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To achieve a sustainable circular economy for wood ash, the reuse of wood ash in agriculture and forestry is important. To evaluate the usability of ash from the combustion of natural as well as waste wood for application as fertilizer, wood fuel and corresponding ash fraction samples (n = 86) of four industrial wood-fired heat and power plants (20 MW) were investigated. In different ash fractions, the concentrations of heavy metals (As, Cd, Pb, Ni, Tl, Zn) and plant nutrients (N, P, K, Ca) were assessed with regard to relevant legislation from the European Union and from selected European countries (Germany, Austria and Finland). Depending on fuel composition and combustion kinetics within the respective plants, the investigated ash fractions showed a wide range of nutrient and heavy metal contents. Apart from N which is mainly emitted with the flue gas, plant nutrients were present in substantial concentrations with mean values corresponding to 20% P, 55 % K and95% Ca content compared to nutrient compound fertilizer. A direct application of most ash fractions from both natural and waste wood combustion is however not possible due to high contents of Cd, Pb and Ni. In order to develop the ash for secondary use, investigation for a suitable treatment process is necessary. An estimation of the nutrient recovery potential from industrial wood energy plants in southwest Germany showed that approx. 3.1% (P), 7.5% (K) and 22.8% (Ca) of raw material for fertilizers could be substituted by ash.

Ratios of phosphorous (P) to iron (Fe) in Precambrian banded iron formations (BIFs) have previously been used to estimate dissolved seawater phosphate concentrations in the ancient oceans. Such studies rely on an assumed composition of the primary iron minerals, the concentrations of the major ions in seawater, and empirical partitioning coefficients for phosphate sorption to Fe(III) (oxyhydr)oxides. There is limited data, however, regarding the post-depositional stability of phosphate associated with presumed primary BIF iron minerals, such as ferrihydrite under low-grade metamorphic temperature and pressure conditions. Here we experimentally formed ferrihydrite in the presence of silica, which was abundant in the Precambrian oceans, and then incubated it at 170 °C and 1.2 kbar in the presence or absence of organic carbon (Corg; either glucose or microbial biomass) as a proxy for ancient planktonic biomass. We found that the post-metamorphic mineral assemblage resulting from thermochemical Fe(III) reduction of Si-doped ferrihydrite depended on Corg reactivity: In the presence of highly reactive glucose, siderite, magnetite, and vivianite were formed, with less than 1.2 mol% of phosphate (0.5 M NaCl extractable) being mobilized. In contrast, the reaction of Si-doped ferrihydrite with less reactive microbial biomass resulted in the formation of hematite and siderite, but not vivianite, and approximately 10 mol% of phosphate was remobilized into the pore fluids. Collectively, our data suggest that the fidelity with which BIFs record ancient oceanic phosphate concentrations depends on the mineralogy and diagenetic history of individual BIFs but should be reliable within 10%.

As conventional end-of-life disposal, municipal solid waste (MSW) incineration residues can be problematic due to potential release of toxic compounds into the environment. Using municipal solid waste incineration residues as urban-mine of valuable metals (e.g. precious metals) could provide a trash-to-treasure possibility. The objectives of the study are to (i) determine the contents of different contaminant metallic elements (Zn, Cu, Ba, Pb, Cr and Ni) in four size fractions of MSW incineration residues and discuss their mobility potential by using the modified BCR sequential extraction method; (ii) investigate the level of valuable critical contents (precious metals, rare earth elements, etc.) in these wastes. We also characterized mineralogy and elemental composition of four different grain size fractions (0–0.5, 0.5–2.0, 2.0–4.0 and 4.0–16.0 mm) of processed municipal solid waste incineration residue (PIR) from the Southwestern region of Germany, using X-ray fluorescence, X-ray powder diffraction and different spectroscopic techniques. Among all studied size fractions, grains smaller than 2 mm contained higher amounts of total extractable heavy metals in most cases. The most important finding of the study is that the total contents of Cu, Au and Pt in the incineration residues reached economically profitable levels (5.1 g/kg, 21.69 mg/kg and 17.45 mg/kg, respectively).

The crucial point in inorganic particle formation from biomass combustion is the temperature-dependent release of inorganic compounds, especially potassium (K). Currently common wood fuels comprise a comparatively low amount of K, but the increased usage of wood energy requires new feedstocks in the future. Potentially new feedstocks like short-rotation-coppice (SRC), fuels from agriculture (e.g. straw) or wood from broad-leafed trees of low rotation contain usually high ash contents and/or high potassium concentrations. Apparently, these feedstocks will cause increased inorganic particle emissions from biomass combustion processes. The principle of a decreased firebed temperature as primary measure aiming at a retention of K in the ashes of the firebed is a common approach for particle emission reduction and was investigated in several previous studies. The present study describes the usage of an ash-rich fuel from SRC-pellets made from willow in a residential pellet boiler modified with an unique protot...

We have investigated the effect of JNK1 ko, JNK2 ko, JNK3 ko, JNK2+3 ko and c-JunAA mutation on neuronal survival in adult transgenic mice following ischemia, 6-hydroxydopamine induced neurotoxicity, axon transection and kainic acid induced excitotoxicity. Deletion of JNK isoforms indicated the compartment-specific expression of JNK isoforms with 46-kDa JNK1 as the main phosphorylated JNK isoform. Permanent occlusion of the MCA significantly enlarged the infarct area in JNK1 ko, which showed an increased expression of JNK3 in the penumbra. Survival of dopaminergic neurons in the substantia nigra compacta (SNC) following intrastriatal injection of 6-hydroxydopamine was transiently improved in JNK3 ko and c-JunAA mice after 7 days, but not 60 days. Following transection of the medial forebrain bundle, however, JNK3 ko conferred persisting neuroprotection of axotomised SNC neurons. None of the JNK ko and c-JunAA mutation affected the survival of facial motoneurons following peripheral axotomy when investigated after 90 days. Finally, we determined the impact of JNK ko on the survival of animals and the degeneration of hippocampal neurons following kainic acid. JNK3 ko mice were substantially resistant against and survived kainic acid-induced seizures. JNK3 ko and JNK1 ko showed a nonsignificant tendency for decreased or increased death of hippocampal neurons, respectively. Surprisingly, the deletion of a single JNK isoform did not attenuate the immunocytochemical signal of phosphorylated c-Jun irrespective on the experimental set-up. This comprehensive study provides novel insights into the context-dependent physiological and pathological functions of JNK isoforms.