Fingerprinting sources of bacterial input into small residential watersheds: fate of fluorescent whitening agents

The presence of fecal coliform bacteria in many watersheds is often linked to septic system effluent. Fluorescent whitening agents (FWA) are part of most laundry detergent formulations and previously have been used for fingerprinting anthropogenic sewage waters. This study was carried out to investigate the fate of FWA in spring water downstream from a well-monitored septic system in a small forest watershed. Samples for FWA were collected at the spring and along the flow path downstream and analyzed fluorometrically. Selected sampling events were scheduled at night and daytime and after rainstorms to investigate possible changes in the spring water composition. In addition, reference fluorescence spectra were prepared for humic and tannic acid and for the laundry detergent used exclusively in the household discharging into the test septic system. The results indicate that FWA can be detected in spring water, but interference with increasing humic acid concentration downstream limits the fingerprinting value of the method to the vicinity of the spring. Also, sampling for FWA after rainstorms only yielded results if at least 4 days had passed. Otherwise, dissolved organic substances transported into the spring water interfered with the FWA spectrum. No significant differences between night and daytime sampling were found. Overall, the method, as used at this study site, is of limited value for fingerprinting FWA in natural waters.     

433 Eros lineaments: Global mapping and analysis

Using images and laser ranging data from the NEAR-Shoemaker mission, we map lineaments on the surface of Eros in order to investigate the relationship between surface morphology and interior structure. Several sets of lineations are clearly related to visible impact craters, while others suggest that different parts of the asteroid may have undergone different stress histories. Some of these sets infer internal structure, at least on a local level. This structure may derive from Eros' parent body and suggest, although largely coherent, Eros' interior may have portions that have not undergone a common history.     

Effects of a Beach Nourishment Project in Jamaica Bay,New York,on Horseshoe Crab (<Emphasis Type="Italic">Limulus polyphemus</Emphasis>) Spawning Activity and Egg Deposition

Restoration of horseshoe crab spawning habitats through beach nourishment may be considered as a potential strategy to enhance reproductive success in areas where estuarine beaches have been lost to coastal erosion and development. The US Army Corps of Engineers performed a beach nourishment project at Plumb Beach (Jamaica Bay, Brooklyn, NY) in 2012 to stabilize the shoreline. While the addition of sand was done to protect infrastructure, it created an opportunity to examine the responses of American horseshoe crabs (Limulus polyphemus) to beach nourishment using a BACI (before-after control impact) design. During Spring 2012, before beach nourishment, horseshoe crabs made minimal use of the highly degraded western section of Plumb Beach in comparison to a nearby reference site, as quantified by numbers of spawning adults at high tide and densities of horseshoe crab eggs in core samples. In the first post-nourishment field season (Spring 2013), there was no detectable increase in horseshoe crab spawning activity on the newly restored beach. In 2014 and 2015, the density of spawning females began to increase at the nourished beach, although their numbers and especially the density of horseshoe crab eggs remained much lower than at the reference site. Three years after beach nourishment, differences in sediments texture (mean grain diameter, percent gravel, sorting, skewness, and hardness) were still evident between the nourishment and reference sites. Our results suggest that (1) at this site, beach nourishment appeared to bring about only slow increases in horseshoe crab spawning density after several seasons and (2) subtle differences in beach geomorphology over relatively short distances can be detected by horseshoe crabs and may underlie their selection of specific nesting sites.     

The characteristics of magma reservoir failure beneath a volcanic edifice

Eruptions fed from subsurface reservoirs commonly construct volcanic edifices at the surface, and the growth of an edifice will in turn modify the subsurface stress state that dictates the conditions under which subsequent rupture of the inflating reservoir can occur. We re-examine this problem using axisymmetric finite element models of ellipsoidal reservoirs beneath conical edifices, explicitly incorporating factors (e.g., full gravitational loading conditions, an elastic edifice instead of a surface load, reservoir pressures sufficient to induce tensile rupture) that compromise previous solutions to illustrate why variations in rupture behavior can occur. Relative to half-space model results, the presence of an edifice generally rotates rupture toward the crest of a spherical reservoir, with increasing flank slope (for an edifice of constant volume) and larger edifices (or greater reservoir scaled depths) normally serving to enhance this trend. When non-spherical reservoirs are considered, the presence of an edifice amplifies previously identified half-space failure characteristics, shifting rupture to the crest more rapidly for prolate reservoirs while forcing rupture closer to the midpoint of oblate reservoirs. Rupture is always observed to occur in the σ_t orientation, and depending on where initial failure occurs rupture favors the initial emplacement of either lateral sills, circumferential intrusions or vertically ascending dikes. Ultimately, integration of our numerical model results with other information, for instance the sequence of intrusion/eruption events observed at a given volcano, can provide useful new insight into how a volcano's subsurface magma plumbing system evolved. We demonstrate this process through application of our model to Summer Coon, a well-studied stratocone on Earth, and Ilithyia Mons, a large conical shield volcano on Venus.     

Why are hatching and emergence success low? Mercury and selenium concentrations in nesting leatherback sea turtles (Dermochelys coriacea) and their young in Florida

Leatherback sea turtles (Dermochelys coriacea) have low hatching and emergence success compared to other sea turtle species. Postmortem examinations of hatchlings showed degeneration of heart and skeletal muscle that was similar to that found in other neonates with selenium deficient mothers. Selenium deficiency can result from elevated concentrations of bodily mercury. Ingested mercury is detoxified by the liver through mercury-selenium compound formation. In animals persistently exposed to mercury, the liver’s ability to detoxify this element may decrease, especially if dietary selenium is insufficient. We measured mercury and selenium concentrations in nesting female leatherbacks and their hatchlings from Florida and compared the levels to hatching and emergence success. Both liver selenium and the liver selenium-to-mercury ratio positively correlated with leatherback hatching and emergence success. This study provides the first evidence for the roles of mercury and selenium in explaining low reproductive success in a globally imperiled species, the leatherback sea turtle.     

A Gas Chromatographic/Chemical Indicator Approach to Assessing Ground Water Contamination by Petroleum Products

The water-soluble fractions of unleaded gasoline, kerosene and diesel fuel were evaluated by U.S. EPA Methods 602, 610, and 625.
Several chemical indicator compounds useful in assessing petroleum contamination of ground water, including benzene, substituted benzenes, n-alkanes, and polynuclear aromatic hydrocarbons, were identified. These were applied to the interpretation of data collected from monitoring wells at gasoline service stations that were undergoing ground water remediation. The chemical indicators are used to identify the likely type(s) of petroleum contamination. Certain hydrocarbons may be unique to specific fuel types.
Gas chromatograms of field sample extracts were compared with chromatograms of laboratory water-soluble fractions (WSFs) and neat fuels (unleaded gasoline, kerosene, and diesel). In some situations, field samples represented water-soluble fractions of the contaminating fuel. In others, a fuel-water agglomeration was indicated, with the chromatograms showing peaks that represented components of both the WSFs and the neat fuels.
The use of both gas chromatography pattern identification and chemical indicators appears to be a viable approach to assessing ground water contamination caused by petroleum products.