Synchronous variation in water chemistry for 80 lakes in Southern Sweden

Variation in water chemistry was studied in 80 lakes in southern Sweden. The lakes had forest dominated catchments. The length of the time series was 14 years. Synchrony was calculated as Pearsons product moment correlation coefficients for all combinations of lakes, i.e. 3160 lake-pairs. The chemical variables studied were non-marine sulphate (SO₄ ^*), non-marine calcium (Ca^*), absorbance and acid neutralising capacity (ANC). Statistically significant synchrony occurred in 93% of all lake-pairs for SO₄ ^*, and between 58 and 67% for absorbance, Ca^* and ANC. In 70% of all lake-pairs, the synchrony was \s>0.71 for SO₄ ^*, which means that more than half of the variation in one lake could be explained by the variation in the other lake. For absorbance, Ca^* and ANC, about 25% of the lake-pairs had a synchrony \s>0.71. The relatively high synchrony for SO₄ ^* occurred during an overall downward trend in SO₄ ^* concentration.The degree of synchrony in our study was at a level comparable to other studies in northern America and England. However, our study included lakes in a much larger area, with distances of up to 500 km between the lakes, while earlier studies were made on small lake districts with lakes located within approximately 50 km. In contrast to these earlier studies, there was no correlation between synchrony and distance, lake characteristics or catchment characteristics. However, when a small subset of 15 lakes in the southeast of Sweden was selected, such relations were found.     

Analysis of river water samples utilising a prototype industrial sensing system for phosphorus based on micro-system technology

The application of a phosphorus monitoring device based on microsystems technology (MST) to the analysis of river water is presented. An alternative to the standard molybdenum blue method known as the yellow vanadomolybdophosphoric acid method has been very effectively implemented. The method is simple, a reagent and sample are mixed in a 1:1 ratio forming a yellow complex that absorbs strongly below 400 nm in the UV spectrum. The kinetics of the reaction are rapid and sample turnaround is typically 3 min at room temperature. Therefore a very uncomplicated microfluidic design can be adopted. The working wavelength was chosen as 380 nm to coincide with the peak output of a UV-LED narrow bandwidth light source recently developed by Nichia. The limit of detection for the yellow method in the microfluidic system is 0.2 ppm with a dynamic linear range from 0-50 ppm. The method was applied to a measurement of phosphorus in a local river at specific sampling points along its course.     

Vision complements echolocation in an aerial-hawking bat

The northern bat Eptesicus nilssonii normally hunts flying insects in the air using frequency-modulated echolocation calls. It is also known to detect and catch visually conspicuous prey (white moths) hovering low among grass stalks. To overcome the problem with acoustic clutter from the grass, which interferes with target echo detection, the bats make use of visual cues in addition to those of echolocation. We therefore investigated the minimum size of prey that the bats could distinguish by using vision, by presenting the bats with different sized dead and spread moths. We found that vision increased the chance of detection only when the moths had a wingspan of at least 5 cm. Smaller targets were detected using echolocation alone. The mean detection range was 3.5 m, suggesting that the bats need a visual acuity of 49 of arc to detect the prey. This is consistent with results of optomotor response tests and counts of retinal ganglion cells in closely related species. Our results suggest that the visual acuity of Eptesicus bats may not be adequate for prey detection under normal conditions, but that the bats can use vision when the prey is unusually large and conspicuous. The northern bats display a flexibility in prey detection techniques not previously recognised among aerial-hawking bats and they are able to use their full visual capacity in the field.     

Seasonal nitrogen fluxes of the Lena River Delta

The Arctic is nutrient limited, particularly by nitrogen, and is impacted by anthropogenic global warming which occurs approximately twice as fast compared to the global average. Arctic warming intensifies thawing of permafrost-affected soils releasing their large organic nitrogen reservoir. This organic nitrogen reaches hydrological systems, is remineralized to reactive inorganic nitrogen, and is transported to the Arctic Ocean via large rivers. We estimate the load of nitrogen supplied from terrestrial sources into the Arctic Ocean by sampling in the Lena River and its Delta. We took water samples along one of the major deltaic channels in winter and summer in 2019 and sampling station in the central delta over a one-year cycle. Additionally, we investigate the potential release of reactive nitrogen, including nitrous oxide from soils in the Delta. We found that the Lena transported nitrogen as dissolved organic nitrogen to the coastal Arctic Ocean and that eroded soils are sources of reactive inorganic nitrogen such as ammonium and nitrate. The Lena and the Deltaic region apparently are considerable sources of nitrogen to nearshore coastal zone. The potential higher availability of inorganic nitrogen might be a source to enhance nitrous oxide emissions from terrestrial and aquatic sources to the atmosphere.Supplementary InformationThe online version contains supplementary material available at 10.1007/s13280-021-01665-0.     

Does the Coase theorem hold in real markets? An application to the negotiations between waterworks and farmers in Denmark

The Coase theorem depends on a number of assumptions, among others, perfect information about each other's payoff function, maximising behaviour and zero transaction costs. An important question is whether the Coase theorem holds for real market transactions when these assumptions are violated. This is the question examined in this paper. We consider the results of Danish waterworks' attempts to establish voluntary cultivation agreements with Danish farmers. A survey of these negotiations shows that the Coase theorem is not robust in the presence of imperfect information, non-maximising behaviour and transaction costs. Thus, negotiations between Danish waterworks and farmers may not be a suitable mechanism to achieve efficiency in the protection of groundwater quality due to violations of the assumptions of the Coase theorem. The use of standard schemes or government intervention (e.g. expropriation) may, under some conditions, be a more effective and cost efficient approach for the protection of vulnerable groundwater resources in Denmark.     

Occurrence and distribution of PCB metabolites in blood and their potential health effects in humans: a review

In recent years, attention has been directed to chemicals with possible endocrine-disrupting properties. Polychlorinated biphenyls (PCBs) and their metabolites belong to one group of environmental contaminants that have been shown to interact with the endocrine system in mammals, including humans. Although recent developments have been made in terms of determination of PCB metabolites in blood samples, still limited number of studies have been able to elucidate their profiles and toxicological and health effects in humans. This review aims to evaluate and compare the levels of hydroxylated PCBs (OH-PCBs) and methyl sulfone PCBs (MeSO₂-PCBs) in blood and their relationship to parent compounds and also address the potential risks and adverse health effects in humans. Levels of OH-PCBs varied between 0.0002 and 1.6 ng g^?1 w/w in human serum/plasma from the selected literature, correlating well with ∑PCBs. In contrast, ∑OH-PCB/∑PCB ratio in animals did not show a significant correlation, which might suggest that the bioaccumulation plays an even more important role in the concentration of OH-PCBs compared to PCB metabolism. Highest levels of MeSO₂-PCBs were reported in marine mammals with high selectivity retention in the liver. Health effects of PCB metabolites included carcinogenicity, reproductive impairment, and developmental neurotoxicity, being more efficiently transferred to the brain and across the placenta from mother to fetus in comparison to the parent PCBs. Based on the lack of knowledge on the occurrence and distribution of lower chlorinated OH-PCBs in humans, further studies to identify and assess the risks associated to human exposure are essential.     

Modelling atmospheric bulk deposition of Pb,Zn and Cd near a former Pb–Zn mine in West Greenland using transplanted Flavocetraria nivalis lichens

Atmospheric deposition of lead (Pb), zinc (Zn) and cadmium (Cd) was investigated near the former Black Angel Pb–Zn mine in Maarmorilik, West Greenland during 2010–2011. Thalli of the lichen Flavocetraria nivalis were transplanted from an uncontaminated site into sites near the mine and collected the following year. At 20 of the total 21 sites, concentrations of Pb, Zn and Cd were significantly elevated in lichens after 1 year of transplantation compared to initial concentrations. Elevated concentrations were observed within a distance of approx. 20 km from the mining area. Concentrations decreased with increasing distance from the mine and the relation was well described using a power function with a negative exponent (r² = 0.90; 0.83 and 0.83 for Pb; Zn and Cd). To examine the relation between metal concentrations/uptake in lichen transplants and atmospheric bulk deposition, 10 Bergerhoff dust samplers were placed near lichen transplants and samplers and lichens were collected after a 7-weeks exposure period. A significant linear correlation was observed between metal concentrations in lichen transplants and atmospheric bulk metal deposition (r² = 0.94; 0.88 and 0.89 for Pb; Zn and Cd). Combining the results and including an area distribution within a defined metal deposition area, the “annual” deposition of Pb, Zn and Cd as dust was estimated during the 2010–2011 snow-free period (～5 months). The results reveal that 20 years after mine closure, 770 kg Pb, 3700 kg Zn and 24 kg Cd were still being deposited as dust per year (snow-free period only) within a distance of 20 km from the mine.     

Dispersion and bioaccumulation of elements from an open-pit olivine mine in Southwest Greenland assessed using lichens, seaweeds, mussels and fish

This study investigated dispersion and bioaccumulation of mining-related elements from an open-pit olivine mine at Seqi in Southwest Greenland (64°?N) using lichens (Flavocetraria nivalis), seaweeds (Fucus vesiculosus), mussels (Mytilus edulis) and fish (Myoxocephalus scorpius). The mine operated between 2005 and 2009, and samples were taken every year within a monitoring area 0–17 km from the mine during the period 2004–2011. A total of 46 elements were analysed in the samples. After mining began, highly elevated metal concentrations, especially nickel (Ni), chromium (Cr), iron (Fe) and cobalt (Co), were observed in lichens relative to pre-mining levels (up to a factor of 130) caused by dust dispersion from the mining activity. Elevated metal concentrations could be measured in lichens in distances up to ~5 km from the mine/ore treatment facility. Moderately elevated concentrations of Ni and Cr (up to a factor of 7) were also observed in seaweeds and mussels but only in close vicinity (<1 km) to the mine. Analyses of fish showed no significant changes in element composition. After mine closure, the elevated metal concentrations in lichens, seaweeds and mussels decreased markedly, and in 2011, significantly elevated metal concentrations could only be measured in lichens and only within a distance of 1 km from the mine.     

Occurrence and sorption properties of arsenicals in marine sediments

The content of total arsenic, the inorganic forms: arsenite (As(III)) and arsenate (As(V)), the methylated forms: monomethylarsonic acid and dimethylarsinic acid (DMA), trimethylarsenic oxide, tetramethylarsenonium ion and arsenobetaine was measured in 95 sediment samples and 11 pore water samples from the Baltic Sea near the island of Bornholm at depths of up to 100 m. As(III+V) and DMA were detected in the sediment and As(III+V) was detected in the sediment pore water. Average total As concentration of 10.6?±?7.4 mg/kg dry matter (DM) in the sediment corresponds to previously reported values in the Baltic Sea and other parts of the world. Existing data for on-site measurements of sorption coefficients (Kd) of arsenicals in marine and freshwater sediments show large variability from <1 to >1,000 L/kg. In this work, calculated sorption coefficients (Kd and Koc) for As(III+V) showed significant correlation with depth, dissolved oxygen (DO), salinity and sediment classification; for depths <70 m, salinity <11 %, DO >9 mg/L and sand/silt/clay sediments the Kd was 118?±?76 L/kg DM and for depths >70 m, salinity >11 %, DO?<?9 mg/L and muddy sediments the Kd was 513?±?233 L/kg DM. The authors recommend using the found Kd value for arsenic in marine sediments when conditions are similar to the Baltic Sea. At locations with significant anthropogenic point sources or where the local geology contains volcanic rock and sulphide mineral deposits, there may be significantly elevated arsenic concentrations, and it is recommended to determine on-site Kd values.     

Quantification of centimeter-scale spatial variation in PAH, glucose and benzoic acid mineralization and soil organic matter in road-side soil

The aim of the study was to determine centimeter-scale spatial variation in mineralization potential in diffusely polluted soil. To this end we employed a 96-well microplate method to measure the mineralization of ¹⁴C-labeled organic compounds in deep-well microplates and thereby compile mineralization curves for 348 soil samples of 0.2-cm³. Centimeter-scale spatial variation in organic matter and the mineralization of glucose, benzoic acid, and PAHs (phenanthrene and pyrene) was determined for urban road-side soil sampled as arrays (7 × 11 cm) of 96 subsamples. The spatial variation in mineralization was visualized by means of 2-D contour maps and quantified by means of semivariograms. The geostatistical analysis showed that the easily degradable compounds (glucose and benzoic acid) exhibited little spatial variation in mineralization potential, whereas the mineralization was highly heterogeneous for the PAH compounds that require specialized degraders. The spatial heterogeneity should be taken into account when estimating natural attenuation rates.