19 Bedrock Composition Soil Chemistry and Animal Health

19. Bedrock Composition, Soil Chemistry, and Animal Health: Global Case Studies in Applied Medical Geology Rachel Johnson Abstract Introduction This poster examines relationships between regional bedrock geology, soil composition, and plant nutrient quality. Animals are affected by changes in bedrock composition and attendant soil mineralogy. Mineral deficiencies and poisonings occur due to geochemical anomalies in a given region. Mineral imbalances can also cause diseases as the excessive uptake of one element blocks absorption of other necessary nutrients. Changes in soil moisture, organic matter content, clay content, ph levels, and cation exchange capacity affect bulk soil chemistry and hence plant nutrient uptake. Plants in turn absorb these elements and sicken foraging animals if they do not contain the proper mineral balance. Deficiencies are further exacerbated by droughts, excessive snowfall, and temperature extremes that restrict animal diets to less efficient food sources. Animals require the proper balance of trace elements in their diets. Improper levels of these elements leads to deficiencies or intoxications, both of which can be fatal. Plants absorb the elements in the local soil and wild herbivores are most susceptible to geochemical anomalies (Jones, 2005). Case studies are presented to illustrate bedrock-plant nutrient associations. Farmers have experienced ruminants succumbing to molybdenosis and copper deficiency. Molybdenum creates an endocrine imbalance leading to weight loss, lethargy, emaciation, and behavioral Disturbances. Wild herbivores are most affected by excessive or deficient mineral quantities in plants. For example, Swedish moose commonly develop type-2 diabetes due to chronic molybdenosis and elevated glucose levels. In Africa, animal migration patterns follow the availability of plants that contain essential trace elements that are endemic to a particular geologic terrain. Soil Properties Nutrient deficiencies are often prevented by animal migrations. Habitat destruction prevents migration and animals are often restricted to reservations which do not contain of the nutrients that they would have received by migrating (Maskall and Thornton, 1996). In regions that are seeing an increasing demand for agricultural lands the local animals die from lack of food or suffer from mineral deficiencies on reservations. Agriculture and other activities cause changes to the local soil conditions. Increases or decreases in the total amount of trace elements, or changes in the flora’s ability to absorb them leads to regional diseases in animals. Soil properties that influence the amount of trace elements that are absorbed by plants include the total amount of the element, soil p. H, and moisture content. The parent bedrock material of the soil is the main source of elements in the soil, but organic decomposition also plays a role (Maskall and Thornton, 1996). Soil p. H is a negative logarithm that represents the number of hydrogen ions in the soil and is related to sodium and calcium concentrations (Maskall and Thornton, 1996). Different plant species grow in acidic and alkaline soils. Soil p. H also determines how much of an element a plant can absorb. Moisture content is determined by precipitation and evapotranspiration rates. When there is more precipitation leeching occurs causing soil to become more acidic. p. H determines how much of the surrounding trace elements can be absorbed by the plants. Swedish Moose Soils in southwestern Sweden are highly acidic. Acidic soils cause plants to absorb more molybdenum (Mo). Mo in turn blocks the absorption of copper and cadmium in ruminants (Frank, 2003). Copper deficiency causes a condition known as “mysterious moose disease” and “wasting disease” in moose. It is characterized by diarrhea, loss of appetite, discoloration or loss of hair, apathy, neurologic problems, hemorrhages, gastrointestinal lesions, and dilated flabby hearts in ruminants, see Figure 4 (Frank, 2003). Symptoms don’t all appear in the same animal. This moose disease is molybdenosis which causes copper deficiencies as molybdenum blocks the absorption of copper. Copper deficiency leads to glucose intolerance. Moose with molybdenosis were also affected by diabetes due to long-term high glucose levels (Frank, 2003). Kenyan Herbivores Livestock Much of the native wildlife of Kenya resides in national parks and wildlife reserves in order to preserve them while using their old rangeland for other purposes. Soil samples show that each reserve is abundant in some nutrients, but lacking in others (Maskall and Thornton, 1996). Lac of migration prevents herbivores from reaching more plentiful minerals. Arid conditions also create layers of salt at the soil surface (Maskall and Thornton, 1996). African elephants rely on these sources of sodium as well as cave salts in order to meet their nutritional needs (Bowell et al. , 1996), see Figures 1 and 2. The reliance on confined reserves to provide the nutritional needs of many animals is inadequate. Competition for quality lands means that these reserves are located on marginal quality land (Maskall and Thornton, 1996). Latin American cattle suffer from calcium and phosphorus deficiency. This causes subnormal growth, low reproduction, and pica; the region’s pigs suffer from poor growth, gait disturbances, lameness, bone deformation, and vertebrae fractures (Jones, 2005). Iodine deficiency is common in mountainous regions (inner Siberia, Africa, and South America; Himalayas, Alps, Pyrenees, Andes) and places where excessive leeching has occurred. This condition is known as goiter and causes enlargement of the thyroid gland (Jones, 2005). It causes newborn lambs and calves to die of suffocation soon after birth due to increased pressure on the trachea by the thyroid. (Jones, 2005). Adult ruminants don’t produce sufficient thyroid hormones and this leads to lethargy, increased fat deposits, and impaired reproduction in the form of irregular or suppressed estrous cycles (Jones, 2005). Arsenic poisoning is common in Bangladesh, Argentina, Mexico, and the US. It is used in herbicides and pesticides and remains in the soil (Jones, 2005). Exposed cattle suffer from diarrhea, weight loss, eye inflammation, respiratory infection, changes in hair coat, and is lethal in acute cases (Jones, 2005) Conclusions Anthropogenic activity has caused soils to change. Irrigation increases leeching. Herbicides and pesticides add trace elements that are meant to hurt unwanted competitors, but also poison livestock. We have also moved animals to new lands with different nutrient balances and prevented migration, prohibiting animals from reaching their ideal food sources. Figure 1. African Elephant scraping a cave for salts (Bowell et al. , 1996). Figure 2. Elephant with a worn tusk, most likely from digging rocks and soil (Bowell et al. , 1996) Increased production needs will create more problems for animals. As long as people continue to modify landscapes animals that have relied on the way the land previously was will starve or suffer from malnutrition. References Figure 3. Thyroid glands from cattle. The middle is a normal thyroid gland; the others show growth due to insufficient iodine intake (Jones, 2005). Figure 4. Sheep wool discoloration caused by molybdenosis (Jones, 2005) Bowell, R. , Warren, A. , Redmond, I. (1996) Formation of cave salts and utilization by elephants in the Mount Elgon region, Kenya: Geological Society, London, Special Publications, v. 113; p. 63 -79. Fordyce, F. , Masara, D. , Appleton, J. (1996) Stream Sediment, soil and forage chemistry as indicators of cattle mineral status in northeast Zimbabwe: British Geological Survey, Overseas Geology Series, no. WC/94/3. Frank, A. (2003) Molybdenosis Leading to Type 2 Diabetes Mellitus in Swedish Moose, in geology and health: closing the gap. By Skinner, H. , Berger, A. p. 7981. Jones, B. (2005) Animals and Medical Geology: in Essentials of Medical Geology , edited by Selinus, O. p. 513 -526. Maskall, J. , Thornton, I. (1996) The distribution and major elements in Kenyan soil profiles and implications for wildlife nutrition: Geological Society, London, Special Publications, v. 113, p. 47 -62.