Water quality and ecosystem management: Data‐driven reality check of effects in streams and lakes

Abstract

This study investigates nutrient‐related water quality conditions and change trends in the first management periods of the EU Water Framework Directive (WFD; since 2009) and Baltic Sea Action Plan (BASP; since 2007). With mitigation of nutrients in inland waters and their discharges to the Baltic Sea being a common WFD and BSAP target, we use Sweden as a case study of observable effects, by compiling and analyzing all openly available water and nutrient monitoring data across Sweden since 2003. The data compilation reveals that nutrient monitoring covers only around 1% (down to 0.2% for nutrient loads) of the total number of WFD‐classified stream and lake water bodies in Sweden. The data analysis further shows that the hydro‐climatically driven water discharge dominates the determination of waterborne loads of both total phosphorus and total nitrogen across Sweden. Both water discharge and the related nutrient loads are in turn well correlated with the ecosystem status classification of Swedish water bodies. Nutrient concentrations do not exhibit such correlation and their changes over the study period are on average small, but concentration increases are found for moderate‐to‐bad status waters, for which both the WFD and the BSAP have instead targeted concentration decreases. In general, these results indicate insufficient distinction and mitigation of human‐driven nutrient components in inland waters and their discharges to the sea by the internationally harmonized applications of the WFD and the BSAP. The results call for further comparative investigations of observable large‐scale effects of such regulatory/management frameworks in different parts of the world.

Dominant Hydro-Climatic Drivers of Water Temperature, Salinity, and Flow Variability for the Large-Scale System of the Baltic Coastal Wetlands

“…This is an important coastal-marine water environment for the nine countries within the total Baltic Sea catchment area of 1,739,400 km 2 [3]. From this catchment, the Baltic Sea receives a total freshwater discharge of around 480 km 3 /year; this total discharge also carries with it considerable waterborne nutrient loads [19] that depend greatly on the discharge magnitude [20] and its hydro-climatically determined variability and change [21]. Furthermore, the Baltic Sea has a relatively small exchange of sea water through its narrow connection with the North Sea at the Danish Straits [22].…”

Zones of untreatable water pollution call for better appreciation of mitigation limits and opportunities

“…The near-complete lack of phosphorous concentration response (Figure 3b; dashed red line) to the land-surface and surface-water oriented measures is consistent with dominant contributions from subsurface legacy sources, which are not affected by these measures. Such legacy source contributions can also more generally explain failures to meet WFD-related goals in the regional Norrström basin (Andersson, Jarsjö, & Petersson, 2014;Darracq et al, 2008) and elsewhere in Sweden (Destouni et al, 2017).…”

Scenarios of Nutrient-Related Solute Loading and Transport Fate from Different Land Catchments and Coasts into the Baltic Sea

“…Furthermore, the nutrient-related solute release scenarios in this study remain relevant even though the nutrient data used to quantify them are for earlier periods (1984-2000 for the Kalmar case and 1980-1993 for the Vistula case). Since then, nutrient concentrations discharged from Kalmar County have remained stable, or even increased rather than decreased, over the period 2003-2013 (see [45] and specifically the trend data for TP and TN at the Kalmar coast in their figures 7 and 8, respectively). Meanwhile reported flow-normalized nutrient loads at the Vistula coast have been stable for TP (statistically insignificant decrease) and decreasing (statistically significant) for TN over the period 1995-2014 (see [24] and specifically the TP and TN trends in their figures 29 and 28, respectively).…”