Export pathways of biosolid derived microplastics in soil systems - Findings from a temperate maritime climate.

The environmental fate of microplastics (MPs) added to agricultural soils remains poorly understood, particularly regarding their mobility in soils. Here we investigate the potential for MP export from soil to surface waters and groundwater in two agricultural settings with a 20-year history of biosolid treatment. A third site where biosolids had never been applied served as a reference (Field R). The potential for MP export along overland and interflow pathways to surface waters was determined from MP abundances in shallow surface cores (10 cm) along ten down-slope transects (five each for Field A and B), and through MP abundances in effluent from a sub-surface land drain. The risk of vertical MP migration was assessed from 2 m cores, and from MP abundances in groundwater sampled from the core boreholes. XRF Itrax core scanning was conducted on two of the deep cores to capture high-resolution optical and 2-D radiographic imaging. Results suggest limited MP mobility at depths >35 cm, with MPs largely recovered in surface soils characterised by lower compaction. Furthermore, abundances of MPs across the surface cores were comparable, with no evidence of MP accumulations observed. Average MP abundance in the top 10 cm of soil across Field A and B was 365 ± 302 MP kg-1, with 0.3 MP l-1 and 1.6 MP l-1 recovered from the groundwater and field drainpipe water samples, respectively. MP abundances were significantly higher in fields treated with biosolids than in Field R (90 ± 32 MP kg-1 soil). Findings suggest ploughing is the most significant driver of MP mobility in upper soil layers, however the potential for overland or interflow movement cannot be excluded, particularly for fields that may be artificially drained.

Microplastics in Freshwater Biota: A Critical Review of Isolation, Characterization, and Assessment Methods.

Freshwater systems provide key pathways for microplastic (MP) pollution, and although existing studies have demonstrated the susceptibility of freshwater biota to ingestion, translocation, and trophic transfer, specific challenges pertaining to methodological standardization remain largely unresolved, particularly with respect to isolating, characterizing, and assessing MPs. Here, a critical review is performed outlining the challenges and limitations currently faced by freshwater MP researchers, which may well apply across the MP research spectrum. Recommendations are provided for methodological standardization, particularly in MP characterization, quality assurance, and quality control (QA/QC) procedures as well as reporting. Considerations for the assessment of MPs in freshwater biota as a means of improving comparisons between studies are discussed. Technological advancements, including the improvement of laboratory infrastructure for identifying MPs within the smaller size range as well as methodological standardization are essential in providing policy makers with tools and measures necessary to determine the distribution of MPs within freshwater ecosystems, while also allowing for comparability and providing compliance for future monitoring requirements.

Microplastics in brown trout (Salmo trutta Linnaeus, 1758) from an Irish riverine system.

Rivers play an important role in the overall transport of microplastic pollution (1 µm to 5 mm), with fluvial dynamics expected to influence biotic interactions, particularly for fish. So far, there have been few assessments of microplastics in freshwater salmonids. The prevalence (i.e. percentage occurrence) and burden (i.e. abundance per fish) of microplastics were assessed in the gastrointestinal tracts (GITs) and stomach contents (SCs) of 58 brown trout Salmo trutta Linnaeus, 1758 sampled at six sites along the River Slaney catchment in south-east Ireland. Sites were divided into two classifications (high and low exposure) based on proximity to microplastic pollution sources, comprising three sites each. Analysis of biological traits (e.g. fish length) and diet was performed on the same fish to determine possible factors explaining microplastic burden. Microplastics were found in 72% of fish having been recovered from 66% of GITs (1.88 ± 1.53 MPs fish⁻1) and 28% of SCs (1.31 ± 0.48 MPs fish⁻1). Fibres were the dominant particle type recovered from GITs (67%) and SCs (57%) followed by fragments. No difference in median microplastic burden was observed between fish collected in high and low exposure sites. Microplastic burden was unrelated to fish fork length, while microplastic size distribution (100 ≤ 350 µm, 350 µm to ≤ 5 mm) was unrelated to S. trutta age class estimates. Furthermore, microplastic burden was not explained by dietary intake. Though further research is necessary, this study showed the presence of microplastics in wild S. trutta collected from an Irish riverine system, which could have further implications for top-level consumers that feed on the species, including humans. Further analysis is required to determine possible trophic linkages for the species, with respect to microplastics, and to assess the suitability of S. trutta for monitoring microplastics in river systems.

Cost utility evaluation of extracorporeal membrane oxygenation as a bridge to transplant for children with end-stage heart failure due to dilated cardiomyopathy.

BACKGROUND: Extracorporeal membrane oxygenation (ECMO) and cardiac transplantation are recognized to be expensive. METHODS: We performed a cost utility evaluation with a decision model approach, including 75 children with dilated cardiomyopathy. A cohort of patients with end stage heart failure who were offered ECMO bridging was compared with a similar cohort offered only conventional intensive care. Outcome was measured in cost per quality adjusted life year (QALY). RESULTS: Median follow-up was 4.39 years (interquartile range, 1.83-5.74 years), during which 50 children underwent transplantation, 16 had a period of recovery, and 25 died. ECMO bridging was highly effective (hazard ratio, 0.181; 95% confidence interval, 0.067-0.489; p = 0.001) but exceeded conventional criteria for cost-effectiveness. The reference incremental cost-effectiveness ratio (ICER) was pound65,645 per QALY and pound54,284 per life-year gained. Average life expectancy rose from 6.78 to 9.79 years and costs from pound146,398 to pound309,599 per patient with ECMO bridging. The ICER was sensitive to ECMO cost, the long-term transplant survival rate, and quality of life in transplant recipients. CONCLUSIONS: ECMO bridging is effective but expensive. The eligible target population is small, nationally, positively influencing affordability. We strongly support our national policy of mechanical bridge to transplant for suitable children in end stage heart failure. Cost effectiveness could be optimized by: 1) increased availability of organ donors, 2) reduction in mechanical support costs possibly by alternate devices and 3) inclusion of patients most likely to benefit.