As we predicted, 2021 was a quiet year for the project due to Covid restrictions, although Filip and Sara still managed to take monthly samples from the catchment outflow where the Anråse river enters the sea. But things look more hopeful for 2022 already, and at the start of February the first synoptic sampling campaign went ahead. This involved visiting the 16 regular sites, plus 24 river mouths draining into the fjord system between Gothenburg and Uddevalla. Filip and Mike went off to sample the regular sites, where everything went to plan, apart from the surprise finding that an entire forest below one of the headwater lakes had been felled (thus making the approach rather more 'interesting'). Whilst Sara and Johanna did the long drive across the islands of Tjörn and Orust to Uddevalla, before returning south along the mainlaind, to sample the river mouths (which included several scenic woodland streams but also some less-pleasant channelised urban rivers). The next synoptic sampling should be in a few months, when the terrestrial work will be complemented by a thorough sampling of the marine waters along the coast and out towards the open sea.
DAEMONS has now been up and running for just over a year. Despite the logistical problems caused by COVID, monthly sampling has gone ahead every month except for April. January 2021 was the final month for the routine sampling programme led by Filip and Sara. There aren’t many daylight hours in January, so head torches were needed for an epic 12 hour field day. There’s also the time-consuming process of collecting lake samples under ice to contend with.
What happens next for DAEMONS? Last year we had planned four seasonal synoptic campaigns to sample fifty lakes and rivers, and fifty coastal locations. They were cancelled due to travel restrictions, and seem unlikely to happen until at least the latter half of 2021. So now we have a window of time to analyse lab and field data, and to start to draft manuscripts. We hope that, sooner or later, circumstances will allow all the project team to make it to the Gårdsjön Research Catchment for sampling and paper writing. Tuesday 8th September was the meeting of the Gårdsjön foundation. Because several of the DAEMONS sampling sites are within the Gårdsjön catchment, Filip attended to present an overview of the project and results so far. The preliminary data show distinct patterns between the four land uses (forest, lake, agriculture, mire), and some degree of consistency within each land use grouping. One clear finding is that the small percentage of agricultural land within the entire Anråse catchment appears to be responsible for a large proportion of phosphorus export. Phosphorus concentrations at the outflow of the Anråse catchment then appear to be a mix of the inputs from the three tributary rivers Rördalsån, Lerån, and Porsån. Of course, these early findings may not hold true for the duration of the project as more sampling takes place and more data are generated, but it’s certainly an encouraging start. The Gårdsjön foundation has been organising scientific meetings, so-called Gårdsjökonferens, held periodically in Stenungsund. Our new DAEMONS results inspired the discussion on organising the next (8th) meeting in spring 2022. The conference theme “From source to the sea” has been discussed, which would fit perfectly for presenting the future DAEMONS results at the meeting. Figure showing box plots of total phosphorus concentration for streams in different land uses (agriculture, forest, mire), lakes, and the four rivers.
In our last blog we discussed a forest fire that had recently burned in the DAEMONS catchment. Last week Filip and Sara went hunting for the burned area but, after 3.5 hrs roaming the woods of Svartedalen nature reserve in the rain, gave up without any success. Subsequent inquiries with the fire brigade shed light on the problem: all media reports had placed the fire in the wrong place! The fire didn’t burn near Måkevatten, but occurred approximately 1.5 km away on the northern shores of Stora Holmevatten. Armed with this new information, Filip and Sara ventured out again and successfully found the fire area.
On the ground the fire burned an area of 300 m x 100 m, running right down to the lake shore. Small trees and shrubs have gone, but the larger pines look set to survive. A cursory investigation suggests that the fire didn’t penetrate too deeply into the soil; Filip and Sara reported that under a few centimeters of burned material was a normal looking FH horizon. They collected several samples from the lake and headwater streams which will be analysed for water chemistry to determine the local impact of the fire. The revised location of the fire means that the only DAEMONS sample sites that could possibly be affected will be the outflows of the Rördalsån and the Anråse. However, considering the small size of the fire, and the large size of the catchment, it seems extremely unlikely that any signal will be detected in the water chemistry. On 4th June a forest fire was reported in Svartedalen nature reserve. The fire was brought under control, but at its peak was several hundred metres wide. This nature reserve is approximately 2km south of the Gårdsjön catchment where several DAEMONS sampling sites are located. It seems likely that these sampling sites will be unaffected, but we plan to visit the area for a closer look during the July sampling round.
The Svartedalen nature reserve lies across a watershed; some of its streams drain east into the Göta älv, but some also drain west into the Rördalsån, one of the three main subcatchments that DAEMONS is studying. The affected area appears to be near the lake of Måkevatten, which drains into the Rördalsån. It is therefore feasible that two DAEMONS sampling sites will be affected: the outflows of the Rördalsån and the Anråse, with possible fire-induced changes in the concentrations of C, N and P. Likely responses into the aquatic system will be a large spike in nitrate concentration, and a lesser spike in phosphorus concentration, coupled with increased sediment release and a possible pulse of sulphate and acidity. Considering the legacy of acid deposition in the area this could have negative effects on lake and stream ecosystems, including fish populations. These aquatic biogeochemical effects will likely began when the first significant precipitation occurs. Members of the DAEMONS team have an interest in wildfire and so we will be keeping a keen eye on the project data and the Svartedalen nature reserve over the next few months. In our first blog we briefly mentioned the monthly water sampling program. This is the core fieldwork behind DAEMONS. Twelve waterbodies are sampled which cover the different land uses in the area (identified as key end members), and the four main rivers within the catchment are also sampled. In this blog we thought we’d give a tour of the sampling sites in virtual form so readers can get a feel for the area. The main catchment is that of the Anråse river. Within this are the three subcatchments of the rivers Rördalsån, Lerån, and Porsån. First up we have three headwater lakes: Stora Hästevatten North, Gaffeln and Svallesjön. Stora Hästevatten North and Gaffeln are both in the well-studied Gårdsjön catchment, which then drains into the Rördalsån. Svallesjön drains into the Lerån. Next we have three headwater streams draining forests: one each for each subcatchment. The forest stream that drains into the Rördalsån is named F1. A nondescript name, but aficionados of research into acidification may recognise it as the reference stream for the famous Gårdsjön roof experiment, where a huge plastic roof was used to cover the G1 subcatchment and prevent rain and throughfall (and therefore acid deposition) from reaching the ground. Two of the mire streams are in the Rördalsån subcatchment, and the third is in the Porsån subcatchment. There’s certainly no shortage of mires in the catchment, and so here we were rather spoiled for choice. In contrast to mire streams, finding headwater streams with a dominant agricultural influence was difficult, as most of the land is forest. One of the agricultural streams is in the Lerån subcatchment, whilst the two others are downstream of the confluence where the Rördalsån, Lerån, and Porsån meet and form the Anråse river. Finally, we have the three rivers of the subcatchments, and then a sampling site in the Anråse river just above the tidal limit before it flows into the Hake Fjord.
DAEMONS kicked off in early 2020, with the first field samples collected in the Anråse river catchment in January. Shortly afterwards the COVID-19 pandemic began, putting a temporary stop to sampling. Despite this, the first stakeholder meeting went ahead as planned on the 15th April, albeit in the virtual, rather than physical world. Present for the meeting were a small but diverse range of stakeholders, with representatives from:
Representing the DAEMONS project team were Filip Moldan, Sara Jutterström and Johanna Stadmark (IVL), Martyn Futter (SLU), and Sofia Hjalmarsson and Lars Johansson (DHI). The team gave an overview of the project, including the aims, scientific background and model simulations of the dispersion of solutes from the river mouth into the fjord system, before the preliminary data were presented from the January, February and March sampling campaigns. The monthly sampling sites cover a range of the main land uses (identified as key end members) present in the Anråse river catchment: agricultural streams, forest streams, mire streams, lakes and river outlets. Total phosphorus concentrations in January for the different lake and stream sampling sites. The two sites with the highest concentrations (LE1.5 and LE2) are agricultural streams. The stakeholder group provided feedback on the early results with particular discussion about high phosphorus levels in some streams: is this diffuse emission from agriculture, or coming from point sources such as septic tanks? A question to investigate in future, and one that could perhaps be answered with extra analyses (e.g. E.coli). There were also requests to include specific lakes in the large-scale synoptic sampling campaigns that are planned quarterly, and to ensure oxygen concentrations were measured. Useful local information was also provided about water treatment works, pumping stations and other relevant people to make contact with. All in all, a very productive first meeting.
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