Role of humic substances in agriculture and variability of their content in freshwater lake sapropel

ArticleThe term ‘humic substances’ (HS) refers to a general category of naturally occurring, biogenic, heterogeneous organic substances. They create the most widespread natural organic matter found in sediments, soils and waters. Organic carbon in soil (up to 70%) and peat (up to 90%) usually occurs in the form of HS. HS influence the formation process of fossil fuels, as well as they are involved in the plant nutrition process, have an influence on availability and toxicity of metallic and other elements. Furthermore, HS play a significant role in the global carbon geochemical cycle. Properties and application efficiency of humus depend on the source of HS. Freshwater sapropel is a huge reservoir of HS with superior biological activity, although their total content is lower than in peat. The aim of this paper, firstly, was to present the information about the options of HS in agriculture and their main effects on plant growth. Secondly, determination and characterization of HS content in freshwater lake sapropel was performed as sapropel nowadays becomes a popular natural organic-mineral fertilizer and soil conditioner. Sapropel samples were derived from Lake Pilvelis, Lake Pilcines, Lake Vevers, Lake Liducis and Lake Padelis situated in Eastern Latvia. Investigation of HS content in sapropel is significant for the Baltic States and Northern Europe due to wide distribution and availability of sapropel in freshwater bodies. That promotes a search for new ways of extraction methods and bioeconomically effective utilization of this natural resource, obtainable in economically significant amounts, with high opportunities of its use especially in agriculture. Contemporary agriculture strongly desiderates in new products of high effectivity enhancing soil and crop productivity and quality hand in hand with sustainable development and careful attitude to the nature and surrounding environment, thus, one of the ways how it can be achieved is understanding how, where and how much HS preparations can be applied

Data for: Accumulation of metals and changes in the composition of freshwater lake organic sediments during the Holocene

Distribution of metals in freshwater sediment strata formed during the Holocene in the territory of Latvia has been studied rather insufficiently. Considering the large volume of accumulated organic matter in sediments, studies of the content of metal elements in sediments can help to determine the peculiarities of metal accumulation process in limnic systems and biogeochemical cycling of metals. Lake Pilvelis, located in the eastern part of Latvia (the northern part of Europe), was selected as the study site. Lake Pilvelis is a small lake of a glacial origin, and more than 90% of its depression is filled with organic-rich sediments, such as gyttja or freshwater sapropel, with an average thickness of 450 cm. Development stages of Lake Pilvelis since circa 10 000 cal BP are described in detail by means of reconstruction of the Holocene palaeoenvironmental conditions in the lake using multiproxy sedimentary records. This study represents analysis of the elemental composition and content of metallic elements in gyttja with the main target to characterise the accumulation rate of metals in a full profile of gyttja and to determine the anthropogenic impact depending on the evolution of the lake and genesis of sediment organic matter. Correlation among the components characterising such sediments as gyttja and metallic elements showed element distribution into three main groups according to the content of organic or mineral compounds. The principal component analysis revealed four main impact factors indicating the origin of metallic elements and the accumulation tendencies of metals in sediment layers

Data for: Accumulation of metals and changes in the composition of freshwater lake organic sediments during the Holocene

Distribution of metals in freshwater sediment strata formed during the Holocene in the territory of Latvia has been studied rather insufficiently. Considering the large volume of accumulated organic matter in sediments, studies of the content of metal elements in sediments can help to determine the peculiarities of metal accumulation process in limnic systems and biogeochemical cycling of metals. Lake Pilvelis, located in the eastern part of Latvia (the northern part of Europe), was selected as the study site. Lake Pilvelis is a small lake of a glacial origin, and more than 90% of its depression is filled with organic-rich sediments, such as gyttja or freshwater sapropel, with an average thickness of 450 cm. Development stages of Lake Pilvelis since circa 10 000 cal BP are described in detail by means of reconstruction of the Holocene palaeoenvironmental conditions in the lake using multiproxy sedimentary records. This study represents analysis of the elemental composition and content of metallic elements in gyttja with the main target to characterise the accumulation rate of metals in a full profile of gyttja and to determine the anthropogenic impact depending on the evolution of the lake and genesis of sediment organic matter. Correlation among the components characterising such sediments as gyttja and metallic elements showed element distribution into three main groups according to the content of organic or mineral compounds. The principal component analysis revealed four main impact factors indicating the origin of metallic elements and the accumulation tendencies of metals in sediment layers.THIS DATASET IS ARCHIVED AT DANS/EASY, BUT NOT ACCESSIBLE HERE. TO VIEW A LIST OF FILES AND ACCESS THE FILES IN THIS DATASET CLICK ON THE DOI-LINK ABOV

Trace element concentration and stable isotope ratio analysis in blueberries and bilberries:a tool for quality and authenticity control

Abstract Vaccinium genus berries—wild bilberries (Vaccinium myrtillus L.) and cultivated highbush blueberries (Vaccinium corymbosum L.)—are consumed worldwide, and their consumption has a trend of stable increase. Thus, considering their wide use in ethnomedicine, for juice and jam production, as functional food, as well as their use in preparations of extracts which have application potential in pharmaceutical and cosmetics industries, studies regarding the composition of these berries are of special importance. The aim of this study is to characterise the elemental and isotopic composition, as well as variation in element concentration in bilberries gathered from different sites in Northern Europe and in commercially available blueberry samples from across the World. Furthermore, our aim was to develop tools for authenticity and quality control of these berries. The elemental composition of berries was analysed using inductively coupled plasma with optical emission detection (ICP-OED), while isotope ratio mass spectrometry (IRMS) was used for the determination of isotope ratio values. The results demonstrated detectable differences between macro- and microelement values in bilberries. IRMS analysis of blueberries revealed significant differences in isotope ratios based on the place of origin, indicating the possibility to use this analytical method for authenticity testing. In none of the samples, pollution was detected, even though there were indications of different growth conditions and geochemical differences affecting bilberry composition