Water Quality and Toxic Metal Effects

Hydrology Overview

• Hydrology is the study of water and its movement through various pathways within the hydrological cycle.
• It's applied by engineers to compute river flows, water movement in soils, and evaporation rates.

Water Properties

• Water is a clear, odorless, and tasteless liquid essential for most plant and animal life.
• Under chemical nomenclature, its scientific name is dihydrogen monoxide, but this name is rarely used.
• Water's intrinsic color is a slight blue hue, but in small quantities it appears colorless.
• Water vapor, however, is essentially invisible as a gas.
• Water is a universal solvent, dissolving salts, sugars, acids, alkalis, and some gases (especially oxygen and carbon dioxide).
• Substances that dissolve in water are known as hydrophilic (water-loving).
• Substances that do not mix well with water are known as hydrophobic (water-fearing), examples being fats and oils.

Boiling Point and Density

• The boiling point of water varies depending on barometric pressure.
• At the top of Mt. Everest, water boils at 68°C, while at sea level, it boils at 100°C.
• Water's maximum density occurs at 3.98°C.
• When cooled further, it expands to become ice, which accounts for 9% greater volume than the liquid form. This allows ice to float on water, as seen in icebergs for instance.

Water Trivia and Facts

• Only 3% of Earth's water is fresh water.
• Over 90% of the world's fresh water supply is stored in Antarctica.
• The average adult human body contains 37 liters of water.
• The human brain is comprised of 75% water.
• Dehydration results if a human does not absorb enough water.
• Water (in the three forms of liquid, gas and solid) is the only substance found naturally on Earth.
• In a 100-year period, a water molecule spends 98 years in the ocean, 20 months as ice, 2 weeks in lakes and rivers, and less than a week in the atmosphere.
• Frogs absorb water through their skin.
• Mauna Kea, an inactive volcano in Hawaii, is taller than Mount Everest when measured from its base on the ocean floor.

Hydrology Applications

• Hydrology is the study of the movement of water and its use in various processes like;
• Calculating river flows from rainfall.
• Studying water movement in soils.
• Determining evaporation rates.

Groundwater Supply

• Groundwater is both a direct and indirect supply of water.
• In the zone of aeration (near the surface) soil pore spaces hold both air and water, with moisture held on soil particles by capillary forces.
• Below the aeration zone, is the zone of saturation, where pores are filled with water and is commonly referred to as groundwater.
• A stratum containing substantial groundwater is called an aquifer.
• The surface of this saturated layer is known as the water table.
• Unconfined aquifers are underlain by an impervious stratum.
• Confined aquifers are trapped between two impermeable layers.

Surface Water Supplies

• Surface water supplies are less reliable than groundwater sources.
• Water quantities fluctuate widely over time and are easily polluted.

Water Quality

• Water in its natural evaporation state is nearly pure in composition.
• Human activities such as industrial and domestic waste, agricultural chemicals and other contaminants add to water impurities during its passage through the hydrologic cycle.
• Water quality encompasses its physical, chemical, biological, bacteriological or radiological characteristics for acceptability assessment.
• Classifications typically include potable (fit for drinking), palatable (pleasant taste), contaminated (unfit for drinking due to substances present), and infected with pathogenic matter.

Physical Water Quality Parameters

• Suspended solids: are inorganic material (clay, silt) and organic material (plant fibers, biological solids, algae, bacteria) or other solids resulting from human use of water bodies.
• Total solids (organic and inorganic combined): measured by evaporating a sample to dryness and weighing the residue.
• Dissolved solids: pass through a filter paper. This is determined by Total solids - suspended solids
• Turbidity: a measure of the extent to which light is scattered by suspended matter in water. It is not a direct measure of suspended solids.
• Color: can be apparent (due to suspended solids) and true (due to dissolved solids)
• Measuring color typically involves comparing it with standardized colored materials or using spectrophotometric techniques common amongst industries.

Taste and Odor

• Substances that produce odor in water usually also impart a taste - Mineral substances give taste without odor.
• Sources include minerals, metals, salts, biological reactions, and organic substances (like petroleum products and decomposition of organics like H2S).
• Measurement involves human sensory assessment (TON) or spectrophotometric techniques.
• A TON of 3 is a recommended limit for drinking water.

Temperature

• Water temperature is an important parameter affecting biological species activity and chemical reactions in natural water systems.
• The temperature of surface waters governs the biological species present and their rates of activity.
• Temperature affects the solubility of gases in water.
• Sources of temperature variation in water bodies include ambient temperature, and industrial waste heat dissipation which can alter the temperature of receiving streams.
• Impacts: lower temperatures lead to lower biological activity.
• Fish are affected by temperature and dissolved oxygen levels.
• Increased rates of biological activity at elevated temperatures also lead to accelerated growth of algae, which can cause eutrophication.

Electrical Conductivity

• Measures how well water can conduct electricity.
• High conductivity indicates high contaminant content.
• Potable and ultra-pure water has extremely low conductivity.
• Electrical conductivity is reported in micromhos per centimeter (µmhos/cm) or microsiemens per centimeter (µS/cm).

Hardness

• Hardness is a term used to express the properties of highly mineralized water.
• Mainly caused by the presence of calcium and magnesium ions.
• These ions are present as bicarbonates, sulfates, and sometimes chlorides and nitrates.
• Groundwater is typically harder than surface water.
• The sum of calcium and magnesium ions is a measure of Total Hardness.

Fluorides

• Seldom found in surface waters but appears in ground water in some regions.
• Toxic to humans and animals in high concentrations but beneficial at low concentrations.
• Levels: 1.0 mg/L helps prevent dental cavities, 2.0 mg/L can cause tooth discoloration, >5 causes bone fluorosis, 1.5 mg/L is a limit in drinking water.
• Bone fluorosis leads to osteoporosis.

Metals

• Metals dissolve somewhat in water.
• Excessive amounts of heavy metals can pose health hazards.
• Toxic heavy metals include cadmium, lead, chromium, etc. and their exposure can lead to nervous system breakdown, kidney damage, mutation, and tumor induction.
• Non-toxic metals include calcium, magnesium, sodium, iron, manganese, aluminum, copper, and zinc.

Nutrients (Nitrogen and Phosphorus)

• Essential nutrients for the growth and reproduction of plants, animals and aquatic species.
• Nitrogen and phosphorus regulate plant and animal growth and reproduction.
• Sources include animal wastes, chemical fertilizers, and wastewater discharges. Runoff from agricultural lands and industrial activities also contribute significantly to nutrient levels in water bodies.
• Excessive nitrogen can cause nitrate poisoning in babies (blue baby syndrome), and phosphorus affects water quality by causing eutrophication (algal blooms).

Organics

• Come from natural sources (decay products of organic solids) or result from human activity (wastewater discharges and agricultural practices).
• Two categories of dissolved organics: biodegradable and non-biodegradable.
• Biodegradable organics consist of starches, fats, proteins, alcohols, acids, aldehydes, and esters, and can be easily used as food by micro-organisms.

Dissolved Oxygen

• A key indicator of water pollution.
• Higher concentration of dissolved oxygen indicates better water quality.
• Actual dissolved oxygen varies depending on pressure, temperature, and salinity of water body.
• Drinking water with very little or no oxygen can have an undesirable taste.

Biochemical Oxygen Demand (BOD)

• Measure of the organic material in water.
• Amount of dissolved oxygen needed by aerobic biological organisms to break down organic material over a specified time period correlated with the amount of organic matter in water body.
• High BOD in water indicates higher organic waste and potential pollution issues.

Chemical Oxygen Demand (COD)

• Measures all organic substances, both biodegradable and non-biodegradable, based on the amount of strong oxidizing chemicals needed.
• COD values are typically higher than BOD values for the same sample, as COD considers both biodegradable and non-biodegradable organics.

Radioactive Substances

• Potential sources include nuclear power plants, industries, medical research, and uranium mining.
• Decay of radioactive substances releases beta, alpha and gamma radiation.
• Exposure can cause genetic and somatic damage to living tissues, including harmful effects on both human and animal health and reproductive capability.
• Radon gas is naturally found in groundwater and is a cause for concern as it's volatile and can be inhaled during water use activities such as showering, and drinking.

Maximum Allowable Level (MAL)

• Standards commonly used to regulate specific chemicals and substances present in drinking water, with each chemical or substance having its prescribed limit.

Biological Water Quality Parameters

• May cause water-borne diseases and water contact diseases.
• Pathogens are biological organisms in water capable of infecting and transmitting diseases to humans.
• Pathogens require a host for growth and reproduction and often survive in water for long periods of time.
• Common water-borne pathogens include bacteria, viruses, protozoa and helminths

Additional Terms

• Endemic: refers to a disease prevalent in a specific population.
• Epidemic: an outbreak of an infectious disease spreading widely within an area
• Pandemic: if the outbreak of an infectious disease spreads widely worldwide
• Epidemiology: studies the causes of a disease spreading in a community.
• Microbiology: the study of microorganisms and their activities.

This quiz explores key concepts related to water quality, including hardness, essential minerals, and the health implications of heavy metals and other elements. Test your knowledge on the effects of these substances, particularly focusing on their presence and impact on human health.