AUTHOR=Khalid Hira , Kashif Zahoor Muhammad , Riaz Danish , Arshad Madeeha , Yaqoob Rabia , Ranian Kanwal TITLE=Sewage Sludge-Induced Effect on Growth, Enzyme Inhibition, and Genotoxicity can be Ameliorated Using Wheat Straw and Biochar in Pheretima posthuma Earthworms JOURNAL=Frontiers in Environmental Science VOLUME=10 YEAR=2022 URL=https://www.frontiersin.org/journals/environmental-science/articles/10.3389/fenvs.2022.888394 DOI=10.3389/fenvs.2022.888394 ISSN=2296-665X ABSTRACT=

Sewage sludge, rich in organic matter and nutrients, is widely used as a fertilizer to increase the fertility of soil. The direct application of sewage sludge without any treatment causes soil contamination as well as significantly affects the earthworm population. In the present study, the effect of sewage sludge-amended soil on growth, enzyme activities, and the DNA damage in Pheretima posthuma earthworms was studied under wheat straw and biochar treatment of 30-day laboratory incubation. Wheat straw, biochar, and sewage sludge were applied at 0 (control), 5, 10, and 25% w/w along with combined treatment of sewage sludge with biochar and wheat straw, respectively at 25% each. After the incubation period, the percentage change in mean weight and length was measured and esterase and phosphatase enzyme activities were quantitatively determined. RAPD-PCR and the comet assay were performed to assess the genotoxicity. A significant weight loss was observed (26%) at a 25% rate of sewage sludge and biochar (11%). Similarly, a maximum decrease in length was observed with sewage sludge (2.5%) followed by biochar (0.80%) at a 25% application rate. Mean weight and length both decreased by increasing the rate of sewage sludge and biochar. In addition, no change was observed in the weight and length of P. posthuma in the treatment consisting of sewage sludge and wheat straw. Moreover, sewage sludge caused inhibition of esterase and phosphatase activities as well as induced DNA damage. The comet parameters showed that wheat straw and biochar ameliorated the toxic effects of sewage sludge. It is, therefore, concluded that sewage sludge has a tangible impact on earthworms which ultimately disrupts ecosystem functions and wheat straw and biochar can thus be utilized to reduce the toxicity of sewage sludge in Pheretima posthuma earthworms.