High Rates of Biochar Soil Amendment Cause Increased Incidences of Neurotoxic and Oxidative Stress in <i>Eisenia fetida</i> (Oligochaeta) Exposed to Glyphosate
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 <i>Eisenia fetida</i> to 0, 2, 4 and 8 m...
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| Format: | Article |
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MDPI AG
2022-02-01
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| Series: | Applied Sciences |
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| Online Access: | https://www.mdpi.com/2076-3417/12/5/2381 |
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| author | Nomasonto Portia Dlamini Patricks Voua Otomo |
| author_facet | Nomasonto Portia Dlamini Patricks Voua Otomo |
| author_sort | Nomasonto Portia Dlamini |
| collection | DOAJ |
| description | 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 <i>Eisenia fetida</i> 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 (LC<sub>50</sub>) could be computed due to the lack of sufficient mortality, in the absence of biochar, a lethal concentration 10% (LC<sub>10</sub>) of 5.540 mg/kg and a lethal concentration 20% (LC<sub>20</sub>) 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 concentration of 10% (EC<sub>10</sub>) of 5.23 mg/kg and an effective concentration of 20% (EC<sub>20</sub>) of 6.848 mg/kg. In the amended soil, overall, slight non-significant increases in biomass were recorded and no effective concentrations could be calculated due to the lack of significant biomass loss. The assessment of neurotoxicity via the activity of acetylcholine esterase (AChE) showed no change in AchE due to GLY in all the non-amended treatments. However, in the biochar-amended treatments, statistically high levels of AchE occurred (<i>p</i> < 0.05) even in the control (in the absence of GLY). The assessment of oxidative stress through catalase (CAT) activity, showed similar results with no significant effects of GLY alone on CAT activity, but rather dramatic increases in activity in the control and GLY treatments in the biochar-amended soil, with one significant increase in the 10% amended in 8 mg GLY/Kg (<i>p</i> < 0.05). Such significant increases in both AChE and CAT were only observed in soil amended with 10 and 15% biochar. Our findings show that although seemingly beneficial for whole body endpoints, biomarker responses indicate that a biochar amendment higher than 5% adds considerable additional stress to earthworms and should be avoided. |
| first_indexed | 2024-03-09T20:49:01Z |
| format | Article |
| id | doaj.art-e4b97dd50b384a0193269fc27bb8d7c6 |
| institution | Directory Open Access Journal |
| issn | 2076-3417 |
| language | English |
| last_indexed | 2024-03-09T20:49:01Z |
| publishDate | 2022-02-01 |
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| spelling | doaj.art-e4b97dd50b384a0193269fc27bb8d7c62023-11-23T22:39:49ZengMDPI AGApplied Sciences2076-34172022-02-01125238110.3390/app12052381High Rates of Biochar Soil Amendment Cause Increased Incidences of Neurotoxic and Oxidative Stress in <i>Eisenia fetida</i> (Oligochaeta) Exposed to GlyphosateNomasonto Portia Dlamini0Patricks Voua Otomo1Department of Zoology and Entomology, University of the Free State, Private Bag x13, Phuthaditjhaba 9866, South AfricaDepartment of Zoology and Entomology, University of the Free State, Private Bag x13, Phuthaditjhaba 9866, South AfricaDespite 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 <i>Eisenia fetida</i> 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 (LC<sub>50</sub>) could be computed due to the lack of sufficient mortality, in the absence of biochar, a lethal concentration 10% (LC<sub>10</sub>) of 5.540 mg/kg and a lethal concentration 20% (LC<sub>20</sub>) 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 concentration of 10% (EC<sub>10</sub>) of 5.23 mg/kg and an effective concentration of 20% (EC<sub>20</sub>) of 6.848 mg/kg. In the amended soil, overall, slight non-significant increases in biomass were recorded and no effective concentrations could be calculated due to the lack of significant biomass loss. The assessment of neurotoxicity via the activity of acetylcholine esterase (AChE) showed no change in AchE due to GLY in all the non-amended treatments. However, in the biochar-amended treatments, statistically high levels of AchE occurred (<i>p</i> < 0.05) even in the control (in the absence of GLY). The assessment of oxidative stress through catalase (CAT) activity, showed similar results with no significant effects of GLY alone on CAT activity, but rather dramatic increases in activity in the control and GLY treatments in the biochar-amended soil, with one significant increase in the 10% amended in 8 mg GLY/Kg (<i>p</i> < 0.05). Such significant increases in both AChE and CAT were only observed in soil amended with 10 and 15% biochar. Our findings show that although seemingly beneficial for whole body endpoints, biomarker responses indicate that a biochar amendment higher than 5% adds considerable additional stress to earthworms and should be avoided.https://www.mdpi.com/2076-3417/12/5/2381biochar effectsecotoxicological effectsmechanistic biomarkersherbicide toxicityearthworm ecotoxicology |
| spellingShingle | Nomasonto Portia Dlamini Patricks Voua Otomo High Rates of Biochar Soil Amendment Cause Increased Incidences of Neurotoxic and Oxidative Stress in <i>Eisenia fetida</i> (Oligochaeta) Exposed to Glyphosate Applied Sciences biochar effects ecotoxicological effects mechanistic biomarkers herbicide toxicity earthworm ecotoxicology |
| title | High Rates of Biochar Soil Amendment Cause Increased Incidences of Neurotoxic and Oxidative Stress in <i>Eisenia fetida</i> (Oligochaeta) Exposed to Glyphosate |
| title_full | High Rates of Biochar Soil Amendment Cause Increased Incidences of Neurotoxic and Oxidative Stress in <i>Eisenia fetida</i> (Oligochaeta) Exposed to Glyphosate |
| title_fullStr | High Rates of Biochar Soil Amendment Cause Increased Incidences of Neurotoxic and Oxidative Stress in <i>Eisenia fetida</i> (Oligochaeta) Exposed to Glyphosate |
| title_full_unstemmed | High Rates of Biochar Soil Amendment Cause Increased Incidences of Neurotoxic and Oxidative Stress in <i>Eisenia fetida</i> (Oligochaeta) Exposed to Glyphosate |
| title_short | High Rates of Biochar Soil Amendment Cause Increased Incidences of Neurotoxic and Oxidative Stress in <i>Eisenia fetida</i> (Oligochaeta) Exposed to Glyphosate |
| title_sort | high rates of biochar soil amendment cause increased incidences of neurotoxic and oxidative stress in i eisenia fetida i oligochaeta exposed to glyphosate |
| topic | biochar effects ecotoxicological effects mechanistic biomarkers herbicide toxicity earthworm ecotoxicology |
| url | https://www.mdpi.com/2076-3417/12/5/2381 |
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