Long-Term (2001–2020) Nutrient Transport from a Small Boreal Agricultural Watershed: Hydrological Control and Potential of Retention Ponds

Agriculture contributes significantly to phosphorus and nitrogen loading in southern Finland. Climate change with higher winter air temperatures and precipitation may also promote loading increase further. We analyzed long-term nutrient trends (2001–2020) based on year-round weekly water sampling and daily weather data from a boreal small agricultural watershed. In addition, nutrient retention was studied in a constructed sedimentation pond system for two years. We did not find any statistically significant trends in weather conditions (temperature, precipitation, discharge, snow depth) except for an increase in discharge in March. Increasing trends in annual concentrations were found for nitrate, phosphate, and total phosphorus and total nitrogen. In fact, phosphate concentration increased in every season and nitrate concentration in other seasons except in autumn. Total phosphorus and total nitrogen concentrations increased in winter as well and total phosphorus also in summer. Increasing annual loading trend was found for total phosphorus, phosphate, and nitrate. Increasing winter loading was found for nitrate and total nitrogen, but phosphate loading increased in winter, spring, and summer. In the pond system, annual retention of total nitrogen was 1.9–4.8% and that of phosphorus 4.3–6.9%. In addition, 25–40% of suspended solids was sedimented in the ponds. Our results suggest that even small ponds can be utilized to decrease nutrient and material transport, but their retention efficiency varies between years. We conclude that nutrient loading from small boreal agricultural catchments, especially in wintertime, has already increased and is likely to increase even further in the future due to climate change. Thus, the need for new management tools to reduce loading from boreal agricultural lands becomes even more acute

Attentional modulation of interhemispheric (a)symmetry in children with developmental language disorder

Publisher Copyright: © 2022, The Author(s).The nature of auditory processing problems in children with developmental language disorder (DLD) is still poorly understood. Much research has been devoted to determining the extent to which DLD is associated with general auditory versus language-specific dysfunction. However, less emphasis has been given to the role of different task conditions in these dysfunctions. We explored whether children with DLD demonstrate atypical interhemispheric asymmetry during the auditory processing of speech and non-speech sounds and whether this interhemispheric balance is modulated by attention. Magnetoencephalography was used to record auditory evoked fields in 18 children (9 to 10 years old), 9 with DLD and 9 with language typical development, during active or passive listening to speech and non-speech sounds. A linear mixed model analysis revealed a bilateral effect of attention in both groups. Participants with DLD demonstrated atypical interhemispheric asymmetry, specifically in the later (185–600 ms) time window but only during the passive listening condition. During the active task, the DLD group did not differ from the typically developed children in terms of hemispheric balance of activation. Our results support the idea of an altered interhemispheric balance in passive auditory response properties in DLD. We further suggest that an active task condition, or top–down attention, can help to regain leftward lateralization, particularly in a later stage of activation. Our study highlights the highly dynamic and interhemispheric nature of auditory processing, which may contribute to the variability in reports of auditory language processing deficits in DLD.Peer reviewe

Plankton metabolism and sedimentation in a small boreal lake — a long-term perspective

Peer reviewe

Mitigating agricultural nitrogen load with constructed ponds in northern latitudes : A field study on sedimental denitrification rates

Constructed agricultural ponds and wetlands can reduce nitrogen loading from agriculture especially in areas where warm climate predominates. However, in cold climate temperature-dependency of microbiological processes have raised the question about the applicability of constructed wetlands in N removal. We measured in situ denitrification rates in a constructed agricultural pond using N-15-isotope pairing technique at ambient light and temperature throughout a year as well as diurnally. The field IPT measurements were combined with a wide set of potentially important explanatory data, including air temperature, photosynthetically active radiation, precipitation, discharge, nitrate plus other water quality variables, sediment temperature, oxygen concentration and penetration depth, diffusive oxygen uptake and sediment organic carbon. Denitrification varied, on average, diurnally between 12 and 314 mu mol N m(-2) h(-1) and seasonally between 0 and 12409 mu mol m(-2) h(-1). Light and oxygen regulated the diel variation of denitrification, but seasonally denitrification was governed by a combination of temperature, oxygen and turbidity. The results indicated that the real N removal rate might be 30-35% higher than the measured daytime rates, suggesting that neglecting the diel variation of denitrification we may underestimate N removal capacity of shallow sediments. We conclude, that by following recommended wetland:catchment - size ratios, boreal agricultural ponds can efficiently remove nitrogen by denitrification in summer and in autumn, while in winter and in spring the contribution of denitrification might be negligible relative to the loading, especially with short residence time.Peer reviewe

The Use of Ribosomal RNA as a Microbial Source Tracking Target Highlights the Assay Host-Specificity Requirement in Water Quality Assessments

Funding Information: We thank Tiina Heiskanen, Tarja Rahkonen, and Tarja Yli-Tuomi for their technical assistance and local health and environment authorities, and communal water supply personnel Jukka Meriluoto, Salla Leppänen, Anu Väänänen, Päivi Rissanen, Katja Ylönen, Hanna Jääskeläinen, and especially Ville Soininen and Inkeri Eronen, who received funding for the work from the North Ostrobothnia Centre for Economic Development, Transport, and the Environment (grant number POPELY/2687/2017), for organizing sample collection. Funding. This research was supported in part by the cities of Kalajoki, Tampere, Kuopio, and the municipal wastewater treatment plants Hämeenlinnan Seudun Vesi Ltd., Nokian Vesi Ltd., and Oulun Vesi Ltd., who provided samples for the study. Further, the work was partially funded by the Regional Council of Häme, grant number 518 HL/106/04.01.01/2018. We acknowledge all of the project partners and collaborators, especially the personnel of HAMK University of Applied Sciences, Hämeenlinnan Seudun Vesi Ltd., the Lammi Biological Station, and Ilkka Hirvonen of Led Future Ltd. Funding Information: This research was supported in part by the cities of Kalajoki, Tampere, Kuopio, and the municipal wastewater treatment plants Hämeenlinnan Seudun Vesi Ltd., Nokian Vesi Ltd., and Oulun Vesi Ltd., who provided samples for the study. Further, the work was partially funded by the Regional Council of Häme, grant number 518 HL/106/04.01.01/2018. We acknowledge all of the project partners and collaborators, especially the personnel of HAMK University of Applied Sciences, Hämeenlinnan Seudun Vesi Ltd., the Lammi Biological Station, and Ilkka Hirvonen of Led Future Ltd. Publisher Copyright: © Copyright © 2021 Rytkönen, Tiwari, Hokajärvi, Uusheimo, Vepsäläinen, Tulonen and Pitkänen.For microbial source tracking (MST), the 16S ribosomal RNA genes (rDNA) of host-specific bacteria and mitochondrial DNA (mtDNA) of animal species, known to cause fecal contamination of water, have been commonly used as molecular targets. However, low levels of contamination might remain undetected by using these DNA-based qPCR assays. The high copy numbers of ribosomal RNA (rRNA) could offer a solution for such applications of MST. This study compared the performance of eight MST assays: GenBac3 (general Bacteroidales), HF183 (human), BacCan (dog), Rum-2-Bac (ruminant), Pig-2-Bac (swine), Gull4 (gull), GFD, and Av4143 (birds) between rRNA-based and rDNA-based approaches. Three mtDNA-based approaches were tested: DogND5, SheepCytB, and HorseCytB. A total of 151 animal fecal samples and eight municipal sewage samples from four regions of Finland were collected for the marker evaluation. The usability of these markers was tested by using a total of 95 surface water samples with an unknown pollution load. Overall, the performance (specificity, sensitivity, and accuracy) of mtDNA-based assays was excellent (95-100%), but these markers were very seldom detected from the tested surface water samples. The rRNA template increased the sensitivity of assays in comparison to the rDNA template. All rRNA-based assays (except Av4143) had more than 80% sensitivity. In contrast, only half (HF183, Rum-2-Bac, Pig-2-Bac, and Gull4) of rDNA-based assays reached this value. For markers targeted to bird feces, the use of the rRNA-based assay increased or at least did not change the performance. Regarding specificity, all the assays had >95% specificity with a DNA template, except the BacCan assay (71%). While using the RNA template for the assays, HF183 and BacCan exhibited only a low level of specificity (54 and 55%, respectively). Further, the HF183 assay amplified from multiple non-targeted animal fecal samples with the RNA template and the marker showed cross-amplification with the DNA template as well. This study recommends using the rRNA-based approach for MST assays targeting bird fecal contamination. In the case of mammal-specific MST assays, the use of the rRNA template increases the sensitivity but may reduce the specificity and accuracy of the assay. The finding of increased sensitivity calls for a further need to develop better rRNA-based approaches to reach the required assay performance.peerReviewe

Organic carbon causes interference to nitrate and nitrite measurements by UV/Vis spectrometers : The importance of local calibration

Compared with sporadic conventional watersampling, continuous water-quality monitoring with opti-cal sensors has improved our understanding of freshwaterdynamics. The basic principle in photometric measure-ments is the incident light at a given wavelength that iseither reflected, scattered, or transmitted in the body ofwater. Here, we discuss the transmittance measurements.The amount of transmittance is inversely proportional tothe concentration of the substance measured. However, thetransmittance is subject to interference, because it can beaffected by factors other than the substance targeted in thewater. In this study, interference with the UV/Vis sensornitrate plus nitrite measurements caused by organic carbonwas evaluated. Total or dissolved organic carbon as well asnitrate plus nitrite concentrations were measured in variousboreal waters with two UV/Vis sensors (5-mm and 35-mmpathlengths), using conventional laboratory analysis re-sults as references. Organic carbon increased the sensornitrate plus nitrite results, not only in waters with highorganic carbon concentrations, but also at the lower con-centrations (< 10 mg C L−1) typical of boreal stream, river,and lake waters. Our results demonstrated that local cali-bration with multiple linear regression, including bothnitrate plus nitrite and dissolved organic carbon, can cor-rect the error caused by organic carbon. However, high-frequency optical sensors continue to be excellent tools forenvironmental monitoring when they are properly calibrat-ed for the local water matrix.Peer reviewe

Responses of zooplankton to long-term environmental changes in a small boreal lake

Peer reviewe

Causal analysis of phytoplankton development in a small humic lake using structural equation modelling

The factors affecting phytoplankton development in a small boreal, dystrophic lake during summer stratification were explored using structural equation models (SEM). Phosphorus had the highest positive impact on phytoplankton, and higher temperatures also enhanced the biomass. Water colour, and to a lesser extent intense zooplankton grazing, restricted phytoplankton biomass. Grazers generally seemed to be ineffective at controlling phytoplankton, however, which could be partly due to the high abundance of Gonyostomum semen (Raphidophyceae), a large motile algae not readily grazed by zooplankton. The importance of water colour, a significant factor in dystrophic lakes, emerged clearer in SEM than from regression models. SEM proved to be an effective and informative technique for exploring the factors affecting phytoplankton development, the role of each variable, and their interactions. Incorporating Bayesian analysis into the traditional SEM enabled a more detailed examination of variation in the variable estimates and possible sources of uncertainty and provided more reliable error estimates. We used total chlorophyll a as a proxy for total phytoplankton biomass, but the results clearly indicated that some of the emerging questions could have been better addressed by separating different phytoplankton groups. Nevertheless, SEM provided new insights from standard data, and we encourage its further applications in aquatic science

Ecosystem responses to increased organic carbon concentration: comparing results based on longterm monitoring and whole-lake experimentation

Recent increases in terrestrial dissolved organic carbon (DOC) concentrations in northern inland waters have many ecological consequences. We examined available data on carbon cycles and food webs of 2 boreal headwater lakes in southern Finland. Basic limnology and catchment characteristics of a pristine lake, Valkea-Kotinen (VK), were monitored over the past 25 years while the lake has undergone browning and DOC increased from similar to 11 to 13 mg L-1. Pronounced changes in the early 2000s represent a regime shift in DOC concentration and color. Lake Alinen Mustajarvi (AM) was manipulated for 2 years by additions of labile DOC (cane sugar), raising the DOC concentration from similar to 10 to 12 mg L-1, but not changing light conditions. The 2 different approaches both revealed increased concentrations and efflux of carbon dioxide (CO2) from the lakes and thus net heterotrophy and changes in the pelagic community structure following an increase in DOC concentration. Long-term monitoring of VK revealed a decline in phytoplankton primary production (PP) along with browning, which was reflected in retarded growth of young (1-2-year-old) perch. In the experimentally manipulated lake (AM), PP was not affected, and the growth of young perch was more variable. The results suggested the importance of a pathway from labile DOC via benthic invertebrates to perch. Although provided with this extra resource, the food chain based on DOC proved inefficient. Long-term monitoring and whole-lake experimentation are complementary approaches for revealing how freshwater ecosystems respond to climate and/or atmospheric deposition-induced changes, such as browning.Peer reviewe