Water and Nutrients - Principles of Ecology - Lecture Slides, Slides of Ecology and Environment

Download Water and Nutrients - Principles of Ecology - Lecture Slides and more Slides Ecology and Environment in PDF only on Docsity! Lecture 2: Adaptation to Physical Environment: Water and Nutrients Docsity.com Topics: 2.1 Global water cycling 2.2 Water has many properties favorable to life 2.3 Many inorganic nutrients are dissolved in water 2.4 Plants obtain water and nutrients from soil 2.5 Maintain salt and water balance by plants and animals Docsity.com The Hydrologic Cycle • Precipitation (PPT) • Interception • Infiltration • Groundwater recharge • Runoff • Evaporation (E) • Transpiration (T) Distribution of water is not static (processes) Docsity.com Global water budget Land Pools (10^3 km3): Glaciers: 29,000 Groundwater:4,000 Lake: 229 Soil: 67 Fluxes (km3/yr): PPT: 111,000 ET: 71,000 River flow:40,000 Ocean Pools: (10^3 km3) Ocean:1.37*10^6 Fluxes: (km3/yr) PPT:385,000 ET: 425,000 Docsity.com 2.2 Properties of water that favorable to life Basic Structure 1. Covalent bonding of 2H + O atoms 2. Polar-covalent bond 3. Inter-molecule attraction 4. H-bonds among water moleculars Docsity.com • High viscosity Viscosity: property of a material that measures the force necessary to separate the molecules and allow passage of an object through liquid. • Frictional resistance is 100 times greater than air. • Water is 860 times denser than air. – Organisms in water have similar density to water, the neutral buoyancy helps against the force of gravity, thus require less investment in structure material such as skeletons – Organisms in deep water need to adapt to the high pressure (20 to 1000 atm). Docsity.com 2.3 Many inorganic nutrients are dissolved in water Solution: a homogeneous liquid with 2 or more substances mixed. Solvent: dissolving agent Solute: substance that is dissolved Aqueous solution: water as solvent Ions: Compounds of electrically charged atoms Cations: positive Anions: negative Practical salinity units (PSU, o/oo): grams of salt per kilogram of water. Ocean: 35 unit, Fresh water: 0.065-0.30 unit) Docsity.com Hydrogen ions in ecological systems Hydrogen ions are very active: 1) affect enzyme activities, and thus influence life processes; 2) dissolve minerals from rocks and soils. Acidity: the abundance of hydrogen ions (H+) in solution. Alkalinity: abundance of hydroxyl ions (OH-) in solution Acidity in water is related to carbon dioxide (CO2). Docsity.com 2.4 Plants obtain water and nutrients from soil  Plants and animals need water and nutrients to growth and reproduce. Docsity.com Plants acquire the inorganic nutrients as ions dissolved in water • N: ammonium (NH4+), nitrate (NO3-) • P: phosphate ions (PO43-) • K: K+ • Na: Na + • Ca: Ca2+ The availability in soil is determined by their chemical forms in soil, temperature, acidity, and presence of other ions. Docsity.com 2.4.1 Ion exchange capacity is important to soil fertility Soil soluble nutrients are charged particles, ions. Cations: positively charged (Ca2+, Mg2+, NH4+) Anions: negatively charged (NO3–, PO34–) Ions are attached to soil particles, so they do not leach out of the soil. Ion exchange capacity: total number of charged sites on soil particles in a standard volume of soil. Docsity.com 2.4.2 Soil structure and water-holding capacity • Texture – Variation in size and shape of soil particles • Gravel (NOT) – >2mm • Sand – 0.05mm to 2mm • Silt – 0.002mm to 0.05mm • Clay – <0.002mm Soil texture is percentage of sand, silt and clay. (Texture chart) Docsity.com Water holding capacity is an essential feature of soils • Soil can become saturated if all pores filled • All water is hold by soil particulars, at field capacity (FC) • Capillary water is usually present – Extractable by plants • Wilting point (WP) – Plant no long extract water Available water capacity (AWC) • All affected by soil texture – Sand • Lower capacity – Clays • Higher capacity Docsity.com Water potential • Water moving between soil and plants flows down a water potential gradient. • Water potential ( ) is the capacity of water to do work, potential energy of water relative to pure water. – Pure Water = 0. • in nature generally negative. • solute measures the reduction in due to dissolved substances. ψ ψ ψ ψ ψ Docsity.com 2.5.1 Management of salt balance by plants Transpiration – water uptake – dissolved salts along water will get into roots When salts concentrations in soil water are high, plants pump excess salts back into soil by active transport across their root surface, function as plant’s “kidneys”. One example: Mangroves on coastal mudflats Salt glands on the leaf surface Docsity.com 2.5.2 Water and salt balance in terrestrial animals  Terrestrial – Input Drinking  Eating Produced by metabolism (respiration) – Output – Need to control in extreme environments Urine – Concentrated to avoid water loss (Kidneys). Human: 4 times high than in blood; Kangaroo rat: 14 times  Feces  Evaporation – No sweat glands in some mammals; “salt glands” in birds and reptiles Breathing Docsity.com 2.5.3 Water and salt balance in aquatic animals – Freshwater (hyper-osmotic, high salt in body) • Prevent excess uptake of water • Remove excess water – Large amounts of very dilute urine – Retain salt in special cells (gills, kidneys) – Saltwater (hypo-osmotic, low salt in body) • If salt concentration is higher than in body, dehydrate – Drinking a lot to gain water – Some sharks: retain urea in the bloodstream (balance body surface water loss) – Ion pumps, gill (fish) – Kidneys (eliminate salts, marine mammals) – Salt secreting glands in birds Docsity.com