In a laboratory study, alkaline phosphatase, arylsulpha-tase, -glucosidase, catalase, urease activities and soil respiration were used as bioindicators of the Cd toxicity. The metal was added to six agricultural soils as Cd(NO3)2 at 1000 mg•kg-1 rate. The soil samples were incubated at 25 °C and at 50% of the field capacity during a period of 28 days. The addition of Cd lowered soil pH, with a general reduction of about 0.4 pH units below control values. The ammonium acetate + EDTA extractable amounts of Cd ranged from 70 to 87%. The greatest recovery of extractable-Cd was observed in the soil with the lowest pH, the smallest in the soil with the highest level of carbonates. Generally, Cd contaminated soils showed reduced enzyme activities and respiration rates. In the soil with the highest level of organic matter the biochemical parameters were less sensitive to Cd addition. No strong relationship was ob-served between extractable Cd content and the degree of in-hibition of the examined biochemical activities. The amount of decrease in enzyme activity differed among enzymes with catalase, alkaline phosphatase and arylsulphatase being the most affected by Cd addition. Cadmium reduced soil respiration, on average 75%, in all the contaminated soil samples and changed the pattern of CO2 evolution from soils. Patterns of control soils were described adequately by the first-order model while the zero-order model better described C mineralization in the Cd contaminated soils. The data suggest that in Cd contaminated soils very common biochemical properties, representing the functioning of the ecosystem, decreased. The results chiefly indicate that alterations of the microbial parameters, particularly catalase, alkaline phosphatase, arylsulphatase and soil respiration, allowed useful quantification of soil disturbance by Cd and can be recommended for monitoring Cd contamination of soils.
Biochemical parameters in monitoring soil contamination by cadmium
CARDELLI, ROBERTO;SAVIOZZI, ALESSANDRO;
2009-01-01
Abstract
In a laboratory study, alkaline phosphatase, arylsulpha-tase, -glucosidase, catalase, urease activities and soil respiration were used as bioindicators of the Cd toxicity. The metal was added to six agricultural soils as Cd(NO3)2 at 1000 mg•kg-1 rate. The soil samples were incubated at 25 °C and at 50% of the field capacity during a period of 28 days. The addition of Cd lowered soil pH, with a general reduction of about 0.4 pH units below control values. The ammonium acetate + EDTA extractable amounts of Cd ranged from 70 to 87%. The greatest recovery of extractable-Cd was observed in the soil with the lowest pH, the smallest in the soil with the highest level of carbonates. Generally, Cd contaminated soils showed reduced enzyme activities and respiration rates. In the soil with the highest level of organic matter the biochemical parameters were less sensitive to Cd addition. No strong relationship was ob-served between extractable Cd content and the degree of in-hibition of the examined biochemical activities. The amount of decrease in enzyme activity differed among enzymes with catalase, alkaline phosphatase and arylsulphatase being the most affected by Cd addition. Cadmium reduced soil respiration, on average 75%, in all the contaminated soil samples and changed the pattern of CO2 evolution from soils. Patterns of control soils were described adequately by the first-order model while the zero-order model better described C mineralization in the Cd contaminated soils. The data suggest that in Cd contaminated soils very common biochemical properties, representing the functioning of the ecosystem, decreased. The results chiefly indicate that alterations of the microbial parameters, particularly catalase, alkaline phosphatase, arylsulphatase and soil respiration, allowed useful quantification of soil disturbance by Cd and can be recommended for monitoring Cd contamination of soils.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
