Surface Water 3

bedrock and surficial geology on water chemistry

weathering products, groundwater water storage and flow paths may change water chemistry

climate on water chemistry

runoff magnitude and flow paths

rate of chemical and biological activity and evaporative enrichment all change water chemistry

increasing climate will increase turnover and weathering

ecosystems on water chemistry

soils - OM, controls on water balance, redox conditions, wetlands (anoxic) may all change water chemistry

land use on water chemistry

altered water balance, flow paths, point source and diffuse pollution

changes in water chemistry

based on connectivity of different source waters

surface run off can cause erosion or sediments

throughflow can have high concentrations of OM, nutrients and pollutants

ground water can have high concentrations of dissolved salts

also can be due to biological activity - photosynthesis, decomp, redox chemistry

variability in water chemistry

light and photosynthesis changes pH, oxygen, temp day and night

changes in flowpaths, can increase throughflow and surface runoff during storms

seasonal temp changes, plant nutrient uptake, and discharge

fire, human land use, climate change

physical water quality

total suspended solids, turbidity, colour, taste, odour, temp, electrical conductivity

chemical water quality

pH, hardness, alkalinity, salinity, total dissolved solids, major cations and anions, dissolved OM, nutrients, metals, dissolved gases, biological oxygen demand

synthetic organic compounds, pesticides, pharmaceuticals, microplastics

biological water quality

bacteria, protozoa, virus, algae

pathogens - total coliform, e coli, giardia, chloera, salmonella, shigella

turbidity

optical measure of light dispersion

cloudy samples have higher

mainly clay/silt, w contribution from algae and natural organic compounds

measured in nephelometric turbidity units (NTU)

turbidity vs TSS

turbidity is easier to measure, of interest for water/habitat quality

TSS of interest for sediment transport and land management

primary productivity and turbidity

algal/macrophyte productivity inhibited by turbidity - restricted to near surface (less O2 production)

but sediments also carry nutrients like phosphorous which can cause eutrophication when they settle

habitat quality and turbidity

fish cant see and catch prey, gills get clogged, eggs can be buried, macroinvertebrates are also buried

increases heat absorption, esp in shallow water, reduces oxygen, increases thermal stratification

water treatment and turbidity

suspended sediment can carry pathogens, heavy metals, organic contaminants

removal of turbidity a requirement prior to disinfection

anthropogenic increases of turbidity and TSS

construction/ag/forestry increase availability of sediments for erosion

urbanization increases stream channel erosion by increasing peak flow

can also increase with invasive, bottom feeding fish - carp

water temperature

influences metabolic rate (productivity), optimal habitat (varies), dissolved O2 (max solubility decreases with temp), solubility of salts and EC, water density (thermal strat), compound toxicity (of heavy metals)

thermal pollution

cooling of power plants returns warm water

urban industrial discharge

forestry/ag - removal of shading

impoundments or reservoirs, increases residence time, absorption of solar radiation

total dissolved solids and salinity

a measure of the mass of dissolved solids/salts

often estimated from EC

ex road salts in the north sask when passing through edmonton

electrical conductivity

a measure of how well a sample can conduct electricity, which increases with greater amounts of dissolved salts and temperature

easily measured, in microsiemens/cm

often normalized to 25 degrees and made specific

differs for different salts

alkalinity

when limestone and dolomite (carbonate bedrock) is dissolved

concentration of HCO3-

waters capacity to resist changes in pH - buffering capacity

will change with acid added to a sample

hardness

when limestone and dolomite (carbonate bedrock) is dissolved

concentration of Ca2+ and Mg2+

buildups of carbonates in water systems, effectiveness of detergents, higher can reduce toxicity of metals to aquatic life

can be reported in terms of HCO3-

will not change w acids

pH

indicates acidity, measured as log concentrations of hydrogen ions in water

range from 0-16

normal rain is 5.6, surface water 6-8 (buffered by alkalinity)

bog water is 4, ocean is 8.2

importance of pH

animals and plants have specific ranges they can tolerate (aquatic 6.5-9)

influences solubility and toxicity of metals in water

• aluminium can increase at low pH and can kill fish

above 8 is hard to disinfect

solubility of phosphorus is highest at 6.5 which leads to eutrophication

acid rain

pH in rain as low as 4.2

peaked in 80s and 90s mainly where there was high emissions and low alkalinity (decreased buffering)

recovery has been slow and uneven, biologically has been slow

where does acid rain have a large impact

low alkalinity (decreased buffering) and higher emissions

maritime canada, canadian shield

how does acid rain occur

so2 and nox emissions from industry - burning coal, metal smelting

led to deposition of sulfuric and nitric acids

metals and water

many can be beneficial in moderate concentrations, but others with few biological uses are considered toxic

acid mine drainage, tailing ponds, ag, domestic waste, etc all lead to contamination in water

acid mine drainage

very acidic - pyrite and FeS

and often very high metal concentrations but depend on the mine

point source pollution of water

methylmercury

mercury is transmitted frmo industry operations into the environment, converted to methylmercury under anoxic conditions by microbial activity

so often increases in wetlands and

bioaccumulates or magnifies

tropical alluvial mining

increasing process for gold and other metals have led to small scale mining in tropical regions

mercury is used to separate the gold - source of pollution

also increases turbidity in rivers

selenium concern

an emerging concern from coal mines in rocky mountains

causes deformities in fish

bioaccumulates and biomagnifies

fluoride concern

added to municipal water for oral health

but pollution from industries, fertilizers, smelters go into surface water
directly toxic, affects metabolism

tailing ponds have high concentration

bioaccumulates and biomagnifies

dissolved organic matter (DOM)

derived from plant material as it decomposes

diverse chemical composition - sugars, carbs, proteins, fats, humic acids, fulvic acids

contains dissolved organic phosphorus, carbon and nitrogen

peatlands are a large source

water treatment and DOM

removal is necessary

unpleasant taste, vector for pathogens

needs to be removed prior to chlorination or carcinogenic compounds created

DOM and aquatic functions

determines light conditions - habitat quality, algal productivity, thermal conditions

contains imp nutrients, enters food web through microbial activity, determines GG balance of lakes

recovery of acid rain and DOM

brownification in the recent years, increases costs for water treatment

recovery from acidification is a major cause, higher pH increases solubility of DOM

climate warming also contributes

phytoplankton

contains chlorophyll A and can photosynthesize

filtration and measurement of chl a is used to measure the abundance

cyanobacteria

warm, high phosphorus conditions lead to blooms

nitrogen fixing from the atmosphere

can release toxins

dissolved oxygen (DO)

in surface water can come from diffusion and mixing with atmosphere or produced as byproduct of photosynthesis - varies seasonally and day to night

used by animals and microbes for decomp

often have threshold for requirements, stratification can lead to depletion at depth

biological oxygen demand (BOD)

amount of oxygen used by bacteria to decompose organic mater - indicates risk for o2 depletion

done at standardized temp (20 C) for 5 days

waste water, pulp and paper mill waste can increase

but DOM from terrestrial sources usually have low numbers

coliform bacteria

found in intestines

total amount can indicate fecal pathogens (environmental contamination)

some specific e coli can be pathogenic themselves

sources are leaking sewer lines, wildlife waste, septic/pet waste, and farm wastes

persistent organic pollutants (POPs)

hydrocarbons from coal, oil, gas or synthesized

PAHs - maybe carcinogenic

industrial chemicals like PCBs largely banned

pesticides like organochlorines (DDT)

can evaporate and deposit back into the mountains etc

pahs and oil sands

atmospheric deposition up to 10X at oil sands mines

may have increased from mining, but also wild fires