Selenium concentration of Finnish foods: Effects of reducing the amount of selenate in fertilizers

The original two supplementation levels of selenium in multinutrient fertilizers (Se 16 and 6 mg kg-1 fertilizer as sodium selenate; started in 1985) were reduced to one (6 mg kg-1 fertilizer) in 1991. The 16 mg supplementation level was intended for use in cereal production. Due to the lowering of the level of Se application, the Se content of spring cereals (spring wheat, oats and barley) has decreased more than that of any other food in the monitoring programme. The present level, 0.1 mg kg-1 for cereal grains, is about 40% of the concentrations common in 1990. The Se concentrations have decreased less in other foods than in cereals. The present Se concentrations in milk products, meat and liver are about 70, 60 and 50%, respectively, of the concentrations in 1990. The average daily human Se intake was 0.08 mg day-1 at an energy level of 10 MJ in 1994. Animal protein is the main source of Se. About 40% of the intake comes from meat, 24% from dairy products and eggs, and 11% from fish

Results of the Finnish selenium monitoring program 2000-2001

In Finland compound fertilizers have been supplemented with selenium (Se) since 1984. In 1998, the Finnish Ministry of Agriculture and Forestry raised the Se supplementation level in fertilizers from 6 to 10 mg Se/kg fertilizer. The most important sources of Se are milk, meat, and milk and meat products, which together cover nearly 70 % of the total Se intake

The intake of inorganic arsenic from long grain rice and rice-based baby food in Finland : Low safety margin warrants follow up

AbstractWe evaluated total and inorganic arsenic levels in long grain rice and rice based baby foods on Finnish market. Inorganic arsenic was analysed with an HPLC–ICP-MS system. The total arsenic concentration was determined with an ICP-MS method. In this study, the inorganic arsenic levels in long grain rice varied from 0.09 to 0.28mg/kg (n=8) and the total arsenic levels from 0.11 to 0.65mg/kg. There was a good correlation between the total and inorganic arsenic levels in long grain rice at a confidence level of 95%. The total arsenic levels of rice-based baby foods were in the range 0.02 – 0.29mg/kg (n=10), however, the level of inorganic arsenic could only be quantitated in four samples, on average they were 0.11mg/kg. Our estimation of inorganic arsenic intake from long grain rice and rice-based baby food in Finland indicate that in every age group the intake is close to the lowest BMDL0.1 value 0.3μg/kg bw/day set by EFSA. According to our data, the intake of inorganic arsenic should be more extensively evaluated

Quality of the ryegrass and lettuce yields as affected by selenium fertilization

The effect of Se-fertilization on the chemical composition and anti-oxidative properties of ryegrass and lettuce was studied in a pot experiment. The addition of Se enhanced its relative incorporation in soluble and insoluble proteins and diminished it in free amino acids. It also affected the anti-oxidative systems of the plants. The glutathione peroxidase (GSH-Px) activity found in both plant species increased with increasing Se-fertilization, whereas the superoxide dismutase (SOD) activity as well as the concentration of vitamin E decreased. This may indicate that the synthesis of SOD and vitamin E was reduced because the requirement of these anti-oxidants was diminished by antioxidative function of Se

Flocculation of dissolved organic matter controls the distribution of iron in boreal estuarine sediments

Iron (Fe) plays a key role in sedimentary diagenetic processes in coastal systems, participating in various redox reactions and influencing the burial of organic carbon. Large amounts of Fe enter the marine environment from boreal river catchments associated with dissolved organic matter (DOM). However, the fate of this Fe pool in estuarine sediments has not been extensively studied. Here we show that flocculation of DOM along salinity gradients in an estuary of the northern Baltic Sea efficiently transfers Fe from the dissolved phase into particulate material that accumulates in the sediments. Consequently, we observe a decline with distance offshore in both the Fe content of the sediments and proportion of terrestrial material in the sedimentary organic matter pool. Mössbauer spectroscopy and sequential extractions suggest that large amounts of Fe in sediments of the upper estuarine zone are associated with organic matter as unsulfidized Fe (II) complexes, or present in the form of ferrihydrite, implying a direct transfer of flocculated material to the sediments. Accordingly, the contribution of these components to the total sedimentary Fe declines with distance offshore while other Fe phases become proportionally more important. Sediment core records show that the observed lateral distribution of Fe minerals has remained similar over recent decades, despite variable Fe inputs from anthropogenic sources and eutrophication of the coastal zone. Pore water data suggest that the vertical zonation of diagenetic processes in the sediments is influenced by both the availability of Fe and by bottom water salinity, which controls the availability of sulfate (SO42−).Output Type: Discussion Pape

Impacts of flocculation on the distribution and diagenesis of iron in boreal estuarine sediments

Iron (Fe) plays a key role in sedimentary diagenetic processes in coastal systems, participating in various redox reactions and influencing the burial of organic carbon. Large amounts of Fe enter the marine environment from boreal river catchments associated with dissolved organic matter (DOM) and as colloidal Fe oxyhydroxides, principally ferrihydrite. However, the fate of this Fe pool in estuarine sediments has not been extensively studied. Here we show that flocculation processes along a salinity gradient in an estuary of the northern Baltic Sea efficiently transfer Fe and OM from the dissolved phase into particulate material that accumulates in the sediments. Flocculation of Fe and OM is partially decoupled. This is likely due to the presence of discrete colloidal ferrihydrite in the freshwater Fe pool, which responds differently from DOM to estuarine mixing. Further decoupling of Fe from OM occurs during sedimentation. While we observe a clear decline with distance offshore in the proportion of terrestrial material in the sedimentary particulate organic matter (POM) pool, the distribution of flocculated Fe in sediments is modulated by focusing effects. Labile Fe phases are most abundant at a deep site in the inner basin of the estuary, consistent with input from flocculation and subsequent focusing. The majority of the labile Fe pool is present as Fe (II), including both acid-volatile sulfur (AVS)-bound Fe and unsulfidized phases. The ubiquitous presence of unsulfidized Fe (II) throughout the sediment column suggests Fe (II)-OM complexes derived from reduction of flocculated Fe (III)-OM, while other Fe (II) phases are likely derived from the reduction of flocculated ferrihydrite. Depth-integrated rates of Fe (II) accumulation (AVS-Fe + unsulfidized Fe (II) + pyrite) for the period 1970-2015 are greater in the inner basin of the estuary with respect to a site further offshore, confirming higher rates of Fe reduction in near-shore areas. Mossbauer Fe-57 spectroscopy shows that refractory Fe is composed largely of superparamagnetic Fe (III), high-spin Fe (II) in silicates, and, at one station, also oxide minerals derived from past industrial activities. Our results highlight that the cycling of Fe in boreal estuarine environments is complex, and that the partial decoupling of Fe from OM during flocculation and sedimentation is key to understanding the role of Fe in sedimentary diagenetic processes in coastal areas.Peer reviewe

Jätevesien ravinteet hyötykäyttöön

Vesihuoltoratkaisuja on muutettava. Uusilla jätevesien ja jätevesilietteen käsittelyn tekniikoilla ravinteet saataisiin talteen nykyistä tehokkaammin ja puhtaampina, ja ne pystyttäisiin hyödyntämään ruuan tuotannossa ja teollisuudessa. Samalla ympäristöhaitat vähenisivät. Ravinteiden talteenotto lisäisi huoltovarmuutta epävarmassa maailmantilanteessa, jossa ravinteiden saatavuus voi entisestään vaikeutua

Enhanced utilization of wastewater nutrients

Water management solutions need to be improved. New technologies in wastewater and sewage sludge treatment would enable more efficient nutrient recovery, allowing them to be utilised in food production and industry due to their greater degree of purity. This would also reduce negative environmental impacts. The recovery of nutrients would increase security of supply in an uncertain world situation, where the availability of nutrients can become even more difficult

Seleenityöryhmän raportti 2016

Suomessa 1970–luvulla tehdyissä tutkimuksissa havaittiin elintarvikkeiden seleenipitoisuuksien olevan erittäin pieniä ja väestön seleeninsaanti jäi selvästi alle saantisuositusten. Taustalla oli seleenin ja erityisesti liukoisen, kasveille käyttökelpoisen seleenin pieni määrä viljelymaissa. Tilanteen korjaamiseksi natriumselenaattia on lisätty moniravinteisiin lannoitteisiin vuodesta 1984 lähtien. Seleenilannoituksen avulla epäorgaaninen lannoiteseleeni muuttuu kasveissa orgaanisiksi seleeniyhdisteiksi, joita ihmiset ja eläimet pystyvät hyödyntämään tehokkaammin kuin epäorgaanista seleeniä. Seleenilannoituksen myötä kotimaisten viljelykasvien ja rehujen ja sitä kautta elintarvikkeiden seleenipitoisuudet ovat kasvaneet. Liukoisen seleenin määrä viljelymaissa ei ole kuitenkaan kasvanut 30 vuoden aikana, sillä Suomen olosuhteissa seleeni muuttuu nopeasti niukkaliukoiseen muotoon. Lannoitteiden kautta maahan vuosittain tuleva seleenilisä tarvitaan kasvien seleenitason ylläpitämiseksi. Viljelykasvien seleenipitoisuus riippuu täysin lannoitteiden seleenitasosta ja seleenipitoisten lannoitteiden käyttömääristä. Väestön keskimääräinen seleeninsaanti on nykyisin sekä koti- että ulkomaisten saantisuositusten mukaista. Tärkeimmät saantilähteet ovat maitotuotteet ja liha, mutta myös kasvisruokavaliosta voidaan saada riittävästi seleeniä. Ihmisen veren seerumin seleenipitoisuus on 2000-luvulla ollut keskimäärin 1,4 µmol l-1, mikä on 60 % suurempi kuin ennen lannoitteiden seleenilisäystä vuonna 1984. Vuonna 2007 tehty lannoittei-den seleenipitoisuuden nosto (10→15 mg kg-1) näkyy seerumista mitatun seleenitason vakiintumi-sena >1,4 µmol l-1 pitoisuuksiin. Seleenilannoitustasoa on muutettu kolme kertaa vuosina 1990, 1998 ja 2007. Muutokset ovat pohjautuneet seleeninsaannissa tapahtuneisiin muutoksiin. Seleenilannoitus on tehokas, turvallinen, edullinen ja toimiva tapa vaikuttaa tuotantoeläinten ja väestön seleeninsaantiin ja sitä kautta kansanterveyteen. Se parantaa eläinten hyvinvointia vähentämällä tarvetta lisätä seleeniä rehuihin sekä vähentämällä tarvetta eläinten seleenilääkintään ja se ehkäisee seleeninpuutossairauksia kuten esim. lihasrappeumaa. Suomen olosuhteissa toimenpide on osoittautunut hyväksi ja turvalliseksi keinoksi vaikuttaa kotieläinten ja väestön seleeninsaantiin. Suunnitelmallisen ja tarkkaan kohdennetun seurannan myötä systeemi on kontrolloitavissa ja seleeninsaannissa tapahtuviin muutoksiin pystytään reagoimaan nopeasti.201

Report of the Selenium Working Group 2022

In Finland selenium has been added to compound fertilizers since 1984. In the background of this action were studies of the low selenium contents of domestic foods and feeds and concern about its negative effects for public health. Climatic and soil conditions increase the conversion of selenium into forms unavailable to plants and selenium fertilization is needed annually to maintain adequate selenium levels in domestic foods and feeds. During the growing season plants convert inorganic fertilizer selenium into organic selenium compounds that humans and animals can utilize more efficiently than inorganic selenium. Already in the growing season 1985 the effects of selenium supplemented fertilization were seen in domestic foods and feeds. Selenium contents increased 3–4-fold. With fertilization selenium concentrations in foods have been at adequate level to maintain the selenium adequate intake which is in accordance with recommendations. Additional selenium supplements are not needed. Selenium intake can be regulated by the amount of selenium in fertilizers (changed in 1990, 1998, 2007, 2013). Reasons behind these revisions were the changes in fertilization practises. Recent years interest towards bio-based fertilizers (BBFs) have increased due to both environmental and economic reasons. Fertilizing Products Regulation provides means for free movement of BBFs within the EU and a way to reduce EU:s dependency on imported mineral fertilizers. Due to various sources of materials for producing BBFs concentrations of selenium varies as well. However, bioavailability of selenium was poor. Changes in the selenium contents of fertilizers affect directly to the selenium intake of the population and selenium concentrations in human serum. 2010s selenium intake was about 0.08 mg/day/10 MJ and the serum selenium level 1.5 µmol/l. Both intake and serum selenium are at good and adequate level. Soluble selenium concentration in cultivated soils has remained about the same low level during the past 37 years despite annual application of selenium supplemented fertilizers. This is probably due to small annual application rates of selenium and its binding to insoluble form and thus requiring annual application to ensure adequate selenium uptake by plants. Selenium fertilization has not affected into amount of soluble selenium in cultivated soils during the 36 years of selenium fertilization. The input through fertilizers is small and during the growing season selenium is transferred into insoluble forms and binds into soil constituents. The selenium concentrations in surface waters and fishes have been at acceptable level. During floods and heavy rains soil erosion can increase selenium input somewhat, but generally selenium fertilization has not affected surface waters or any other environment. However, environmental issues should be followed regular basis