Natural water chemistry

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Natural Water Chemistry Water Quality Parameters Temperature - Dissolved Oxygen (DO) - pH Alkalinity - Hardness Nitrates and Phosphates - Turbidity Conductivity - Temperature Affects: Water density Gas solubility Chemical reaction rates Organism growth rates Conductivity pH Dissolved Oxygen Temperature – naturally varies because of… … Changes in seasonal/diurnal air temperature … Thermal stratification in lakes … Size and temperature of inflows … Residence time (lakes) Temperature – artificially varies because of… … Heated industrial effluent … Runoff from asphalt/pavement … Deforestation Q10 rule cold-blooded aquatic organisms Predicts that growth rate will double if temperature increases by 10˚C (18˚F) within their "preferred" range Dissolved Oxygen (DO) DO is the measurement of oxygen dissolved in water and available for fish and other aquatic life Indicates health of an aquatic system Can range from 0-18 ppm Most natural water systems require 56 ppm to support a diverse population Varies with time of day, weather, temperature Dissolved Oxygen (DO) Increase in organic waste Increase in algae/plant vegetation Decrease in DO available to organisms Leads to changes in ecosystem as organisms needing lots of DO are replaced by organisms needing little Hood Canal, Wash DO Hood Canal Global distribution of oxygen-depleted coastal zones Annual = yearly events (summer or autumnal stratification) Episodic = occurring at irregular intervals > one year Periodic = occurring at regular intervals < one year Persistent = all-year-round hypoxia Sources: Boesch 2002, Caddy 2000, Diaz and others (in press), Green and Short 2003, Rabalais 2002 Source: Patrick Heffer, Short Term Prospects for World Agriculture and Fertilizer Demand 2002/03 - 2003/04 (Paris: International Fertilizer Industry Association (IFA), December 2003); IFA Secretariat and IFA Fertilizer Demand Working Group, Fertilizer Consumption Report (Brussels: December 2001); historical data from Worldwatch Institute, Signposts 2002, CD-ROM, compiled from IFA and the U.N Food and Agriculture Organization, Fertilizer Yearbook (Rome: various years) Solutions?? Wetland restoration Reduce emissions – WWTP/industry Reduce fertilizers Reduce soil erosion Turbidity Measures how “murky” the water is Estimates: Mineral fraction Organics Inorganics Soluble organic compounds Plankton Microscopic organisms MODIS Image from NASA http://rapidfire.sci.gsfc.nasa.gov/ Causes of highly • In open waters, phytoplankton • Closer to shore, particulates Resuspended bottom sediments (wind) • Organic detritus from stream and/or wastewater discharges • Dredging operations • Channelization • Increased flow rates • Floods • Too many bottom-feeding fish (such as carp) • Hippos waters Effects of highly waters • Modify light penetration • Increase sedimentation rate • Smother benthic habitats • Settling clay particles can suffocate newly hatched larvae • Fine particulate material also can damage sensitive gill structures • Decrease organism resistance to disease • Prevent proper egg and larval development • Macrophyte growth may be decreased • Reduced photosynthesis can lead to lower daytime release of oxygen From waterontheweb.org http://waterontheweb.org/under/waterquality/turbidity.html Conductivity Ability of a substance to conduct an electrical current In water, conductivity determined by types and quantities of dissolved solids (Commonly called Total Dissolved Solids = TDS) Cl- Current carried by ions (negatively or positively charged particles) Cl- Na+ Eg: NaCl(aq) = Na + Cl + Cl- Na+ – Cl- ClCl- Na+ Na+ Na+ Cl - Cl- ClNa+ Cl- Na+ Cl- Na+ ClNa+ Cl- Cl- Na+ Na+ ClNa+ Na+ Na+ Cl- Na+ Cl- Cl- Cl- Na+ ClNa+ Na+ Na+ Na+ ClNa+ Conductivity Conductivity of natural waters depends upon: Ion characteristics (mobility, valence, concentration) Water temperature Geology Size of watershed Evaporation Some artificial factors that can affect conductivity: Wastewater Urban runoff (especially road salt) Agricultural runoff Electrical Conductivity and TDS TDS (μS/cm) (mg/L) Divide Lake 10 4.6 Lake Superior 97 63 Lake Tahoe 92 64 Grindstone Lake 95 65 Ice Lake 110 79 Lake Independence 316 213 Lake Mead 850 640 Atlantic Ocean 43,000 35,000 Great Salt Lake 158,000 230,000 ? ~330,000 Dead Sea Salt present in 1L water EC From wateronthweb.org http://www.waterontheweb.org/under/waterquality/conductivity.html [...]... by aquatic life In natural water systems, determined largely by geology and soils pH of natural waters Sea water due to humic acid Limestone, marble, CO3 rich Pure rain, snow Modified from www.waterwatch.org http://www.vic.waterwatch.org.au/fortheteacher/manual/sect4f.htm Factors that affect pH • Algal blooms • Bacterial activity • Water turbulence • Chemicals flowing into the water body • Sewage... capability of water to neutralize acid Buffering capacity – resistance to pH changes Common natural buffer: CO3 (carbonates – like limestone) Protects aquatic life Commonly linked to water hardness Limestone outcrop In natural systems: 50 – 150 mg/L as CaCO3 Hardness Reflects dissolved carbonate minerals Mostly of concern for drinking water standards Metals precipitate out of solution Create scale/hard water. .. Hard water From USGS http:/ /water. usgs.gov/owq/news.html and Nitrate (NO3-) naturally-occurring form of nitrogen found in soil Forms by microbial decomposition of fertilizers, plants, manures or other organic residues Plants uptake nitrates (Spinach a good source) Phosphate (PO4-3) naturally occurs in rocks and minerals Plants uptake weathered-out elements and compounds Animals ingest plants Water. .. Synthetic fertilizers Can lead to: eutrophication of natural water systems (overproduction of vegetation) Blue baby syndromne The U.S EPA has set a maximum contaminant level for NO3- in drinking water of 10 parts per million (ppm) Phosphates Artificial sources: • Sewage • Laundry, cleaning fluids • Synthetic fertilizers Can also lead to eutrophication of natural water systems (overproduction of vegetation)... larval development • Macrophyte growth may be decreased • Reduced photosynthesis can lead to lower daytime release of oxygen From waterontheweb.org http://waterontheweb.org/under/waterquality/turbidity.html Conductivity Ability of a substance to conduct an electrical current In water, conductivity determined by types and quantities of dissolved solids (Commonly called Total Dissolved Solids = TDS) Cl-... Turbidity Measures how “murky” the water is Estimates: Mineral fraction Organics Inorganics Soluble organic compounds Plankton Microscopic organisms MODIS Image from NASA http://rapidfire.sci.gsfc.nasa.gov/ Causes of highly • In open waters, phytoplankton • Closer to shore, particulates Resuspended bottom sediments (wind) • Organic detritus from stream and/or wastewater discharges • Dredging operations...Sill Saltwater from entry point Freshwater from stream and river runoff Highly stratified Slow-circulating Long residence time Hood Canal Jan Apr Jun Sept Dec Modified from Hood Canal Dissolved Oxygen Project, Collias, UW, PRISM 2005 http://www.hoodcanal.washington.edu/observations/historicalcomparison.jsp Potential causes Natural • • • • • increased sunlight or other... (wind) • Organic detritus from stream and/or wastewater discharges • Dredging operations • Channelization • Increased flow rates • Floods • Too many bottom-feeding fish (such as carp) • Hippos waters Effects of highly waters • Modify light penetration • Increase sedimentation rate • Smother benthic habitats • Settling clay particles can suffocate newly hatched larvae • Fine particulate material also can... EPA http://www.epa.gov/glnpo/monitoring/limnology/SprNOx.html Hypoxia in the Gulf of Mexico Gulf of Mexico Mississippi River drainage basin – 41% of US landmass Hypoxia in the Gulf of Mexico Hypoxic waters Image from Jacques Descloitres, MODIS Land Rapid Response Team, NASA/GSFC, January 2003 Hypoxia in the Gulf of Mexico From NCAT (Nat’l Center for Appropriate Technology) http://www.ncat.org/nutrients/hypoxia/hypoxia.html
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