Activity of Exoenzymes in Treated Wastewater Irrigated Soils

The reuse of reclaimed wastewater for irrigation of agricultural fields greatly influences the activity of soil microorganisms through the input of organic compounds. Due to the production of exoenzymes by microorganisms for the decomposition of substrates it can be assumed that the irrigation with treated wastewater (TWW) has a strong influence on the soil enzyme pool. In this study the activity of ten exoenzymes, which catalyses processes in C, N and P nutrient cycles, were determined in 3 different soils in 0-10, 10-20, 20-30, 30-50, 50-70 and 70-100 cm soil depth. The soils were used for agriculture and irrigated with reclaimed wastewater reused after a secondary treatment step. Additionally a control after freshwater irrigation was studied. Due to the influence of TWW on the soil biology of these soils, also clear effects on soil exoenzymes in freshwater and TWW irrigated soils could be seen. According to Sinsabaugh et al. (2008) we calculated indices which describe the enzymatic resources for acquisition of organic P and organic N relative to C and therefore give insides into the functional convergence of extracellular enzyme activities in soils and the relative nutrient demand. The distribution pattern of these functional enzyme activities varied between freshwater and TWW irrigated soils and shows therefore a strong influence of the TWW irrigation on the activity of exoenzymes. (Sinsabaugh et al. (2008): Stoichiometry of soil enzyme activity at global scale. Ecology Letters 11 (11), 1252-1264.

Comparison of four different algorithms for the calculation of radioimmunoassay standard curves

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