Disturbed soil biology

Westergaard K., A.K. Muller, S. Christensen, J. Bloem, and S.J. Spiensen (2001). Effect of tylosin as a disturbance on the soil microbial community. Soil Biology and Biochemistry 33 2061-2071. 

Health nd SMety Factors. The lowest pubhshed human oral toxic dose is 430 mg/kg, causing nervous system disturbances and gastrointestinal symptoms. The LD q (rat, oral) is 750 mg/kg (183). Thiocyanates are destroyed readily by soil bacteria and by biological treatment systems in which the organisms become acclimatized to thiocyanate. Pyrolysis products and combustion products can include toxic hydrogen cyanide, hydrogen sulfide, sulfur oxides, and nitrogen oxides. 

Cadmium is found naturally deep in the subsurface in zinc, lead, and copper ores, in coal, shales, and other fossil fuels it also is released during volcanic activity. These deposits can serve as sources to ground and surface waters, especially when in contact with soft, acidic waters. Chloride, nitrate, and sulfate salts of cadmium are soluble, and sorption to soils is pH-dependent (increasing with alkalinity). Cadmium found in association with carbonate minerals, precipitated as stable solid compounds, or coprecipitated with hydrous iron oxides is less likely to be mobilized by resuspension of sediments or biological activity. Cadmium absorbed to mineral surfaces (e.g., clay) or organic materials is more easily bioaccumulated or released in a dissolved state when sediments are disturbed, such as during flooding. 

Biological activity is an important indicator of the decomposition of soil organic matter within the soil. High biological activity promotes metabolism between soil and plants and is an essential part of sustainable plant production and fertiliser management. Earthworms, as a key species for soil macro-fauna, are an appropriate indicator of soil s biological activities due to their sensitivity to any kind of soil disturbance. Microbial activity of soils is an indicator of soil micro-fauna. Both indicators are reviewed below. 

Edaphic factor A composite of physical and biologic characteristics of the soil that disturbs the ecosystem. 

Weathering of primary minerals as a source of nutrients for trees results eventually in almost complete depletion of these minerals near the soil surface. In soils of the Appalachian area in the southeastern USA, layers of saprolite (undisturbed weathered rock), up to tens of meters in thickness, develop below most of the biologically active soil and thus are relatively protected from disturbance by bioturbation. However, even in saprolites weathering is not complete, and tree roots are still able to get enough nutrients from the saprolite for growth (Velbel, 1985). 

Microelements are present in soils only in very low concentrations, mostly up to 0.001%. In the life of plants and animals, including man, they play a very important role, since they are components of vitamins, enzymes, hormones and other biological substances with a high physiological activity. Their insufficiency can lead to different diseases and disturbances and thus, they are a focus of agricultural and nutritional interest. 

Terrestrial recovery is even more difficult to project than aquatic recovery. Given the life span of trees and the delay in the response of soil to decreases in acidic deposition, it is reasonable to suggest that decades will be required for affected trees on sensitive sites to recover once chemical conditions in the soil are restored. Overall, the timing and extent of chemi cal and biological recovery depend on how soon and how significantly emissions that cause acidic deposition are reduced. Moreover, human influences (e.g., land disturbance, introduction of exotic or invasive species), in addition to acidic deposition, can delay biological recovery after chemical recovery has occurred. 

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