The 2019-2020 volcanic eruption of Late'iki (Metis Shoal), Tonga.

Late'iki (previously known as Metis Shoal) is a highly active volcano in the Tofua arc with at least four temporary island-building eruptions and one submarine eruption in the last 55 years. The most recent eruption, commencing in October 2019, resulted in lava effusion and subsequent phreatic explosions, the construction of a short-lived island that was quickly eroded by wave action and possibly further phreatic activity that continued into January 2020. The two-pyroxene dacite from the 2019 eruption is similar to the 1967/8 eruptions suggesting the magma is residual from earlier eruptions and has not undergone further differentiation in the last 50 years. New observations of the 2019 eruption site confirm the lava-dominant character of the volcano summit but a thin veneer of wave-reworked, finely fragmented lava material remains that is interpreted to have been produced by phreatic explosions from hot rock-water interactions during the effusive eruption. A notable absence of quench-fragmented hyaloclastite breccias suggests that non-explosive quench fragmentation processes were minimal at these shallow depths or that hyaloclastite debris has resedimented to greater depths beyond our summit survey area.

Sea to land transfer of anthropogenic radionuclides to the North Wales coast, Part I: external gamma radiation and radionuclide concentrations in intertidal sediments, soil and air.

Previous projects specifically aimed at performing radiological assessments in the vicinity of North Wales, investigating the presence and transfer of radionuclides from sea to land, were in 1986 and 1989. Since then, changes have occurred in the radioactive discharges from the British Nuclear Group Sellafield site. Annual discharges of (137)Cs, (238)Pu, (239,340)Pu and (241)Am have decreased markedly whereas, up until recent years, discharges of (99)Tc have increased. It is therefore desirable to quantify current transfer processes of radionuclides in the North Wales region and thus provide an update on 15-year-old studies. A field campaign was conducted collecting soil samples from 10 inland transects and air particulates on air filters from three High Volume Air Samplers, along the northern coast of Wales at Amlwch, Bangor Pier and Flint. Complementary field data relating to external gamma dose rates were collected at the soil sites. The field data generated for (137)Cs, (238)Pu, (239,340)Pu and (241)Am were consistent with what had been reported 15 years previously. Therefore, there has been no increase in the supply of these Sellafield-derived radionuclides to the terrestrial environment of the North Wales coast. The (99)Tc data in sediments were consistent with reported values within annual monitoring programmes, however, a relatively high activity concentration was measured in one sediment sample. This site was further investigated to determine the reason why such a high value was found. At present there is no clear evidence as to why this elevated concentration should be present, but the role of seaweed and its capacity in accumulating (99)Tc and transferring it to sediment is of interest. The analysis of the field samples for (99)Tc, (137)Cs, (238)Pu, (239,240)Pu and (241)Am has provided a data set that can be used for the modelling of the transfer of anthropogenic radionuclides from sea to land and its subsequent radiological implications and is reported in an accompanying paper.

Sea to land transfer of anthropogenic radionuclides to the North Wales coast, Part II: aerial modelling and radiological assessment.

Modelling calculations have been performed to predict the radiological impact of the sea to land transfer pathway to members of the public in North Wales from 1952 to 2004. The radionuclides of interest were (99)Tc, (137)Cs, (239,240)Pu and (241)Am and the exposure routes considered were food consumption, external and inhalation. The consumption of locally grown terrestrial food in the early to mid 1980s was the most significant source of exposure to all of the groups considered, with (239,240)Pu being the radionuclide contributing most to the dose. A maximum dose of 1.46microSvy(-1) was calculated for adult members of the critical consumption group in 1985, with doses for 2004 reducing to 0.59microSvy(-1). Despite the conservative approach of the dose calculations, the dose rate values are very low, less than 0.15% of the annual limit of 1000microSvy(-1) for the UK public from controlled radiation sources (excluding medical).

Field and model investigations of external gamma dose rates along the Cumbrian coast, NW England.

A survey of the contribution to external dose from gamma rays originating from intertidal sediments in the vicinity of the British Nuclear Group Sellafield site showed that the major anthropogenic contributions were due to (137)Cs and (60)Co. At some sites, traces of other anthropogenic radionuclides were detected, namely (106)Ru, (125)Sb, and (154)Eu. The proportions of fine grained material (<63 microm) were used to improve model predictions of dose contribution due to external exposure to gamma rays, using the CUMBRIA77/DOSE77 model. Model dose predictions were compared to those directly measured in the field. Using the new proportions of fine grained material (1-17.5%) in conjunction with field gamma-ray spectra, model predictions were improved considerably for most sites. Exceptions were at Drigg Barn Scar and Whitehaven Coal Sands sites, which had their own unique characteristics. The highest (60)Co activity concentrations in this study were detected at Drigg Barn Scar. These relatively high activity concentrations of (60)Co were due to the presence of (60)Co in mussels and barnacles, hence upsetting the fine sediment relationships used in previous dose calculations. Whitehaven Coal Sands was unusual in that it contained higher levels of radionuclides than would be expected in sandy sediment. The mineralogy of these sediments was the controlling factor on (137)Cs binding, rather than the proportion of fine grained material. By adjusting the effective fine grained sediment proportions for calculations involving (60)Co and (137)Cs at Drigg Barn Scar and Whitehaven Coal Sands respectively, the CUMBRIA77/DOSE77 model predictions could be improved upon significantly for these sites. This work highlights the influence of particle size and sediment composition on external dose rate calculations, as well as the potential for external dose contributions from biota.

Comparison of measured and modelled copper binding by natural organic matter in freshwaters.

Fifteen freshwater samples containing significant concentrations of dissolved organic carbon-[DOC]-were titrated with copper under standardised conditions (pH 6 and 7), and concentrations of Cu(2+)-[Cu(2+)]-were measured with an ion-selective electrode. Measured values of [Cu(2+)], which were in the range 10(-11)-10(-5) moll(-1), were compared with those simulated using Humic Ion-Binding Models V and VI. It was assumed that copper speciation was controlled by the organic matter, represented by fulvic acid (FA), together with inorganic solution complexation (calculated with an inorganic speciation model). The models were calibrated by adjusting a single quantity, the concentration of FA. The optimised value-[FA](opt)-was that giving the best agreement, according to least squares, between measured and simulated [Cu(2+)]. The calculations took into account competition by other dissolved (filterable) metals (Mg, Al, Ca, Fe(II), Fe(III), Zn); in the case of Fe(III) it was assumed either that all the dissolved metal was truly in solution, or that the activity of Fe(3+) was controlled by equilibrium with Fe(OH)(3). The assumption about Fe(III) had relatively small effects on the fitting of Model V, but was significant for Model VI, because Model VI represents low-abundance, high-affinity binding sites in humic matter, which are sensitive to Fe(III) competition. Because of its inclusion of the high-affinity sites, Model VI provided better fits of the data than did Model V. Furthermore, Model VI with Fe(3+) activity controlled by Fe(OH)(3) gave smaller variation in the ratio of [FA](opt) to [DOC] than Model VI with all Fe(III) assumed to be in solution. The average [FA](opt)/[DOC] found from the Cu titrations was 1.30, which implies that 65% of the organic matter is 'active' with respect to metal binding. The average ratio of 1.30 is in reasonable agreement with ratios obtained by applying the model to field data sets for charge balance (1.22), Al speciation (1.56) and base titrations of Cu-amended waters (1.45). It is concluded that Model VI/Fe(OH)(3) provides the most reliable predictions of dissolved metal speciation in natural waters; at a total Cu concentration of 1 microM, the predicted concentration of Cu(2+) is expected to be correct to within a factor of 3.6 in 95% of cases.

Infraspecific taxonomy and essential oil chemotypes in sweet basil, Ocimum basilicum.

Essential oil compositions of fresh and freeze-dried leaves were determined for 16 accessions of Ocimum basilicum belonging to different varieties to see whether they could be used as infraspecific taxonomic characters. One accession of O. x citriodorum was also studied. Some 30 monoterpenoids, sesquiterpenoids and phenylpropanoids were identified, the major components (more than 20% of the total essential oil composition in one or more accessions) being geranial and neral in O. x citriodorum, and linalool, methyl chavicol, eugenol, methyl eugenol and geraniol in O. basilicum. Based on a combination of the latter compounds, five major essential oil profiles could be distinguished in the accessions studied for O. basilicum. These profiles were largely the same for fresh and freeze-dried material of the same plant, although in the dried leaves, methyl chavicol and eugenol concentrations had generally declined in comparison to those of linalool. There appeared to be little correlation between essential oil patterns and varietal classification within O. basilicum. In view of the chemical heterogeneity of O. basilicum and its use as an essential oil-producing crop, culinary herb, medicinal plant and insect-controlling agent, in all of which chemicals play an important role, the infraspecific classification of this taxon should take chemical characters into consideration. A system for the classification of essential oil chemotypes in O. basilicum is proposed.

Effects of ionic strength on endogenous nuclease activity in chelated and nonchelated chromatin.

Calf thymus chromatin, isolated using a standard (low ionic strength, but nonchelating) isolation protocol, dialyzed against either Tris-PMSF or Tris-EDTA, was reconstituted in a high salt compacting buffer (COM) or a low salt dispersing buffer (DIS) prior to digestion with endogenous nucleases. A greater level of enzyme activity occurred when chromatin was in a condensed state (COM buffer) and not chelated prior to digestion. In contrast, chromatin chelated by dialysis against Tris-EDTA prior to digestion showed higher levels of enzyme activity in the dispersed state (DIS buffer). Nonchelated undigested chromatin contained 0.280 +/- 0.16 ug copper/mg DNA and and 0.305 +/+- 0.09 ug zinc/mg DNA. Chelation removed about 78% of copper per mg DNA and approximately 65% of zinc per mg DNA. In COM buffer after a 20 min digestion, the solubilized fraction was enriched in copper showing about 20 X more metal per mg DNA than nonchelated chromatin. Approximately the same amount of zinc was found in both chelated and nonchelated chromatin while there was less zinc in chelated chromatin solubilized in DIS buffer. Thus, chelation has important effects on the digestibility of chromatin and on the type of ionic environment that provides the most favorable conditions for endogenous nuclease activity.

Copper-rich nucleoprotein generated by micrococcal nuclease.

Nuclei from calf thymus tissue digested with micrococcal nuclease under nonchelating conditions yielded soluble nucleoprotein enriched in copper. Following limited digestion, the ratio of µg Cu:mg DNA was inversely related either to percent solubility of chromatin or to levels of enzyme maintaining an enzyme:A 260 ratio of 0.059. The enzyme appeared to cleave preferentially regions of chromatin where copper is localized, releasing no additional metal upon further digestion. Moreover, the highest copper: DNA ratio was always associated with the least-digested sample.The distribution between copper and angiotensin II (AII) in chromatin fragments following slight nuclease digestion suggests a possible link between copper and nuclear AII binding. When nuclei are incubated with AII prior to digestion and dialysis, solubilized chromatin contained about three times more copper than buffer control. Metal profiles generated from gel (A-5 M) chromatography for these samples were distinctive: copper peaks appeared near or adjacent to linker DNA regions, and in the case of AII, coincided with fragments containing specific AII receptors; thus, there appears to be an enrichment of copper in these active nucleoprotein fragments.

Angiotensin II receptors in chromatin.

When isolated rat hepatic nuclei or bovine thymus nuclei were incubated with 125I-angiotensin II (ANG II) in the presence or absence of cold hormone, displaceable binding was consistently detected in micrococcal nuclease generated fragments Nanomolar concentrations of ANG II produced detectable displacement. Little or no specific binding was found when nuclei were first digested and then treated with hormone, suggesting that ANG II solubilizes its own receptor. The binding moiety was partially purified by DNP gel electrophoresis. These studies indicate the existence in chromatin of high affinity receptors for ANG II, and further suggest that hormone binding to these receptors produces conformational changes in chromatin similar to those seen during enhanced transcriptional activity. Thus, the present studies suggest the existence of functional intracellular renin-angiotensin systems.

Angiotensin II receptors in chromatin fragments generated by micrococcal nuclease.

Rat liver nuclei were digested with micrococcal nuclease following incubation with 125I-angiotensin II (AII) or with 125I-AII and excess unlabeled hormone. Chromatin enriched in 125I was solubilized after 3 min and was applied to a BIO-GEL A-5 M column. Labeled hormone was 40-60% displaceable by unlabeled hormone, in nucleoprotein eluting with a V/Vo near 1.9, indicating that these solubilized chromatin fragments contained specific receptors for AII. Furthermore, a discrete AII binding nucleoprotein particle was resolved on DNP gel electrophoresis. Additionally, binding to specific AII nuclear receptors appeared to bring about changes in chromatin structure consistent with the induction of transcriptional activity.

Nuclear-hormone mediated changes in chromatin solubility.

Rat liver nuclei were incubated with either thyroid hormone or angiotensin (AII) at varying concentrations or with buffer (control) prior to digestion with micrococcal nuclease. Concentrations of hormones greater than 10(-10)M were effective in increasing the solubilization of chromatin with physiological levels (10(-9)M) of AII showing an approximate 2.4 fold increase over control. Nuclei were also isolated from animals treated in-vivo with either AII or buffer (control) and chromatin solubility was increased in the AII treated nuclei even prior to the addition of exogenous nuclease, presumably from the action of endogenous nucleases. The data suggest that hormone-induced increases in solubility are a reflection of structural changes in chromatin which enhance the accessibility of DNA to endonuclease attack.

The movement of zinc and copper from the fertilized egg into metallothionein-like proteins in developing chick hepatic tissue.

The movement of copper and zinc from the fertilized egg into the developing embryo and the subsequent association of the two metals with metallothionein-like proteins (MT) of chick liver was investigated. Hepatic levels of MT in 1-d-old chicks, estimated from specifically bound(115m)Cd, were increased eightfold over endogenous levels of these copper- and zinc-binding proteins in adult liver. Copper was assimilated from the oocyte into the embryo more rapidly than zinc in the early stages of embryogenesis. Between 15 and 16 d of development, during the time that (MT) was detected, there was a significant increase in copper concentration, whereas hepatic zinc concentration remained relatively constant.

Heavy metal composition of polysomal fractions following cadmium challenge.

Endogeneous levels of zinc and copper were found to be 1.2±0.1×10(-2) and 0.3±0.1×10(-2) µg/A260 unit, respectively, in polysomal fractions from control animals; cadmium, however, was undetectable. In experimental animals (injected with cadmium) zinc, copper, and cadmium were found in polysomal fractions isolated by two different methods. One hour after a cadmium injection there was a rise in both the zinc and copper content of the polysomal fractions, which then declined steadily to below control levels by 16 h. Neither zinc nor cadmium were dialyzable from these fractions by a TRIS buffer; however, addition of 0.01M EDTA to the buffer resulted in removal of 75% of the zinc and all of the detectable cadmium.The addition of cadmium (CdCl2) to control supernatants (adjusted to the cadmium concentration present in supernatants 6 h after in vivo exposure) resulted in metal binding to polysomal fractions in levels comparable to those observed after in vivo exposures to the metal. When cadmium was added in the form of cadmium thionein, a smaller fraction of the metal was isolated with the polysomal fraction. Cadmium bound to polysomal fractions in vivo (24 h after exposure) was sensitive to release by protease digestion, but insensitive to release by ribonuclease digestion.

Partitioning of zinc and copper within subnuclear nucleoprotein particles.

Nuclei from frozen calf thymus suspended in buffer were analyzed for metal content prior to and after repeated washing. After three such extractions about 0.1 micrograms Zn/mg DNA and 0.025 micrograms Cu/mg DNA remained tightly associated with chromatin. This level of metal was essentially unchanged with subsequent washings. Digestion of extracted nuclei with micrococcal nuclease yielded soluble nucleoprotein containing zinc and copper. Metal enriched regions of chromatin appeared to be preferentially solubilized by digestion, and the solubilized metal was only partially dializable either with or without EDTA. Metal profiles generated from gel (A-5m) chromatography analysis of chelated and non-chelated solubilized chromatin were distinctive in that copper was undetectable (by flame AA) while zinc was associated only with low molecular weight products when EDTA was used. In contrast, both metals were detected with higher molecular weight oligonucleosomes in the absence of chelating agents. Additionally, the two metals localized within nucleoprotein peaks and these metal-containing regions were only resolved by gel chromatography when EDTA was omitted throughout the procedure. A discrete Cu-rich species in a region of the profile suggests a subset of Cu-rich nucleoprotein complexes.

Cadmium, an effector in the synthesis of thionein.

Cadmium can elicit the synthesis of thionein in liver cells independent of tissue-organ interactions. The metal diffuses across the plasma membrane and is partitioned between subcellular components in a time dependent manner such that thionein synthesis responds to levels of nonspecifically and specifically bound cytoplasmic metal. Cadmium appears to function at the transcriptional level, and the metal may act to increase the pool of specific m-RNA's.

Induction of cadmium-thionein in isolated rat liver cells.

The uptake of cadmium by isolated liver cells was linearly related to the cadmium concentration to which the cells were exposed in the medium. Cadmium-treated cells synthesized proteins de novo with the characteristics of cadmium-thionein induced in the liver of cadmium-treated animals. Thionein from liver cells incorporated cadmium and [35S]cysteine, had a Ve/Vo (Sephadex G-50) of 1.8-1.9, and was separated into two subfractions by DEAE-cellulose ion-exchange chromatography. Cycloheximide and actinomycin D when added after a cadmium exposure prevented the synthesis of thionein. However, addition of actinomycin D after synthesis had started only decreased the total amount of thionein synthesized. The concentration of cadmium to which the cells were exposed affected the amount of cadmium-thionein synthesized in 6h. The maximum response occurred when cells were exposed to 0.5 microgram of cadmium/ml; at higher metal concentrations the total amount of cadmium-thionein synthesized declined. The system described in the present paper can be used to study the mode of metal toxicity and the mechanism of cadmium-thionein synthesis.