HCl-soluble Fractions Research Articles

Distribution and bioavailability of mercury in size-fractioned atmospheric particles around an ultra-low emission power plant in Southwest China

Ultra-low emission (ULE) technology retrofits significantly impact the particulate-bound mercury (Hg) emissions from coal-fired power plants (CFPPs); however, the distribution and bioavailability of Hg in size-fractioned particulate matter (PM) around the ULE-retrofitted CFPPs are less understood. Here, total Hg and its chemical speciation in TSP (total suspended particles), PM10 (aerodynamic particle diameter ≤ 10 µm) and PM2.5 (aerodynamic particle diameter ≤ 2.5 µm) around a ULE-retrofitted CFPP in Guizhou Province were quantified. Atmospheric PM2.5 concentration was higher around this ULE-retrofitted CFPP than that in the intra-regional urban cities, and it had higher mass Hg concentration than other size-fractioned PM. Total Hg concentrations in PM had multifarious sources including CFPP, vehicle exhaust and biomass combustion, while they were significantly higher in autumn and winter than those in other seasons (P < 0.05). Regardless of particulate size, atmospheric PM-bound Hg had lower residual fractions (< 21%) while higher HCl-soluble fractions (> 40%). Mass concentrations of exchangeable, HCl-soluble, elemental, and residual Hg in PM2.5 were higher than those in other size-fractioned PM, and were markedly elevated in autumn and winter (P < 0.05). In PM2.5, HCl-soluble Hg presented a significantly positive relationship with elemental Hg (P < 0.05), while residual Hg showed the significantly positive relationships with HCl-soluble Hg and elemental Hg (P < 0.01). Overall, these results suggested that atmospheric PM-bound Hg around the ULE-retrofitted CFPP tends to accumulate in finer PM, and has higher bioavailable fractions, while has potential transformation between chemical speciation.

Investigation of the key factors that affect drip loss in Japanese strawberry cultivars as a result of freezing and thawing

The strawberry (Fragalia ananassa) is commonly used in industry and is thus often frozen; however, drip loss tends to occur following freezing and factors that may reduce drip loss remain unclear. In this study, the role that cell structure, particularly pectin and the cell membrane, has on the drip loss that occurs in different strawberry cultivars was investigated. The relationship between the cell structure in fresh or frozen strawberries and drip loss in thawed strawberries were investigated in ten Japanese strawberry cultivars, with results showing different amounts of drip loss in the various strawberry cultivars. The amount of HCl soluble pectin fraction (HSP) in frozen strawberries was found to correlate with drip loss when thawed at 4 °C. Higher amounts of HSP in the alcohol insoluble solid (AIS) of frozen strawberries showed a higher water holding capacity (WHC). It is therefore suggested that the WHC of the pectin chains in frozen strawberries, which may be adjusted by the neutral sugars in pectin, has the potential of regulating drip leakage during thawing.

Impact of MgCl&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt; Modified Biochar on Phosphorus and Nitrogen Fractions in Coastal Saline Soil

Biochar application is claimed to improve nutrient availability in many problem soils; however, pristine biochars are often reported to produce inconsistent results. Therefore, appropriate biochar modification techniques are required to retain soil nutrients at an optimum level. To increase Nitrogen (N) and Phosphorus (P) availability in coastal saline soil, two slow pyrolyzed biochars viz domestic organic waste (DWB) and farmyard manure (FMB) were modified with MgCl2. Ten different treatments comprising the biochars (pristine and modified) with and without the recommended fertilizer were applied (2% w/w) to the soil and incubated for ninety days. The soils were analyzed for pH, EC, available , and different phosphorus fractions sequentially extracted by NH4Cl, NaHCO3, NaOH, and HCl. During the incubation period, biochar treatments increased all phosphorus and nitrogen fractions than the control and recommended fertilizer treatment. The application of FMB significantly (p 4Cl, NaHCO3, and NaOH extractable P fractions from DWB, while HCl soluble fraction was enhanced (p > 0.05) by DWB. The increased Al and/or Fe bound phosphate after 60 days of incubation had significant correlations to decreasing soil pH and NaHCO3-P, indicating reduced availability with time. Further Mg modification slightly increased P availability only after 60 days of incubation. The modification also improved both nitrogen fractions but significantly (p 3-N content which could be the result of electrostatic attraction between Mg2+ and ions. Overall, Mg-modified biochar may retain both phosphates and nitrates in soil. However, the magnitude of retention will vary depending on biochar type, nutrient species, and aging in soil.

Chemical Bonds of Cations in Grapevine Berries and Stems of Some Important Cultivars of Vitis vinifera (L.) and Their Relevance for Viticulture and Enology

Cations are essential for plant growth, tissue build-up and its stabilization. Divalent cations are necessary for cell wall stability and other interstitial tissues. They may be cross-linked with pectins or form looser ionic bindings. This is of importance for grape processing during the technical operations of juice extraction. Monovalent ions are more involved in vacuolar homeostasis and pH stabilization.With a specific extraction procedure H2O-soluble, 1N NaCl-soluble, 2% CH3COOH-soluble, and 5% HCl-soluble fractions as well as the total content of K, Ca, and Mg were analyzed in grapevine berries and stems. The monovalent K is only found in the water and the NaCl fraction; both in berries and stems. But only 50-60% of the total K can be extracted with both solutes. The divalent cation Ca is found in all four fractions with differing amounts, but water soluble Ca is in most cases highest. Ca may also have an indicator value for BSN, because the water soluble fraction is lowest in the most susceptible variety. Mg is not found in HCl fraction.An analysis of variance shows that the varieties have a significant influence on nutrient distribution in different tissues. It seems that the relation Ca/Mg (NaCl fraction) in stems is a good indicator for BSN because susceptible varieties show lower ratios than resistant ones. Some more research is necessary to clear up this possible relationship.

Selective leaching studies of sediments from a seamount flank in the Central Indian Basin: Resolving hydrothermal, volcanogenic and terrigenous sources using major, trace and rare-earth elements

We have investigated the sediments from a site where a newly discovered submarine hydrothermal alteration of recent origin is located to identify the source components and estimate their relative contribution. The site is situated on the flank of a seamount in the Central Indian Basin along the 76° 30′ E fracture zone which traces the movement of the Rodriguez triple junction. Detailed analyses of major, trace and rare earth elements (REE) on the bulk, leach, residue and clay fraction, and infra red spectroscopy studies of the clay fraction helped characterize the hydrothermal nature of the sediments. Selective dissolution carried out using HCl has allowed the discrimination between a leach phase (leachable Fe–Mn oxide) and a residue phase (refractory). The sediments are iron-rich, majority of Fe, Mn is in leachable fraction and are compositionally comparable to ridge-crest metalliferous sediments. Elemental ratios and geochemical discrimination plots of major element data reveal that the sediments are a mixture of Fe-rich mineral phases on one hand apparently from hydrothermal sources and aluminosilicates such as illite, zeolites, micaceous clays and smectites contributed from the Bengal fan, weathering of basinal basalts and authigenic processes. Ternary mixing calculations of bulk sediment major element data show that 35–45% metalliferous sediments could reproduce Fe and Mn values of our sediments. The shale normalized REE patterns of the bulk sediments are remarkably similar to those of the HCl soluble leach fraction, implying that the REEs in the HCl soluble leach fraction dominate the bulk fraction. HCl leacheates exhibit characteristics of vent fluids as well as seawater with pronounced Eu anomaly with HREE enrichment and negative Ce anomaly. The residue on the other hand has a high concentration of Fe, V, Zn, and Pb indicating a sulfidic input to the sediments. Ternary mixing calculations of REEs carried out on the residual fraction indicate that the sulfide-like material dominates (64–72%) over terrigenous (10–20%) and MORB derived (16–18%) components. This study helped us identify and quantify two types of hydrothermal material in the sediments, dominated by Fe–Mn phases (ferruginous oxides and silicates; Mn-oxides) in leachable fraction and sulfide-like material in residual phases. The clay fraction is mainly composed of dioctahedral smectites and has a composition similar to Alvin nontronite. The geochemical and mineralogical characteristics collectively suggest that these sediment-hosted precipitates formed at relatively low temperatures ranging between 50 and 100 °C from a mixture of seawater and hydrothermal fluids. The presence of hydrothermal sediments in the vicinity of a fracture zone suggests the occurrence of localized hydrothermal activity associated with intra plate volcanism. This is probably induced by reactivation of tectonic forces along the fracture zones.

Thyroid Hormones Induce Sumoylation of the Cold Shock Domain-Containing Protein PIPPin in Developing Rat Brain and in Cultured Neurons

We previously identified a cold shock domain (CSD)-containing protein (PIPPin), expressed at high level in brain cells. PIPPin has the potential to undergo different posttranslational modifications and might be a good candidate to regulate the synthesis of specific proteins in response to extracellular stimuli. Here we report the effects of T(3) on PIPPin expression in developing rat brain. We found that a significant difference among euthyroid and hypothyroid newborn rats concerns sumoylation of nuclear PIPPin, which is abolished by hypothyroidism. Moreover, T(3) dependence of PIPPin sumoylation has been confirmed in cortical neurons purified from brain cortices and cultured in a chemically defined medium (Maat medium), with or without T(3). We also report that about one half of unmodified as well as all the sumoylated form of PIPPin could be extracted from nuclei with HCl, together with histones. Moreover, this HCl-soluble fraction remains in the nucleus even after treatment with 0.6 M KCl, thus suggesting strong interaction of PIPPin with nuclear structures and perhaps chromatin.

HCl-soluble 87Sr/86Sr ratio in sediments impacted by penguin or seal excreta as a proxy for historical population size in the maritime Antarctic

The strontium (Sr) isotopic compositions in the HCl-soluble and insoluble fractions of sediments impacted by penguin and seal excreta in the maritime Antarctic were analyzed. The HCl-soluble phase of the sediments impacted by penguin guano has a high 87 Sr/ 86 Sr ratio (average 0.7087), close to the ratio in seawater (average 0.7092), suggesting that the 87 Sr/ 86 Sr ratios in the sediments are significantly impacted by penguin guano. The 87 Sr/ 86 Sr ratios in the HCl-soluble phase of the sediments impacted by seal excreta vary between 0.705066 and 0.706117, with an average of 0.705507, higher than those of the local bedrock, but lower than the ratio in modern seawater; they are interpreted to be a mixture of Sr from seal excreta (30 to 50 %) and the weathering products of the local bedrock (50 to 70 %). The Sr contributions from penguin guano and seal excreta were calculated using the 2-member isotope mixing equation, and they have a significant correlation with the historical penguin population size as estimated from other geochemical analyses and the seal hair density in the sediments, respectively. These results suggest that the 87 Sr/ 86 Sr ratios in the HCl-soluble fraction of sediments impacted by penguin or seal excreta can potentially be used as an indirect and new proxy for the historical population size of these sea animals in the maritime Antarctic.

Effect of heat treatments on cell wall degradation and softening in strawberry fruit

Strawberries (75% red color) were harvested and heat-treated at 45 °C, 3 h in an air oven. After treatment, fruit were stored at 20 °C for 2 days. Firmness, content of cell wall components and activity of enzymes related to cell wall degradation was determined in the external and internal fruit zones of control or heat-treated fruit. Therefore, the total content of pectins and hemicelluloses was measured, along with the water, EDTA and HCl soluble pectin fractions, and the enzyme activity of endo-1,4-β- d-glucanase (EGase), β-xylosidase (β-Xyl), polygalacturonase (PG), β-galactosidase (β-Gal), and pectin methylesterase (PME). Heat-treated fruit remained firmer than control fruit in both zones after 1 day of storage at 20 °C. After 2 days of storage, the difference was still observed in the external zone. Heat treatments reduced EGase and β-Xyl activity in both zones and delayed hemicellulose degradation. PG and β-Gal activity was also inhibited by the treatment. Heat-treated fruit maintained higher level of HCl soluble pectins while had lower amount of water-soluble pectins than control fruit. PME activity was increased by the treatments and heat-treated fruit showed higher amount of EDTA soluble pectins than the control. Results show that firmness, activity of assayed enzymes and cell wall composition are different in the external and internal zones of strawberry fruit. Furthermore, the application of heat treatment affected the solubilization of pectins and hemicelluloses.

Vertical distribution of major, minor, and rare elements in a Haplic Podzol

Total and 0.2 M HCl-soluble concentrations of 44 mineral elements were studied in four profiles (0–110 cm) of a Haplic Podzol, developed from a 13,000–14,000-year-old quartzite–gneiss moraine deposit in south Sweden. Depending on element and soil fraction of the element considered, concentration maxima occurred in different horizons in the soil. The E horizon was impoverished in HCl-soluble fractions of nearly all and of total contents of most elements. Most alkali (sodium, potassium, rubidium, and caesium), alkaline-earth (magnesium, calcium, strontium, and barium), and several divalent transition metals (vanadium, cobalt, nickel, zinc, cadmium, mercury, and lead) had their HCl-soluble concentration peaks in the topsoil (01 or 02 horizons, rich in organic matter), iron and gallium in the B1 horizon, aluminium together with chromium, lithium, beryllium, scandium, silicon, thorium, zirconium, and molybdenum in the B2 horizon. HCl-soluble lanthanum, yttrium, and the lanthanides (cerium, dysprosium, gadolinium, neodymium, praseodymium, samarium, thulium, and ytterbium) peaked further down in the soil. Factor (PCA) analysis (all samples and horizons considered in the HCl extraction) arranged the elements in three groups. One group was composed of the rare-earth elements but also included several less heavy transition metals as well as phosphorus, boron, and aluminium. A second group, also containing organic carbon, comprised most alkali and alkaline-earth elements but also heavy metals such as nickel, copper, lead, zinc, cadmium, and mercury. Iron and gallium were discerned as a third group in the PCA analysis. Relative budget estimates based on total amounts per unit soil volume indicated that the greatest losses since deglaciation from the E+B horizons had occurred of alkaline-earths, lanthanides, uranium, and some divalent transition metals (cadmium, cobalt, and zinc). Accumulation in the 01 and 02 horizons, however, had compensated for the losses from the mineral soil of particularly cadmium and lead, to a large extent elements originating from atmospheric deposition of long-distance transported pollutants.

Radionuclides from Chernobyl hot particles in the environment of North-Eastern Poland - A leaching experiment

The north-eastern Poland is the area where fallout of Chernobyl fuel-like hot-particles occurred. Experiment on the leaching out of radionuclides from forest litter was performed. Five samples were subsequently leached out by : a weak hydrochloric acid (fulvic acid fraction), ammonia water (humic acid fraction) and 2 M HCl (soluble fraction). Residue was analysed as well, after full mineralisation. Results on total activities and its distribution between fractions obtained for : 137 Cs, 90 Sr, 239+240 Pu, 238 Pu and 241 Am are presented. Relatively high activities of plutonium were observed in humic acid fractions. This founding support suggestions by other authors on possible complexing of Pu by humic acid.

Extraction, purification and chemical characterisation of xylogalacturonans from pea hulls

Pea hulls contained 925 mg/g sugar including 659 mg/g cellulosic glucose and 90 mg/g uronic acid. They were de-esterified by NaOH (pH>13 at 4°C, 2 h) and treated with HCl (0.1 mol/l, 80°C, 24 h). The HCl-soluble fraction represented 95 mg/g initial pea hulls. It was rich in galacturonic acid (259 mg/g), xylose (93 mg/g) and rhamnose (91 mg/g), which co-eluted in anion-exchange chromatography. The HCl-soluble fraction was degraded by a rhamnogalacturonan-hydrolase and the reaction products were fractionated by size-exclusion chromatography. Two fractions, representing together 18 mg/g initial pea hulls, were composed almost exclusively of galacturonic acid and xylose and could be defined as xylogalacturonans. The first fraction exhibited a high molar mass, a molar ratio Xyl/GalA of 1 and contained almost 5% of rhamnose. The molar mass of the second fraction was much lower and the molar ratio Xyl/GalA was 0.6. Methylation analysis showed the presence in both fractions of a α(1→4) galacturonan backbone highly substituted on O-3 either by terminal xylosyl residues or by short side-chains of (1→2) linked xylosyl residues.

Involvement of terminal-arabinose and -galactose pectic compounds in mealiness of apple fruit during storage

Abstract Among eight apple cultivars (Malus domestica Borkh) held at 0 or 20°C for 4 or 8 weeks, mealiness was highest in ‘Starking Delicious’ (83%) and lowest in ‘Golden Delicious’ (0%) after 20°C for 8 weeks. In ‘Starking Delicious’ and ‘Golden Delicious’ fruit, total uronic acid contents [amount of water (WSP)+hexametaphosphate (HMP)+HCl soluble (HCP) pectic fractions] of the alcohol insoluble solids (AIS) of flesh hardly changed during storage at 20°C, although the ratio of uronic acid in WSP to total uronic acid increased during storage. Total (WSP+HMP+HCP) pentose contents in AIS decreased in most cultivars during storage, and the decrease was greatest in the fruit stored at 20°C. In ‘Starking Delicious’ fruit, the ratio of pentose in WSP to total pentose increased during storage at 20°C. Among pentoses, arabinose (Ara) content in the fruit stored at 20°C decreased more than in the fruit stored at 0°C. The linkages of the arabinose residue in each fraction were mainly T (terminal)-Ara, 5-Ara and 3,5-Ara, determined by methylation analysis. The ratio of T-Ara and 3,5-Ara to total arabinose linkage decreased both in HMP and HCP. The decrease in T-Ara and 3,5-Ara was higher in ‘Starking Delicious’ fruit compared with that in ‘Golden Delicious’ fruit in storage at 20°C. The linkages of the galactose residues in each fraction identified were mainly T-Gal, 3,6-Gal, 2,4-Gal and 6-Gal. The ratio of T-Gal to total galactose linkage increased both in HMP and HCP. The increase in T-Gal was higher in ‘Starking Delicious’ fruit than in ‘Golden Delicious’ fruit in storage at 20°C. The possible effect on mealiness of the release of T-Ara and increase of T-Gal in pectic substances is discussed.

Role of Wheat Protein Fractions in the Expansion of Yakifu(Baked Gluten Product).

The relationship between wheat flour protein and the expansion of yakifu, one of the traditional foods in Japan, was studied. Wheat flour proteins were fractionated by their solubility in various solvents. The protein fraction (PF) and wheat starch were blended into reconstructed flours (RFs). In RF 1, the protein content was equal to that of hard wheat flour, while in RF 2 part (10%, 20%, or 30%) of the protein originally included in soft or hard wheat flour was replaced with a PF extracted from each flour. Among RF 1, those blended with water-soluble and NaCl-soluble fractions did not produce substantial gluten doughs and therefore failed to form well expanded structures when baked. A smooth and well homogenized gluten dough was prepared with 70% ethyl alcohol-soluble and HCl-soluble fractions although the acetic acid-soluble, acetic acid-insoluble, and HCl-insoluble fractions produced a tough and coarse gluten dough. The specific volume of yakifu was greater when smooth and well homogenized gluten doughs were baked than when tough and coarse ones were. In RF 2, the specific volume gradually increased with the increase of the HCl-soluble fraction ratio, while it remained almost constant with the increase of the HCl-insoluble fraction ratio. These results demonstrated the primary role of the 70% ethyl alcohol-soluble fraction and HCl-soluble fraction, that is, the gliadin-rich fraction, in the expansion of yakifu.

Effect of supplementation of dry cat food with D,L-methionine and ammonium chloride on struvite activity product and sediment in urine.

Feeding dry foods supplemented with urine acidifier (D,L-methionine (Met) or ammonium chloride) decreased urinary pH and struvite activity product in clinically normal cats. As a result, the number of struvite crystals in urine was greatly reduced. Supplementation with 3% Met but not 1% Met caused decrease in the urinary concentration of sediment, which resulted from a reduction in the HCl-soluble fraction. The concentration of HCl-insoluble sediment was not affected by supplementation with the urine acidifier.

‘イエロー紅心’キウイフルーツ果実の樹上軟化に伴う細胞壁多糖類の経時変化

In studying the mechanism of softening of in kiwifruit (Actinidia chinensis Planch. cv. Yellow Koshin) on the vine, the changes of cell wall polysaccharides were compared with those induced by ethylene treatment. Cell wall polysaccharides were prepared from 80% alcohol-insoluble residue (AIR) by extracting the AIR with water, EDTA, HCI, and KOH in succession as described by Yoshioka et al. (1992 ; 1994). The decrease in the amount of monosaccharides in the water-insoluble fraction (WIF) derived from EDTA, HCl, and KOH soluble fractions was followed. 1. Ethylene evolution was not detected in the fruit during softening on the tree. 2. Fruit softening on the vine was accompanied with a decrease in galacturonic acid, but not of neutral sugars in the WIF. 3. Ethylene treatment led to a drastic decrease in rhamnose, arabinose, and galactose levels in the WIF ; galacturonic-acid decreased with or without the ethylene treatment. These findings suggest that fruit softening on the vine is associated with the dissolution of homogalacturonan which is insensitive to ethylene. Furthermore, ethylene treatment seems to induce the solubilization of homogalacturonan and rhamunogalacturonan, followed by fruit softening.

Long‐distance transport of 35S‐sulphur in 3‐year‐old beech trees (Fagus sylvatica)

35S‐L‐cysteine was fed to a mature leaf of 3‐year‐old beech trees via a flap. After 1 to 4 h the distribution of 35S‐radioactivity was analysed in the leaves as well as the bark and wood of the trunk and the main root. Transport of 35S out of the fed leaf amounted to 0.3–1.2% of the total 35S taken up. The branches of the trees did not act as sink organs for the exported radioactivity. The main portion of the 35S‐radioactivity transported out of the fed leaf was found in basipetal parts of the trunk. Only a small portion of 35S‐radioactivity was transported in acropetal direction. The distribution of the 35S‐radioactivity within the trunk showed a higher portion of 35S in the bark than in the wood. In both tissues, bark (70 to 80%) and wood (60 to 70%), the 35S was predominantly found in the HCl soluble fraction. However, 35S‐cysteine, the compound fed to the leaves was not exported out of the fed leaf. Along the trunk 35S‐cysteine was neither determined in bark nor in wood sections. The only low molecular mass S‐compounds found was 35S‐glutathione (GSH). The 35S‐sulphate detected in bark and wood origined from cysteine oxidation in the leaf tissue and from contamination of the 35S‐cysteine feeding solution. The ratio of GSH to sulphate decreased with increasing distance from the fed leaf. Apparently, 35S‐radioactivity was transported as sulphate and GSH in the phloem in basipetal direction, but GSH was removed preferentially out of the phloem along the transport path. 35S‐radioactivity exported out of the phloem and transported into the wood of the trunk was not retranslocated in the xylem. It may therefore be assumed that part of the 35S translocated was stored in ray cells, medullary sheath cells and/or pith parenchyma cells. Girdling experiments in which the bark of the trunk was peeled off basipetal to the branch containing the fed leaf support these assumptions.

Molecular Weight and Degree of Methoxylation in Cell Wall Polyuronide during Softening in Pear and Apple Fruit

The concentrations of water-soluble polyuronides in apples [Malus domestica Borkh.) and pears (Pyrus communis L.) increased, but those of EDTA- and HCl-soluble polyuronides decreased during softening. Total polyuronide content decreased slightly during softening in both fruits. Depolymerization of polyuronides was observed only in the water-soluble fraction in pear fruit during softening, concomitant with an increase in polygalacturonase (PG) activity. No detectable depolymerization was observed in any of the polyuronide fractions during softening of apple fruit nor was any PG activity detected. The polyuronide fractions extracted from pear and apple cell walls contained various amounts of methoxyl groups. Polyuronides with a high degree of methoxylation were preferentially lost from EDTA- and HCl-soluble polyuronides during softening of both fruit. The water-soluble polyuronide had a lower degree of methoxylation than those lost in the EDTA- and HCl-soluble fractions. These results suggest de-esterification of polyuronides with a high degree of methoxylation rather than the depolymerization of polyuronides in the solubilization of polyuronides during ripening of apples and pears.

Uranium distribution and 234U/238U activity ratios in a sedimentary bauxite deposit, from Yangwa mine, China, and its implication for sedimentation process.

Concentrations of uranium and other elements in bauxite deposit from Yangwa mine at Jiaozuo area in Henan Province, China, were determined, and geochemical behavior of 234U and sedimentation process were studied by leaching experiments. An inverse correlation between two major components, Al2O3 and Fe2O3, was observed. Al2O3 has a distinct correlation with Ti, Cr, U and V, while Fe2O3 correlated with Mn, Ca and Cu. Cr, V and U were enriched in the deposit compared with crustal abundance, while SiO2, MnO, MgO, CaO, Na2O, Cu, Sr and Ba were depleted. In phase extraction experiments, the Fe, Mn, Mg, Ca, and Sr were predominantly in the “HCl soluble fraction”. With one exception, most of the U in the bauxite was in the “HF soluble fraction” (∼60%), and ∼30% of the U was in the “resistate fraction”. The 234U/238U activity ratios in these fractions were less than unity, and have a good correlation with the fractional U content. This relation suggests that 234U was leached out from the surface of the U-containing mineral grains. In comparison, the activity ratios of HCl soluble U were more than unity, and are inversely correlated with the fractional U contents. This suggests that an almost constant amount of mobile 234U was present in the deposits. The principal bauxite ore body could be thought to be sedimentary in origin: A terra rossa was formed on the karstic Ordovician limestone. It was rich in Fe2O3, which suggests relatively oxidative sedimentary condition. The clay minerals, fine-grained materials originated from Pre-Cambrian basement were then transported and deposited repeatedly on the terra rossa. The deposition of the clay minerals changed the sink from oxidative to reducing condition, favoring for the deposition of U. The original clay minerals in the bauxite deposit were kaolinite and gibbsite. As the reversible change from kaolinite to gibbsite depends on the H4SiO4 concentration, the alteration degree of gibbsite might have been controlled by the movement of H4SiO4. 234U was estimated to have been ejected from the surface of U-containing minerals and migrated through the ore deposits, then adsorbed by iron hydroxides at the bottom of the ore body.

Metalloproteinases in the mineralized compartments of porcine dentine as detected by substrate-gel electrophoresis

Several gelatinolytic activities were detected in the 4 M guanidine HCl-soluble fraction extracted from demineralized porcine dentine matrix. These matrix proteinases were active in the range of pH 6–9, and the activities were enhanced by calcium ions. The enzymes also degraded some of the non-collagenous proteins coexisting in the extract. The results indicate that the changes in the composition of non-collagenous proteins during the development of dentine are related to proteolytic enzyme activity.

Fluorine contamination of soils and earthworms (Lumbricus spp.) near a site of long-term industrial emission in southern Germany

The F contamination of soils and Lumbricus spp. around a site of long-term industrial emission in southern Germany was examined. Among total, water extractable, and HCl-soluble fractions, the latter most appropriately characterized anthropogenic F accumulation. Based on the HCl-soluble fractions from 88 sampling sites, a contamination map consisting of three zones was established. F accumulation in the calcareous soils of the area was restricted to the top 40–50 cm and can be explained by precipitation as CaF2. Earthworms (Lumbricus spp.) collected from the different zones reflected the F contamination well in the significant correlations found between total F in earthworms with and without gut and the corresponding soils. The bioaccumulation of F in earthworms is obvious, and may become hazardous for the earthworms themselves and for other animals feeding on contaminated soil and/or its fauna. A significantly higher F value was recorded in the linings of earthworm tubes than in the corresponding soil. F translocation by earthworm burrowing may be a mechanism of subsoil contamination.