Characterizing export of land-based microplastics to the estuary - Part II: Sensitivity analysis of an integrated geospatial microplastic transport modeling assessment of tire and road wear particles.

Integrated models addressing microplastic (MP) generation, terrestrial distribution, and freshwater transport are useful tools characterizing the export of MP to marine waters. In Part I of this study, a baseline watershed-scale MP mass balance model was developed for tire and road wear particles (TRWP) in the Seine watershed. In Part II, uncertainty and sensitivity analysis (SA) methods were used to identify the parameters that determine the transport of these particles to the estuary. Local differential, local range and global first-order variance-based SA identified similar key parameters. The global SA (1000 Monte Carlo simulations) indicated that most of the variance in TRWP exported to the estuary can be apportioned to TRWP diameter (76%), TRWP density (5.6%), the fraction of TRWP directed to combined sewers with treatment (3.9%), and the fraction of TRWP distributed to runoff (versus roadside soil; 2.2%). The export fraction was relatively insensitive to heteroaggregation processes and the rainfall intensity threshold for road surface washoff. The fraction of TRWP exported to estuary in the probabilistic assessment was centered on the baseline estimate of 2%. This fraction ranged from 1.4 to 4.9% (central tendency defined as 25th to 75th percentile) and 0.97% to 13% (plausible upper bound defined as 10th to 90th percentiles). This study emphasizes the importance of in situ characterization of TRWP diameter and density, and confirms the baseline mass balance presented in Part I, which indicated an appreciable potential for capture of TRWP in freshwater sediment.

Characterizing export of land-based microplastics to the estuary - Part I: Application of integrated geospatial microplastic transport models to assess tire and road wear particles in the Seine watershed.

Human and ecological exposure to micro- and nanoplastic materials (abbreviated as MP, < 5 mm) occurs in both aquatic and terrestrial environments. Recent reviews prioritize the need for assessments linking spatially distributed MP releases with terrestrial and freshwater transport processes, thereby providing a better understanding of the factors affecting MP distribution to the sea. Tire and road wear particles (TRWP) have an estimated generation rate of 1 kg tread inhabitant-1 year-1 in Europe, but the fate of this MP source in watersheds has not been systematically assessed. An integrated temporally and geospatially resolved watershed-scale MP modeling methodology was applied to TRWP fate and transport in the Seine (France) watershed. The mass balance considers TRWP generation and terrestrial transport to soil, air, and roadways, as well as freshwater transport processes including particle heteroaggregation, degradation and sedimentation within subcatchments. The per capita TRWP mass release estimate in the Seine watershed was 1.8 kg inhabitant-1 yr-1. The model estimates indicated that 18% of this release was transported to freshwater and 2% was exported to the estuary, which demonstrated the potential for appreciable capture, degradation, and retention of TRWP prior to export. The modeled pseudo-steady state sediment concentrations were consistent with measurements from the Seine watershed supporting the plausibility of the predicted trapping efficiency of approximately 90%. The approach supported the efficient completion of local and global sensitivity analyses presented in Part II of this study, and can be adapted to the assessment of other MPs.

Short-term foraging costs and long-term fueling rates in central-place foraging swans revealed by giving-up exploitation times.

Foragers tend to exploit patches to a lesser extent farther away from their central place. This has been interpreted as a response to increased risk of predation or increased metabolic costs of prey delivery. Here we show that migratory Bewick's swans (Cygnus columbianus bewickii), though not incurring greater predation risks farther out or delivering food to a central place, also feed for shorter periods at patches farther away from their roost. Predictions from an energy budget model suggest that increasing metabolic travel costs per se are responsible. Establishing the relation between intake rate and exploitation time enabled us to express giving-up exploitation times as quitting harvest rates (QHRs). This revealed that net QHRs were not different from observed long-term net intake rates, a sign that the birds were maximizing their long-term net intake rate. This study is unique because giving-up decisions were measured at the individual level, metabolic and predation costs were assessed simultaneously, the relation with harvest rate was made explicit, and finally, short-term giving-up decisions were related to long-term net intake rates. We discuss and conceptualize the implications of metabolic traveling costs for carrying-capacity predictions by bridging the gap between optimal-foraging theory and optimal-migration theory.

[A literature review of equine piroplasmosis after an episode of acute babesiosis in a Dutch Standardbred foal after a stay in Normandy]. / Een literatuuroverzicht van equine piroplasmose naar aanleiding van acute babesiose bij een Nederlands draverveulen na verblijfin Normandië.

Piroplasmosis, a disease endemic to most tropical and subtropical areas, appears to be spreading to more temperate zones. This article gives a review of equine piroplasmosis and describes an acute case of infection with Babesia caballi in a Dutch Standard bred foal after a short stay at a stud in Normandy (France). A 3-month-old stallion foal was presented with lethargy, fever of 41 degrees C, and pale mucosal membranes. Haematology revealed a low packed cell volume (14 l/l) leucytosis (25 G/l) and a high blood urea nitrogen concentration (20.1mmol/l). Infection with B. caballi was diagnosed on the basis of Giemsa staining blood smears and was confirmed by polymerase chain reaction in combination with RLB. Treatment with imidocarb dipropionate and a blood transfusion resolved the haemolytic crisis.