Elin Gjengedal

Metal sorption by peat and algae treated peat: kinetics and factors affecting the process.

The article presents a new approach that can be used for the purification of water contaminated by heavy metals. The treatment of peat with microalgae showed to be an effective way of increasing metal uptake by peat. Metal sorption was studied for a multimetal solution containing Cu, Cd, Ni, Zn, Cd, and Pb. Cu and Pb were found to be the metals having the highest affinity to peat. Water hardness has a strong effect on the uptake of borderline metals (Cd, Ni, Zn, Cd) from a solution. The use of algae for peat treatment resulted in less time to reach an equilibrium (24 h vs. 72 h for pure peat), and the effect of water hardness (Ca²⁺) on metal uptake was considerably reduced. Both peat and algal-treated peat were able to take up metals from rather acidic solutions (pH 3.0). pH had less influence on the metal uptake compared with water hardness. The affinity of heavy metals to peat was the following: Pb>Cu>Ni>Cd>Zn>Co. It slightly changed to Pb>Cu>Ni>Cd≈Co≈Zn when the combined sorbent, peat treated with microalga, was applied.

Background levels of some major, trace, and rare earth elements in indigenous plant species growing in Norway and the influence of soil acidification, soil parent material, and seasonal variation on these levels.

Baseline levels of 43 elements, including major, trace, and rare earth elements (REEs) in several native plant species growing in boreal and alpine areas, are presented. Focus is placed on species metal levels at different soil conditions, temporal variations in plant tissue metal concentrations, and interspecies variation in metal concentrations. Vegetation samples were collected at Sogndal, a pristine site in western Norway, and at Risdalsheia, an acidified site in southernmost Norway. Metal concentrations in the different species sampled in western Norway are compared with relevant literature data from Norway, Finland, and northwest Russia, assumed to represent natural conditions. Except for aluminium (Al) and macronutrients, the levels of metals were generally lower in western Norway than in southern Norway and may be considered close to natural background levels. In southern Norway, the levels of cadmium (Cd) and lead (Pb) in particular appear to be affected by air pollution, either by direct atmospheric supply or through soil acidification. Levels of some elements show considerable variability between as well as within plant species. Calcium (Ca), magnesium (Mg), and potassium (K) are higher in most species at Sogndal compared to Risdalsheia, despite increased extractable concentrations in surface soil in the south, probably attributed to different buffer mechanisms in surface soil. Antagonism on plant uptake is suggested between Ca, Mg, and K on one hand and Al on the other. Tolerance among calcifuges to acid conditions and a particular ability to detoxify or avoid uptake of Al ions are noticeable for Vaccinium vitis-idaea.

Apatite–Biotite–Carbonatite (Stjernøy, N-Norway): Potential and Obstacles Regarding a Multinutrient Rock-Fertilizer

Apatite–biotite–carbonatite (ABC) from the Lillebukt alkaline complex (N-Norway) contains 42 wt% calcite, 30% biotite, and 7.5% apatite. Agrochemically, it is lime with a K, P, and Mg nutrient potential. Previous K-fertilizing trials with ABC rock-powder have provided good results, and renewed experiments have started to examine the overall effect of ABC rock-powder on soil and plants.The underlying problems with ABC rock-fertilizer are (i) Potential ecotoxicity of high barium and strontium of up to 15 g/kg, substituting K in biotite and Ca in calcite, respectively. An in situ soil and vegetation study on Stjernoy has shown that Ba-content in plants is related to plant species and Ca in plant. Highest Ba-concentration showed the nitrogen-fixing legume Vicia cracca L., lowest grasses. Strontium follows mainly Ca-content in plants. (ii) Low plant availability of P from magmatic apatite at high pH, when applying whole-rock powder. (iii) To find adequate dry mineral separation methods, in particular, to separate calcite and apatite, with the aim to increase nutrient concentration in possible fertilizer products. Vegetation study, plant and soil experiments, and mineral separation tests will hopefully give a decision base for application of ABC as rock-fertilizer.

Method validation in analytical sciences: discussions on current practice and future challenges

Eurachem held a workshop on method validation in analytical sciences in Gent, Belgium, on 9–10 May 2016. A summary of the working group discussions is provided here. The discussions covered a range of issues concerned with current practice and future challenges in method validation, i.e. setting requirements for a method to be validated; planning validation studies; validation of qualitative and semi-quantitative methods; validation of multi-parameter methods; determination of trueness/bias; assessment of working range; validation in microbiology; and method validation under flexible scope of accreditation. Delegates (129) from 24 different countries and from different backgrounds, e.g. from both public and private laboratories, laboratory associations, accreditation bodies and universities, attended the working groups, thus providing opportunities to collect a variety of views and experiences as well as to identify potential gaps in current guidance and regulations. While the practicalities of assessing method performance characteristics are generally well understood, the issue of setting requirements for those characteristics beforehand is less straightforward. Although a number of documents addressing the principles of method validation are available, guidance on dealing with more complex and ‘non-ideal’ situations, as well as examples of good practice, would be welcomed and greater harmonisation of approaches was deemed necessary. There remains a need for guidance on both the concepts that apply to ‘qualitative’ or ‘nominal’ test methods and on the practical implementation of validation studies in such cases.