Summary We assessed the influence of agricultural land use on aquatic–terrestrial linkages along streams arising from changes in the emergence of aquatic insects. We expected that terrestrial predators would respond to a change in the abundance and/or the size structure of the emerging aquatic insects by an increase or decrease in population size. We measured the flux of emergent aquatic insects and the abundance of terrestrial invertebrate predators and birds along 10 streams across a forest‐to‐agriculture land‐use gradient. We also performed stable isotope analyses (hydrogen, carbon and nitrogen) of terrestrial invertebrate predators. Small aquatic insects (Nematocera) were most abundant under agricultural land use, whereas larger bodied aquatic insects (Plecoptera and Trichoptera) were more associated with forest land use. Carabid beetles and linyphiid spiders were associated with agricultural streams (where there was a high abundance of small aquatic insects), whereas lycosid spiders and birds were associated with forest streams and a high abundance of large‐sized aquatic insects. The contribution of aquatic insects to the diets of riparian Lycosidae, Linyphiidae and Carabidae was estimated to be 44%, 60% and 43%, respectively, indicating the importance of aquatic subsidies to the terrestrial system. Our results show that agricultural land use in an overall forested landscape can have significant effects on the abundance and diet of terrestrial consumers through its impact on the size structure of the assemblage of emerging insects, rather than the overall magnitude (numbers) of the aquatic subsidy. Hence, our results suggest that the composition, not just quantity, of a cross‐habitat resource may influence the recipient system.

Land use is known to alter the nature of land–water interactions, but the potential effects of widespread forest management on headwaters in boreal regions remain poorly understood. We evaluated the importance of catchment land use, land cover, and local stream variables for macroinvertebrate community and functional trait diversity in 18 boreal headwater streams. Variation in macroinvertebrate metrics was often best explained by in-stream variables, primarily water chemistry (e.g. pH). However, variation in stream variables was, in turn, significantly associated with catchment-scale forestry land use. More specifically, streams running through catchments that were dominated by young (11–50 years) forests had higher pH, greater organic matter standing stock, higher abundance of aquatic moss, and the highest macroinvertebrate diversity, compared to streams running through recently clear-cut and old forests. This indicates that catchment-scale forest management can modify in-stream habitat conditions with effects on stream macroinvertebrate communities and that characteristics of younger forests may promote conditions that benefit headwater biodiversity.Electronic supplementary materialThe online version of this article (doi:10.1007/s13280-016-0837-y) contains supplementary material, which is available to authorized users.

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Microplastics (plastic particles < 5 mm) is a pollution of growing concern. Microplastic pollution is a complex issue that requires systematic attempts to provide an overview and avoid management solutions that have marginal effects or only move the pollution problem. Substance flow analysis (SFA) has been proposed as a useful tool to receive such an overview and has been put forward as valuable for substance management. However, as the research on microplastics has only emerged recently, detailed and reliable SFAs are difficult to perform. In this study, we use three SFA studies for three pollutants (cadmium, copper and pharmaceuticals) to compare flows and strategies to control the flows. This in order to seek guidance for microplastic management and evaluate potential strategies for controlling microplastics. The analysis shows that there has been rigorous control on different levels to abate pollution from cadmium, copper and pharmaceuticals, but where in the system the major control measures have been carried out differ. For microplastics, there are many potential solutions, both in terms of preventive actions and treatment depending on the type of source. When forming management plans for microplastics, the responsibility for each measure and the impact on the whole urban system should be taken into consideration as well as which receiving compartments are particularly valuable and should be avoided.

Microplastics are omnipresent in the environment, and wastewater treatment plants (WWTPs) have been highlighted as a transport pathway. The aim of this study is to contribute to increased understanding of microplastic sources in wastewater and test the possibilities of source tracking. Previous research has focused either on estimating microplastic contribution from various sources or on quantifying occurrence based on measurements. In this paper, these two approaches are compared. Microplastic types detected in the influent to a WWTP in Sweden are compared with estimations of sources in the WWTP catchment area. The total load from the identified sources was estimated to 1.9–14 tonnes/year, and the measurement-based load was 4.2 tonnes/year. In general, there was a good agreement between the two approaches; microplastic types with large shares at the inlet also had large contributions in the source estimates. An exception was cellulose acetate, which was not found at the inlet despite a large theoretical contribution. Many uncertainties remain, which lead to large intervals for the source estimates. The comparison can give an indication into which part of the intervals is most likely. Investigating more WWTPs with different characteristics and including particle morphology will further increase the understanding of sources that contribute to the presence of microplastics in wastewater.

With the responsibility for stormwater, drinking water and wastewater, the water and wastewater sector handles a considerable amount of environmental pollution. In Sweden, the sector has developed strategies for reducing and controlling environmental pollution through a practice called 'upstream work'. 'Upstream work' consists of different strategies (e.g. mapping out industries, water sampling in the pipe system and information campaigns to the public) to hinder chemicals and other pollution from reaching the wastewater treatment plant. In this contribution, 'upstream work' is compared to the wider concept of source control to evaluate if there are any aspects of source control that can help develop 'upstream work'. Further, examples of tools, methods and approaches that facilitate source control and 'upstream work' are presented. A tool, method or approach can be used in different parts of the process of controlling environmental pollution and provide assistance with different challenges. Therefore, the efforts/measures are categorized based on which process step they address (identification, quantification, prioritization and control). Further, tools, methods and approaches that can be performed by the water and wastewater sector are highlighted. The categorization provides practical ways to work on controlling environmental pollution for organizations that currently work with source control and/or upstream work and for the organizations that have not started the process yet. Source control can provide insights to develop upstream work, especially for diffusing pollution. By developing 'upstream work' to include the entire urban water cycle, important steps towards a more sustainable urban water management are taken.

Water pollution has long been considered a challenge in urban areas, and new types of pollution are continuously introduced to society. Urban wastewater and stormwater act as transport pathways of pollution from urban areas to receiving waterways. Microplastics are a new type of pollution that is being highlighted as problematic, and the presence of microplastics is widespread in the environment. The knowledge about behaviour, sources and transport pathways is still limited. Still, there have been suggestions for ways to control microplastic pollution. Moreover, many other pollutants have been introduced, and to a various extent controlled, in the urban water system before, which means that there are strategies for pollution control in place.

Wastewater treatment plants (WWTPs) are not designed to handle many harmful substances that are present in the wastewater. The substances can also be transferred to the sewage sludge, which can make it unsuitable as a fertiliser. To alleviate these problems, Sweden has a practice called upstream work (uppströmsarbete) that aims to prevent harmful substances from entering the wastewater via efforts to control the pollution closer to the source. Upstream work has produced positive results in terms of reduced pollution in water and sludge and is seen as an important practice by both practicians and policymakers. In this paper, we investigate the incentives and challenges for upstream work as experienced by practitioners at municipal water utilities. The results show that there are two types of incentives: one related to practical problems and the other related to a perceived responsibility for the wastewater system and for the environment. The challenges were primarily related to an insufficient organisational structure for upstream work, manifested in unclear responsibilities, lack of prioritisation, and insufficient resources. The findings can be used to expand and initiate pollution control upstream of the WWTP as part of the urban water management, as well as decision support for policymakers.