Dehydogenase Activity in Soils: Influence of Copper, Lead, Cadmium and Varying Soil Types

Abstract

Soil quality and health are currently tipping points in soil science which will decide if the bearing capacity of our food system will last to feed 10 billion of people in the near future. Important will be also in that conjunction that soil pollution with heavy metals (HM) will play a crucial role. In a pot experiment five different soils were spiked with Cu, Pb (50, 100, 200 and 400 ppm each) and Cd (0,75, 1,5, 3.0 and 6,0 ppm) and incubated at optimal water content at 27 oC for 56 d. In weekly intervals samples were taken and tested for dehydrogenase activity. It was found that Cu inhibited DHA already at 50 ppm for max. 50%. Higher Cu rates went up to 80%. Pb action was not so high but also at 50 ppm the reduction of DHA reached 40%. Cd exerted its inhibitory capacity at spiking levels of 3 and 6 ppm. The toxicity level of the tested HMs will be in the order Cu > Pb > Cd. Threshold values should be revised in order to assure future soil quality and fertility.

Keywords

• enzyme activity
• heavy metals
• threshold values
• time series