Studies on microplastics in soils is currently being established as a new research field. So far, mainly 'explorative studies' have been carried out to detect microplastics in different soil environments. To generate a deeper understanding of microplastics dynamics, 'systematic studies' are required. Such research must built on a targeted sampling strategy and considerate fieldwork and sample handling. From literature enquiry, a five‐stage methodological workflow was deduced for studies on microplastics in soils. In the present review, the spatial representation of soils/soilscapes with microplastics in soils research is conceptually and practically assessed. We discuss judgmental, randomized, and metric soil sampling strategies. Then, we explain sample pre‐processing and give a brief overview of methods for microplastics identification and quantification. We conclude that the establishment of the novel field of research 'microplastic dynamics in soils' requires more intensive consideration of soil sampling strategies. As soil is a complex medium and the soilscape is spatially heterogeneous, we highlight systematic sampling strategies as the best possible options for sophisticated research. However, no overall optimum methodology can be defined because the specific strategy must be in line with the particular research question. For all studies on microplastics in soils, practical improvement is needed to prevent contamination of soil samples with plastics during sampling and sample pre‐processing.

A geoarchaeological soil phosphorus (P) prospection is used to identify a gate within the prehistoric rampart of the Milseburg hillfort (Hesse, Germany). This study compares the application of a P fractionation scheme and P extraction with ammonium‐oxalate. We hypothesized that oxalate‐extractable P (P‐ox) and the related degree of P saturation (DPS) could replace the more expensive and time‐consuming fractionation schemes for geoarchaeological investigations. Comparing the results, the P fractionation helped to verify the existence of another section of the prehistoric ramparts and to identify the location of a gate within it. It also helped to discover the archaeologically relevant soil depths in the investigated area. This information could not be retrieved from the P‐ox data alone. Soil P‐ox contents and DPS values are relatively unspecific with regard to prehistoric land use. However, DPS at least indicates settled versus unsettled areas. Still, the results of the P fractionation more clearly delineate Iron Age land use areas including settlement, non‐settlement, rampart, and rampart gap (probable gate). Thus, in geoarchaeological contexts, this method seems to be preferable to a singular P‐ox extraction. However, for better results, P‐ox determination could be integrated into a P fractionation scheme.

Climate change is projected to aggravate water quality impairment and to endanger drinking water supply. The effects of global warming on water quality must be understood better to develop targeted mitigation strategies. We conducted water and sediment analyses in the eutrophicated Antrift catchment (Hesse, Germany) in the uncommonly warm years 2018/2019 to take an empirical look into the future under climate change conditions. In our study, algae blooms persisted long into autumn 2018 (November), and started early in spring 2019 (April). We found excessive phosphorus (P) concentrations throughout the year. At high flow in winter, P desorption from sediments fostered high P concentrations in the surface waters. We lead this back to the natural catchment-specific geochemical constraints of sediment P reactions (dilution- and pH-driven). Under natural conditions, the temporal dynamics of these constraints most likely led to high P concentrations, but probably did not cause algae blooms. Since the construction of a dammed reservoir, frequent algae blooms with sporadic fish kills have been occurring. Thus, management should focus less on reducing catchment P concentrations, but on counteracting summerly dissolved oxygen (DO) depletion in the reservoir. Particular attention should be paid to the monitoring and control of sediment P concentrations, especially under climate change.