BIOLOGY 157: LIFE SCIENCE: AN ENVIRONMENTAL APPROACH (Nutrients & Biogeochemical Cycles)

NUTRIENTS AND NUTRIENT CYCLING NUTRIENTS: are elements (C, H, N, etc.) and simple inorganic compounds of these elements (H 2 O, CO 2, etc.) that are essential for life. FOODS: are organic compounds (contain carbon, hydrogen, usually oxygen and sometimes other elements) that organisms use to fuel their metabolism. Foods would include lipids (fats and oils) carbohydrates (sugars, starch, etc.) and proteins.

Essential Minerals (Nutrients) needed by Animals AND Plants) Major Elements Trace Elements (= Macronutrients) (= Micronutrients) Carbon (C) Iron (Fe) Hydrogen (H) Manganese (Mn) Oxygen (O) Zinc (Zn) Nitrogen (N) Molybdinum (Mo) Phosphorus (P) Chlorine (Cl) Calcium (Ca) Copper (Cu) Potassium (K) Vanadium Sulfur (S) Silicon (Si) Magnesium (Mg) Cobalt (Co) Sodium (Na)

TRACE Essential Minerals (= Nutrients) needed by certain animals or plants Boron (B), Chromium (Cr), Fluorine (Fl), Iodine (I), Nickle (Ni), Selenium (Se), Tin (Sn)

BIOGEOCHEMICAL CYCLES (I) The more or less circular paths of the chemical elements passing back and forth between organisms and environment are known as Biogeochemical Cycles (also called Nutrient Cycles). Essential elements are rarely (if ever) homogeneously distributed, nor present in only one chemical form throughout an ecosystem. These materials exist in compartments or pools which have varying exchange rates between them.

BIOGEOCHEMICAL CYCLES (II) From the standpoint of the earth as a whole, Biogeochemical Cycles Fall into two groups: Perfect (= gaseous) cycles cycles (nitrogen, carbon, oxygen) that have a large gaseous, rather easily exchangeable, reservoir which makes them less likely to get out of balance for long periods of time over large areas Imperfect (= sedimentary) cycles cycles (calcium, phosphorus, iron) that involve the more earthbound elements and large portions of the supply may become unavailable for long periods of time over large areas (thus disturbing the cycle)

AVAILABILITY OF NUTRIENTS Even if the nutrient elements are in the soil and/or water of an area, they may be unavailable to organisms. Some organisms can only utilize an element when it is present in a specific compound. pH also affects the availability by either changing the chemical form of the element or simply by interfering with the uptake of that substance

pH & RELATIVE NUTRIENT AVAILABILITY

EXAMPLES OF BIOGEOCHEMICAL CYCLES Generalized Cycle Sedimentary Cycles –Calcium –Phosphorus Gaseous Cycles –Nitrogen –Carbon

GENERALIZED BIOGEOCHEMICAL CYCLE

CALCIUM CYCLE

PHOSPHORUS CYCLE

TROPHIC LEVEL CONCENTRATION DEFINITION: The selective retaining of certain elements or compounds by an organism so that the concentration builds up in these organism above what it is in their immediate habitat and/or food AKA: trophic level magnification, biological concentration or biological magnification T. L. Concentration can occur for: essential materials (even to toxic levels) non-essential materials (many are toxic)

TROPHIC LEVEL CONCENTRATION

NITROGEN CYCLE (I)

NITROGEN CYCLE (II)

CARBON CYCLE (I)

CARBON CYCLE (II)

PLEASE NOTE You are not responsible for the Sulfur Cycle diagram on p. 45 of your text. What you need to know about sulfur and the sulfur cycle at this time is: Sulfur compounds are a major contributor to acid precipitation Sulfur may be involved in a feedback loop that helps to stabilize temperatures