A pollution history of Chesapeake Bay

Present day anthropogenic fluxes of some heavy metals to central Chesapeake Bay appear to be intermediate to those of the southern California coastal region and those of Narragansett Bay. The natural fluxes, however, are in general higher. On the bases of Pb-210 and Pu-239 + 240 geochronologies and of the time changes in interstitial water compositions, there is a mixing of the upper 30 or so centimeters of the sediments in the mid-Chesapeake Bay area through bioturbation by burrowing mollusks and polychaetes. Coal, coke and charcoal levels reach one percent or more by dry weight in the deposits, primarily as a consequence of coal mining operations.     

What information do policy makers need to develop climate adaptation plans for smallholder farmers? The case of Central America and Mexico

Scientific and technical information can increase the ability of policy makers to make strategic decisions. However, climate change policy is often formulated without significant input from science. We examine whether the availability and accessibility of information related to climate change is a major barrier for policy action on climate change adaptation for smallholder farmers. We also investigate whether scientific information related to climate change is available and used in policy making in Central America and Mexico. Our online survey of 105 decision makers indicated that a lack of scientific and technical information hinders policy makers from developing policies to help smallholder farmers adapt to climate change. Specific needs include information on the impacts of climate change on water availability for agriculture and the areas that are or will be prone to flooding, droughts or landslides. Information about the location of the farmers who are most vulnerable to climate change, the projected temperature and precipitation in agricultural areas and the expected impacts of climate change on crop yields or animal productivity, is also needed. Despite high interest in having scientific information guide policy making, many respondents indicated that policy makers rarely use this information in adaptation planning. In addition to ensuring that relevant information is available to inform policy making, technical and scientific information must be published in venues that are readily accessible for policy makers, easy to understand, and written in a format that is policy-relevant. It is also critical that scientific articles provide specific recommendations for achieving desired policy outcomes.     

Die Messung ultravioletter Strahlung mit einem Photoresist als Empfänger

Zusammenfassung Es wird ein photochemisches UV-Meßverfahren angegeben, das als Empfänger eine strahlungsempfindliche Härtungsschicht (Photoresist) benutzt. Das Maß der Härtung ist die der eingestrahlten Energie proportionale Schichtdicke, welche interferometrisch bestimmt wird.Das Verfahren ist vor allem als Feldmethode gedacht; Messung und Auswertung lassen sich zeitlich und räumlich trennen. Das Meßzubehör ist leicht, transport-unempfindlich und ohne besondere Kenntnis zu bedienen. Eine zentrale Stelle kann zu beliebigem Zeitpunkt die Messungen zahlreicher Beobachter auswerten.Die praktische Anwendungsmöglichkeit des Resist-Verfahrens wurde in über 300 Feldversuchen im Tiefland und in Höhenlagen geprüft. Unter Verwendung von Filtergläsern, dem Flüssigkeitsfilter nach Bäckström und zweier Interferenzfilter wurden das Gesamt-UV, das UV-A und das UV-B getrennt gemessen.Dem Resist-Verfahren sind wie jeder integrierenden UV-Meßmethode bestimmte Grenzen gesetzt, bedingt durch den nicht linearen Verlauf der spektralen Empfindlichkeitskurve des Empfängers, und durch die nicht senkrecht abfallenden Transmissionskurven der verwendeten Filter. Dieser Umstand ist bei vergleichenden UV-Intensitätsbestimmungen zu berücksichtigen, da er gewisse Fehlerquellen in sich schließt. Trotz dieser Einschränkung, die speziell für das Gesamt-UV und für das UV-B gilt, nicht dagegen für das UV-A, dürfte sich das feldmäßig anwendbare Resist-Verfahren zur Lösung bestimmter medizinisch-bioklimatologischer UV-Strahlungsprobleme als brauchbar erweisen.

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Summary The authors discuss a photo-chemical ultra-violet measuring procedure which uses as receiver a hardening coating (photoresist) sensitive to radiation. The measure of hardening is the thickness of the coating which is proportional to the irradiated energy interferometrically determined.The procedure is mainly intended as a field method; measurement and evaluation can be separated relating to time and place. The measuring accessories are light, insensible to transport and can be worked without special knowledge. A central institute may evaluate the measurements of various observers at any date chosen.The practical application of the resist procedure has been examined in the lowland and in altitudes by more than 300 field measurements. UV total, UV-A und UV-B have been measured separately by means of filter glasses, the Bäckström liquid filter and two interference filters.Limits are set to the resist procedure as to every integrating UV measuring method, caused by the non-linear course of the spectral sensitivity curve of the receiver and by the transmission curves of the filters not vertically falling off. This fact has to be considered for the comparative determinations of UV intensity since it includes certain sources of error. In spite of this restriction which applies especially to UV total and UV-B, but not to UV-A, the resist procedure may prove useful, especially for field measurements, for the solution of certain medical-bioclimatological UV radiation problems.

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Résumé On décrit ici une méthode de mesure photochimique de l'ultraviolet. Cette méthode utilise comme récepteur une couche d'insolubilisation (photorésist) sensible au rayonnement. Le degré d'insolubilisation est donné par l'épaisseur de la couche qui est, elle, proportionnelle à l'énergie du rayonnement reçu. Cette épaisseur est ensuite déterminée par interférométrie.Cette méthode est applicable surtout en campagne. En effet, la mesure et son évaluation peuvent être disjointes aussi bien dans le temps que dans l'espace. L'appareil de mesure est léger, robuste et peut être utilisé par un personnel n'ayant pas de connaissances particuliéres. Un poste centralisateur peut mettre en valeur les mesures faites par plusieurs observateurs et cela à un moment choisi librement.Les possibilités d'utilisation du procédé «résist» ont été mises à l'épreuve au cours de plus de 300 essais et cela aussi bien en plaine qu'en montagne. En utilisant des verres filtrants, un filtre à liquide selon Bäckström et deux filtres à interférence, on a pu mesurer séparément l'ultra-violet complet, l'UV-A et l'UV-B.Comme pour chaque méthode de mesure par intégration de l'ultraviolet, le procédé «résist» n'est utilisable que dans certaines limites. Celles-ci sont conditionnées par l'état non linéaire de la courbe de sensibilité spectrale du récepteur et par le fait que les courbes de transmission des filtres utilisés ne sont pas perpendiculaires. Ces phénomènes doivent être pris en considération lors de la détermination comparative de l'intensité des rayons ultra-violets, car ils impliquent certaines sources d'erreurs. Malgré ces restrictions—valables surtout pour l'ultra-violet total et l'UV-B, mans pas pour l'UV-A, le procédé «résist» devrait s'imposer pour la solution de certains problèmes de rayonnement ultra-violet en bioclimatologie médicale.

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Mit 12 Textabbildungen     

Site characterisation of a basin-scale CO<Subscript>2</Subscript> geological storage system: Gippsland Basin,southeast Australia

Geological storage of CO₂ in the offshore Gippsland Basin, Australia, is being investigated by the Cooperative Research Centre for Greenhouse Gas Technologies (CO2CRC) as a possible method for storing the very large volumes of CO₂ emissions from the nearby Latrobe Valley area. A storage capacity of about 50 million tonnes of CO₂ per annum for a 40-year injection period is required, which will necessitate several individual storage sites to be used both sequentially and simultaneously, but timed such that existing hydrocarbon assets will not be compromised. Detailed characterisation focussed on the Kingfish Field area as the first site to be potentially used, in the anticipation that this oil field will be depleted within the period 2015–2025. The potential injection targets are the interbedded sandstones of the Paleocene-Eocene upper Latrobe Group, regionally sealed by the Lakes Entrance Formation. The research identified several features to the offshore Gippsland Basin that make it particularly favourable for CO₂ storage. These include: a complex stratigraphic architecture that provides baffles which slow vertical migration and increase residual gas trapping and dissolution; non-reactive reservoir units that have high injectivity; a thin, suitably reactive, lower permeability marginal reservoir just below the regional seal providing mineral trapping; several depleted oil fields that provide storage capacity coupled with a transient production-induced flow regime that enhances containment; and long migration pathways beneath a competent regional seal. This study has shown that the Gippsland Basin has sufficient capacity to store very large volumes of CO₂. It may provide a solution to the problem of substantially reducing greenhouse gas emissions from future coal developments in the Latrobe Valley.     

The origin of groundwater arsenic and fluorine in a volcanic sedimentary basin in central Mexico: a hydrochemistry hypothesis

A groundwater sampling campaign was carried out in the summer of 2013 in a low-temperature geothermal system located in Juventino Rosas (JR) municipality, Guanajuato State, Mexico. This groundwater presents high concentrations of As and F^? and high Rn counts, mainly in wells with relatively higher temperature. The chemistry of major elements was interpreted with different methods, like Piper and D’Amore diagrams. These diagrams allowed for classification of four groundwater types located in three hydrogeological environments. The aquifers are hosted mainly in alluvial-lacustrine sediments and volcanic rocks in interaction with fault and fracture systems. The subsidence, faults and fractures observed in the study area can act as preferential channels for recharge and also for the transport of deep fluids to the surface, especially in the basin plain. The formation of a piezometric dome and the observed hydrochemical behavior of groundwater suggest a possible origin of the As and F^?. Geochemical processes occurring during water–rock interaction are related to high concentrations of As and F^?. High temperatures and alteration processes (like rock weathering) induce dissolution of As and F^?-bearing minerals, increasing the content of these elements in groundwater.     

Landslide deposits as stratigraphical markers for a sequence‐based glacial stratigraphy: a case study of a Younger Dryas system in the Eastern Alps

Detailed ¹⁰Be and ¹⁴C dating and supporting pollen analysis of Alpine Lateglacial glacial and landslide deposits in the Hohen Tauern Mountains (Austria) constrain a sequence‐based stratigraphy comprising a major landslide (13.0±1.1 ka) overlain by till and termino‐lateral moraines of an advancing (12.6±1.0 ka) and retreating (11.3±0.8 ka) glacier in turn overlain by a minor landslide (10.8±1.1 ka). These results define glacier activity during the Younger Dryas age Egesen stadial bracketed by landslide activities during the Bølling‐Allerød interstadial and the Preboreal. In contrast to recent studies on Holocene glaciation in the Alps, no traces of any Holocene glacier advance bigger than during the Little Ice Age are documented. Furthermore, this study demonstrates the advantages of using an allostratigraphical approach based on unconformity‐bounded sedimentary units as a tool for glacial stratigraphy in formerly glaciated mountain regions, rather than a stratigraphy based on either isolated morphological features or lithostratigraphical characteristics.     

Geology, ore deposits and hydrothermal venting in Bahía Concepción, Baja California Sur, Mexico

Abstract Bahía Concepción is located in the eastern coast of the Baja California peninsula and it is shaped by northwestern–southeastern normal faults. These are associated with a 12–6 Ma rifting episode, although some have been reactivated since the Pliocene. The most abundant rocks correspond to the arc related Comondú Group, Oligocene to Miocene, which forms a mainly calc‐alkaline volcanic and volcaniclastic sequence. There are less extensive outcrops of sedimentary rocks, lava flows, domes and pyroclastic rocks of Pliocene to Quaternary ages. The Neogene volcanism in the area indicates a shift from a subduction regime to an intraplate volcanism related to continental extension and the opening of an oceanic basin. The Bahía Concepción area contains numerous Mn ore deposits, being the biggest at El Gavilán and Guadalupe. The Mn deposits occur as veins, breccias and stockworks, and are composed by Mn oxides (pyrolusite, coronadite, romanechite), dolomite, quartz and barite. The deposits are hosted in volcanic rocks of the Comondú Group and, locally, in Pliocene sedimentary rocks. Thus, the Mn deposits formed between the Middle Miocene and the Pliocene. The mineralized structures are associated with Miocene northwestern–southeastern fault systems, which are analogous to those associated with the Cu‐Co‐Zn‐Mn deposits of El Boleo. The Bahía Concepción area also bears subaerial and submarine hot springs, which are associated with the same fault systems and host rocks. The submarine and subaerial geothermal manifestations south of the bay are possibly related with recent volcanism. The geothermal manifestations within the bay are intertidal hot springs and shallow submarine diffuse venting areas. Around the submarine vents (5–15 m deep, 87°C), Fe‐oxyhydroxide crusts with pyrite and cinnabar precipitate. In the intertidal vents (62°C), aggregates of opal, calcite, barite and Ba‐rich Mn oxides occur covered by silica‐carbonate stromatolitic sinters. Some 10–30 cm thick crustiform veins formed by chalcedony, calcite and barite are also found close to the vents. The hydrothermal fluids exhibit mixed isotopic compositions between δ¹⁸O‐enriched meteoric and local marine water. The precipitation of Ba‐rich Mn oxides around the vent sites could be an active analog for the processes that produced Miocene to Pliocene hydrothermal Mn‐deposits.     

Plankton copper requirements and uptake in the subarctic Northeast Pacific Ocean

We undertook the first measurements of metabolic Cu requirements (net Cu:C assimilation ratios) and steady-state Cu uptake rates (ρCu_ss) of natural plankton assemblages in the northeast subarctic Pacific using the short-lived radioisotope ⁶⁷Cu. Size-fractionated net Cu:C assimilation ratios varied ～3 fold (1.35–4.21 μmol Cu mol C^?1) among the stations along Line P, from high Fe coastal waters to the Fe-limited open ocean. The variability in Cu:C was comparable to biogenic Fe:C ratios in this region. As previously observed for Fe uptake, the bacterial size class accounted for half of the total particulate ρCu_ss. Interestingly, carbon biomass-normalized rates of Fe uptake from the siderophore desferrioxamine B (DFB) (ρFe_DFB; a physiological proxy for Fe-limitation) by the >20 μm size class were positively correlated with the intracellular net Cu:C assimilation ratios in this size class, suggesting that intracellular Cu requirements for large phytoplankton respond to increased Fe-limitation. At Fe-limited Ocean Station Papa (OSP), we performed short-term Cu uptake (ρCu_L) assays to determine the relative bioavailability of Cu bound to natural and synthetic ligands. Like the volumetric ρCu_ss measured along Line P, the bacterial size class was responsible for at least 50% of the total ρCu_L. Uptake rates of Cu from the various organic complexes suggest that Cu uptake was controlled by the oxidation state of the metal and by the metal:ligand concentration ratio, rather than the concentration of inorganic species of Cu in solution. Collectively, these data suggest that Cu likely plays an important role in the physiology of natural plankton communities beyond the toxicological effects studied previously.     

The impact of urbanization on water vulnerability: A coupled human–environment system approach for Chennai,India

While there is consensus that urbanization is one of the major trends of the 21^st century in developing countries, there is debate as to whether urbanization will increase or decrease vulnerability to droughts. Here we examine the relationship between urbanization and water vulnerability for a fast-growing city, Chennai, India, using a coupled human–environment systems (CHES) modeling approach. Although the link between urbanization and water vulnerability is highly site-specific, our results show some generalizable factors exist. First, the urban transformation of the water system is decentralized as irrigation wells are converted to domestic wells by private individuals, and not by the municipal authority. Second, urban vulnerability to water shortages depends on a combination of several factors: the formal water infrastructure, the rate and spatial pattern of land use change, adaptation by households and the characteristics of the ground and surface water system. Third, vulnerability is dynamic, spatially variable and scale dependent. Even as household investments in private wells make individual households less vulnerable, over time and cumulatively, they make the entire region more vulnerable. Taken together, the results suggest that in order to reduce vulnerability to water shortages, there is a need for new forms of urban governance and planning institutions that are capable of managing both centralized actions by utilities and decentralized actions by millions of households.