Why analysing microplastics in floodplains matters: application in a sedimentary context.

Microplastics in the environment are a relatively new form of anthropogenic contamination. Right now, the research focus is on the detection of microplastic accumulation in different environmental compartments and understanding the processes that have led to its transport. Detailed information on microplastics in floodplain areas and their distribution in depth are still missing to better understand accumulation points. Therefore, this study presents on the one hand microplastic detection in fluvial sediments from nine sampling sites along a river course. Polymers were determined with infrared spectroscopy and additional sedimentary analysis of the grain size and heavy metal concentration was performed. In total, there was less microplastic in the upper than in the lower river course and slip-off slopes were identified as accumulation hotspots also in deeper sediment layers. Mostly, microplastic particles were detected in fine sediment and heavy metal concentrations along the river were similar to those of microplastics. On the other hand, besides the spatial distribution of microplastics and accumulation in floodplain areas, microplastic analysis offered information in a sedimentary context. Sedimentation rates (0.29-4.00 cm a-1) and patterns between temporal deposition and microplastic polymers were identified. The basis for the development of a dating method by detection of MPs in sediments was thus established. Microplastics as a contaminant provide, in addition to the identification of deposition areas, further data in a temporal and sedimentary perspective.

Canola oil extraction in conjunction with a plastic free separation unit optimises microplastics monitoring in water and sediment.

Microplastics are widely distributed in the environment and to define contamination hot spots, environmental samples have to be analysed by means of cost-as well as time-efficient and reliable standardised protocols. Due to the lipophilic characteristics of plastics, oil extraction as a fast and density-independent separation process is beneficial for the crucial extraction step. It was extensively validated (480 experiments) in two test setups by using canola oil and a cost-effective, plastic-free separation unit with spiked microplastics (19 different polymer types) in the density range from ρ = 11-1760 kg m-3 and in the size range from 0.02-4.4 mm. Thus, an innovative, new method combination was developed and profoundly validated for water and sediment samples using only a short settling time of 15 minutes. Some experiments were also carried out with zinc chloride to obtain additional reference data (particles ≤ 359 µm). The total mean recovery rate was 89.3%, 91.7% within the larger microplastic fraction and 85.7% for the small fraction. Compared to zinc chloride (87.6%), recovery rates differed not significantly with oil (87.1%). Furthermore, size limits were set, since the method works best with particles 0.02 mm ≥d≤ 3 mm. The proposed method exhibits higher efficiency (84.8% for 20-63 µm) for the potentially most harmful microplastic size fraction than the classic setup using brine solution. As a result, oil is a comparably effective separation medium and offers further advantages for separating water and sediment samples due to its density independence, simple and fast application and environmental friendliness. Based on this, a new extraction protocol is presented here that confirms oil separation as a sound and effective separation process in microplastic analysis and identifies previously missing information.

The way of microplastic through the environment - Application of the source-pathway-receptor model (review).

Microplastics in the environment is a highly relevant research topic. However, although more and more studies on environmental concentrations of microplastics are published, a profound risk assessment could not be carried out yet. This is mainly attributable to the fact that the current sampling and analysis methods do not provide a representative picture of the environmental pollution, as the fundamental knowledge about transport processes of microplastic is not present, and the ecotoxicological studies therefore cannot consider the relevant exposures of the organisms. To provide a methodological basis for further research and risk assessments, this paper applies the Source-Pathway-Receptor model to the context of microplastics, whereby the current state of knowledge can be compiled in a structured way and important knowledge gaps can be identified.

Project house water: a novel interdisciplinary framework to assess the environmental and socioeconomic consequences of flood-related impacts.

Protecting our water resources in terms of quality and quantity is considered one of the big challenges of the twenty-first century, which requires global and multidisciplinary solutions. A specific threat to water resources, in particular, is the increased occurrence and frequency of flood events due to climate change which has significant environmental and socioeconomic impacts. In addition to climate change, flooding (or subsequent erosion and run-off) may be exacerbated by, or result from, land use activities, obstruction of waterways, or urbanization of floodplains, as well as mining and other anthropogenic activities that alter natural flow regimes. Climate change and other anthropogenic induced flood events threaten the quantity of water as well as the quality of ecosystems and associated aquatic life. The quality of water can be significantly reduced through the unintentional distribution of pollutants, damage of infrastructure, and distribution of sediments and suspended materials during flood events. To understand and predict how flood events and associated distribution of pollutants may impact ecosystem and human health, as well as infrastructure, large-scale interdisciplinary collaborative efforts are required, which involve ecotoxicologists, hydrologists, chemists, geoscientists, water engineers, and socioeconomists. The research network "project house water" consists of a number of experts from a wide range of disciplines and was established to improve our current understanding of flood events and associated societal and environmental impacts. The concept of project house and similar seed fund and boost fund projects was established by the RWTH Aachen University within the framework of the German excellence initiative with support of the German research foundation (DFG) to promote and fund interdisciplinary research projects and provide a platform for scientists to collaborate on innovative, challenging research. Project house water consists of six proof-of-concept studies in very diverse and interdisciplinary areas of research (ecotoxicology, water, and chemical process engineering, geography, sociology, economy). The goal is to promote and foster high-quality research in the areas of water research and flood-risk assessments that combine and build off-laboratory experiments with modeling, monitoring, and surveys, as well as the use of applied methods and techniques across a variety of disciplines.

A persistent northern boundary of Indian Summer Monsoon precipitation over Central Asia during the Holocene.

Extra-tropical circulation systems impede poleward moisture advection by the Indian Summer Monsoon. In this context, the Himalayan range is believed to insulate the south Asian circulation from extra-tropical influences and to delineate the northern extent of the Indian Summer Monsoon in central Asia. Paleoclimatic evidence, however, suggests increased moisture availability in the Early Holocene north of the Himalayan range which is attributed to an intensification of the Indian Summer Monsoon. Nevertheless, mechanisms leading to a surpassing of the Himalayan range and the northern maximum extent of summer monsoonal influence remain unknown. Here we show that the Kunlun barrier on the northern Tibetan Plateau [~36°N] delimits Indian Summer Monsoon precipitation during the Holocene. The presence of the barrier relocates the insulation effect 1,000 km further north, allowing a continental low intensity branch of the Indian Summer Monsoon which is persistent throughout the Holocene. Precipitation intensities at its northern extent seem to be driven by differentiated solar heating of the Northern Hemisphere indicating dependency on energy-gradients rather than absolute radiation intensities. The identified spatial constraints of monsoonal precipitation will facilitate the prediction of future monsoonal precipitation patterns in Central Asia under varying climatic conditions.