Water Pollution Lecture 6 2024 PDF

Water Pollution ENH524-Pollution and Waste Management School of Occupational and Public Health Toronto Metropolitan University Water Pollution Contamination of water with chemicals or other foreign substances. Affects humans, animals, and the earth The release of subst...

Water Pollution ENH524-Pollution and Waste Management School of Occupational and Public Health Toronto Metropolitan University Water Pollution Contamination of water with chemicals or other foreign substances. Affects humans, animals, and the earth The release of substances into subsurface groundwater or into lakes, streams, rivers, and oceans to the point where the substances interfere with beneficial use of the water or with the natural functioning of ecosystems  Causes of Water Pollution Oil spillage Agricultural activities (fertilizers, pesticides) Mining activities Landfills (leachate) Industrialization Nuclear waste Inadequate Sewage treatment Plastics in the ocean  Inadequate Sewage Treatment Less than 8% of wastewater is treated in developing and under-developed nations The 2017 World Water Development Report shows that improved wastewater management is as much about reducing pollution at the source, as removing contaminants from wastewater flows, reusing reclaimed water, and recovering useful by-products https://unesdoc.unesco.org/ark:/48223/pf0000247153  Effects of Water Pollution Deaths of several animal and plant species Diseases affecting humans: Cholera, Hepatitis etc. Destroys the balance of ecosystem https://globalnews.ca/video/4836137/lessons-learned- from-walkerton-water-tragedy Walkerton Tragedy An outbreak of gastroenteritis in Town of Walkerton in 2000- 7 people died-over 2300 became ill. Robbie Schnurr, who suffered a degenerative disease after drinking water with E. coli in Walkerton, at his Mississauga condo, a day before he fulfilled his final wish. Photo Courtesy of Toronto Star, (May, 2018) https://www.thestar.com/news/canada/2018/05/11/in- 2000-walkertons-poisoned-water-ruined-his-life-he- decided-it-was-time-to-end-it.html Groundwater  Groundwater Pollution Risk of groundwater pollution depends on groundwater vulnerability and contaminant load Vulnerability = intrinsic susceptibility of aquifer – Affected by depth, soil type (permeability and porosity), recharge (infiltration, precipitation), attenuation Contaminant load: – Contaminant type, amount released, timescale and mode of release  Hazardous Organic Chemicals Contamination can occur from chemicals during transport, storage, use and disposal (e.g. fuel tanks, dry-cleaning) Non-aqueous phase liquids (NAPLs) are of particular concern – Liquids that do not readily dissolve in water (e.g. chlorinated solvents and petroleum products) – Those lighter than water (LNAPLs) tend to float on top of the water table (e.g. petroleum products) – Those denser than water (DNAPLs) migrate rapidly through soil and sink to the bottom of the water table (e.g. chlorinated solvents and halogenated hydrocarbons)  Persistent Organic Pollutants Persistent organic pollutants (POPs) are environmentally stable and highly toxic chemicals that accumulate in adipose tissue and have a very destructive effect on aquatic ecosystems The overall rank order based on the concentration and prevalence of POPs were surface water > drinking water > seawater > groundwater. The most to the least polluted areas included: South Africa, India, Turkey, Pakistan, Canada, Hong Kong, and China https://pubmed.ncbi.nlm.nih.gov/34273825/  Nutrient Pollution Refers to excess nitrogen and phosphorus released into the environment – Disrupts ecosystem health through promotion of algae growth, and can contaminate groundwater Caused by many sources: – Agriculture – Household activities – Stormwater – Wastewater – Fossil fuels  Nutrient Pollution: Agriculture Crop production relies on essential nutrients from soil, but excessive cropping/monoculture has depleted these nutrients Nitrogen, phosphorus, and potassium (macro-nutrients) augmented through fertilizers (including human and animal waste) Poor fertilizer use and improper waste management practices can contribute to land or water pollution  Nutrient Pollution: Agriculture Reducing nutrient pollution: – Nutrient management (regulated under Nutrient Management Act and O. Reg. 267) – Watershed protection – Cover crops – Buffer strips – Conservation tillage – Managing livestock waste  Nutrient Pollution: Households Fertilizers are used by homeowners to maintain and improve landscape beauty and quality – Improper use can lead to nutrient pollution Major sources of household pollution are: – Phosphorus in runoff from lawn clippings and tree leaves – Nitrate from fertilizer spills and over-application Recommendations: – Apply fertilizers only when necessary and at recommended amount – Controlled watering after fertilizing – Clippings/leaves should be left on the lawn or used for compost – Aerate compacted or high thatch lawns  Nutrient Pollution: Other Sources Stormwater collects excess nutrients and other pollutants from various human activities and flows over streets, parking lots, and other impervious sources – Can be mitigated through green infrastructure (e.g. rain gardens, permeable pavement, rain barrels) – Video: Engineered Wetland gone wrong! Wastewater contains nitrogen and phosphorus from human waste, food, and certain soaps and detergents – Not all nutrient pollution is removed in the treatment process – During heavy rainfall or snowmelt, some wastewater systems will overflow and discharge excess untreated sewage directly to nearby water bodies – Approximately 20% of Canadians use septic systems, which can release elevated nitrogen and phosphorus levels if improperly managed  Nutrient Pollution: Groundwater Nitrates are one of the most pervasive groundwater contaminants – Levels usually higher in shallow wells – Can cause “methaemoglobinemia” in infants (AKA blue- baby syndrome) – Difficult and expensive to remediate contamination – Most effective approach is to prevent contamination through best management practices – Routine monitoring of private wells is recommended in high-risk areas  Surface Water Pollution Indicators Biological oxygen demand (BOD): – Amount of oxygen consumed by microorganisms while they decompose organic matter under aerobic conditions – Measured by comparing dissolved oxygen (DO) of water samples from initial collection to 5 days after incubation – The difference in DO readings is plotted as the BOD for the series of days (usually 5 days) – BOD of 1-2 ppm is very good; 3-5 is moderately clean; 6-9 is somewhat polluted; 100 or more is very polluted – High BOD levels contribute to decreasing DO levels, leading to eutrophication Surface Water Pollution Indicators Total suspended solids (TSS): – Solids suspended in water that are >2 µm in size – Increasing levels can affect aquatic life, and absorbs heat – Many pollutants can attach to TSS – Measured by weight of sample or acoustic Doppler meters Turbidity: – Optical measure of water clarity – Measures scattering of light from a water sample using turbidimeter – Measured in nephelometric turbidity units (NTUs) Source: http://news.nationalpost.com/news/canada/ontario-cottagers-warned-not-to-drink-water-after- toxic-blue-green-algae-found-in-upper-rideau-lake  Cyanobacteria Blue-green algae, are photosynthetic bacteria naturally present in surface waters Phosphorus- and nitrogen-enriched waters from human activities can cause “blooms” of algae (excessive growth) Cyanobacteria can produce cyanotoxins: – Up to 75% of algal blooms are toxic – Can produce off-tastes/odours, but not always – Usually the toxins are produced inside the cells and are released into the water upon cell death; however, some species can release toxins without cell breaking (lysis) – Blooms are greenish, thick, and paint-like Cultural Eutrophication https://coastalscience.noa a.gov/news/climate/new- report-addresses-re- eutrophication-hypoxia- lake-erie/  Cyanobacteria Source: J. Winter, MOE: http://www.wlpp.ca/linked/algalbloomsonlakesguide.pdf  Cyanobacteria The most common cyanobacterial toxins are microcystins – Produced by numerous species, and can bioaccumulate in various aquatic species (e.g. fish, mussels, zooplankton) – Primarily affects the liver (hepatotoxin), but can also affect the kidney and reproductive system – Classified as possibly carcinogenic (IARC Group 2B) – Health Canada has established max. concentrations of 1.5 µg/L in drinking water and 20 µg/L in recreational water for microcystin-LR Other toxins include cylindrospermopsin, anatoxins, and saxitoxins Exposure route of primary concern is drinking water, with bottle-fed infants at greatest risk Skin contact and inhalation can also occur  https://www.youtube.com/watch?v=kNL99X VJjQo https://www.youtube.com/watch?v=S9iyKdH t5_c  Cyanobacteria Acute clinical symptoms can include: – Gastroenteritis, fever, headache, sore throat, dry cough, pneumonia, liver and kidney damage Bloom-forming conditions include: – increases in nutrient levels (water or sediments) – turbid (but not turbulent) waters – strong sunlight – high air and water temperatures – relatively shallow water Increase by climate change  Public Health Implications Exposure to toxins through surface water Exposure through food contamination – https://pubs.ciphi.ca/doi/10.5864/d2017-021 – https://www.sciencedirect.com/science/article/ pii/S1474706521001571 Some studies suggest long-term exposure to HABs may be linked to human neurodegenerative disease “Concentrations of microcystin have been reported in crops and grain in Brazil, New Zealand and China. Microcystin concentrations of 8.31, 0.78 and 22 μg/kg were detected in lettuce, rape (Brassicas) and rice, respectively. Therefore, cyanotoxin transfers can occur through application of cyanobacteria contaminated water during food production.” https://www.sciencedirect.com/science/article/pii/S1474706521001571  Cyanobacteria Prevention of excessive nutrient contamination is the most effective strategy (e.g. watershed management) Are difficult to remove, some options include: – Addition of chemicals to source waters to reduce nutrient availability (e.g. ferric sulphate to precipitate phosphorus) – Artificial mixing/aerating – Use of algicides (e.g. copper sulfate) or other agents (e.g. alum) to precipitate and kill cyanobacteria  Cyanobacteria Monitoring of drinking water sources for limits (1.5 µg/L) in Canada Ongoing research on potential transfer of toxins to food, through contaminated water New guidelines for other cyano-toxins (e.g. Anatoxin A) – which currently have no limits  Mercury Mercury contamination of surface water primarily due to atmospheric deposition and run-off – Common sources in Canada include waste incineration, coal combustion, base metal smelting Under certain environmental conditions, inorganic mercury transforms to form methylmercury – Is persistent in the environment, leading to bioaccumulation in predatory fish / birds through process of biomagnification Bioaccumulation = increase in concentration from environment to living organisms (first link in food chain) Biomagnification = increase in concentration from one organism to another in food chain  Mercury Mercury is a potent toxin in all forms – Can cross the blood-brain and placental barriers – Causes development effects and impacts on central and peripheral nervous system in a fetus or young child – Also affects the liver and kidneys of adults and children Risk-reduction approach taken to limit exposure http://www.ottawapublichealth.ca/en/public-health- topics/resources/Documents/fish_women_children_ en.pdf http://www.cbc.ca/news/canada/thunder-bay/ontario-mercury-clean-up-1.3979912  https://www.cbc.ca/news/canada/thunder-bay/grassy- narrows-mercury-poisoining-study-1.6387194  Plastics https://www.youtube.com/watch?v=veMdowmPSbw http://www.cbc.ca/news /technology/microplastic s-fish-shellfish-1.3954947  A Canadian team found that steeping a plastic tea bag at a brewing temperature of 95°C releases around 11.6 billion microplastics – tiny pieces of plastic between 100 nanometres and 5 millimetres in size – into a single cup. That is several orders of magnitude higher than other foods and drinks. “The particles did not kill the water fleas, but did cause significant behavioural effects and developmental malformations,” she says. However, she says that more research is needed to understand possible health impacts in humans. https://www.newscientist.com/article/2217483-plastic-tea-bags-shed-billions-of- microplastic-particles-into-the-cup/