Copper and zinc fractions affecting microorganisms in long-term sludge-amended soils

• Published in: Bioresource technology 2001-09, Vol.79 (2), p.135-146
• Main Authors: Kunito, Takashi, Saeki, Kazutoshi, Goto, Shigeko, Hayashi, Hiroaki, Oyaizu, Hiroshi, Matsumoto, Satoshi
• Format: Article
• Language: English
• Subjects: acid phosphatase; agricultural soils; Agriculture; Agronomy. Soil science and plant productions; alkaline phosphatase; arylsulfatase; Bacteria - drug effects; Bacteria - growth & development; beta-fructofuranosidase; beta-glucosidase; Biodegradation, Environmental; Biological and medical sciences; Biomass; carbon; Compost; composts; copper; Copper - analysis; Copper - pharmacology; endo-1,4-beta-glucanase; enzyme activity; Enzymes - drug effects; Enzymes - metabolism; Fundamental and applied biological sciences. Psychology; General agronomy. Plant production; Hydrogen-Ion Concentration; Metals; microbial activity; Microbial biomass; microorganisms; nitric acid; Other nutrients. Amendments. Solid and liquid wastes. Sludges and slurries; potassium nitrate; proteinases; Refuse Disposal - methods; regression analysis; Sewage - chemistry; Sewage sludge; sodium hydroxide; Soil - analysis; soil amendments; Soil and water pollution; Soil enzymes; Soil Microbiology; Soil Pollutants - analysis; Soil science; Soil-plant relationships. Soil fertility. Fertilization. Amendments; Statistics as Topic; Time Factors; toxicity; urease; zinc; Zinc - analysis; Zinc - pharmacology
• ISSN: 0960-8524; 1873-2976
• DOI: 10.1016/S0960-8524(01)00047-5

The influences of Zn and Cu on soil enzyme activities (acid phosphatase, alkaline phosphatase, arylsulfatase, cellulase, dehydrogenase, protease (z-FLase), urease, β-D-glucosidase and β-D-fructofuranosidase (invertase)) and microbial biomass carbon were investigated in agricultural soils amended with municipal sewage sludge or compost since 1978. The trace metals in the soils were fractionated using a sequential extraction method. Long-term application of the sewage sludge and composts caused accumulations of Cu and Zn in the soils, ranging from 140 to 144 and from 216 to 292 mg kg −1 , respectively. The percentage of Cu was highest in the NaOH- and HNO 3-extractable fractions (44–51% and 38–46%, respectively), while the percentage of Zn was highest in the HNO 3- and EDTA-extractable fractions (65–83% and 11–32%, respectively). Although the percentage of the bioavailable fractions (sum of KNO 3+H 2O-, NaOH-, and EDTA-extractable amounts) of Cu (53–64%) was higher than that of Zn (15–37%), the percentage of the most labile fractions (KNO 3+H 2O) of Zn (2.1–5.9%) was larger than that of Cu (1.1–2.4%). The size of the microbial biomass carbon increased with the application of sewage sludge or compost. For some enzymes, however, the ratio of the enzyme activity to microbial biomass was lower in the soils amended with sewage sludge or compost than that in the control soil. The soil enzyme activities were more adversely affected by Zn than by Cu. From a multiple regression analysis, it was found that dehydrogenase, urease, and β-D-glucosidase activities were reduced by the KNO 3+H 2O-extractable fraction of Zn in the soils. These microbial activities seem to be sensitive to Zn stress, indicating the possibility that they might be useful bioindicators for evaluation of the toxic effects of Zn on microorganisms in the soils.