Histological anomalies and alterations in enzyme activities of the earthworm Glyphidrillus tuberosus exposed to high concentrations of phosphogypsum

Morphophysiological and Histopathological Effects of Ammonium Sulfate Fertilizer on Aporrectodea trapezoides (Dugès, 1828) Earthworm

The present study used the adult earthworm Aporrectodea trapezoides as a bioindicator species to look into the possible dangers of ammonium sulfate (AS) fertilizer. Two complementary toxicity tests were conducted to determine the LC50values, growth rate inhibition, morphological alterations, and histopathological texture of worms. The lethality test included four increasing concentrations of AS fertilizer (ranging from 2500 to 7500 mg/kg of dry soil weight (d.w.)), while sub-lethal concentrations were based on 10%, 30%, 40%, and 50% of the 14-day median lethal concentration (LC50), with a control group included for both tests. The LC(50) values for AS fertilizer were significantly higher at 7 days (4831.13 mg/kg d.w.) than at 14 days (2698.67 mg/kg d.w.) of exposure. Notably, earthworms exhibited significant growth rate inhibition under exposure to various concentrations and time durations (14/28 exposure days). Morphological alterations such as clitellar swelling, bloody lesions, whole body coiling and constriction, body strangulation, and fragmentation were accentuated steadily, with higher concentrations. Histopathological manifestations included severe injuries to the circular and longitudinal muscular layers, vacuolation, muscle layer atrophy, degradation of the chloragogenous tissue in the intestine, collapsed digestive epithelium of the pharynx with weak reserve inclusion, and fibrosis of blood vessels. These effects were primarily influenced by increasing concentrations of fertilizer and time exposure. The study highlights the strong relationship between concentration and exposure time responses and underscores the potential of A. trapezoides earthworms as valuable biological control agents against acidic ammonium sulfate fertilizer. Importantly, this research contributes to the use of such biomarkers in evaluating soil toxicity and the biological control of environmental risk assessment associated with chemical fertilizers.

Toxicity of carbon nanofibers in earthworms (Lumbricus terrestris) naturally infected with Monocystis sp

Although the ecotoxicity of carbon-based nanomaterials (CBNs) is known, the potential effect of carbon nanofibers (CNFs) on edaphic organisms has been insufficiently explored. Thus, we aimed at the ecotoxicity of CNFs (at 10 and 100 mg/kg) in Lumbricus terrestris earthworms naturally infected with Monocystis sp. After 28 days of exposure, treatments did not affect the survival rate. However, we observed a significant loss of body biomass, and Monocystis sp. infection in seminal vesicles was potentiated by exposure to CNFs. Earthworms exposed to CNFs showed a redox imbalance in the seminal vesicle, muscle, and intestine and an alteration in nitric oxide production in these organs. In muscles, we also noticed a significant reduction in AChE activity in earthworms exposed to CNFs. The histopathological analyses revealed the treatments' significant effect on the structures of the different evaluated tissues. Although we did not notice a concentration-response for several of the biomarkers, when taken together and after the application of Integrated Biomarker Response (IBR) and principal component analysis (PCA), we noticed that the response of earthworms to CNFs at 100 mg/kg showed a more significant deviation from the unexposed group. This was mainly determined by inhibiting antioxidant activity in the seminal vesicle, biochemical biomarkers assessed in muscle and intestine, and histomorphometric muscle biomarkers from earthworms exposed to CNFs at 100 mg/kg. Thus, we demonstrate that CNFs increase the parasite load of Monocystis sp. of adult L. terrestris earthworms and induce biochemical and histopathological changes, especially at 100 mg/kg. Our results point to the additional impact these nanomaterials can have on the health of earthworms, signaling the need for greater attention to their disposal and ecotoxicological effects on soil organisms.

Classification of target tissues of Eisenia fetida using sequential multimodal chemical analysis and machine learning

Acquiring comprehensive knowledge about the uptake of pollutants, impact on tissue integrity and the effects at the molecular level in organisms is of increasing interest due to the environmental exposure to numerous contaminants. The analysis of tissues can be performed by histological examination, which is still time-consuming and restricted to target-specific staining methods. The histological approaches can be complemented with chemical imaging analysis. Chemical imaging of tissue sections is typically performed using a single imaging approach. However, for toxicological testing of environmental pollutants, a multimodal approach combined with improved data acquisition and evaluation is desirable, since it may allow for more rapid tissue characterization and give further information on ecotoxicological effects at the tissue level. Therefore, using the soil model organism Eisenia fetida as a model, we developed a sequential workflow combining Fourier transform infrared spectroscopy (FTIR) and matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) for chemical analysis of the same tissue sections. Data analysis of the FTIR spectra via random decision forest (RDF) classification enabled the rapid identification of target tissues (e.g., digestive tissue), which are relevant from an ecotoxicological point of view. MALDI imaging analysis provided specific lipid species which are sensitive to metabolic changes and environmental stressors. Taken together, our approach provides a fast and reproducible workflow for label-free histochemical tissue analyses in E. fetida, which can be applied to other model organisms as well.

Bibliometric analysis of phosphogypsum research from 1990 to 2020 based on literatures and patents

The demand together with the urgency of phosphogypsum (PG) treatment will pose significant challenges for many countries. This research aims to explore the research progress of PG, including basic status, cooperation situation, research fields, and development trends, based on the Web of Science database through bibliometric analysis of publications (articles and patents) from 1990 to 2020. The results show that academic research on PG originated early, but the number of patents grew quickly. China is a global leader in terms of the number of publications and plays a significant role in international cooperation. The knowledge of PG has remained concentrated in the fields of natural radioactivity, cement paste backfilling, soil, crystal morphology, and synthetic gas. However, academic hotspots focus on the microstructure of chemical processes and various environmental impacts; patents and hot technologies are based on the production of refractory materials, ceramics, surface materials, cement mortar, and composite materials. The academic frontiers of PG will be centered on exploiting the methods of recovering rare earth elements from PG, the conditions of ion solidification/stabilization in PG, the impact of reaction conditions on product quality, and the reaction mechanism at the micro-level. The frontiers of patents need to focus on the improvement of manufacturing equipment, new wall materials, and chemically modified polymer materials. Envisaging the number of articles and patents to be published in the future, architectural research has a large room for improvement. This paper conducts an in-depth analysis of PG and provides information on the technological development prospects and opportunities, which is helpful for researchers engaged in PG management.

Metagenomic Insights and Genomic Analysis of Phosphogypsum and Its Associated Plant Endophytic Microbiomes Reveals Valuable Actors for Waste Bioremediation

The phosphogypsum (PG) endogenous bacterial community and endophytic bacterial communities of four plants growing in phosphogypsum-contaminated sites, Suaeda fruticosa (SF), Suaeda mollis (SM), Mesembryanthmum nodiflorum (MN) and Arthrocnemum indicum (AI) were investigated by amplicon sequencing. Results highlight a more diverse community of phosphogypsum than plants associated endophytic communities. Additionally, the bacterial culturable communities of phosphogypsum and associated plant endophytes were isolated and their plant-growth promotion capabilities, bioremediation potential and stress tolerance studied. Most of plant endophytes were endowed with plant growth-promoting (PGP) activities and phosphogypsum communities and associated plants endophytes proved highly resistant to salt, metal and antibiotic stress. They also proved very active in bioremediation of phosphogypsum and other organic and inorganic environmental pollutants. Genome sequencing of five members of the phosphogypsum endogenous community showed that they belong to the recently described species Bacillus albus (BA). Genome mining of BA allowed the description of pollutant degradation and stress tolerance mechanisms. Prevalence of this tool box in the core, accessory and unique genome allowed to conclude that accessory and unique genomes are critical for the dynamics of strain acquisition of bioremediation abilities. Additionally, secondary metabolites (SM) active in bioremediation such as petrobactin have been characterized. Taken together, our results reveal hidden untapped valuable bacterial actors for waste remediation.

The forgotten role of toxicodynamics: How habitat quality alters the mite, Oppia nitens, susceptibility to zinc, independent of toxicokinetics

Soil habitat quality is thought to influence metal toxicity via changes in speciation and thereby toxicokinetics. Here, we assessed the toxicokinetic and toxicodynamic effects of habitat quality on mite, Oppia nitens when exposed to zinc (Zn) contaminated soils. Forty-seven soils were ranked into three habitat qualities; high, medium, and low based on biological reproduction of Folsomia candida, Enchytraeus crypticus, and Elymus lanceolatus. From the 47 soils, eighteen soils (comprising of six soils from each habitat quality) were randomly selected and dosed with field relevant concentrations of Zn. Mite survival and reproduction were assessed after 28 days. Total Zn, bioaccessible Zn, Zn bioavailability, Zn body burden, lactate dehydrogenase activity (LDH) and glucose-6-phosphate dehydrogenase (G6PDH) activities of the mites were determined. Zinc toxicity and potency were much less in the high compared to low quality soils and the mites in the high habitat quality soils tolerated higher zinc body burdens (2040 ± 130 μg/g b.w) than the lower habitat quality (1180 ± 310 μg/g b.w). Lower LDH activity (20 ± 2 μU mg^-1) in the high quality soils compared to lower quality soils (50 ± 8 μU mg^-1) suggested that there was less stress in the high habitat quality mites. Despite changes in speciation across habitat qualities, bioavailability of zinc was similar (∼20%) irrespective of habitat quality. Our results suggest that the influence of soil properties on survival is modulated by toxicodynamics rather than toxicokinetics. Restoring habitat quality may be more important for soil invertebrate protection than metal concentration at contaminated sites.

Setal-epidermal, muscular and enzymatic anomalies induced by certain agrochemicals in the earthworm Eudrilus eugeniae (Kinberg)

Eudrilus eugeniae, the vermicomposing worm, is found in considerable numbers in agricultural fields in India due to their eventual transfer through vermimanure. These worms are very often exposed to pesticides, herbicides, chemical fertilisers and other soil amendments. This paper reports the effects of variable concentrations of urea, phosphogypsum (PG), paper mill sludge (PMS) and two organophosphorus agrochemicals, monocrotophos and glyphosate, on certain morphological, histological and biochemical parameters of E. eugeniae. Results indicated setal anomalies, epidermal lesions, clitellar swelling and constriction of the body. Disintegration of connective tissue, vacuolation of dermis and significant alterations in protein, lipid peroxidation levels and activities of lactate dehydrogenase, acetylcholinesterase and catalase have also been observed in the treated worms. It is proposed that setae, connective tissue, protein and enzymes in E. eugeniae could be useful markers to evaluate toxicity due to the test chemicals.