Patricks Otomo | University of the Free State (original) (raw)

Papers by Patricks Otomo

Environmental Toxicology and Chemistry

Sustainable development goals series, 2023

doerjesi (Oligochaeta) to combined effects of temperature and metal contamination by

Applied Sciences, 2022

Despite several known beneficial attributes, biochar is suspected to cause harm to soil organisms... more Despite several known beneficial attributes, biochar is suspected to cause harm to soil organisms when present in relatively high quantities in the soil. To determine the potential detrimental effects of biochar, for 96 h, we exposed the earthworm Eisenia fetida to 0, 2, 4 and 8 mg glyphosate (GLY) per kg in non-amended and biochar-amended soil at rates of 5, 10 and 15%. The results indicated that in non-amended soil, survival was significantly decreased in the highest GLY concentration. Although no median lethal concentration (LC50) could be computed due to the lack of sufficient mortality, in the absence of biochar, a lethal concentration 10% (LC10) of 5.540 mg/kg and a lethal concentration 20% (LC20) of 7.067 mg/kg were calculated. In the biochar-amended soil, no mortality occurred in the control and GLY treatments for all three biochar amendment rates. Biomass results showed significant biomass loss in the highest GLY treatment in the absence of biochar, with an effective concen...

Additional file 2. Benchmark articles.

Additional file 3. Search strings.

Additional file 1. ROSES checklist.

Integrative zoology, 2020

The ingestion of organic and mineral materials by earthworms is a prominent functional role that ... more The ingestion of organic and mineral materials by earthworms is a prominent functional role that has profound consequences for the decomposition and stabilization of soil organic matter. To investigate the litter consumption of the African nightcrawler earthworm Eudrilus eugeniae (Kinberg, 1867) under different tropical conditions, (i) we used DNA barcoding to identify specimens of E. eugeniae collected from sites across the Adamawa region in Cameroon, and (ii) studied the influence of habitat suitability (soil properties), soil moisture, litter type and population density on litter consumption. A total of four litter consumption experiments were carried out using soils collected from refuse disposal sites, agricultural lands and savannahs dominated by the Mexican sunflower Tithonia diversifolia (Hemsl). The results revealed that litter consumption significantly increased in the refuse disposal and agricultural soils as opposed to the Mexican sunflower (T. diversifolia) soil, a cow ...

Environmental science and pollution research international, 2018

The present study investigated the use of biochar for the alleviation of the toxic effects of a n... more The present study investigated the use of biochar for the alleviation of the toxic effects of a nanosilver colloidal dispersion and a chloronicotinyl insecticide. The survival and reproduction of the potworm Enchytraeus albidus were assessed after exposure to imidacloprid and silver nanoparticles (AgNPs). E. albidus was exposed to 0, 25, 50, 100, 200, and 400 mg imidacloprid/kg and 0, 5, 25, 125, and 625 mg Ag/kg for 21 days in 10% biochar amended and non-biochar amended OECD artificial soil. In both exposure substrates, the effects of imidacloprid on survival were significant in the two highest treatments (p < 0.01). No biochar effect was observed as survival was statistically similar in both soils after exposure to imidacloprid. In the case of AgNPs, significant mortality was only observed in the highest AgNP treatments in both the amended and non-amended soils (p < 0.05). Nevertheless, statistically greater survival occurred in the biochar-amended treatment (p < 0.05). R...

African Zoology, Oct 13, 2013

By submitting this thesis/dissertation electronically, I declare that the entirety of the work co... more By submitting this thesis/dissertation electronically, I declare that the entirety of the work contained therein is my own, original work, that I am the sole author thereof (save to the extent explicitly otherwise stated), that reproduction and publication thereof by Stellenbosch University will not infringe any third party rights and that I have not previously in its entirety or in part submitted it for obtaining any qualification.

Pedobiologia, 2009

... Introduction. Salinization of soil is one of the common problems under irrigated agriculture ... more ... Introduction. Salinization of soil is one of the common problems under irrigated agriculture especially in areas of low rainfall and high evaporative demand (Sumner 1995) including South Africa and Australia. Salinization of soil ...

Ecotoxicology, 2009

Since life-cycle studies showed that the earthworm species Eisenia fetida can develop increased t... more Since life-cycle studies showed that the earthworm species Eisenia fetida can develop increased tolerance after long-term exposure to a sub-lethal concentration of Cd in the laboratory, we assessed both the cytotoxicity and genotoxicity of Cd in a long-term Cd-exposed population. We exposed E. fetida specimens from this population, from a laboratory control population and from a field population to various concentrations of CdSO(4) in artificial soil water. Toxic effects were measured using the MTT test and the comet assay. The group that had been exposed to Cd for more than a decade was found to be more tolerant to the deleterious effects of Cd at both cellular and molecular levels than the laboratory control population. The field population, which came from a severely metal polluted environment, displayed high tolerance at molecular level as well. The results provide novel biomarker evidence of increased Cd tolerance in E. fetida, but the mechanisms supporting the apparent tolerance, still need to be clarified.

Bulletin of Environmental Contamination and Toxicology, 2013

Using the comet assay, the genotoxicity of Cd, Zn and Cd/Zn mixtures in Eisenia andrei was assess... more Using the comet assay, the genotoxicity of Cd, Zn and Cd/Zn mixtures in Eisenia andrei was assessed after 4 weeks of exposure at 15, 20 and 25 °C. Relative to the controls, significant increases in TDNA% were observed in exposures to Cd alone at 500 and 1,000 mg/kg soil at both 20 and 25 °C, while a general decrease occurred at 15 °C. For Zn alone, a decreasing trend in TDNA% occurred at all three temperatures with increasing Zn concentration. For the Cd/Zn mixtures at 15 °C, genotoxicity was reduced at all mixture concentrations relative to the control. At 20 °C, the genotoxic response was similar to the control at all exposures. At 25 °C, the response was elevated at the 50 + 50 and 250 + 250 mg/kg mixture concentrations. In the remaining treatments at 25 °C, TDNA% was similar to the values in the respective control. The lack of consistently significant mixture genotoxicity may indicate antagonistic interactions between Cd and Zn in the mixtures. However, this was not conclusively determined because temperature alone had an inconsistent effect upon TDNA% readings in the control exposures.

Environmental Evidence

Background Mycofiltration is an environment friendly technology which involves the treatment of c... more Background Mycofiltration is an environment friendly technology which involves the treatment of contaminated water by passing it through a network of fungal mycelium. This technology has gained momentum over the years, and the systematic review chartered in this protocol will compile and synthesise literature on mycofiltration studies, paying special attention to the types and levels of contaminants removed. The systematic review should provide insight into the removal efficiency of mycofiltration by synthesising the mycofiltration knowledge base. Moreover, the proposed contribution will inform further research and provide comprehensive information to relevant stakeholders, such as municipalities, which might be in need of interventions for alleviating wastewater-related pollution in surrounding water bodies. Methods This systematic review protocol is based on the question, “What is the effectiveness of mycofiltration for removal of contaminants from water?” A thorough search of pee...

Biochar

Terrestrial and aquatic ecosystems are increasingly threatened by pesticide pollution resulting f... more Terrestrial and aquatic ecosystems are increasingly threatened by pesticide pollution resulting from extensive use of pesticides, and due to the lack of regulatory measures in the developing world, there is a need for affordable means to lessen environmental effects. This study aimed to investigate the impact of biochar amendment on the toxicity of imidacloprid to life-cycle parameters and biomarker responses of the earthworm Eisenia fetida. E. fetida was exposed to 10% biochar-amended and non-amended OECD artificial soils spiked with 0, 0.75, 1.5, 2.25 and 3 mg imidacloprid/kg for 28 days. An LC50 of 2.7 mg/kg was only computed in the non-amended soil but not in the biochar-amended soil due to insignificant mortality. The EC50 calculated in the non-amended soil (0.92 mg/kg) for reproduction (fertility) was lower than the one computed in the biochar amended (0.98 mg/kg), indicating a decrease in toxicity in the biochar-amended substrate. Significant weight loss was observed at the t...

African Studies Review

Nature, climate crisis, and the Anthropocene have carved space in recent inter-, cross-, and mult... more Nature, climate crisis, and the Anthropocene have carved space in recent inter-, cross-, and multi-disciplinary humanities studies. In South Africa, such studies have barely touched literature in African languages. Nyambi and Otomo focus on the tropes of “lady nature,” nostalgia, and dystopia in Zulu writer Bhekinkosi Ntuli’s Imvunge Yemvelo to explore the complex ways in which these tropes test the normative epistemes of ecological crises. Beyond rejecting imperial distortions of indigenous environmentalism, Ntuli’s poems re-center local knowledge of nature in understanding its relationship with humans. That knowledge subverts epistemic structures of colonial conservation, revising and re-visioning racially geo-politicized knowledge hierarchies.