence that fluoride is neurotoxic for

growing children.

Clean Water Act (1972)

• EPA sets up and monitors National Emissions

Limitations

• This law has effectively improved water quality from

point sources, but NOT non-point sources, such as

agriculture. Thus, ag runoff continues to be a problem

Safe Drinking Water Act (1972)

• Set uniform federal standards for drinking water

including maximum contaminant level

How you can help reduce pollution

The most significant ways to reduce your pollution are to reduce meat consumption and rejecting crop-based biofuels

Types of Solid Waste

Industrial Waste = solid

materials discarded by

industry (majority of waste)

Municipal Solid Waste =

solid waste from non-industrial

sources (homes, government

offices, businesses, etc.)

Ways of dealing with solid waste

1. Reduce, Reuse, Repair

2. Composting

3. Recycling

4. Incineration (ideally waste-

to-energy incineration)

5. Sanitary Landfills (over

half)

Sanitary Landfill

a huge pit lined with plastic and clay (to prevent leaking into groundwater) in which

waste is deposited, compacted, then covered with a layer of soil each day (to reduce

smell and animal pests)

Leachate

(potentially hazardous waste fluids mixed with rain) builds

up over time and can overflow into nearby surface waters Solution:

collected by perforated pipes, then pumped out for treatment (using

bacterial decomposition, filtration, evaporation, etc.) before being

released back to landfill, a sewage treatment plant, or nearby

waterway

Incineration

reduces the volume of solid waste by 90% and can

be used to generate electricity. Waste-to-energy incineration

(producing energy while burning waste) in combination with

pollution control devices is less damaging to the environment

than landfills alone.

• Reduces amount of land

needed for waste disposal

• Reduces land needed for

energy production

• Generates energy with less

carbon emissions than coal

Types of Incinerators

Mass burn incinerators = large incinerators that burn all

wastes while generating energy in the process

Refuse derived incinerators = burn only combustible solids.

Non-combustibles like metal and glass are removed and ideally

recycled beforehand.

Incinerator Pollution Control

Incinerators (much like coal-fired power plants) can release significant

amounts of carbon and air pollutants. This can be reduced using:

Lime Scrubbers (spray water with calcium carbonate to remove sulfur

dioxide and other pollutants) and

Electrostatic Precipitators (an electrode gives particulates in furnace

exhaust a negative charge so they are attracted to the positively charged

precipitator wall, then fall down into a collector for disposal)

Incinerator Waste

The main waste products from incineration are bottom ash (ash that falls out

in the furnace) and fly ash (ash/sludge recovered from scrubber and/or

electrostatic precipitator). These must be deposited in a landfill

Recycling

Recycling

• The US recycles 1/3rd of its Municipal Solid Waste, including

62% of paper, 51% of aluminum cans, and 31% of glass

containers, and 14% of plastic containers

• Recycling is most successful for products that are cheaper to

manufacture from recycled vs. raw materials (e.g., making

aluminum cans from recycled aluminum requires only 5%

as much energy as production from mined aluminum)

• Products that contain multiple types of plastics, metals, or other

materials that are not easily separated pose the biggest

challenge to recycling

COmposting

One of the best ways to deal with solid waste and food scraps is through composting!

Reduce, Reuse, Repair

• While it is important to identify the best approach to handling waste,

an even better option is to not produce it in the first place. Source

reduction = products designed and manufactured to decrease the

volume of solid waste. This is accomplished by cutting down on

packaging, dematerialization, and reusing and recycling wastes at the

plant where they are generated

• Another option for reducing waste is to repeatedly reuse products

(e.g., using refillable bottles and mugs instead of aluminum, plastic,

paper, or polystyrene foam containers, or cloth napkins, hand towels,

and diapers instead of disposable alternatives)

• Similarly, buy durable products that are easily repaired rather than

cheaper, short-lived products that must be replaced frequently (e.g.,

phones, computers, vacuum cleaners, etc.)

Integrated Waste Management

Similarly to IPM, Integrated Waste Management uses a cominbation of best options for handling waste to minimize the overall environmental impact.

Hazardous Waste

Takes up ~1% of all waste in US

Includes Batteries, Fluorescent lights, Chemicals and Cleaners, Oil Soaked Rags, Pesticides , Spray cans, paint

Examples of Hazardous Wastes

Dioxins = form as a byproduct of combustion of chlorine

compounds, primarily through incineration of medical and

municipal waste. Cause cancer and damage reproductive,

immune and nervous systems.

 PCBs (polychlorinated biphenyls) = used as cooling fluid, fire

retardant, lubricator. Damage multiple bodily systems and cause

mental impairment in individuals exposed in utero. Though

PCBs were banned in 1979, they continue to contaminate

groundwater from the old landfills and fields they were dumped

on previously.

 Both dioxins and PCBs bioaccumulate and biomagnify through

food web, which is why humans are most at risk if they eat meat,

particularly fish and marine mammals

SuperFund Act

Comprehensive Environmental

Response, Compensation, and Liability Act,

established legal obligations for parties responsible for hazardous

waste to clean it up

SuperFund National Priorities List

Lists sites most dangerous to human health, provides federal funding to support cleaning it up.

Management of Hazardous Waste

• Source reduction (using green chemistry to find less

hazardous alternatives or finding ways to use smaller

amounts of a given chemical)

• Convert wastes to less hazardous materials (most often by

incineration, especially very high temperature incineration

using a plasma torch – 5 times as hot as normal

incinerators)

• Long-term storage (in a specialized hazardous waste

landfill or deep well injection)