EFFECTS OF ELEVATED ATMOSPHERIC CO2, O3 AND SOIL PHENANTHRENE ON SOIL ENZYME ACTIVITIES AND MICROBIAL BIOMASS

This paper aimed to investigate the effects of elevated [CO2], [O-3] or [CO2 + O-3] on soil physicochemical properties, microbial biomass and soil enzyme activities in phenanthrene-added and - unadded soils. The results showed that elevated [CO2] increased the dissolved organic carbon (DOC), total phosphorus (TP), available phosphorus (AP), total potassium (TK), total carbon (TC), and nitric nitrogen (NN) contents to some extent in phenanthrene-untreated soils, which contrary to the elevated [O-3], and thus differentially promoted the contents of microbial biomass carbon (MBC), microbial biomass nitrogen (MBN) as well as activities of soil protease (PRA), sucrase (SA), acid phosphatase (APA) and neutral phosphatase (NPA) in the soils. The elevated [O-3] increased ratios of MBC/MBN, and led to the decrease of the activities of PRA, APA and NPA to some extent. However, to some extent, [CO2 + O-3] alleviated the inhibition of the soil microbial biomass and soil enzyme activities by [O-3] elevation and basically did not change the tendency of the soil physicochemical properties, microbial biomass and enzyme activities, but their contents in phenanthrene-added soils compared with the phenanthrene-untreated soils. Therefore, the alteration of soil microbial biomass and soil enzyme activities can be used for assessment of the effects of elevated atmospheric CO2, O-3 or phenanthrene-polluted soil on the soil microbial systems.