Extreme 13C depletion of CCl2F2 in firn air samples from NEEM, Greenland

A series of 12 high volume air samples collected from the S2 firn core during the North Greenland Eemian Ice Drilling (NEEM) 2009 campaign have been measured for mixing ratio and stable carbon isotope composition of the chlorofluorocarbon CFC-12 (CCl2F2). While the mixing ratio measurements compare favorably to other firn air studies, the isotope results show extreme 13C depletion at the deepest measurable depth (65 m), to values lower than d13C = -80‰ vs. VPDB (the international stable carbon isotope scale), compared to present day surface tropospheric measurements near -40‰. Firn air modeling was used to interpret these measurements. Reconstructed atmospheric time series indicate even larger depletions (to -120‰) near 1950 AD, with subsequent rapid enrichment of the atmospheric reservoir of the compound to the present day value. Mass-balance calculations show that this change is likely to have been caused by a large change in the isotopic composition of anthropogenic CFC-12 emissions, probably due to technological advances in the CFC production process over the last 80 yr, though direct evidence is lacking

Fluidic Force Discrimination Assays: A New Technology for Tetrodotoxin Detection

Tetrodotoxin (TTX) is a low molecular weight (~319 Da) neurotoxin found in a number of animal species, including pufferfish. Protection from toxin tainted food stuffs requires rapid, sensitive, and specific diagnostic tests. An emerging technique for the detection of both proteins and nucleic acids is Fluidic Force Discrimination (FFD) assays. This simple and rapid method typically uses a sandwich immunoassay format labeled with micrometer-diameter beads and has the novel capability of removing nonspecifically attached beads under controlled, fluidic conditions. This technique allows for near real-time, multiplexed analysis at levels of detection that exceed many of the conventional transduction methods (e.g., ELISAs). In addition, the large linear dynamic range afforded by FFD should decrease the need to perform multiple sample dilutions, a common challenge for food testing. By applying FFD assays to an inhibition immunoassay platform specific for TTX and transduction via low magnification microscopy, levels of detection of ~15 ng/mL and linear dynamic ranges of 4 to 5 orders of magnitude were achieved. The results from these studies on the first small molecule FFD assay, along with the impact to detection of seafood toxins, will be discussed in this manuscript

Clustering, advection and patterns in a model of population dynamics with neighborhood-dependent rates

We introduce a simple model of population dynamics which considers birth and death rates for every individual that depend on the number of particles in its neighborhood. The model shows an inhomogeneous quasistationary pattern with many different clusters of particles. We derive the equation for the macroscopic density of particles, perform a linear stability analysis on it, and show that there is a finite-wavelength instability leading to pattern formation. This is the responsible for the approximate periodicity with which the clusters of particles arrange in the microscopic model. In addition, we consider the population when immersed in a fluid medium and analyze the influence of advection on global properties of the model.Comment: Some typos and some problems with the figures correcte

Non-Traditional Vectors for Paralytic Shellfish Poisoning

Paralytic shellfish poisoning (PSP), due to saxitoxin and related compounds, typically results from the consumption of filter-feeding molluscan shellfish that concentrate toxins from marine dinoflagellates. In addition to these microalgal sources, saxitoxin and related compounds, referred to in this review as STXs, are also produced in freshwater cyanobacteria and have been associated with calcareous red macroalgae. STXs are transferred and bioaccumulate throughout aquatic food webs, and can be vectored to terrestrial biota, including humans. Fisheries closures and human intoxications due to STXs have been documented in several non-traditional (i.e. non-filter-feeding) vectors. These include, but are not limited to, marine gastropods, both carnivorous and grazing, crustacea, and fish that acquire STXs through toxin transfer. Often due to spatial, temporal, or a species disconnection from the primary source of STXs (bloom forming dinoflagellates), monitoring and management of such non-traditional PSP vectors has been challenging. A brief literature review is provided for filter feeding (traditional) and non-filter feeding (non-traditional) vectors of STXs with specific reference to human effects. We include several case studies pertaining to management actions to prevent PSP, as well as food poisoning incidents from STX(s) accumulation in non-traditional PSP vectors

A record of carbonyl sulfide from Antarctic ice over the last 1000 years

Carbonyl sulfide (COS) is a trace gas, present in the troposphere, and also in the stratosphere, where it contributes to the stratospheric sulfate aerosol layer. It has both natural and anthropogenic sources. Natural processes include uptake by plants, while oceans, wetlands, volcanism and biomass burning all contribute to natural COS emissions. We have measured COS in Antarctic ice cores from Dronning Maud Land, drilled in 1998, the DE08 core drilled at Law Dome in 1987, and the DSS0506 core drilled in 2006. Ice samples with COS gas ages between about 1050 AD and the early 20th centrury have been examined. A large volume ice crusher at the CSIRO Marine and Atmospheric Research laboratory was used to extract air from bubbles occluded in the ice cores. These air samples were analysed for CO2, CH4, CO and 13CO2 at CSIRO, and then for COS and several halocarbons at the University of East Anglia on a high sensitivity gas chromatograph/tri-sector mass spectrometer system. Initial results indicate that good sample integrity can be achieved. Measurements from the DML samples indicate low and uniform abundances across the last few hundred years, and at concentrations significantly below those in the modernday atmosphere. Measurements in more recent ice from DE08 show the start of increasing concentrations in the early 1900s, confirming earlier evidence that the global atmospheric abundance of COS has increased as a result of industrial activity during the 20th century

New Iguanid Lizards From Northwestern San Juan Province (San Guillermo Natural Reserve), Argentina

Se describe por primera vez la herpetofauna de una significativa área andina de la Reserva Provincial San Guillermo, cerca del refugio de la misma, en las planicies de Llano de los Hoyos y Caserones, a 3.500 m s.n.m. Caracterizada por un alto porcentaje de endemismo, esta fauna incluye formas de pastizales y saxícolas entre los reptiles, todos iquánidos, y hasta ahora una única especie de anfibio común en vegas y mallines: Bufo spinulosus. Entre los iguánidos se han identificado dos especies nuevas de Liotae- mus, ambas de pastizal arbustivo, que se describen como Liolaemus eleodori sp. nov. y Liolaemus sp. (grupo anomalus), este último todavía no denominado definitivamente como taxón por haberse recolectado un solo ejemplar adulto. Otro Liolaemus de roquedal es Liolaemus elongatus, no señalado más al norte de Uspallata, en Mendoza. Siempre en roquedales, se ha identificado una nueva especie de Phyma- turus, Phymaturus punae sp. nov., afín a P. pal turna de Uspallata, al cual ecológicamente reemplaza. También resulta interesante la presencia de Pristidactylus scapulatus, iguánido anoloide de costumbres crepusculares y reservadas, por lo tanto de difícil captura. Su hallazgo, más frecuente en las asociaciones de Lycium chañar, desplaza ahora unos 200 km más al norte la distribución geográfica de la forma, cuyas localidades más septentrionales eran las del Paramillo de Uspallata (2600 - 3000 m s.n.m.) en el departamento Las Heras, Mendoza.In the austral summer of 1982-83, during the course of field work in the Andes of northwestern San Juan Province, Argentina, a significant and apparently localized herpetofauna was discovered at about 3.500 m s.n.m. in the Reserva Provincial de San Guillermo (29° 18' S. lat; 69° 15' W long). Liolaemus eleodori sp. nov. is described; it is morphologically most similar to L. ruibali of the Andean steppe in San Juan and Mendoza provinces to the south. Phymaturus punae sp. nov. is also described; it appears to be most closely allied to P. palluma, a saxicolous form of the same region as L. ruibali. A single individual of a probably new species of Liolaemus of the anomalus group is described but not named. Additional species reported from the region are: Liolaemus elongatus, a widespread Andean-Patagonlan form; Pristidactylus scapulatus, a secretive lizard heretofore known only from the Uspallata Plateau and Choi- que Pass in Mendoza Province; and, Bufo spinulosus. Our findings indicate a probably high percentage of endemism for the San Guillermo herpetofauna, associated with its topographical isolation as an Andean embossment surrounded by high, and in some areas entirely azoic. Cordilleras.Material digitalizado en SEDICI gracias a la colaboración del Dr. Jorge Williams (FCNM-UNLP).Facultad de Ciencias Naturales y Muse