Combining a Standardized Batch Test with the Biotic Ligand Model to Predict Copper and Zinc Ecotoxicity in Soils

Extraction of soil samples with dilute CaCl2 solution in a routinely performed batch test has potential to be used in site-specific assessment of ecotoxicological risks at metal-contaminated sites. Soil extracts could potentially give a measure of the concentration of bioavailable metals in the soil solution, thereby including effects of soil properties and contaminant "aging." We explored the possibility of using a 0.001 M CaCl2 batch test combined with biotic ligand models (BLMs) for assessment of ecotoxicity in soils. Concentrations of Cu2+ and Zn2+ in soil extracts were linked to responses in ecotoxicity tests (microbial processes, plants, and invertebrates) previously performed on metal-spiked soils. The batch test data for soils were obtained by spiking archived soil materials using the same protocol as in the original studies. Effective concentration values based on free metal concentrations in soil extracts were related to pH by linear regressions. Finally, field-contaminated soils were used to validate model performance. Our results indicate a strong pH-dependent toxicity of the free metal ions in the soil extracts, with R-2 values ranging from 0.54 to 0.93 (median 0.84), among tests and metals. Using pH-adjusted Cu2+ and Zn2+ concentrations in soil extracts, the toxic responses in spiked soils and field-contaminated soils were similar, indicating a potential for the calibrated models to assess toxic effects in field-contaminated soils, accounting for differences in soil properties and effects of contaminant "aging." Consequently, evaluation of a standardized 0.001 M CaCl2 batch test with a simplified BLM can provide the basis for an easy-to-use tool for site-specific risk assessment of metal toxicity to soil organisms. Environ Toxicol Chem 2022;00:1-14. (c) 2022 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC

Многоэлектродный емкостной датчик уровня

Материалы XIII Междунар. науч.-техн. конф. (науч. чтения, посвящ. 125-летию со дня рождения П. О. Сухого), Гомель, 22 окт. 2020 г

Carbon and nitrogen pools and fluxes above and below ground in spruce, pine and birch stands in southern Sweden

We synthesised results on soil carbon (C) and nitrogen (N) fluxes and the accumulation of soil organic C and N under adjacent 50-year-old Norway spruce, Scots pine and silver birch stands growing on similar soils and evaluated the different processes involved. C and N budgets were calculated. Spruce stands had larger stocks of C and N in biomass and soil than birch stands, with pine intermediate. The differences in soil stocks were mainly found in the organic layer, whereas differences in the mineral soil were small. The study showed that there is no simple answer to what is causing the differences in soil C and N stocks, because several processes are interacting. Spruce and pine trees had higher biomass and litter production than birch trees, but total litter inputs showed no significant difference between stands, because the rich ground vegetation under pine and birch contributed with substantial litter inputs, in contrast to the poor ground vegetation under spruce. Decomposition rate (per g of C) was markedly higher under birch than under spruce and pine resulting in lower C and N stocks in the organic layer. This effect was amplified by higher abundance and biomass of earthworms, favoured by higher pH and palatable litter under birch. Earthworm bioturbation probably both increased decomposition rate and damaged the ectomycorrhizal network with negative consequences for the formation of mycorrhizal litter and C storage. In conclusion, the direct effects of spruce, pine and birch litter on C and N pools and fluxes were modified by indirect effects of understorey structure, pH and earthworm responses

Processes controlling production and transport of dissolved organic carbon in forest soils

Dissolved organic carbon (DOC) leached from the O horizon of forest soils is a major source of soil organic carbon in the mineral soil, where a major proportion of the organic carbon in forest ecosystems is located. The relative contribution of recent litter and humified organic matter to the leaching of DOC from the O horizon is still being debated. In the present work, I studied the sources of DOC leached from the O horizon by manipulating the amounts of litter and humus and measuring DOC concentrations and fluxes, isotopic composition (13C and 14C) and chemical characteristics (measured by NMR, UV absorbance and fractionation into hydrophilic and hydrophobic compounds). A computer model (DyDOC) was used to simulate the DOC leaching processes. Furthermore, DOC was measured at different soil moisture conditions at three sites along a climate gradient in Sweden. In addition, 14C measurements of DOC were made at two of these sites to reveal the fate of the DOC leached from the O horizon. I concluded that about half or more of the DOC leached from recent litter is lost during passage through the O horizon. Despite this, both recent litter in the Oi horizon and more humified organic matter in the Oe and Oa horizons contribute significantly to the DOC leaving the O horizon, but with the major proportion coming from the Oe and Oa horizons. To successfully model DOC leaching, the DyDOC model had to be modified to allow DOC to also be leached from recent litter. Measurements along the climatic gradient showed that the concentration and fluxes were highest in the south and lowest in the north. I suggest that these differences can be related to differences in net primary production. Both differences in mean annual temperature and the gradient in nitrogen status from south to north contribute to this effect of net primary production. Soil moisture had no effect on DOC leaching out of the O horizon. The DOC concentration in the B horizon, which is a sink for DOC, is largely governed by the physical and chemical properties of the mineral soil. The 14C measurements showed that the major proportion of the DOC in the B horizon is derived from the carbon stored in the mineral soil itself, rather than in the O horizon, suggesting extensive exchange of DOC by sorption/desorption processes in the mineral soil

Dissolved organic carbon and nitrogen leaching from Scots pine, Norway spruce and silver birch stands in southern Sweden

The effects of three common tree species – Scots pine, Norway spruce and silver birch – on leaching of dissolved organic carbon and dissolved nitrogen were studied in an experimental forest with podzolised soils in southern Sweden. We analyzed soil water collected with lysimeters and modeled water fluxes to estimate dissolved C and N fluxes. Specific UV absorbance (SUVA) was analyzed to get information about the quality of dissolved organic matter leached from the different stands. Under the O horizon, DOC concentrations and fluxes in the birch stands were lower than in the spruce and pine stands; annual fluxes were 21 g m-2 y-1 for birch and 38 g m-2 y-1 and 37 g C m-2 y-1 for spruce and pine, respectively. Under the B horizon, annual fluxes for all tree species ranged between 3 and 5 g C m-2 y-1, implying greater loss of DOC in the mineral soil in the coniferous stands than in the birch stands. We did not find any effect of tree species on the quality of the dissolved organic matter, as measured by SUVA, indicating that the chemical composition of the organic matter was similar in leachates from all three tree species. Substantial amounts of nitrogen was leached out of the soil profile at the bottom of the B horizon from the pine and birch stands, whereas the spruce stands seemed to retain most of the nitrogen in the soil. These differences in N leaching have implications for soil N budgets

Spreading of TBT from marinas

Syftet med föreliggande uppdrag var att ta fram data för att på en övergripande nivå börja täta de kunskapsluckor som identifierats i t.ex Bengtsson & Wernersson (2012) och SGI (2018), genom att undersöka spridningen av aktiva substanser i båtbottenfärger från markområden till och inom en ytvattenrecipient. Uppdraget är tänkt att utgöra en grund för en större forskningsinsats, där spridningsvägar för TBT ska kunna undersökas. Ett mål med projektet är också att etablera en fältlokal som kan användas som test-site för fortsatt forskning om spridning av TBT och andra föroreningar kopplade till båtuppställningsplatser. Sådan forskning kan i förlängningen generera kunskap som behövs som grund för förbättrade riskbedömningar och därmed väl underbyggda beslut om åtgärder av TBT-förorenade områden

Förbättrad skattning av typhalter av N och P från skogs- och myrmark i södra Sverige införPLC6 – kan modeller baserade på kNN-data användas?

Inom PLC5 beräknades typhalterna för kväve (N) och fosfor (P) i avrinningen från skog i norra Sverige utgående från deras höjdberoende, medan de oorganiska fraktionerna hanterades som konstanter. För södra Sverige användes typhalter baserade på medianvärden uppmätta i ett antal vattendrag med skog och myr som dominerande markslag i avrinningsområdet. Den enda skogsskötselåtgärd som man tog hänsyn till var hyggen. För N baserades hyggestyphalterna på ett samband med Nnedfallet och uppmätta halter i markvatten i södra Sverige. I norra Sverige skattades hyggestyphalten genom att multiplicera skogstyphalten med faktorn 2. För fosfor multiplicerades på samma sätt skogstyphalten med en faktor för att erhålla en hyggestyphalt. Inom ramen för tre tidigare SMED-projekt (SMED rapport nr 52:2011, SMED rapport nr 100:2011, SMED rapport nr 109:2012) har halterna av kväve (N) och fosfor (P) i avrinningen från skogs- och myrmark studerats genom mätningar i bäckvatten vid utloppet av ca 200 slumpmässigt utvalda små avrinningsområden i Dalälven och sydvästra Sverige (Viskan, Ätran, Nissan och Lagan). I dessa tidigare projekt har skogstillståndet (tillväxt, biomassa, trädslag etc.) klassificerats genom analyser baserade på metoden Probilistic Classifier och data från satellitbilder och Riksskogsinventeringen (RIS). Modeller har därefter skapats för att skatta typhalterna för N och P. Dessa modellers förklaringsgrad var betydligt högre än de som användes inom PLC5. Mätdata från de slumpade vattendragen visade också att PLC5 typhalterna påtagligt underskattade halterna N och P i sydvästra Sverige. Inför PLC6 föreligger det därför ett behov att förbättra N och P typhalterna från skog och myr särskilt i södra Sverige. Skogstillståndet klassat med Probilistic Classifier metoden saknas för stora delar av landet, vilket innebär att förbättrade typhalter inte kan tas fram till PLC6 för dessa områden. I detta projekt har vi därför använt rikstäckande geografiska data från kNN-Sverige och Lantmäteriet för att beskriva skogstillståndet. kNN-Sverige är en annan metod för att karaktärisera skogstillståndet och även den baseras på satellitbilder och RIS-data. Med hjälp av dessa allmänt tillgängliga data över skogstillståndet har kväveoch fosforhalterna i avrinningen från skogs- och myrmark i södra Sverige, söder om Siljan, modellerats för fyra årstider. Validering av modellresultaten har därefter skett mot 22 vattendrag i södra Sverige som ingår i nationell och regional miljöövervakning samt Skogsstyrelsens skogsmarkskalkningsprojekt (SKOKAL). Resultaten av analyserna visar att data för skogstillståndet baserat på kNN inte tillför någon väsentlig information till modelleringen. De viktigaste förklarande variablerna var istället geografiska koordinater (nordlig och ostlig koordinat samt höjd över havet) och andelen skog och myr i avrinningsområdet. Baserat på modeller utan kNN-data som förklaringsvariabler visade sig modelleringen fungera relativt bra för total-N med R 2 mellan 0,22 och 0,46 för de slumpmässigt utvalda bäckarna i kalibreringsdatasetet och R 2 mellan 0,11 och 0,51 för de 17 bäckarna med data för total-N i testdatasetet. För total-P fungerade modelleringen sämre, med R 2 mellan 0,04 till 0,27 för kalibreringsdatasetet och förklaringsgrad nära noll för testdatasetet (22 bäckar). Med de nya modellerna skedde dock i många fall en viss överskattning av koncentrationerna av både kväve och fosfor i vattendragen i testdatasetet. Orsaken är sannolikt vattnets längre omsättningstid i de senare, vilket innebär större potential för retention av N och P. Baserat på modeller utan kNN-data som förklaringsvariabler beräknades nya N- och P-koncentrationer för PLC5-delavrinningsområden. I genomsnitt är de nya koncentrationsskattningarna högre än de som användes i PLC5, framför allt i låglänta områden i sydligaste Sverige. De nya typhalterna för N är bättre än de som användes i PLC5 och kan användas i södra Sverige (söder om Siljan) för PLC6. I sydost är N-typhalterna osäkra p.g.a. avsaknad av vattenkemisk data från slumpmässigt utvalda småbäckar. Där bör nya studier initieras för att verifiera modellernas giltighet. De modellerade typhalterna för P bör inte användas för PLC6 p.g.a. låg precision i skattningarna.In PLC5, the type concentrations for nitrogen (N) and phosphorus (P) in discharge from forest land in northern Sweden were estimated from their relations to altitude, while the inorganic fractions were handled as constants. For southern Sweden, the type concentrations were based on median values obtained from measurements in a number of streams with forests and wetlands as dominating land cover in the catchment. The only forest operation taken into account was clear-felling. In southern Sweden, the N type concentration from clear-felling was based on the relation between N deposition and the N concentration in soil water. In northern Sweden the N type concentration was obtained by multiplying the forest type concentration with a factor of 2. For P, the type concentration from clearfelling was obtained in a similar way by multiplying the forest type concentration with a factor. In earlier SMED projects (SMED report no 52:2011, SMED report no 100:2011, SMED report no 109:2012), nitrogen and phosphorus concentrations in runoff from forest land and wetlands have been studied by measurements in stream water in about 200 randomly selected small forest and wetland dominated catchments. In these earlier projects forest status (increment, biomass, tree species etc. was classified by the Probabilistic Classifier method and data from satellite images and the national forest inventory (NFI). Thereafter, models have been created to estimate the N and P type concentrations. The explanatory power of these models was much higher compared with those used for PLC5. Additionally, the data from the randomly selected streams showed that the PLC5 type concentrations tangibly underestimated the N and P concentrations in southwest Sweden. For PLC6, there is a need of improved N and P type concentrations from forest land and wetland, especially in southern Sweden. Forest data based on the Probilistic Classifier method do not exist from large areas of Sweden, which implies that improved PLC6 type concentrations cannot be developed for these regions. In this project we have therefore used nationally covering geographic information from kNNSverige and Lantmäteriet to describe forest status. kNN-Sverige is another method for characterizing forest status and it is also based on satellite and NFI data. These publically available forest status data were used to model nitrogen and phosphorus concentrations in runoff from forest land and wetland in southern Sweden south of Lake Siljan during four seasons. The models were validated against independent data from 22 streams in southern Sweden. This data originate from national and regional monitoring and the Swedish Forest Agency forest soil liming project (SKOKAL). It was found that forest status based on kNN-data did not add any significant information to the models. The most important explanatory variables were instead geographic coordinates (longitude, latitude, altitude) and the proportion of forests and wetlands in the catchment. Based on models without kNN-data as explanatory variables, the modeling was relatively successful for total N with R2 between 0.22 and 0.46 for the randomly selected streams and R2 between 0.11 and 0.51 for the 17 streams with data on total-N in the test dataset. For total P modeling was less successful with R2 between 0.04 and 0.27 for the calibration dataset and R2 close to zero for the test dataset. For the strams in the test dataset, the new models overestimated the N and P concentrations in many cases. This may be explained by longer water residence time in these systems, which creates prerequisites for larger N and retention. Based on models without kNN-data as explanatory variables, calculations of new N and P type concentrations were made for the PLC5 sub-catchments. On average, the new estimates of concentrations are higher than those used in PLC5, especially in low elevation areas in southernmost Sweden. The new N concentrations are better than those used in PLC5 and can be used for southern Sweden (south of lake Siljan) in PLC6. In southeast, the modeled N concentrations are less certain due to lack of water chemical data from randomly selected streams. Such studies should be initiated in order to validate the model estimates. The modeled P concentrations should not be used for PLC6 due to low accuracy in the estimates