Modelling and visualising trends of extreme values in acidifying variables

The southern regions of Sweden, Norway and Finland are among the areas in Europe most affected by surface water acidification (European Environment Agency, 2016). Since the 1980s, some steps have been taken to contrast this issue, which have contributed to a steady recovery of the water chemistry (Erlandsson et al., 2010). Among others, the Geneva Convention on Long Range Transboundary Air Pollution and its associated protocols have made an important contribution to the reduction of sulfate emissions (ibid.). In addition, monitoring programs have been put in place to detect patterns of acidification, and predict the long-term path to full recovery (European Environment Agency, 2016; Fölster et al., 2014). A number of models have been developed in order to study the long-term trends in the levels of PH and other acidifying variables of relevance (Moldan et al., 2013; Wright and Cosby, 2003). Those models are useful to evaluate the overall trend in the levels of water acidity, and discuss whether the process of recovery is going in the right direction. However, a limitation of those models is that they might overlook the occurrence of episodic acidification, which can have severe impacts on local ecosystems (Baker et al., 1996; Heard et al., 1997; Laudon, 2008). Sudden changes in the levels of acidity can be deadly to a large number of fish species, and undermine long-term biodiversity (ibid.). The purpose of this research is to contribute to fill this knowledge gap, by developing a framework to analyse, graphically and numerically, trends in the occurrence of episodic acidification. By combining the use of generalised additive models and quantile regression, models able to incorporate both seasonal and long-term time trends are developed. Patterns in episodic acidification are then illustrated with the help of visual tools first introduced by von Brömssen et al. (2021)

Characteristics of Membership in Agricultural Cooperatives

Peer reviewe

Temporal trend evaluation in monitoring programs with high spatial resolution and low temporal resolution using geographically weighted regression models

Data from monitoring programs with high spatial resolution but low temporal resolution are often overlooked when assessing temporal trends, as the data structure does not permit the use of established trend analysis methods. However, the data include uniquely detailed information about geographically differentiated temporal trends driven by large-scale influences, such as climate or airborne deposition. In this study, we used geographically weighted regression models, extended with a temporal component, to evaluate linear and nonlinear trends in environmental monitoring data. To improve the results, we tested approaches for station-wise pre-processing of data and for validation of the resulting models. To illustrate the method, we used data on changes in total organic carbon (TOC) obtained in a monitoring program of around 4800 Swedish lakes observed once every 6 years between 2008 and 2021. On applying the methods developed here, we identified nonlinear changes in TOC from consistent negative trends over most of Sweden around 2010 to positive trends during later years in parts of the country

Sammanställning av långsiktiga vattenkemiska förändringar i Mälaren och övergripande analys av möjliga drivvariabler och trender

Mälarens vattenvårdsförbund, SMHI och Norrvatten har under mer än 50 år (1967-2019) samlat in vattenkemiska och meteorologiska data över ett antal viktiga vattenkvalitetsparametrar. Denna unika långa serie användes i denna rapport för att studera vilka signifikanta förändringar över tid som kan urskiljas, vilka som är de viktigaste drivvariablerna och om data kan användas för att dra slutsatser om Mälarens framtida vattenkvalitet i ett förändrat klimat

Fyrisåns avrinningsområde 2020

Under året har provtagning utförts en gång i månaden vid 4 stationer i Fyrisån samt i tillflödena Vendelån, Jumkilsån och Sävjaån. Provtagning och analys har utförts av det ackrediterade kemiska laboratoriet vid institutionen för vatten och miljö, SLU (SWEDAC nr 1208) på uppdrag av Fyrisåns vattenförbund. Utöver detta har under sommaren 2020 provtagning för analys av 12 PFAS-substanser och cirka 80 andra organiska mikroföroreningar utförts vid tre av de ordinarie provtagningsstationerna samt vid fyra tillfälliga stationer, se Tabell 1. Dessa prover har analyserats på POPs-laboratoriet, forskningslaboratoriet för organiska miljöföroreningar, vid institutionen för vatten och miljö, SLU. Resultaten bifogas detta nyhetsbrev. Detta nyhetsbrev innehåller en kortfattad sammanfattning av årets analysresultat

A snapshot of forest buffers near streams, ditches, and lakes on forest land in Sweden – lessons learned

Forest buffers beside surface water can mitigate negative effects of logging. To gain more information on buffer implementation in operational forestry, forest buffers were inventoried during 2018 on 174 harvested and site-prepared compartments traversed by or bordering streams, ditches and lakes in three regions across Sweden 2–4 years after clearcutting. Most of the inventoried stream and ditch reaches were ≤5 m wide. The water reaches were categorized as lakes (n = 16), natural streams (n = 50), modified streams (n = 21) or ditches (n = 87). Forest buffers with 100% shoreline coverage were present along all lake reaches and 55% and 10% of the natural or modified stream and ditch reaches, respectively. Buffers were absent beside 14% of the natural or modified stream reaches and 61% of the ditch reaches. Lake reaches had significantly wider buffers on average than ditch reaches and natural or modified stream reaches. The mean (SE) buffer widths beside lakes, natural or modified stream reaches and ditch reaches across all three regions and shoreline coverage classes were 12 (1.1), 6.6 (0.6) and 1.5 (0.5) m, respectively. The character of the local stream networks (natural or modified streams or ditches) containing each inventoried reach, were assessed using map information and the reaches´ field classifications. This illustrated the difficulty of judging a streams´ character based solely on field inspections of individual reaches on forest land where historic drainage activities have been performed. We recommend that also upstream and downstream conditions should be considered when planning environmental measures to protect surface water bodies