Implications of 21st century climate change for the hydrology of Washington State

Pacific Northwest (PNW) hydrology is particularly sensitive to changes in climate because snowmelt dominates seasonal runoff, and temperature changes impact the rain/snow balance. Based on results from the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC AR4), we updated previous studies of implications of climate change on PNW hydrology. PNW 21st century hydrology was simulated using 20 Global Climate Models (GCMs) and 2 greenhouse gas emissions scenarios over Washington and the greater Columbia River watershed, with additional focus on the Yakima River watershed and the Puget Sound which are particularly sensitive to climate change. We evaluated projected changes in snow water equivalent (SWE), soil moisture, runoff, and streamflow for A1B and B1 emissions scenarios for the 2020s, 2040s, and 2080s. April 1 SWE is projected to decrease by approximately 38–46% by the 2040s (compared with the mean over water years 1917–2006), based on composite scenarios of B1 and A1B, respectively, which represent average effects of all climate models. In three relatively warm transient watersheds west of the Cascade crest, April 1 SWE is projected to almost completely disappear by the 2080s. By the 2080s, seasonal streamflow timing will shift significantly in both snowmelt dominant and rain–snow mixed watersheds. Annual runoff across the State is projected to increase by 2–3% by the 2040s; these changes are mainly driven by projected increases in winter precipitation.     

Persistence and biodegradation of kerosene in high-arctic intertidal sediment

A kerosene type hydrocarbon fraction (equivalent to 7 L m(-2)) was added to enclosures in the surface layer of high-arctic intertidal beach sediment. The experimental spill was repeated in two consecutive years in the period July-September. The rate and extent of hydrocarbon removal and the accompanying bacterial response were monitored for 79 days (2002) and 78 days (2003). The bulk of added kerosene, i.e. 94-98%, was lost from the upper 5 cm layer by putatively abiotic processes within 2 days and a residual fraction in the range 0.6-1.2mg per g dry sediment was stably retained. Concomitant addition of oleophilic fertilizer led to higher initial retention, as 24% of the kerosene remained after 2 days in the presence of a modified, cold-climate adapted version of the well-known Inipol EAP 22 bioremediation agent. In these enclosures, which showed an increase in hydrocarbon-degrader counts from 6.5 x 10(3) to 4.1 x 10(7) per g dry sediment within 8 days, a 17% contribution by biodegradation to subsequent hydrocarbon removal was estimated. Stimulation in hydrocarbon-degrader counts in fertilizer-alone control enclosures was indistinguishable from the stimulation observed with both kerosene and fertilizer present, suggesting that the dynamics in numbers of hydrocarbon-degrading bacteria was primarily impacted by the bioremediation agent.     

Evaluation of image analysis methods used for quantification of particle angularity

Angularity is an important parameter in the characterization of particle morphology that is used to interpret the transport history of particles in sedimentary deposits. In the past, visual classification using silhouette charts was widely used to determine particle angularity, but this approach is subjective and time‐consuming. With advances in modern image analysis techniques and low‐cost software packages, it is possible to rapidly quantify particle angularity more objectively than using visual classification methods. This study re‐examines the performance of three existing image analysis methods and one new image analysis procedure, applied to six rock and sediment samples that were visually different in angularity. To facilitate comparison between the angularity results, measurements were reduced to rankings for each aggregate sample. These results show that the four image analysis methods rank the angularity of the samples differently, and that none rank the mean angularity index in the same order as the angularity ranking using visual classification. Therefore, further research is needed to develop an image analysis method that can quantify the angularity of sedimentary particles more precisely.     

The surface energy balance at the Huygens landing site and the moist surface conditions on Titan

The Huygens Probe provided a wealth of data concerning the atmosphere of Titan. It also provided tantalizing evidence of a small amount of surface liquid. We have developed a detailed surface energy balance for the Probe landing site. We find that the daily averaged non-radiative fluxes at the surface are 0.7 W m^?2, much larger than the global average value predicted by McKay et al. (1991) of 0.037 W m^?2. Considering the moist surface, the methane and ethane detected by the Probe from the surface is consistent with a ternary liquid of ethane, methane, and nitrogen present on the surface with mole fractions of methane, ethane, and nitrogen of 0.44, 0.34, and 0.22, respectively, and a total mass load of ～0.05 kg m^?2. If this liquid is included in the surface energy balance, only a small fraction of the non-radiative energy is due to latent heat release (～10^?3 W m^?2). If the amount of atmospheric ethane is less than 0.6×10^?5, the surface liquid is most likely evaporating over timescales of 5 Titan days, and the moist surface is probably a remnant of a recent precipitation event. If the surface liquid mass loading is increased to 0.5 kg m^?2, then the liquid lifetime increases to ～56 Titan days. Our modeling results indicate a dew cycle is unlikely, given that even when the diurnal variation of liquid is in equilibrium, the diurnal mass variation is only 3% of the total liquid. If we assume a high atmospheric mixing ratio of ethane (>0.6×10^?5), the precipitation of liquid is large (38 cm/Titan year for an ethane mixing ratio of 2×10^?5). Such a flux is many orders of magnitude in excess of the photochemical production rate of ethane.     

Macroscopic diffusivity in concrete determined by computational homogenization

Effective moisture and chloride ion diffusivity coefficients for concrete are determined by computational homogenization, where concrete is modeled on the mesoscale as a heterogenous three‐phase composite material. By imposing moisture and chloride ion gradients on a representative volume element, effective macroscale properties are obtained through finite element analysis. A parametric study of the effects of the ballast content was carried out. The numerical results correspond well with an estimate of the Hashin–Shtrikman type available in the literature. The computational homogenization strategy proposed here also includes the interfacial transition zone, and its influence on the effective diffusivity coefficients is assessed. Copyright © 2012 John Wiley & Sons, Ltd.     

Late Archean basement in the Bangenhuken Complex of the Nordbreen Nappe, western Ny-Friesland, Svalbard

The rocks of western Ny-Friesland, northern Svalbard, are part of a tectonostratigraphy including four thrust sheets, each composed mainly of orthogneisses overlain by younger metasedimentary rocks. Previous geochronological studies have shown that the orthogneisses are dominated by ca. 1750 Mya granitoids. This study of a quartz-monzonite in one of the thrust sheets, the Nordbreen Nappe, yields a single-zircon U-Pb ion-microprobe age of 2709 Ø 28 My. This is the oldest rock unit so far reported in the Svalbard Caledonides. However, age-determinations on detrital zircons in the metasediments of western Ny-Friesland have shown that Late Archean rocks were prominent sources. The new ages presented here provide the first evidence of a local source for these sedimentary rocks.     

Magnetic properties and heavy metal content of sanitary leachate sludge in two landfill sites near Bandung,Indonesia

Magnetic properties and heavy metal content of landfill leachate sludge samples from two municipal solid waste disposal sites near Bandung, West Java, Indonesia, and their correlation with heavy metals are studied in the present work. Leachate was found to be sufficiently magnetic with mass-specific magnetic susceptibility that varies from 64.8 to 349.0 × 10⁻⁸ m³ kg⁻¹. It is, however, less magnetic than the soils around the landfill sites. The magnetic minerals are predominantly pseudo-single domain and multidomain magnetite. Leachate samples from the older but inactive disposal site, Jelekong, are found to be more magnetic than that from Sarimukti, the younger and active site. The enhancement of leachate due to the soil-derived ferrimagnetic particles is possibly the same for both Sarimukti and Jelekong. The fact that strong correlation between magnetic parameters and heavy metals is observed in Jelekong but is absent in Sarimukti suggests that the use of magnetic measurement as a proxy measurement for heavy metal content in leachate is plausible provided that the magnetic susceptibility exceeds certain threshold value. Moreover, the accumulation of magnetic minerals and heavy metals in leachate might depend on the activity and the age of landfill site.