FUNGI DIVERSITY AND HEAVY METAL CONCENTRATIONS IN PESTICIDES CONTAMINATED SOIL
Abstract
ABSTRACT
This study investigated fungal diversity and abundance in pesticide-contaminated agricultural soils from Ogume, Delta State, Nigeria, emphasizing their tolerance to heavy metals. Soil samples were collected from pesticide-contaminated and uncontaminated sites. Soil physicochemical parameters were assessed. Heavy metal concentrations were determined using inductively coupled plasma optical emission spectroscopy (ICP-OES) while fungal isolation and identification were carried out on Rose Bengal Chloramphenicol agar following standard protocol. Results showed that the contaminated soil differed notably from the control in physicochemical composition. The pH declined from 6.9 to 5.8, indicating acidification, while essential macronutrients such as calcium (Ca) and magnesium (Mg) reduced from 1100.88 mg/kg and 158.31 mg/kg to 245.62 mg/kg and 56.34 mg/kg, respectively. Heavy metal concentrations were substantially higher in the contaminated soil, with cadmium (Cd) increasing from non-detectable levels to 159.06 mg/kg, mercury (Hg) from 2.91 mg/kg to 46.30 mg/kg, copper (Cu) from 4.37 mg/kg to 17.78 mg/kg, and arsenic (As) from 0.46 mg/kg to 3.95 mg/kg, following the trend Cd > Hg > Cu > As. Correspondingly, the total heterotrophic fungal count declined from 8.05 × 10⁴ CFU/g in the control to 1.45 × 10⁴ CFU/g in the contaminated soil, representing a 55% decrease in fungal abundance. Similarly, the Shannon–Wiener Diversity Index decreased from 1.97 to 1.12, showing reduced biodiversity. Dominant fungi in the control soil included Aspergillus niger and Penicillium chrysogenum, while the contaminated soil was dominated by stresstolerant Aspergillus flavus, Fusarium oxysporum, and Trichoderma spp. The findings demonstrate that pesticide and heavy metal co-contamination disrupt soil microbial balance, reducing fungal abundance and diversity. However, the persistence of tolerant genera highlights their potential for mycoremediation and soil restoration in contaminated farmlands.
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