Physical characteristics of microplastic particles and potential for global atmospheric transport: A meta-analysis.

Recent interest in microplastic pollution of natural environments has brought forth samples which confirm the pollutant's omnipresence in a variety of ecosystems. This includes locations furthest removed from human activity. Atmospheric transport and deposition are suspected as the primary transport pathway to these remote locations. The factors most influential on participation in atmospheric transport are yet to be determined. This meta-analysis aims to identify patterns that exist between physical characteristics of microplastic particles and their potential for atmospheric transport. Our review addresses the following questions: Which characteristics of microplastic particles promote atmospheric transport and deposition into remote regions, and how significant are these factors in determining distance transported from their sources? This article analyzes commonly reported physical attributes-- shape, polymer composition and color-- from studies in urban and remote areas. The analysis of 68 studies, composed of data from 2078 samples, shows higher occurrence of microplastic particles in remote samples with fiber shapes, polyester compositions, and red, blue, and transparent colors. This meta-analysis is the first to identify patterns between physical properties of microplastic particles and extent of their participation in atmospheric transport to global remote locations.

Risk classification of contaminated sites - Comparison of the Swedish and the German method.

To classify contaminated sites into different risk classes, many different methods exist in Europe and worldwide. However, no systematic comparison of European risk classification methods has been carried out so far to carve out the advantages and disadvantages of the methods and to homogenize them. To address this research gap, this study aims at comparing the Swedish Method for Inventories of Contaminated Sites (MIFO) with the German Individual Assessment of Contaminated Sites Method (EB) from the Hessian Agency for Nature Conservation, Environment and Geology (HLNUG) regarding the risk class categorization of 51 contaminated sites. The results revealed that with the MIFO 39% fewer contaminated sites are assigned to risk classes 1 and 2 and thus, subject to remediation compared to the EB. Moreover, in comparison to the EB, the MIFO showed a lower comparability, traceability, and a larger room for interpretation, which could be related to the lack of a quantitative approach such as a point or ranking system in the MIFO. Hence, we recommend providing the MIFO and other methods that lack a quantitative approach with a point and/or ranking system, similar to the EB, to increase their objectivity for the risk class categorization of contaminated sites.

Towards critical white ice conditions in lakes under global warming.

The quality of lake ice is of uppermost importance for ice safety and under-ice ecology, but its temporal and spatial variability is largely unknown. Here we conducted a coordinated lake ice quality sampling campaign across the Northern Hemisphere during one of the warmest winters since 1880 and show that lake ice during 2020/2021 commonly consisted of unstable white ice, at times contributing up to 100% to the total ice thickness. We observed that white ice increased over the winter season, becoming thickest and constituting the largest proportion of the ice layer towards the end of the ice cover season when fatal winter drownings occur most often and light limits the growth and reproduction of primary producers. We attribute the dominance of white ice before ice-off to air temperatures varying around the freezing point, a condition which occurs more frequently during warmer winters. Thus, under continued global warming, the prevalence of white ice is likely to substantially increase during the critical period before ice-off, for which we adjusted commonly used equations for human ice safety and light transmittance through ice.