Determing the effects of El Niño-Southern Oscillation events on coastal water quality

The importance of the El Niño-Southern Oscillation (ENSO) on regional-scale climate variability is well recognized although the associated effects on local weather patterns are poorly understood. Little work has addressed the ancillary impacts of climate variability at the community level, which require analysis at a local scale. In coastal communities water quality and public health effects are of particular interest. Here we describe the historical influence of ENSO events on coastal water quality in Tampa Bay, Florida (USA) as a test case. Using approximate randomized statistics, we show significant ENSO influences on water quality particularly during winter months, with significantly greater fecal pollution levels during strong El Niño winters and significantly lower levels during strong La Niña winters as compared to neutral conditions. Similar significant patterns were also noted for El Niño and La Niña fall periods. The success of the analysis demonstrates the feasibility of assessing local effects associated with large-scale climate variability. It also highlights the possibility of using ENSO forecasts to predict periods of poor coastal water quality in urban region which local agencies may use to make appropriate prepations.     

Inhomogeneity of mercury in the U.S.G.S. rock standards

Mercury inhomogeneity was found between bottles of the same standard for each of the six U.S.G.S. rock standards tested. Variations between bottles amounted to at least a factor of 2 for four of the six standards. Caution is suggested when using these standards as mercury accuracy checks and as estimators of mercury geochemical abundances or cycles.     

Increase in Cliona delitrix Infestation of Montastrea cavernosa Heads on an Organically Polluted Portion of the Grand Cayman Fringing Reef

Abstract. A marked increase in the biomass of Cliona delitrix infesting Montastrea cavernosa substrate occurred in a portion of the Grand Cayman fringing reef affected by the discharge of untreated fecal sewage. It is suggested that the six-fold increase in bacteria biomass (both "coliforms" and natural marine bacterioplankton) in reef waters receiving the sewage effluent is linked to a five-fold increase in sponge biomass at the polluted site relative to a control site. The elevated density of C. delitrix biomass signifies a similar increase in the amount of M. cavernosa skeleton that has been eroded by this sponge and reduced to silt-sized sediment. Thus, the proliferation of a bioeroding organism in the sewage-stressed environment has caused a shift in the carbonate balance on the reef.     

Fresip: A mission to determine the character and frequency of extra-solar planets around solar-like stars

FRESIP (FRequency of Earth-Sized Inner Planets) is a mission designed to detect and characterize Earth-sizes planets around solar-like stars. The sizes of the planets are determined from the decrease in light from a star that occurs during planetary transits, while the orbital period is determined from the repeatability of the transits. Measurements of these parameters can be compared to theories that predict the spacing of planets, their distribution of size with orbital distance, and the variation of these quantities with stellar type and multiplicity. Because thousands of stars must be continually monitored to detect the transits, much information on the stars can be obtained on their rotation rates and activity cycles. Observations of p-mode oscillations also provide information on their age and composition. These goals are accomplished by continuously and simultaneously monitoring 500 solar-like stars for evidence of brightness changes caused by Earth-sized or larger planetary transits. To obtain the high precision needed to find planets as small as the Earth and Venus around solar-like stars, a wide field of view Schmidt telescope with an array of CCD detectors at its focal plane must be located outside of the Earth's at mosphere. SMM (Solar Maximum Mission) observations of the low-level variability of the Sun (1:100,000) on the time scales of a transit (4 to 16 hours), and our laboratory measurements of the photometric precision of charge-coupled devices (1:100,000) show that the detection of planets as small as the Earth is practical. The probability for detecting transits is quite favorable for planets in inner orbits. If other planetary systems are similar to our own, then approximately 1% of those systems will show transits resulting in the discovery of 50 planetary systems in or near the habitable zone of solar-like stars.     

Changes in the abundance of the seagrassesZostera marina L. (eelgrass) andRuppia maritima L. (widgeongrass) in San Diego, California, following and El Niño Event

Changes in environmental conditions can be accompanied by shifts in the distribution and abundances of organisms. When physical factors become unsuitable for growth ofZostera marina (eelgrass), which is a dominant seagrass species in North America, other more ruderal seagrass species, includingRuppia maritima (widgeongrass), often increase in abundance or replace the dominant species. We report the proliferation of widgeongrass into eelgrass beds in Mission Bay and San Diego Bay in San Diego, California, during the 1997 to 1998 El Niño Southern Oscillation (ENSO). Widgeongrass persisted in these eelgrass beds at least one year after a return to non-ENSO conditions and an increase in eelgrass density. We suggest that a warming of the water in two bays in San Diego by 1.5–2.5°C could result, in a permanent shift in the local seagrass vegetation from eelgrass to widgeongrass. This shift, could, have substantial ecosystem-level ramifications.     

Electrical conductivity problems associated with time-domain reflectometry (TDR) measurement in geotechnical engineering

The effect of electrical conductivity (EC) of a dielectric material on its TDR-measured dielectric constant ε_a (called the apparent dielectric constant) was investigated both theoretically and experimentally. The effect of EC on the apparent dielectric constant ε_a was more pronounced at low frequency of the electromagnetic pulse applied to measure ε_a. The assumption of neglecting electrical losses in measuring the dielectric constant by TDR to represent ε_r was not valid for dielectric materials containing free charges, such as electrolyte solutions, bentonite clay, and saline soils. A theory is proposed to separate the real part of the dielectric constant ε_r from the TDR-measured ε_a in lossy dielectrics. An EC - ε_r relationship can be developed that would provide ε_a (=ε_r) at EC = 0 to be used to determine soil-water contents in conductive soils. Na-bentonite mixed with distilled water resulted in considerable magnitude of bulk EC due to the adsorbed cations on the surface of the particles. This EC caused energy loss of the TDR pulse that depended on the length of the probe rod. For a 4.5 cm long probe, the reflected TDR waveform was completely attenuated for EC between 3.05 dS m⁻¹ and 3.72 dS m⁻¹. The waveforms generated in this range of EC were not suitable for analysis by TDR-support software for dielectric constant. With the adsorbed cations, Na-bentonite behaved as a lossy or dispersive material. This revised version was published online in July 2006 with corrections to the Cover Date.     

Modulation of Atmospheric 14C Concentration by the Solar Wind and Irradiance Components of the Hale and SCHWABE Solar Cycles

¹⁴C abundance on the Earth can be modulated by both the solar wind and irradiance components of the solar cycle. The magnetic field component of the solar wind modulates ¹⁴C production whereas the irradiance component can result in a change in the exchange rate between the various reservoirs of the carbon biogeochemical cycle. The effects would be nearly synchronous and difficult to separate. The 0.1% amplitude of irradiance variation during the two most recent solar cycles is well known. A 22-yr cycle exists also in the measured global temperature record.We have divided the University of Washington high-precision data on¹⁴C in tree rings into three 91-yr intervals: AD 1540–1630, 1630–1720 and 1715–1805, before, during and after the Maunder Minimum. Unfortunately the AD 1540–1630 interval includes part of the Spörer Minimum as well as the intermediate interval of high solar activity. These data were analyzed by the DFT, MEM and MTM methods of spectral time series analysis. The ca. 22-yr cycle is prominent during the Maunder Minimum, whereas the 11-yr cycle is most prominent after the Maunder Minimum but totally suppressed during the Maunder Minimum. The lesser amplitude of the 11-yr cycle before the Maunder Minimum is most probably due to overlap with the Spörer Minimum.Vasiliev and Kocharov VK83 have previously suggested that the 22-yr cycle persists through the Maunder Minimum whereas the 11-yr cycle is suppressed. Our calculations show that irradiance forcing of the carbon cycle during the 11-yr cycle is negligible, so the observed 11-yr cycle in¹⁴ C must be the result of production rate changes. The presence of the 22-yr cycle and suppression of the 11-yr cycle during the Maunder Minimum is in accord with a model by Jokipii Jok91.     

Recent Environmental Change and Human Impact on Svalbard: The Lake-Sediment Geochemical Record

As part of a broader investigation into recent environmental change on Svalbard, the inorganic geochemical record of six lake-sediment cores was analysed. The major temporal trends in sediment elemental composition are driven by variations in two contrasting sediment components, both derived from catchment soils: (1) mineral matter, and (2) soil organic matter (SOM), enriched in Fe and Mn oxides and heavy metals. Two environmental impacts are recorded in most or all of the lake sediment sequences. An up-core increase in organic matter can be partly attributed to diagenetic effects, but also requires an enhanced supply of SOM relative to mineral matter. In addition, the central and southern sites all show a ca. 1970 event characterised by an enhanced mineral matter accumulation rate. This requires either an enhanced allochthonous supply or an enhanced mobilisation of littoral sediments. In either case a regional-scale driving force, such as a shift in climate, is required. At five of the lakes the sediment heavy metal concentration profiles can be explained entirely by natural factors. However, at Tenndammen (U), situated close to the Svalbard’s largest settlement at Longyearbyen, possible anthropogenic Pb enrichment is found. Comparison of observed and expected heavy metal profiles (based on Greenland ice-core data) shows that the lakes are generally too insensitive to have recorded a long-transported heavy metal pollution signal.