RESUMO
Ocean acidification, the ongoing decline of surface ocean pH and [CO 3 2 - ] due to absorption of surplus atmospheric CO2, has far-reaching consequences for marine biota, especially calcifiers. Among these are teleost fishes, which internally calcify otoliths, critical elements of the inner ear and vestibular system. There is evidence in the literature that ocean acidification increases otolith size and alters shape, perhaps impacting otic mechanics and thus sensory perception. Here, larval Clark's anemonefish, Amphiprion clarkii (Bennett, 1830), were reared in various seawater pCO2/pH treatments analogous to future ocean scenarios. At the onset of metamorphosis, all otoliths were removed from each individual fish and analyzed for treatment effects on morphometrics including area, perimeter, and circularity; scanning electron microscopy was used to screen for evidence of treatment effects on lateral development, surface roughness, and vaterite replacement. The results corroborate those of other experiments with other taxa that observed otolith growth with elevated pCO2, and provide evidence that lateral development and surface roughness increased as well. Both sagittae exhibited increasing area, perimeter, lateral development, and roughness; left lapilli exhibited increasing area and perimeter while right lapilli exhibited increasing lateral development and roughness; and left asterisci exhibited increasing perimeter, roughness, and ellipticity with increasing pCO2. Right lapilli and left asterisci were only impacted by the most extreme pCO2 treatment, suggesting they are resilient to any conditions short of aragonite undersaturation, while all other impacted otoliths responded to lower concentrations. Finally, fish settlement competency at 10 dph was dramatically reduced, and fish standard length marginally reduced with increasing pCO2. Increasing abnormality and asymmetry of otoliths may impact inner ear function by altering otolith-maculae interactions.
RESUMO
Using a commercial mass spectrometer interfaced with an atmospheric flow tube (AFT) allowed for the detection of a variety of inorganic compounds used as oxidizers in homemade explosives (HMEs) at picogram levels. The AFT provides reaction times of between 3 and 5 s with flows of 6 L/min, enabling detection levels, after thermal desorption, similar to those previously demonstrated for RDX vapor in the low parts per quadrillion range. The thermal desorption of chlorate and perchlorate salts resulted in the production of the corresponding anions which have higher electron affinities than that of the nitrate reactant ions. A dielectric barrier discharge, used as the ionization source, produced the nitrate reactant ions. In some instances, the molecular salt formed adducts with the nitrate, chlorate, and/or perchlorate anions, giving insight into the original identity of the salt cation. Urea nitrate, guanidine nitrate, and potassium nitrate were also detected as adducts with the nitrate reactant ion. The direct room-temperature vapor detection of urea nitrate and hydrogen peroxide, which have relatively high vapor pressures compared to the other salts in this study, is also demonstrated. Room-temperature vapor detection of chlorate and perchlorate salts is possible by the addition of a dilute acid which converts the salt into a more volatile acidic form. A discussion of the instrumentation, methods used, and the ionization chemistry is provided.
RESUMO
Argon-39 can be used as a tracer for age-dating glaciers, oceans, and more recently, groundwater. With a half-life of 269 years, 39Ar fills an intermediate age range gap (50-1,000 years) not currently covered by other common groundwater tracers. Therefore, adding this tracer to the data suite for groundwater studies provides an important tool for improving our understanding of groundwater systems. We present the methods employed for arriving at an age-date for a given sample of argon degassed from groundwater.
