A state-of-the-art review of environmental behavior and potential risks of biodegradable microplastics in soil ecosystems: Comparison with conventional microplastics

Toxicological risk assessment and sources of heavy metal(loid)s using compositional data analysis, Astore River Basin, Himalaya

Himalayan rivers were observed to be more vulnerable having irregular water flows, flooding, and contamination due to various stresses, including climate change, urbanization, and industrial development. This study investigated the occurrence, sources, ecological, and health-based ramifications for heavy metal(loid)s (HM), i.e., As, Cu, Zn, Co, Pb, Sb, Cr, Cd, Mn, and Ni in the Astore river basin (ARB), Himalayas, Pakistan. Results of HM contamination index (HCI) estimations suggested that 2.43 %, 12.2 %, and 24.4 % of water samples from the Astore and Rupal valleys may pose strong, moderate, and low toxicity risks, respectively. Pb, Cu, and Cd contribute more to the aquatic toxicity than any other HM included in the ecological risk index (ERI) estimations. Children are the most vulnerable age group to health ailments caused by HM. Statistical analyses revealed that geogenic sources mainly contribute to HM, except for Ni and Cr, which are mainly derived from anthropic sources in ARB.

Spatiotemporal evolution of small microplastics in agricultural soils from long-term pig manure application

Long-term application of organic fertilizers serves as a nutrient source in agriculture, yet the contamination of these materials with small microplastics (sMPs, 20-500 μm) remains poorly understood. Research on the accumulation and morphological transformation of sMPs in soils under extended fertilization regimes is currently scarce. This study employed Laser Direct Infrared (LDIR) Spectroscopy to quantify and characterize sMPs in soils subjected to four fertilization regimes: no fertilizer (CK), pig manure (M), nitrogen-phosphorus-potassium (NPK) fertilizer, and a combination of NPK and pig manure (MNPK). Temporal and spatial dynamics of sMPs were assessed across treatments with prolonged organic input. A progressive increase in both the abundance and type of sMPs was detected in pig manure, reaching 21,376 ± 1008 items kg-1 in 2023-an increase of 180 % compared to 1979.The initial soil sMPs concentrations in 1979 were approximately 3000 items kg-1; after 44 years, levels in M and MNPK treatments reached 7183 ± 568 items kg-1 and 5557 ± 329 items kg-1, respectively. Soils receiving pig manure consistently exhibited higher sMPs concentrations than untreated controls. The relatively elevated levels of sMPs suggest in-situ degradation of larger MPs. Except in the CK treatment, sMPs abundance increased with soil depth. Across all fertilization types, particles within the 30-100 μm range comprised over 46 % of total sMPs, indicating a consistent size distribution. The polymer types and composition in pig manure-amended soils mirrored those identified in the manure itself. These results demonstrate that long-term pig manure application markedly elevates soil sMPs concentrations, increasing the potential for sMPs contamination in agricultural systems.

Combined pollution of tetracyclines and microplastics in the aquatic environment: Insights into the occurrence, interaction mechanisms and effects

Tetracyclines, a widely used class of antibiotics, and synthetic plastic products are both prevalent in the environment. When released into water bodies, these pollutants can pose significant risks due to their daily influx into aquatic ecosystems. Microplastics can adsorb tetracyclines, acting as a transport vector that enhances their impact on aquatic species. Understanding the co-exposure effects of microplastics and tetracyclines is crucial. This review comprehensively examines the occurrence and distribution of microplastics and tetracyclines across various environmental contexts. The interactions between these two contaminants are primarily driven by electrostatic interactions, hydrophobic effects, hydrogen bonding, π-π interactions, and others. Factors such as the presence of heavy metals, ions, and dissolved organic matter can influence the adsorption and desorption of tetracyclines onto microplastics. The stability of microplastic-tetracycline complexes is highly dependent on pH conditions. The combined pollution tetracyclines and microplastics leads to negative impacts on marine species. Future research should focus on understanding the adsorption behavior of tetracyclines on microplastics and developing effective treatment techniques for these contaminants in aquatic environments.