Nutrient and pollutant metals within earthworm residues are immobilized in soil during decomposition

Analysis of reproductive damage in earthworms (Amynthas corticis) exposed to cypermethrin

Cypermethrin contamination was a potential threat to soil organisms. In the present work, reproductive damage in earthworms (Amynthas corticis) exposed to cypermethrin was investigated. It was found that earthworms could absorb and accumulate residual cypermethrin in soil, and also earthworm activities helped accelerate the degradation of cypermethrin in soil. The accumulation of cypermethrin in earthworms induced sperm damage, and cypermethrin not only caused the imbalance of calcium homeostasis in earthworm sperm cells by inhibiting earthworm sperm Ca²⁺-ATP and Ca²⁺-Mg²⁺-ATP enzyme activities but also caused barriers in acrosome reaction. It also affected sperm energy supply of earthworms by inhibiting the activity of Na⁺-K⁺-ATPase and Mg²⁺-ATPase of earthworm sperm. Meanwhile, the inhibition of acrosome enzyme activity of earthworm sperm by cypermethrin led to hinder fertilization and reduced cocoon production of earthworms, and the damage of cypermethrin to sperm of earthworm was a significant cause of its reproductive toxicity. The results of the evaluation of IBR index showed that reproductive toxicity of cypermethrin to earthworms reduced with the increasing time. The decreased reproductive toxicity of cypermethrin to earthworms at the later stage of exposure (42-56 d) might be due to a combination of reduced absorption of cypermethrin in soil by earthworms, decreased accumulation of cypermethrin in the body, and improved sperm capacitation.

Advances in the application of immobilized enzyme for the remediation of hazardous pollutant: A review

Nowadays, ecofriendly, low-cost, and sustainable alternatives techniques have been focused on the effective removal of hazardous pollutants from the water streams. In this context, enzyme immobilization seems to be of specific interest to several researchers to develop novel, effective, greener, and hybrid strategies for the removal of toxic contaminants. Immobilization is a biotechnological tool, anchoring the enzymes on support material to enhance the stability and retain the structural conformation of enzymes for catalysis. Recyclability and reusability are the main merits of immobilized enzymes over free enzymes. Studies showed that immobilized enzyme laccase can be used up to 7 cycles with 66% efficiency, peroxidase can be recycled to 2 cycles with 50% efficiency, and also cellulase to 3 cycles with 91% efficiency. In this review, basic concepts of immobilization, different immobilization techniques, and carriers used for immobilization are summarized. In addition to that, the potential of immobilized enzymes as the bioremediation agents for the effective degradation of pollutants from the contaminated zone and the impact of different operating parameters are summarized in-depth. Further, this review provides future trends and challenges that have to be solved shortly for enhancing the potential of immobilized systems for large-scale industrial wastewater treatment.

Synthesis of earthworm trace metal uptake and bioaccumulation data: Role of soil concentration, earthworm ecophysiology, and experimental design

Trace metals can be essential for organo-metallic structures and oxidation-reduction in metabolic processes or may cause acute or chronic toxicity at elevated concentrations. The uptake of trace metals by earthworms can cause transfer from immobilized pools in the soil to predators within terrestrial food chains. We report a synthesis and evaluation of uptake and bioaccumulation empirical data across different metals, earthworm genera, ecophysiological groups, soil properties, and experimental conditions (metal source, uptake duration, soil extraction method). Peer-reviewed datasets were extracted from manuscripts published before June 2019. The 56 studies contained 3513 soil-earthworm trace metal concentration paired data sets across 11 trace metals (As, Cd, Cr, Cu, Hg, Mn, Ni, Pb, Sb, U, Zn). Across all field and laboratory experiments studied, the median concentrations of Hg, Pb, and Cd in earthworm tissues that were above concentrations known to be hazardous for consumption by small mammals and avian predators but not for Cu, Zn, Cr, Ni, and As. Power regressions show only Hg and Cd earthworm tissue concentrations were well-correlated with soil concentrations with R² > 0.25. However, generalized linear mixed-effect models reveal that earthworm concentrations were significantly correlated with soil concentrations for log-transformed Hg, Cd, Cu, Zn, As, Sb (p < 0.05). Factors that significantly contributed to these relationships included earthworm genera, ecophysiological group, soil pH, and organic matter content. Moreover, spiking soils with metal salts, shortening the duration of exposure, and measuring exchangeable soil concentrations resulted in significantly higher trace metal uptake or greater bioaccumulation factors. Our results highlight that earthworms are able to consistently bioaccumulate toxic metals (Hg and Cd only) across field and laboratory conditions. However, future experiments should incorporate greater suites of trace metals, broader genera of earthworms, and more diverse laboratory and field settings to generate data to devise universal quantitative relationships between soil and earthworm tissue concentrations.

Trace Elements in Surface Soils and Megascolecidae Earthworms in Urban Forests Within Four Land-Uses Around Poughkeepsie, New York, USA

Amynthas agrestis and Metaphire hilgendorfi are being distributed across North America with unknown ecosystem impacts. Forest soils in urban areas sequester trace elements and earthworms may be bioaccumulating them. This study examined Cd, Cr, Co, Cu, Mn, Ni, Pb, V, and Zn in soils and earthworm tissues at 28 urban forest sites in and surrounding Poughkeepsie, NY, USA. Megascolecidae were present at 22 sites with means of 12 to 27 individuals m^-2 and 4 to 12 dry weight g m^-2. Urban forest soils within commercial uses had Mn, Pb, and Zn concentrations higher than within residential and agricultural uses. Earthworm trace element concentrations were poorly predicted by their respective soil concentrations, except for Pb. Urban forests in commercial uses and land-preserves, earthworm Cd and Pb concentrations were at or above concentrations known to negatively impact small mammal and bird health ( > 10 mg kg^-1) with Co and V approaching toxic concentrations.