Macroplastic fragmentation in rivers.

The process of macroplastic (>0.5 cm) fragmentation results in the production of smaller plastic particles, which threaten biota and human health and are difficult to remove from the environment. The global coverage and long retention times of macroplastic waste in fluvial systems (ranging from years to centuries) create long-lasting and widespread potential for its fragmentation and the production of secondary micro- and nanoplastics. However, the pathways and rates of this process are mostly unknown and existing experimental data not fully informative, which constitutes a fundamental knowledge gap in our understanding of macroplastic fate in rivers and the transfer of produced microparticles throughout the environment. Here we present a conceptual framework which identifies two types of riverine macroplastic fragmentation controls: intrinsic (resulting from plastic item properties) and extrinsic (resulting from river characteristics and climate). First, based on the existing literature, we identify the intrinsic properties of macroplastic items that make them particularly prone to fragmentation (e.g., film shape, low polymer resistance, previous weathering). Second, we formulate a conceptual model showing how extrinsic controls can modulate the intensity of macroplastic fragmentation in perennial and intermittent rivers. Using this model, we hypothesize that the inundated parts of perennial river channels-as specific zones exposed to the constant transfer of water and sediments-provide particular conditions that accelerate the physical fragmentation of macroplastics resulting from their mechanical interactions with water, sediments, and riverbeds. The unvegetated areas in the non-inundated parts of perennial river channels provide conditions for biochemical fragmentation via photo-oxidation. In intermittent rivers, the whole channel zone is hypothesized to favor both the physical and biochemical fragmentation of macroplastics, with the dominance of the mechanical type during the periods with water flow. Our conceptualization aims to support future experimental and modelling works quantifying plastic footprint of different macroplastic waste in different types of rivers.

Mountains of plastic: Mismanaged plastic waste along the Carpathian watercourses.

Plastic waste poses numerous risks to mountain river ecosystems due to their high biodiversity and specific physical characteristics. Here, we provide a baseline assessment for future evaluation of such risks in the Carpathians, one of the most biodiverse mountain ranges in East-Central Europe. We used high-resolution river network and mismanaged plastic waste (MPW) databases to map MPW along the 175,675 km of watercourses draining this ecoregion. We explored MPW levels as a function of altitude, stream order, river basin, country, and type of nature conservation in a given area. The Carpathian watercourses below 750 m a.s.l. (142,282 km, 81 % of the stream lengths) are identified as significantly affected by MPW. Most MPW hotspots (>409.7 t/yr/km2) occur along rivers in Romania (6568 km; 56.6 % of all hotspot lengths), Hungary (2679 km; 23.1 %), and Ukraine (1914 km; 16.5 %). The majority of the river sections flowing through the areas with negligible MPW (< 1 t/yr/km2) occur in Romania (31,855 km; 47.8 %), Slovakia (14,577 km; 21.9 %), and Ukraine (7492; 11.2 %). The Carpathian watercourses flowing through the areas protected at national level (3988 km; 2.3 % of all watercourses studied) have significantly higher MPW values (median = 7.7 t/yr/km2) than those protected at regional (51,800 km; 29.5 %) (median MPW = 1.25 t/yrkm2) and international levels (66 km; 0.04 %) (median MPW = 0 t/yr/km2). Rivers within the Black Sea basin (88.3 % of all studied watercourses) have significantly higher MPW (median = 5.1 t/yr/km2, 90th percentile = 381.1 t/yr/km2) than those within the Baltic Sea basin (median = 6.5 t/yr/km2, 90th percentile = 84.8 t/yr/km2) (11.1 % of all studied watercourses). Our study indicates the locations and extent of riverine MPW hotspots in the Carpathian Ecoregion, which can support future collaborations between scientists, engineers, governments, and citizens to better manage plastic pollution in this region.

The unknown fate of macroplastic in mountain rivers.

Mountain rivers are typically seen as relatively pristine ecosystems, supporting numerous goods (e.g., water resources) for human populations living not only in the mountain regions but also downstream from them. However recent evidence suggests that mountain river valleys in populated areas can be substantially polluted by macroplastic (plastic item >25 mm). It is unknown how distinct characteristics of mountain rivers modulate macroplastic routes through them, which makes planning effective mitigation strategies difficult. To stimulate future works on this gap, we present a conceptual model of macroplastic transport pathways through mountain river. Based on this model, we formulate four hypotheses on macroplastic input, transport and mechanical degradation in mountain rivers. Then, we propose designs of field experiments that allow each hypothesis to be tested. We hypothesize that some natural characteristics of mountain river catchments can accelerate the input of improperly disposed macroplastic waste from the slope to the river. Further, we hypothesize that specific hydromorphological characteristics of mountain rivers (e.g., high flow velocity) accelerate the downstream transport rate of macroplastic and together with the presence of shallow water and coarse bed sediments it can accelerate mechanical degradation of macroplastic in river channels, accelerating secondary microplastic production. The above suggests that mountain rivers in populated areas can act as microplastic factories, which are able to produce more microplastic from the same amount of macroplastic waste inputted into them (in comparison to lowland rivers that have a different hydromorphology). The produced risks can not only affect mountain rivers but can also be transported downstream. The challenge for the future is how to manage the hypothesized risks, especially in mountain areas particularly exposed to plastic pollution due to waste management deficiencies, high tourism pressure, poor ecological awareness of the population and lack of uniform regional and global regulations for the problem.

Can we distinguish meteorological conditions associated with rockfall activity using dendrochronological analysis? - An example from the Tatra Mountains (Southern Poland).

Rockfall leads to visible changes in mountain areas and as high-magnitude event has geohazard potential and should be monitored. On forested slopes, active rockfall could be identified with high precision from visible anatomical changes in tree-rings. To discern possible rockfall events in the Tatra Mountains, dendrogeomorphologic methods were applied and correlated with meteorological conditions. Field research was carried out on Norway Spruce (Picea abies L. Karst) in the Koscieliska Valley. Rockfall signals (RSs) were obtained from both qualitative (scars and traumatic resin ducts) data and quantitative (growth release and suppression) data. Multiple regression and ANOVA analysis were employed to recognize the meteorological conditions, which cause rockfall activity. Different periods of rockfall activity were observed during the years 1950-2014. The weakest activity was observed during 1950-1970 while after 1970 a continuous increase in rockfall activity was observed in our study. There was a clear peak in the number of RSs recorded per year in 1985. Cumulative precipitation and temperatures for January, March, May, June, July, August, September and October are statistically significant as the periods of the year in which rockfall is activated in the Tatra Mountains. In terms of activity, three different Levels of Rockfall Activity (LoRAs) were recognized and show significant correlation with the meteorological data. Distinguished meteorological control factors determining rockfall explains 53% of the total parameters determining rockfall activity. The complexity of the rockfall process means that a better understanding of local conditions and the possible uncertainties associated with the dendrogeomorphologic method and the quality of the meteorological data is needed.

Atrial fibrillation in outpatients with stable coronary artery disease: results from the multicenter RECENT study.

INTRODUCTION: Atrial fibrillation (AF) frequently coexists with other cardiovascular diseases. OBJECTIVES: The aim of this study was to assess the prevalence of AF in outpatients with stable coronary artery disease (CAD) and to determine clinical and laboratory parameters associated with the higher prevalence of this arrhythmia. In addition, we compared the indications for antithrombotic treatment using the older CHADS2 and the currently used CHA2DS2-VASc scores. PATIENTS AND METHODS: We studied the clinical data of 2578 Polish patients with stable CAD participating in the multicenter RECENT study (age, 65 ±10 years; men, 55%; Canadian Cardiovascular Society class I/II/III+IV, 38%/48%/14%). RESULTS: AF was present in 19% of patients with CAD. Advanced age, longer history of CAD, and concomitant heart failure were independently associated with the higher prevalence of AF (all P <0.05). Among patients with CAD and AF, 73% of the patients required antithrombotic treatment according to the CHADS2 score (≥2), and 94%-according to the CHA2DS2-VASc score (≥2). A CHA2DS2-VASc score of 2 or higher was found in 47% of the patients with a CHADS2 score of 0 and 85% of those with a CHADS2 score of 1. Twenty-one percent of patients with CAD and AF did not have unequivocal indications for antithrombotic treatment according to the CHADS2 score (0-1), while they had strong indications for such treatment on the basis of the CHA2DS2-VASc score (≥2). CONCLUSIONS: AF affects every fifth ambulatory patient with CAD. According to the CHA2DS2-VASc score, almost all patients with CAD and AF require antithrombotic treatment, which may complicate coronary revascularization and related antiplatelet treatment.