Water Midterm

What is the water cycle? The water cycle (hydrologic cycle) is the continuous movement of water between the Earth's surface, atmosphere, and underground. It has no beginning or end and involves processes like evaporation, condensation, precipitation, infiltration, and runoff.

Evaporation Evaporation is the process where liquid water on Earth's surface changes into water vapor (gas) due to solar energy/heat. Main sources include oceans, lakes, rivers, and soil moisture. Oceans contribute about 90% of atmospheric moisture.

What is transpiration? Transpiration is the process where plants release water vapor through tiny pores (stomata) in their leaves. Combined with evaporation, it's called evapotranspiration. Plants return nearly 10% of atmospheric moisture.

What is sublimation in the water cycle? Sublimation is the direct conversion of ice or snow to water vapor without passing through the liquid state. This occurs in cold, dry environments or at high altitudes where snow and ice can transition directly to vapor.

What is the biggest reservoir of water? The Ocean

Where does groundwater go? Groundwater flows to streams, lakes, oceans, wetlands, and springs. It can also seep into the ocean or evaporate into the air.

What is the water from clouds called? Meteoric Water

How much of the earths inventory of water is the ocean? 95.6%

How much of it is glaciers? 2.97% btw some of it is melting into the ocean raising sea levels

How much of it is Ground water? 1.05%

Where are the hottest wettest areas in the world? Around the equator

How has the global surface temperature changed? Global Surface temperature has increased by 1.1 C by 2011-2020

What is the latent heat of vaporization in the water cycle? Latent heat of vaporization is the calories absorbed when liquid water transforms into water vapor. As shown in the graph, this occurs at 100°C and requires significant energy input (appears as the horizontal red arrow). This process is crucial for evaporation in the water cycle.

What happens during condensation in terms of heat transfer? During condensation, water vapor releases calories (latent heat) as it changes to liquid water. This is shown in the graph as "Calories released as water vapor condenses to water" with a blue arrow pointing downward. This heat release warms the surrounding atmosphere, creating a cooling climate effect.

Which water phase changes contribute to cooling climate? Water vapor condensing to water (releases latent heat)

Water vapor cooling (releases calories) Both processes release heat, contributing to atmospheric warming while the water itself cools.

Which water phase changes contribute to warming climate? Water warming from 0°C to 100°C (absorbs calories)

Water transforming to water vapor at 100°C (absorbs significant latent heat)

Ice melting at 0°C (absorbs latent heat of melting)

Subfreezing ice warming (absorbs calories) These processes absorb heat from the environment.

Heat capacity the number of heat units needed to raise the temperature of a body by one degree.

How does latent heat affect Earth's climate according to the graph? The graph shows that when water changes state, it either absorbs heat (during melting and vaporization) or releases heat (during freezing and condensation) without temperature change. This latent heat transfer is crucial for redistributing energy in Earth's climate system, creating distinct warming and cooling climate effects.

Rainwater "Meteoric Water" Rainwater is almost pure water, less than 10 ppm total dissolved solids. Rainwater contains dissolved CO2 from atmosphere

What is carbonic acid responsible for? Responsible for weathering mineral on earth's surface

What is the typical unit used to measure dissolved substances in water? Milligrams per liter (mg/L) or parts per million (ppm).

What is total dissolved solids (TDS)? It is the sum of all dissolved substances in water, expressed in mg/L or ppm

What gas does rainwater absorb from the atmosphere? Carbon Dioxide

What happens when CO₂ dissolves in rainwater? It forms carbonic acid (H₂CO₃), making rainwater slightly acidic.

What is chemical weathering? The reaction between oxygenated, acidic waters and Earth materials, breaking down minerals.

What are the two types of chemical weathering reactions? Congruent and incongruent weathering.

What happens in congruent weathering? Minerals completely dissolve, releasing ions into the solution.

Give an example of a congruent weathering reaction. Halite (NaCl) dissolving into Na⁺ and Cl⁻ ions in water.

What is an example of a landscape shaped by congruent dissolution? Karst landscapes, such as the Guilin Lijiang River National Park in China.

What happens in incongruent weathering? Minerals partially dissolve, forming new minerals such as clays and iron oxides.

What are common minerals involved in incongruent weathering? Feldspars, amphiboles, pyroxenes, and micas.

What is an example of an incongruent weathering reaction? Albite feldspar reacting to form kaolinite clay and dissolved ions.

Why is the ocean salty? Dissolved substances from chemical weathering are carried by rivers into the ocean.

What are major sources of dissolved substances in seawater? River discharge, hydrothermal vents, and precipitation of calcium carbonate (CaCO₃) and silica (SiO₂).

How do hydrothermal vents contribute to ocean chemistry? They release minerals and alter seawater composition through interaction with oceanic basalt.

What is groundwater? Groundwater is the mass of water in the ground that occupies pore spaces in rock, sediment, or soil and moves downhill where permeability allows.

What is an aquifer? An aquifer is a body of permeable rock or sediment saturated with water through which groundwater moves (e.g., sand, gravel, sandstone, limestone).

What is porosity? Porosity is the percentage of a rock, sediment, or soil's total volume that consists of pore spaces.

What factors affect porosity? Particle size and shape, compaction, fractures in rock, and cementation.

What is permeability? Permeability is the capacity of a material to transmit fluids, dependent on pore size and connectivity.

What materials have high permeability? Sand and gravel due to large openings

What materials have low permeability? Clay and shale due to the wetting effect, where thin films of water stick to particles

What is the unsaturated zone? The groundwater zone where open spaces in sediment, soil, or bedrock are mainly filled with air.

What is the saturated zone? The groundwater zone where all openings are filled with water.

What is the water table? The upper surface of the saturated zone, which slopes toward the nearest stream or lake

What is percolation? The downward movement of groundwater through soil and rock, occurring at scales of cm/day to m/year.

How does groundwater move? Groundwater moves from areas of high water table to areas of low water table along curved paths.

What is a recharge area? An area where water is added to the saturated zone of a groundwater system.

What is a discharge area? An area where subsurface water exits into streams or bodies of surface water.

What is the High Plains Aquifer? A vast aquifer system (175,000 mi²) underlying 8 U.S. states, primarily in Nebraska, Texas, and Kansas.

What is the main issue facing the Ogallala Aquifer? Water is being extracted faster than it is recharged, leading to significant water table decline.

What are the impacts of the declining water table? Over 30m water table decline

Some areas losing 1.5-2.5m per year

Over 100 feet of decline in many regions

Uneven distribution of depletion (southern regions worse than northern)

What factors determine groundwater quality? Groundwater quality is influenced by:

Mineral particles

Dissolved substances (Ca, Mg, K, Na, Cl, SO₄, HCO₃)

Organic matter & microorganisms (e.g., cholera, typhoid, dysentery)

Industrial contaminants (heavy metals, synthetic chemicals, nuclear waste)

What is the maximum allowable concentration of dissolved solids in drinking water? Water with >500 ppm dissolved solids is unsuitable for human consumption

What are the two main sources of water contamination? 1. Point source contamination - Small, identifiable sources (e.g., leaking storage tanks, landfills).

2. Non-point source contamination - Large, diffuse sources (e.g., pesticides, road salt).

What are the major categories of water contaminants? Trace metals (lead, mercury)

Nutrients (phosphorus, nitrogen compounds)

Microbes (bacteria, viruses)

Organic compounds (pesticides, industrial chemicals)

Radioactive waste

What were the major water crises in the U.S.? Flint, MI: Lead contamination from corroded pipes.

Buffalo, NY: Lead pipe contamination.

Puerto Rico: Toxic waste from industrial sites.

Central Valley, CA: Agricultural contamination (fertilizers, pesticides).

Fracking-related substances: Chemicals used in oil and gas extraction.

What global water issues exist in low- and middle-income countries (LMICs)? Fecal contamination in drinking water.

Limited accessibility (water not available at home).

Seasonal or unreliable supply.

What are the key terms in water quality regulation? Maximum Contaminant Level (MCL): Highest allowed contaminant concentration in drinking water.

Maximum Contaminant Level Goal (MCLG): Level below which no known health risks exist.

Treatment Technique (TT): Required process to reduce a contaminant in drinking water.

What are the health effects of lead in drinking water? Neurotoxicity (cognitive issues in children).

Cardiovascular, renal, and reproductive toxicity.

No safe level of exposure exists.

What are the health risks of arsenic exposure? Skin, bladder, lung cancers.

Cardiovascular and respiratory diseases.

Found in subsurface sediments, mine waste, and groundwater.

Why are nitrates in drinking water dangerous? Can lead to birth defects and cancer due to N-nitroso compound formation.

Common in agricultural areas due to fertilizers and manure runoff.

Q: What are Disinfection Byproducts and their risks? Formed when disinfectants react with organic matter in water.

Common DBPs: Trihalomethanes (THMs), haloacetic acids (HAAs).

Linked to bladder cancer and reproductive health risks.

Why are PFAS a major concern? Extremely persistent in the environment.

Linked to cancer, immune disorders, and birth defects.

Found in industrial sites, consumer products, and contaminated water supplies.

How does uranium affect human health? Alpha radiation exposure increases cancer risk.

Associated with kidney disease and neurological toxicity.

How does fracking impact water quality? Leaks, spills, and well failures can introduce toxic chemicals.

Associated with increased risk of birth defects, cancer, and respiratory diseases.

What are "Safely Managed Drinking Water Services" (SMDWS)? A system that ensures drinking water is:

Improved - Comes from a safe source (e.g., tap, boreholes).

Accessible on premises - Available at home, yard, or delivered.

Available when needed - Households should not experience water shortages.

What triggered the Flint Water Crisis? In April 2014, Flint switched its water source to the Flint River without adequate corrosion control (orthophosphate).

This led to lead leaching from pipes into drinking water.

How long did the lead contamination persist? The issue lasted 17.5 months before Flint switched back to Detroit Water and Sewerage Department (DWSD) in October 2015

What was the role of orthophosphate in the crisis? Orthophosphate is a corrosion inhibitor that prevents lead from dissolving into water.

Its absence caused lead to leach from pipes at dangerous levels.

What were the lead levels in Flint's tap water? Exceeded the EPA action level of 15 µg/L.

Some samples even surpassed 5,000 µg/L, which is classified as hazardous waste.

What elements were found in Flint's corroded pipes? Lead phosphate (Pb₃(PO₄)₂) and hydroxylpyromorphite (Pb₅(PO₄)₃OH).

Aluminum and magnesium were enriched due to selective dissolution of lead phosphate.

What are PFAS? Perfluoroalkyl and Polyfluoroalkyl substances (PFAS) are a class of synthetic chemicals resistant to heat, oil, stains, grease, and water.

Known as "forever chemicals" due to their extreme persistence in the environment.

What products contain PFAS? Waterproof fabrics (e.g., nylon, yoga pants, carpets)

Non-stick cookware (e.g., Teflon)

Food packaging (e.g., microwave popcorn bags, pizza boxes)

Firefighting foam

Cosmetics (e.g., lipstick, mascara, nail polish)

Industrial applications (e.g., electrical insulation, adhesives)

Where are PFAS found in the environment? Drinking water - Found in both public water systems and private wells

Soil and water - Near waste sites, landfills, and hazardous waste areas

Firefighting foam - Used at airports, military bases, and chemical plants

Food sources - Found in fish, dairy products, and packaged foods

Household products - Stain-resistant furniture, carpets, and cleaning supplies

What are the health risks associated with PFAS exposure? Reproductive issues - Decreased fertility, high blood pressure in pregnancy

Developmental delays - Low birth weight, accelerated puberty, bone variations

Increased cancer risk - Prostate, kidney, and testicular cancers

Immune system suppression - Reduced vaccine response

Hormonal interference - Disrupts natural hormone function

Metabolic disorders - Increased cholesterol and obesity risk

How widespread is PFAS exposure? Over 98% of Americans have detectable PFAS in their blood.

An estimated 200 million Americans have drinking water contaminated with PFAS.

The highest PFAS levels are found near industrial facilities where PFAS are produced.

What are the EPA regulations on PFAS in drinking water? April 10, 2024 - The EPA announced the National Primary Drinking Water Regulation (NPDWR) for six PFAS compounds.

PFAS contamination thresholds are now being set to protect public health.

Why is PFAS contamination difficult to regulate? There are over 14,700 PFAS compounds, but testing only detects 20-30 compounds.

PFAS exposure varies by location, age, and lifestyle.

Many PFAS chemicals have unknown health effects, making regulation challenging.

What is arsenic contamination, and where is it found? Arsenic contamination refers to the presence of arsenic in groundwater, particularly in South Asia.

Found in Bangladesh, India, and Southeast Asia due to natural sediment weathering and human activities.

How does arsenic enter groundwater in Bangladesh? Weathering of Himalayan sediments releases arsenic into rivers and groundwater.

Erosion of coal seams and sulfide-rich rocks contributes to arsenic levels.

Microbial reduction of iron oxides releases arsenic from sediments into water.

What are the health effects of arsenic exposure? Cancer risks: Skin, bladder, lung, kidney, breast, pancreatic, and liver cancers.

Other diseases:Respiratory diseasesCardiovascular issuesDiabetes and metabolic disordersImpaired immune functionNeurocognitive problems

What are visible symptoms of arsenic poisoning? Arsenicosis: Long-term arsenic exposure leading to severe health issues.

Skin abnormalities:Melanosis - Dark patches on the skin.Keratosis - Thick, rough skin, especially on hands and feet.

What is the EPA's arsenic standard for drinking water? Maximum Contaminant Level (MCL): 10 µg/L (10 parts per billion).

Maximum Contaminant Level Goal (MCLG): 0 µg/L (no safe level).

Arsenic is detected in over 50% of U.S. Community Water Systems.

How does microbial activity affect arsenic contamination? Microbial Fe(III) reduction releases arsenic from sediments into groundwater.

Organic carbon decomposition accelerates arsenic release.

Gray-colored aquifers contain higher arsenic due to iron oxide reduction.

What factors control arsenic levels in groundwater? Biogeochemical transformations release arsenic from sediments.

Residual sediment adsorption helps regulate dissolved arsenic.

Metabolic by-products like ammonium and methane correlate with arsenic levels.

Why is arsenic contamination difficult to manage? Occurs naturally from sediment weathering.

Microbial processes continuously release arsenic.

Current regulations may not be sufficient to protect public health.