[1] Ground based remote sensing techniques are used to measure volcanic SO 2 fluxes in efforts to characterise volcanic activity. As these measurements are made several km from source there is the potential for in-plume chemical transformation of SO 2 to sulphate aerosol (conversion rates are dependent on meteorological conditions), complicating interpretation of observed SO 2 flux trends. In contrast to anthropogenic plumes, SO 2 lifetimes are poorly constrained for tropospheric volcanic plumes, where the few previous loss rate estimates vary widely (from (1 to >99% per hour). We report experiments conducted on the boundary layer plume of Masaya volcano, Nicaragua during the dry season. We found that SO 2 fluxes showed negligible variation with plume age or diurnal variations in temperature, relative humidity and insolation, providing confirmation that remote SO 2 flux measurements (typically of %500-2000 s old plumes) are reliable proxies for source emissions for ash free tropospheric plumes not emitted into cloud or fog.

Surfactants are a commercially important group of chemicals widely used on a global scale. Despite high removal efficiencies during wastewater treatment, their high consumption volumes mean that a certain fraction will always enter aquatic ecosystems, with marine environments being the ultimate sites of deposition. Consequently, surfactants have been detected within marine waters and sediments. However, aquatic environmental studies have mostly focused on the freshwater environment, and marine studies are considerably underrepresented by comparison. The present review aims to provide a summary of current marine environmental fate (monitoring, biodegradation, and bioconcentration) and effects data of 5 key surfactant groups: linear alkylbenzene sulfonates, alcohol ethoxysulfates, alkyl sulfates, alcohol ethoxylates, and ditallow dimethyl ammonium chloride. Monitoring data are currently limited, especially for alcohol ethoxysulfates and alkyl sulfates. Biodegradation was shown to be considerably slower under marine conditions, whereas ecotoxicity studies suggest that marine species are approximately equally as sensitive to these surfactants as freshwater species. Marine bioconcentration studies are almost nonexistent. Current gaps within the literature are presented, thereby highlighting research areas where additional marine studies should focus. Environ Toxicol Chem

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The formation of basic aluminium sulphate (BAS) minerals [(K,Na) n Al x (OH) y (SO 4 ) z ] has often been invoked to explain sulphate retention in soils. These minerals have not yet, however, been directly observed in the soil. We extracted the clay fractions of Andosols intercepting large inputs of volcanogenic sulphur dioxide and acids (HCl, HF), simply by dispersing clays with Na þ -resins in deionized water without any other chemical treatment. Clay fractions concentrate 39-63% of total sulphur content of soil. Transmission electron microscopy coupled with energy-dispersive analysis revealed the presence of BAS particles, appearing as nodules and spheres. These particles have an equivalent diameter smaller than 0.2 m. They have an Al:S ratio close to 2.2 and 3.8 and are possibly amorphous aluminite or basaluminite, respectively. They seem to have been formed in microenvironments enriched in sulphate, but also in fluoride anions. Their formation seems to have been enhanced by the combination of large inputs of acids and SO 2 and an effective Al supply from weathering of volcanic glass.

Summary Soil response to acid and sulphur inputs is influenced largely by the soil's physico‐chemical properties. We studied the effects of such depositions in two types of Andosols exposed to volcanogenic emission (Masaya, Nicaragua), namely Eutric Andosols rich in allophanic constituents, and Vitric Andosols rich in volcanic glass. Small mineral reserves and large contents of secondary short‐range ordered minerals indicate a more advanced weathering of the Eutric than the Vitric Andosols. Strong correlations between soil specific surface and oxalate‐extractable Al, Si and Fe contents highlight the predominant contribution of short‐range ordered minerals to surface area. Both types of Andosols showed a decrease in pH upon acid input. Sulphur deposition increased the soil's S content to 5470 mg S kg−1. However, the acid neutralizing capacity of the soil solid phase (ANCs) was not significantly affected by the acid and S inputs. Non‐exchangeable (mineral reserve) and exchangeable cations and total contents of sulphur and phosphorus dictate most of the ANCs variation. In the Vitric Andosols, mineral reserves contributed up to 97% to these four additive pools, whereas the exchangeable cations accounted for 1–4%. In the Eutric Andosols, the contribution of mineral reserves was less (71–92%), but the exchangeable cation content was greater (1–20%), whereas the contribution of sulphur and phosphorus was significant at 1–15% and 2–7%, respectively. The main process involved in H+ consumption is mineral weathering in Vitric Andosols and ion exchange in Eutric Andosols.