Extent of Heavy Metal Accumulation in Sewage Irrigated Soils and Their Impact on Distribution of Earthworm Communities: Linking Chromium and Zinc Toxicity on Growth and Reproduction in Selected Earthworm Species.

Abstract

Soil ecosystem polluted by metals affect the structure of soil invertebrate population(s) and dynamics leading to altered distribution of species. This study focuses on earthworm distribution in sewage irrigated agricultural lands around Bangalore. The occurrence of reported species from the sampled areas is Eudrilus eugeniae, Lampito maurutii, Pontoscolex corethrurus, Polypheretima elongata, Perioynx excavates and Eisenia fetida. Laboratory studies conducted to evaluate feed ingestion rate and body mass changes in earthworms exposed to metal spiked soils revealed species specific pattern. Eudrilus eugeniae and Lampito maurutii showed a steep increase in body weight, while Pontoscolex corethrurus exhibited decreased trend upon Zn exposure. Contrarily a significant (p<0.05) decline in body weight was evident in all the three species upon exposure to Cr spiked soils. The observed alterations in feeding and body mass index concomitantly influenced the reproductive parameters. Rate of hatchability and reproductive function found to be decreased in Cr spiked soils in all the three species studied. Contrarily, increased hatchability was observed in E.eugeniea and L.maurutii followed by a decrease rate in P.corethrurus upon exposure of Zn spiked soils. However, reproductive rate found to be increased in E.eugeniea and P.corethrurus with decreased trend in L.maurutii. Thus, use of sewage polluted water for irrigation purpose has led to increased soil metal concentration impacting earthworm physiology and distribution.

Effects of Zinc Accumulation on Earthworm Aporrectodea caliginosa (Haplotaxida: Lumbricidae)

“…In fact, a reduction in growth rate was obtained at 7, 14 and 21 days and was stable at 28 days. A Similar observation was made by Latha and Mahaboob-Basha (2016), who found in their study the effect of Zn on many species of earthworms, which changed in body mass and had a steep decrease in body weight.…”

“…The aim of the current study was to assess the efficiency of Aporrectodea caliginosa in accumulation Zn in the body tissue from polluted soil. Compared to other species of earthworms, it was noted in previous research that they have the ability to accumulate heavy metals (Latha & Mahaboob-Basha 2016) .The study also aims at showing the effect of the key biological processes on the weight and growth rate These findings weight and growth rate also point to a possibility to restore their quality by maintaining in appropriate levels the earthworm populations in the agricultural lands, as well as the specific growth rate of the earthworms, which were estimated to rid the soil of contaminants and increase soil fertility.…”

“…In terms of the sources in the agricultural sector, these can be categorized into, pesticides, manure of animal, and Sewage (Li et al, 2014). Use of polluted wastewater for irrigation purposes has led to increase soil heavy metal concentration effect non-target objects distribution and physiology, especially used Zn because Zn t enters the metabolism process for living organisms (Latha & Mahaboob-Basha, 2016). Heavy metals are known as dangerous pollutants because they are toxic and non-degradable, thus accumulation of Jurnal Riset Biologi dan Aplikasinya https://journal.unesa.ac.id/index.php/risetbiologi heavy metals in soil causes many risks to the ecosystem and human life (Odoh et al, 2011).…”