A summary of sulfur dioxide emission rate measuremnts from Guatemalan volcanoes

Measurements of the sulfur dioxide (SO₂) emission rate from three Guatemalan volcanoes provide data which are consistent with theoretical and laboratory studies of eruptive and shallow magma chamber processes. In particular, unerupted magma makes a major contribution to the measured SO₂ emission rates at Santiaguito, a continuously erupting dacitic volcanic dome. Varying shallow magma convection rates can explain the variations in SO₂ emission rates at Santiaguito. At Fuego, a basaltic volcano currently in repose, SO₂ emission rate measurements are consistent with a high level magma body that is crystallizing and releasing volatiles. At Pacaya, a continuously erupting basaltic volcano, recent SO₂ emission rate measurements support laboratory simulation studies of strombolian eruptions; these studies indicate that the majority of gas escapes during eruptions and little gas escapes between eruptions.Average SO₂ emission rates over the last 20 years for Santiaguito, Fuego and Pacaya are 80, 160 and 260 Mg/d, respectively. On a global scale, these three volcanoes account for 1% of the annual global volcanic output of SO₂. Santiaguito and Pacaya, together, emit 6% of the total annual SO₂ emitted by continuously erupting volcanoes.Even though SO₂ measurements at these volcanoes have been made infrequently and by different investigators, the collective data help to establish a useful baseline by which to judge future changes. A more complete record of SO₂ emission rates from these volcanoes could lead to a better understanding of their eruption mechanisms and reduce the impact of their future eruptions on Guatemalan society.     

Evidence for discrete subpopulations of sea perch (Helicolenus ercoides) across four fjords in Fiordland,New Zealand

In coastal populations of invertebrates and fishes, the distribution of discrete subpopulations is influenced by adult and larval dispersal, as well as by the effects of habitat heterogeneity on site fidelity or connectivity. Here, we examine evidence for spatial structure of sea perch, Helicolenus percoides, populations among four fjords in the Fiordland region of southwestern New Zealand. We examine patterns in adult morphology, length-at-age, δ¹³C and δ¹⁵N of muscle tissue, and trace elemental composition of whole otoliths as proxies for population isolation among the four inner fjord regions. A multivariate analysis of morphometrics reveals significant differences among populations from each of the four sites, suggesting existence of four distinct subpopulations. These patterns are consistent with observed differences in δ¹³C and δ¹⁵N, and length-at-age estimates among the four subpopulations. Differences in whole otolith concentrations of Sr, Ba, Mg and Li, and high classification scores based on the whole otolith elemental fingerprint are also consistent with significant subdivision among areas. Patterns across all four markers are consistent with discrete subpopulation structure of adult sea perch among the four study sites. These data indicate that the newly implemented network of marine protected areas in Fiordland is likely to contain discrete populations of sea perch.     

新疆东准噶尔石炭纪火山机构类型与时限

东准噶尔卡拉麦里大气田的主要储层是石炭纪火山岩,石炭纪古火山机构的样式与组合特征,与火山岩储层展布关系密切。野外调查表明,隐爆角砾岩是东准噶尔石炭纪古火山机构最常见的标志之一。东准噶尔石炭纪古火山机构类型主要有中心式、裂隙式和裂隙-中心式等样式。中心式火山机构以大石头层状火山、柯克巴斯套锥状火山最为典型;巴塔玛依内山附近沿断裂分布的带状火山岩具有裂隙式喷发的特征;东黑山火山具有火山口串珠状排列特征,是裂隙-中心式喷发的产物。大石头地区原缪林托凯陶山组火山岩的锆石SHRIMP U-Pb年龄为345.6±7.1 Ma,而已知巴塔玛依内山组火山岩年龄是350.0±6.3Ma,因此东准噶尔火山活动的主要时期是早石炭世。     

An example of fingerprint detection of greenhouse climate change

As an example of the technique of fingerprint detection of greenhouse climate change, a multivariate signal or fingerprint of the enhanced greenhouse effect is defined using the zonal mean atmospheric temperature change as a function of height and latitude between equilibrium climate model simulations with control and doubled CO₂ concentrations. This signal is compared with observed atmospheric temperature variations over the period 1963 to 1988 from radiosonde-based global analyses. There is a significant increase of this greenhouse signal in the observational data over this period.These results must be treated with caution. Upper air data are available for a short period only, possibly too short to be able to resolve any real greenhouse climate change. The greenhouse fingerprint used in this study may not be unique to the enhanced greenhouse effect and may be due to other forcing mechanisms. However, it is shown that the patterns of atmospheric temperature change associated with uniform global increases of sea surface temperature, with El NinoSouthern Oscillation events and with decreases of stratospheric ozone concentrations individually are different from the greenhouse fingerprint used here.     

Colonisation of South African kelp-bed canopies by the alien mussel Mytilus galloprovincialis: extent and implications of a novel bioinvasion

The Mediterranean mussel Mytilus galloprovincialis is the most significant invasive alien marine species in South Africa and, although not normally found subtidally, has recently been observed colonising heads and stipes of the kelp species Ecklonia maxima in False Bay. We quantified this invasion and explored its ecological implications. Transects laid across kelp beds revealed that 10.34% of kelp individuals surveyed bore canopy mussels, with kelp heads (10.07%) being far more commonly infected than stipes (0.27%). Twenty kelp individuals with infected heads and 20 with infected stipes were separately collected for more-detailed examination. Wet mass of mussels on these kelp heads ranged from 2.5 to 2 462 g (median 86.4 g, interquartile range 14.8–353.8 g) and that of mussels on the stipes from 7.6 to 3 492 g (median 595.5 g, interquartile range 194.0–955.0 g). Mussel clumps consisted mostly of individuals <40 mm in length. Mussel clumps supported a rich biota of 80 invertebrate and 13 algal species. Larger clumps supported more epibiotic species, and those on stipes more species than those of comparable mass on kelp heads. The mussels and their associated epibiotic species negatively affected kelp buoyancy, but rarely enough to overcome natural buoyancy. Some kelp individuals that had been toppled by the weight of mussels and their epibiotic species, however, were encountered in situ. Implications of this invasion include large increases in animal biomass and species richness in the kelp canopy, plus reductions in kelp buoyancy and increased hydrodynamic drag on infected kelps, increasing their probability of being uprooted. Uprooted kelp individuals can raft long distances, potentially transporting both native and alien species to distant sites.     

Natural attenuation of septic system nitrogen by anammox

On-site disposal of sewage in septic systems can lead to groundwater plumes with NO(3)(-)-N concentrations exceeding the common drinking water limit of 10 mg/L. Currently, denitrification is considered as the principal natural attenuation process. However, at a large seasonal-use septic system in Ontario (256 campsites), a suboxic zone exists where nitrogen removal of up to 80% occurs including removal of NH(4)(+)-N. This zone has both NO(3)(-)-N and NH(4)(+)-N at >5 mg/L each. In the distal NH(4)(+)-rich zone, NH(4)(+)-N concentrations (8.1 ± 8.0 mg/L) are lower than in the proximal zone (48 ± 36 mg/L) and NH(4)(+)-N is isotopically enriched (concentration-weighted mean δ(15)N of +15.7‰) compared to the proximal zone (+7.8‰). Furthermore, δ(15)N-NH(4)(+) isotopic enrichment increases with depth in the distal zone, which is opposite to what would result if nitrification along the water table zone was the mechanism causing NH(4)(+) depletion. Bacterial community composition was assessed with molecular (DNA-based) analysis and demonstrated that groundwater bacterial populations were predominantly composed of bacteria from two Candidatus genera of the Planctomycetales (Brocadia and Jettenia). Together, these data provide strong evidence that anaerobic ammonium oxidation (anammox) plays an important role in nitrogen attenuation at this site.     

SO2 from episode 48A eruption,Hawaii: Sulfur dioxide emissions from the episode 48A East Rift Zone eruption of Kilauea volcano,Hawaii

An SO₂ flux of 1170±400 (1) tonnes per day was measured with a correlation spectrometer (COSPEC) in October and November 1986 from the continuous, nonfountaining, basaltic East Rift Zone eruption (episode 48A) of Kilauea volcano. This flux is 5–27 times less than those of highfountaining episodes, 3–5 times greater than those of contemporaneous summit emissions or interphase Pu'u O'o emissions, and 1.3–2 times the emissions from Pu'u O'o alone during 48A. Calculations based on the SO₂ emission rate resulted in a magma supply rate of 0.44 million m³ per day and a 0.042 wt% sulfur loss from the magma upon eruption. Both of these calculated parameters agree with determinations made previously by other methods.     

Precambrian Shield Wetlands: Hydrologic Control of the Sources and Export of Dissolved Organic Matter

Most Precambrian Shield forested catchments have some wetland component. Even small riparian wetlands are important modifiers of stream chemistry. Dissolved organic matter (DOM) is one of the most important products exported by wetlands in streams. Stratigraphic control of hydraulic conductivity generally leads to decreasing conductivity with depth. Thus important flowpaths occur in the uppermost organic rich layers and are reflected in chemical profiles of dissolved organic carbon (DOC). Accumulation of DOC in peat porewaters is the net effect of production, consumption and transport. DOC profiles vary with degree of interaction with the surrounding upland catchment and distance from the edge of the wetland as well as internal processes within the wetland. In wetlands, DOM production is offset by flushing resulting in decreasing DOC concentrations with increasing flows. Despite old carbon (2,000 to 3,000 years) at relatively shallow depths, 14C activity in DOC exported from wetlands is mostly modern (recent carbon), consistent with shallow flowpaths and export of DOM from shallow organic rich horizons. In contrast, the source area for DOM in upland catchments with developed B horizon soils increases with antecedent soil moisture conditions resulting in increasing DOC concentrations with higher stream flows. Activity of 14C in stream DOC from upland catchments span a range from low activities (older carbon) similar to B horizon soil water during dry moisture conditions to values slightly less than modern (more recent carbon) during high moisture conditions. The more modern carbon activities reflect the increased contribution of the organic rich litter and A horizon soil layers in the area immediately bordering the stream under wet antecedent moisture conditions. Reduced hydrologic export or loss of wetlands under drier climatic conditions may result in in larger fluctuations in stream DOC concentrations and reduced DOM loads to lakes.