Risk and mitigation of self-heating and spontaneous combustion in underground coal storage

While the self-heating and spontaneous combustion of coal is a known challenge at coal mines and storage sites, there are known methods for mitigating this challenge for typical open stockpile storage. However, closing the storage will reduce access for corrective action, and it is then important to manage the storage and its transport system with added attention without unduly adding cost or hindering availability. This paper aims to discuss the risk, prevention and extinguishing of fires in closed coal storage facilities, particularly in light of the experience with the Salmisaari underground rock storage facility in Finland. The observed autoignition events have indicated an array of contributing factors, some of which are unique to underground silo storage facilities. On the other hand, many features of the storage facilities can be compared with other extant closed storage systems. The factors affecting fire risk are described and the associated fault and event trees are outlined for autoignition at underground storage. Drawing upon the experiences with past events of self-heating and spontaneous combustion, recommendations are given on cost-effective preventive, corrective and other mitigating action for minimising fire risk and promoting storage availability.     

Gas dynamics in eutrophic lake sediments affected by oxygen, nitrate, and sulfate

In many freshwater ecosystems, the contents of NO3- and SO4(2-) have increased, whereas O2 has been depleted due to the increased acid and nutrient loads. These changes may affect carbon turnover and the dynamics of the major greenhouse gases CO2, CH4, and N2O. We studied the effects of O2, NO3-, and SO4(2-) availability on carbon mineralization, and fluxes of CO2, CH4, and N2O in the sediments of hyper-eutrophic Lake Kev?t?n, Finland. Undisturbed sediment cores from the deep (9 m) and shallow (4 m) profundal were incubated in a laboratory microcosm with oxic and anoxic water flows with NO3- or SO4(2-) concentrations of 0, 30, 100, 300, and 2000 microM. The carbon mineralization rate (i.e., the sum of released CO2-C and CH4-C) was not affected by the oxidants. However, the oxidants did change the pathways of carbon degradation and the release of CH4. All of the oxidants depressed CH4 fluxes in the shallow profundal sediments, which had low organic matter content. In the deep profundal sediments rich in organic matter, the CH4 release was reduced by O2 but was not affected by SO4(2-) (the effect of NO3- was not studied). There was an increase in N2O release as the overlying water NO3- concentration increased. Anoxia and highly elevated NO3- concentrations, associated with eutrophication, increased drastically the global warming potential (GWP) of the sedimentary gases in contrast to the SO4(2-) load, which had only minor effects on the GWP.     

Denitrification in the river estuaries of the northern Baltic Sea

Estuaries have been suggested to have an important role in reducing the nitrogen load transported to the sea. We measured denitrification rates in six estuaries of the northern Baltic Sea. Four of them were river mouths in the Bothnian Bay (northern Gulf of Bothnia), and two were estuary bays, one in the Archipelago Sea (southern Gulf of Bothnia) and the other in the Gulf of Finland. Denitrification rates in the four river mouths varied between 330 and 905 micromol N m(-2) d(-1). The estuary bays at the Archipelago Sea and the Gulf of Bothnia had denitrification rates from 90 micromol N m(-2) d(-1) to 910 micromol N m(-2) d(-1) and from 230 micromol N m(-2) d(-1) to 320 micromol N m(-2) d(-1), respectively. Denitrification removed 3.6-9.0% of the total nitrogen loading in the river mouths and in the estuary bay in the Gulf of Finland, where the residence times were short. In the estuary bay with a long residence time, in the Archipelago Sea, up to 4.5% of nitrate loading and 19% of nitrogen loading were removed before entering the sea. According to our results, the sediments of the fast-flowing rivers and the estuary areas with short residence times have a limited capacity to reduce the nitrogen load to the Baltic Sea.     

Nitrification in polluted soil fertilized with fast- and slow-releasing nitrogen: a case study at a refinery landfarming site

The nitrifying activity and the effect of fertilization with urea and methylene urea were studied in a landfarming site. The site has been operative over 20 years and maintained by heavy nitrogen fertilization. The landfarming soil contained 4-6% (w/w) oil. The nitrate accumulation was 20-50mg NO3-N day(-1)kg(-1) observed after methylene urea fertilization of 889 g Nm(-2). Nitrification ex situ (in laboratory conditions) was 8.8 mg NO3-N day(-1) kg(-1) in the presence of 380 mg kg(-1) NH4+-N. The half-saturation concentration of nitrification was more than 200 mg NH4+-N kg(-1). The results show that nitrification was active in soil with high oil concentration. Urea fertilization of 893 g Nm(-2) caused an increase of soil NH4+-N concentration up to 5500 mg kg(-1) and pH>8.5. This led to inhibition of nitrification, which persisted after NH4+ concentration decreased below 200mg NH4+ kg(-1).     

Prenatal diagnosis of free sialic acid storage disorders (SASD)

Free sialic acid storage disorders, Salla disease (SD) and Infantile sialic acid storage disease (ISSD), are lysosomal storage diseases due to impaired function of a sialic acid transporter, sialin, at the lysosomal membrane. Several mutations of the sialin gene, SLC17A5, are known, leading either to the severe neonatal/infantile disease or to the milder, adult-type developmental disorder, Salla disease. Free sialic acid accumulation in lysosomes causes increased tissue concentration and consequently elevated urinary excretion. Prenatal diagnosis of SASD is possible either by determination of free sialic acid concentration or by mutation analysis of the SLC17A5 gene in fetal specimen, in chorionic villus biopsy particularly. Both techniques have been successfully applied in several cases, sialic acid assay more often in ISSD cases but mutation analysis preferentially in SD. Sialic acid assay of amniotic fluid supernatant or cultured amniotic fluid cells may give erroneous results and should not be used for prenatal diagnosis of these disorders. The present comments are mainly based on our experience of prenatal diagnosis of SD in Finnish families. A founder mutation in SLC17A5 gene, 115C-> T, represents 95% of the disease alleles in the Finnish SD patients, which provides a unique possibility to apply mutation analysis. Therefore, molecular studies have successfully been used in 17 families since the identification of the gene and the characterization of the SD mutations. Earlier, eight prenatal studies were performed by measuring the free sialic acid concentration in chorionic villus samples. Copyright © 2006 John Wiley & Sons, Ltd.     

Phosphorus removal in a wetland constructed on former arable land

Phosphorus in surface runoff water may cause eutrophication of recipient water. This study clarifies the mechanisms of P removal in the wetland of Hovi, Finland, constructed on arable land in 1998. Before the construction, the surface soil (removed in the construction) and subsoil (the current wetland bottom) were analyzed for Al and Fe oxides (Al(ox) and Fe(ox)) reactive in P sorption, and for the distribution of P between various pools as well as for P exchange properties. Retention of P from runoff water within the wetland was studied from 1999 to 2001 in situ and factors affecting the P removal (O2 availability and P concentration in water) were investigated in a laboratory microcosm. The processes taking place in the wetland diminished by 68% the total P load and by 49% the dissolved reactive P load. Desorption-sorption tests indicated that without removal of the surface soil, there would have been a risk of the wetland being a source of P, since the equilibrium P concentration of the soil removed was high compared with the mean P concentration of the inflowing water. The subsoil contained less P and high amounts of reactive oxides, which could bind P. Evidently, the P sorption by Al(ox) played an important role in a first phase removal of P, since the wetland retained P efficiently even under anoxic conditions, where Fe tends to be reduced. Fine-textured, mineral soil on the bottom of the wetland (subsoil of the former arable land) seemed to be very efficient in retaining P from agricultural runoff.     

Genetic basis of lethal junctional epidermolysis bullosa in an affected fetus: Implications for prenatal diagnosis in one family

Fetal skin biopsy at 20 weeks' gestation in a woman at risk for a child with the lethal skin-blistering disorder junctional epidermolysis bullosa (Herlitz) confirmed an affected fetus. Genomic DNA from the aborted fetus was examined for mutations in laminin 5, a macromolecule involved in adhesion at the dermal-epidermal junction, and a candidate protein in this condition. Polymerase chain reaction (PCR) amplification of exon 10 and parts of the flanking introns of the gene encoding the β3 chain of laminin 5 (LAMB3) and subsequent analysis by agarose gel electrophoresis showed a more slowly migrating band in the affected fetus compared with the normal control. Nucleotide sequencing of the abnormal PCR product revealed a homozygous 77 bp duplication within the exon, resulting in a premature termination codon 250 bp downstream from the 3′ end of the duplication. Maternal DNA was heterozygous for the mutant and wild-type alleles. These findings illustrate the genetic basis of the skin disease in this case and also offer the prospects of a simple, rapid, and reliable first-trimester DNA-based prenatal, or even preimplantation, diagnostic test for future pregnancies in this family.     

Production and characterization of bioaerosols for model validation in spacecraft environment

This study aimed to evaluate the suitability of two bioaerosol generation systems(dry and wet generation) for the aerosolization of microorganisms isolated from the International Space Station, and to calibrate the produced bioaerosols to fulfill the requirements of computational fluid dynamics model(CFD) validation. Concentration, stability, size distribution, agglomeration of generated bioaerosol and deposition of bioaerosols were analyzed. In addition, the dispersion of non-viable particles in the air was studied.Experiments proved that wet generation from microbial suspensions could be used for the production of well-calibrated and stabile bioaerosols for model validation. For the simulation of the natural release of fungal spores, a dry generation method should be used. This study showed that the used CFD model simulated the spread of non-viable particles fairly well. The mathematical deposition model by Lai and Nazaroff could be used to estimate the deposition velocities of bioaerosols on surfaces, although it somewhat underestimated the measured deposition velocities.     

Groundwater dependent ecosystems. Part I: Hydroecological status and trends

Groundwater dependent ecosystems (GDEs) include valuable ecosystems such as springs, wetlands, rivers, lakes and lagoons. The protection of these systems and services they provide is highlighted by international agreements, i.e. Ramsar convention on wetlands, and regional legislation, i.e. the European Water Framework Directive. Groundwater provides water, nutrients and a relatively stable temperature. However, the role of groundwater in surface ecosystems is not fully understood. The ecosystem can depend on groundwater directly or indirectly, and the reliance can be continuous, seasonal or occasional. This has implications for the vulnerability of ecosystems, as some may be easily affected by external pressure. Conceptual models and quantitative assessments of how groundwater interacts with the environment are needed. GDEs are also threatened by different land use activities and climate change. Hence, we need to understand how GDEs are affected by changes in groundwater quantity and quality, as severe groundwater changes have been observed in many regions. This study examines key aspects of GDEs (hydrogeology, geochemistry and biodiversity) in order to improve conceptual understanding of the role of groundwater in such ecosystems. The status and baseline of different types of GDEs are discussed, with particular emphasis on past evidence of environmental change and potential thresholds and threats in GDEs in various parts of Europe with different land use, climate and geology.