Microbiological water quality at non-human influenced reference beaches in southern California during wet weather

Although urban wet weather discharges may have elevated concentrations of fecal indicator bacteria impacting water quality at swimming beaches, not all of these bacteria may arise from human sources. In this study, the contribution of non-human fecal indicator bacteria was quantified by sampling coastal reference beaches in southern California. Samples were collected at beaches near stormwater discharges from undeveloped watersheds and analyzed for total coliform, Escherichia coli, and enterococci. Surfzone samples exceeded water quality thresholds >10 times more frequently during wet weather than dry weather. Exceedences were greatest <24 h following rainfall, then steadily declined on successive days. Early season storms exceeded thresholds more frequently, and by greater magnitude, compared to late season storms. Large storms exceeded thresholds more frequently than smaller-sized storms, partly due to the breaching of sand berms. When discharges did reach the surf zone, bacterial concentrations in the wave wash were correlated with watershed bacterial flux.     

Complex erosional response to uplift and rock strength contrasts in transient river systems crossing an active normal fault revealed by 10Be and 26Al cosmogenic nuclide analyses

Understanding the influence of bedrock lithology on the catchment-averaged erosion rates of normal fault-bounded catchments and the effect that different bedrock erodibilties have on the evolution of transient fluvial geomorphology remain major challenges. To investigate this problem, we collected 18 samples for ¹⁰Be and ²⁶Al cosmogenic nuclide analysis to determine catchment-averaged erosion rates along the well-constrained Gediz Fault system in western Türkiye, which is experiencing fault-driven river incision owing to a linkage event ~0.8 Ma and has weak rocks overlying strong rocks in the footwall. Combined with existing cosmogenic data, we show that the background rate of erosion of the pre-incision landscape can be constrained as <92 mMyr⁻¹, and erosion rates within the transient reach vary from 16 to 1330 mMyr⁻¹. Erosion rates weakly scale with unit stream power, steepness index and slip rate on the bounding fault, although erosion rates are an order of magnitude lower than slip rates. However, there are no clear relationships between erosion rate and relief or catchment slope. Bedrock strength is assessed using Schmidt hammer rebound and Selby Rock Mass Strength Assessments; despite a 30-fold difference in erodibility, there is no difference in the erosion rate between strong and weak rocks. We argue that, for the Gediz Graben, the strong lithological contrast affects the ability of the river to erode the bed, resulting in a complex erosional response to uplift along the graben boundary fault. Weak covariant trends between erosion rates and various topographic factors potentially result from incomplete sediment mixing or pre-existing topographic inheritance. These findings indicate that the erosional response to uplift along an active normal fault is a complex response to multiple drivers that vary spatially and temporally.     

Latitudinal variations in Titan’s methane and haze from Cassini VIMS observations

We analyze observations taken with Cassini’s Visual and Infrared Mapping Spectrometer (VIMS), to determine the current methane and haze latitudinal distribution between 60°S and 40°N. The methane variation was measured primarily from its absorption band at 0.61 μm, which is optically thin enough to be sensitive to the methane abundance at 20-50 km altitude. Haze characteristics were determined from Titan’s 0.4-1.6 μm spectra, which sample Titan’s atmosphere from the surface to 200 km altitude. Radiative transfer models based on the haze properties and methane absorption profiles at the Huygens site reproduced the observed VIMS spectra and allowed us to retrieve latitude variations in the methane abundance and haze. We find the haze variations can be reproduced by varying only the density and single scattering albedo above 80 km altitude. There is an ambiguity between methane abundance and haze optical depth, because higher haze optical depth causes shallower methane bands; thus a family of solutions is allowed by the data. We find that haze variations alone, with a constant methane abundance, can reproduce the spatial variation in the methane bands if the haze density increases by 60% between 20°S and 10°S (roughly the sub-solar latitude) and single scattering absorption increases by 20% between 60°S and 40°N. On the other hand, a higher abundance of methane between 20 and 50 km in the summer hemisphere, as much as two times that of the winter hemisphere, is also possible, if the haze variations are minimized. The range of possible methane variations between 27°S and 19°N is consistent with condensation as a result of temperature variations of 0-1.5 K at 20-30 km. Our analysis indicates that the latitudinal variations in Titan’s visible to near-IR albedo, the north/south asymmetry (NSA), result primarily from variations in the thickness of the darker haze layer, detected by Huygens DISR, above 80 km altitude. If we assume little to no latitudinal methane variations we can reproduce the NSA wavelength signatures with the derived haze characteristics. We calculate the solar heating rate as a function of latitude and derive variations of ∼10-15% near the sub-solar latitude resulting from the NSA. Most of the latitudinal variations in the heating rate stem from changes in solar zenith angle rather than compositional variations.     

The geographic distribution of metals in urban soils: the case of Syracuse,NY

A paucity of literature currently exists pertaining to the high-resolution geographic distribution of metal contaminants across urban areas. Thousands of soil samples were collected across Syracuse, NY to secure empirical evidence about such geographic distributions. Metal measurements were made with XRF technology, with quality assessments based upon replicate samples as well as ICP technology summarized here. Both metal covariations and their spatial structure are described, followed by mapping of selected metal measurements based upon sample points, as well as census block group and census tract aggregates. A simple comparison is presented between certain of these empirical results and a selected non-urban landscape (a river floodplain). Finally, implications drawn from the empirical evidence presented include covariation assessments with selected census data that serve as surrogates for poverty.     

Hidden negative spatial autocorrelation

Mostly lip service treatments of negative spatial autocorrelation (NSA) appear in the literature, although spatial scientists confront it in practice. NSA was detected serendipitously in recalcitrant empirical analyses containing a sizeable amount of global positive spatial autocorrelation (PSA) unaccounted for by standard spatial statistical models, and labeled hidden because conventional spatial statistical tools detected only PSA while giving absolutely not hint of NSA existing. The meaning of this phenomenon is explored empirically, with findings including: a better understanding of NSA, spatial filter model construction guidelines, effective illustrations of NSA, and how hidden NSA furnishes a diagnostic for model misspecification.

Trace element concentrations in nesting flatback turtles (Natator depressus) from Curtis Island, Queensland, Australia

The blood and eggs of the flatback turtle (Natator depressus) sampled when nesting at Curtis Island, Queensland, Australia. In the blood, zinc was present at the highest concentration of 151.15 ± 1.45 μg/L followed by copper (7.74 ± 0.09 μg/L). Lead was found only in some individuals. The measured trace elements in the blood were maternally transferred into the eggs. Other metals and metalloids detected in eggs were chromium, manganese, arsenic and selenium. Eggs showed a more complex trace element profile than blood, suggesting that they provided more representative tissues for determining maternal levels of trace element accumulation in N. depressus. Intra-clutch variation was over 15% for most of the studied trace elements suggesting one egg is not in sufficient to determine trace element accumulation within a clutch. Copper was the only element which was positively correlated with breeding age. Furthermore, no detectable levels of tin compound derivates were measured in N. depressus.     

Effect Of A Heat Island On The Meteorology Of A Complex Urban Airshed

A three-dimensional mesoscale model was used to study the effect of an urban heat island in a relatively complex situation. A heat emission inventory was carried out for an urban airshed thatincludes sources such as motor vehicles, waste heat from industries and electricity consumption. To demonstrate the relative significance of anthropogenic heat flux and variant surface characteristics, three model simulations were conducted. In the first simulation, anthropogenic heat flux was ignored and non-variant surface properties were considered for the entire modelling domain. In the second simulation, variant surface characteristics were considered. While in the third simulation, gridded anthropogenic heat flux and variant surface characteristic were utilised. From these experiments, it was inferred that an additional source of heat in urban areas can substantially affect the wind and temperature regime under light wind conditions. During the day, the anthropogenic heat flux has minimum effect on the urban temperature, however it magnifies the intensity of the convergence near the urban areas.     

The Export Behavior of Small Canadian Manufacturing Firms*

This paper reports on a survey of the export behavior of small Canadian manufacturing firms. An analysis of tables (ANOTA) model is used to describe the relationship between export performance and market characteristics. The export transactions of these firms are also examined using ANOTA and latent class analysis. The relationship between export experience and geographic diversification predicted by stages of development models is confirmed. In addition, two types of export transactions are identified: (1) active exports that help firms reach a market of sufficient size and (2) passive exports in response to demand from foreign customers.     

Some analyses and numerical simulations of meiyu in east asia in 1983

In this paper the differences between Meiyu and Baiu front in 1983 have firstly been analysed, the trajectories of air on and to the north side of Meiyu and Baiu fronts during the Meiyu period have then been traced, and the fore-casting and simulating of 4 sets of Meiyu onset of the year have finally been run utilizing the global model at UK Me-teorological Office. The results show: 1) Meiyu fronts are different from Baiu ones in temperature, humidity and stratification fields in lower atmosphere; and the possibly reasons for it are explained. 2) The Bay of Bengal is the main moisture source for Meiyu front, the South China Sea and the Pacific, for Baiu ones; and some existed argu-ments on it are also discussed. 3) The onset of Meiyu and its rainfall and rain belts are sensitive to the Tibetan Plateau, and the water vapour conditions over the Bay of Bengal and the South China Sea, but not sensitive to the SST over the equatorial area or to the East of Japan.