Retrospective evaluation of shoreline water quality along Santa Monica Bay beaches

Santa Monica Bay (SMB) beaches are the most heavily used in the U.S.A., despite an increased number of water quality postings over the last several years. To assess whether water quality problems are concentrated at a small number of chronically affected sites or whether the problems are widely distributed, we compiled 5 years of monitoring data collected at 59 sites, 22 of which are sampled daily. Other locally available rainfall and sewage spill monitoring information data were added to this data set to assess whether sewage spills, dry-weather runoff, or wet-weather runoff contribute the most to exceedences of water quality thresholds. Approximately 13% of the shoreline mile-days along monitored beaches in SMB exceeded the State of California's beach water quality standards during the 5-year study period. Most of the water quality exceedences occurred near urban runoff drains even though areas affected by drains represent only a small portion of the total shoreline. Although storms are relatively infrequent in southern California, the extent of water quality exceedences resulting from storm water runoff was similar to the extent of water quality exceedences found during dry weather. Sewage spills, while potentially more serious because they lead to beach closures rather than to the more limited posting of warning signs, represented less than 0.1% of the shoreline mile-days that exceeded water quality thresholds. During dry weather conditions, most of the water quality problems occurred near five of the largest drains and at two beach areas that have unique physical characteristics, which limited mixing, dispersion, and dilution. During wet weather conditions, water quality problems were more widespread.     

Ledgers and landscapes: Indicators of rural landscape change in southern New Zealand, 1878–1919

Our objective was to develop and calibrate numerical measures to represent the timing and magnitude of landscape change between 1878, and 1919 using information in a stock and station agency's ledgers. Relative expenditures on fencing materials peaked in the 1880s, were lowest in the early 1900s, and rose to one‐fifth of annual expenditures from 1914 onwards. In contrast, relative expenditures on soil preparation, cropping and harvesting grew steadily after 1879, peaked in 1900, and declined from then until 1919. This research found that periods of intensive landscape investment between 1878 and 1919 were separated by longer intervals of landscape maintenance.     

Late Quaternary tephrostratigraphy,Ahklun Mountains,SW Alaska

Radiocarbon‐dated sediment cores from six lakes in the Ahklun Mountains, south‐western Alaska, were used to interpolate the ages of late Quaternary tephra beds ranging in age from 25.4 to 0.4 ka. The lakes are located downwind of the Aleutian Arc and Alaska Peninsula volcanoes in the northern Bristol Bay area between 159° and 161°W at around 60°N. Sedimentation‐rate age models for each lake were based on a published spline‐fit procedure that uses Monte Carlo simulation to determine age model uncertainty. In all, 62 ¹⁴C ages were used to construct the six age models, including 23 ages presented here for the first time. The age model from Lone Spruce Pond is based on 18 ages, and is currently the best‐resolved Holocene age model available from the region, with an average 2σ age uncertainty of about ± 109 years over the past 14.5 ka. The sedimentary sequence from Lone Spruce Pond contains seven tephra beds, more than previously found in any other lake in the area. Of the 26 radiocarbon‐dated tephra beds at the six lakes and from a soil pit, seven are correlated between two or more sites based on their ages. The major‐element geochemistry of glass shards from most of these tephra beds supports the age‐based correlations. The remaining tephra beds appear to be present at only one site based on their unique geochemistry or age. The 5.8 ka tephra is similar to the widespread Aniakchak tephra [3.7 ± 0.2 (1σ) ka], but can be distinguished conclusively based on its trace‐element geochemistry. The 3.1 and 0.4 ka tephras have glass major‐ and trace‐element geochemical compositions indistinguishable from prominent Aniakchak tephra, and might represent redeposited beds. Only two tephra beds are found in all lakes: the Aniakchak tephra (3.7 ± 0.2 ka) and Tephra B (6.1 ± 0.3 ka). The tephra beds can be used as chronostratigraphic markers for other sedimentary sequences in the region, including cores from Cascade and Sunday lakes, which were previously undated and were analyzed in this study to correlate with the new regional tephrostratigraphy. Copyright © 2012 John Wiley & Sons, Ltd.     

Near-infrared spectroscopy of 3:1 Kirkwood Gap Asteroids: (3760) Poutanen and (974) Lioba

A mineralogical assessment of 3:1 Kirkwood Gap Asteroids (3760) Poutanen and (974) Lioba, has been carried out from spectral data obtained May 21, 2008 (974) and May 25, 2009 (3760) UT using the NASA Infrared Telescope Facility. Results indicate (3760) Poutanen as a spinel-bearing asteroid. The spinel contained within this asteroid appears to be embedded in calcium aluminum inclusions (CAIs) much like that of the CV3 chondrite Allende. The preservation of the CAIs implies a lack of igneous processing and places further constraints on the heating that occurred within the early Solar System. This analysis suggests (3760) Poutanen originated in the general formation zone of the CV3 meteorites, but in a sub-region depleted in iron-rich matrix material and enriched in pyroxene-bearing clasts. Analysis of (974) Lioba indicates it is an S(IV) asteroid with a surface silicate assemblage consisting of olivine and orthopyroxene, (Fs_21(±5)Wo_8(±3)), consistent with measured band centers, (0.96 ± 0.01 μm; 1.95 ± 0.02 μm), and the band area ratio (0.59 ± 0.15). The location, delivery efficiency ((24.5%) Farinella, P., Gunczi, R., Froeschlé, Ch., Froeschlé, C. [1993]. Icarus 101, 174-187), calculated mineralogy, and BAR strongly suggest (974) Lioba is a plausible parent body for the LL- or L-ordinary chondrites.     

Mineralogical characterization of near-Earth Asteroid (1036) Ganymed

We present a mineralogical assessment of near-Earth Asteroid, (1036) Ganymed, using data obtained May 18, 2006 UT combined with 24 Color Asteroid Survey data to cover the spectral interval of 0.3-2.45 μm. Results of the analysis indicate (1036) Ganymed is an S (VI) asteroid with a surface silicate assemblage consisting primarily of orthopyroxene, (Fs_23(±5)Wo_3(±3)), consistent with calculated band centers and band area ratios (BAR). (1036) Ganymed appears to be once part of a large mesosiderite containing howardite, eucrite, and diogenite (HED) pyroxenes mixed with metal that was broken apart and dispersed. The calculated composition of the average pyroxenes in the surface material of (1036) Ganymed is consistent with mesosiderite pyroxenes, in particular the diogenites. A second possibility could be (1036) Ganymed is not yet represented in the meteorite collection. Our investigation has confirmed Ganymed is not a parent body of the ordinary chondrites and is not genetically related to (433) Eros.     

Heliophysics Event Knowledgebase for?the?Solar Dynamics Observatory (SDO) and Beyond

The immense volume of data generated by the suite of instruments on the Solar Dynamics Observatory (SDO) requires new tools for efficient identifying and accessing data that is most relevant for research. We have developed the Heliophysics Events Knowledgebase (HEK) to fill this need. The HEK system combines automated data mining using feature-detection methods and high-performance visualization systems for data markup. In addition, web services and clients are provided for searching the resulting metadata, reviewing results, and efficiently accessing the data. We review these components and present examples of their use with SDO data.     

Evaluating the seismic reliability of electrical equipment containing ceramic structural members

A method for evaluating the reliability of ceramic structural members subjected to earthquake-induced vibrations is presented. The method uses the Weibull distribution to represent the probability of failure of the brittle ceramic material and includes the effects of stress concentrations introduced by flaws and the volume of material subjected to stress. The stress concentration introduced by the complex form of insulators and at the mounting interfaces is considered. A numerical example is given to illustrate the application of the method.