Surface Energy Budgets of Arctic Tundra During Growing Season

This study analyzed summer observations of diurnal and seasonal surface energy budgets across several monitoring sites within the Arctic tundra underlain by permafrost. In these areas, latent and sensible heat fluxes have comparable magnitudes, and ground heat flux enters the subsurface during short summer intervals of the growing period, leading to seasonal thaw. The maximum entropy production (MEP) model was tested as an input and parameter parsimonious model of surface heat fluxes for the simulation of energy budgets of these permafrost‐underlain environments. Using net radiation, surface temperature, and a single parameter characterizing the thermal inertia of the heat exchanging surface, the MEP model estimates latent, sensible, and ground heat fluxes that agree closely with observations at five sites for which detailed flux data are available. The MEP potential evapotranspiration model reproduces estimates of the Penman‐Monteith potential evapotranspiration model that requires at least five input meteorological variables (net radiation, ground heat flux, air temperature, air humidity, and wind speed) and empirical parameters of surface resistance. The potential and challenges of MEP model application in sparsely monitored areas of the Arctic are discussed, highlighting the need for accurate measurements and constraints of ground heat flux.Plain Language SummaryGrowing season latent and sensible heat fluxes are nearly equal over the Arctic permafrost tundra regions. Persistent ground heat flux into the subsurface layer leads to seasonal thaw of the top permafrost layer. The maximum energy production model accurately estimates the latent, sensible, and ground heat flux of the surface energy budget of the Arctic permafrost regions.Key PointThe MEP model is parsimonious and well suited to modeling surface energy budget in data‐sparse permafrost environmentsPeer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/150560/1/jgrd55584.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/150560/2/jgrd55584_am.pd

Watershed use and Giardia cyst presence

The presence of Giardia in a heavily visited watershed in the Olympic Mountains was compared to that in an adjacent watershed having much lower human use. Also, statistical relationships between cyst presence and watershed use parameters were examined as indicators of potential causal relationships. The number of Giardia cysts found in water samples ranged from 0.2/1001 to 3/1001 and were highest in areas of high human use. A significantly higher prevalence of Giardia in selected animal species was observed in the heavily visited watershed. Statistically significant relationships were found between aqueous Giardia cyst concentrations and both the prevalence of Giardia in animals and the intensity of human use. Based on the water samples analyzed, a calculated median cyst concentration of 1 cyst per 201 (0.05 cysts/l) can be expected in relatively pristine rivers

Composition and variability of leachate from recent and aged areas within a municipal landfill

A leachate study was conducted at a large, operating, regional municipal solid waste (MSW) landfill near Seattle, Washington, to examine differences in composition and emission rates between old and new areas of the fill. The landfill began operation in 1966, was receiving approximately 2000 tpd of MSW and had 30 x $10^{6}$ ${\rm m}^{3}$ (∼12 x $10^{6}$ tonnes) waste in place at the time of this study. The two areas studied had average ages of 3.7 and 16 years, and contained 5.7 x $10^{6}$ and 2.04 x $10^{6}$ tonnes of MSW, respectively. Variations in flow rate, total dissolved solids (TDS), chemical oxygen demand (COD), total organic carbon (TOC), Fe, and Mn were monitored over a 3-month period in the winter and spring of 1992. Increases in flow driven by precipitation caused gradually increasing leachate mass emission from the aged fill. The rate of mass emission increase with increasing flow from the new fill was more than three times higher than that from the old fill. Leachate flow through the old fill appeared more channelized, resulting in diluting effects with increasing percolation. In leachate from the new fill concentrations were essentially independent of flow. Overall, mass emissions per unit waste mass in place decreased with increasing waste age for TDS and Mn, indicating that these components were leachable independent of degradation processes. Mass emissions per unit waste mass in place increased with increasing waste age for COD, TOC, and Fe, which typify components that increase in availability for leaching with increasing age and progressing stage of decomposition

Assessment of Physical and Chemical Attributes of Sub-Tropical Soil to Predict Long Term Effluent Treatment Potential

On-site wastewater treatment systems aim to assimilate domestic effluent into the environment. Unfortunately failure of such systems is common and inadequate effluent treatment can have serious environmental implications. A research project was undertaken to determine the role of physical and chemical soil properties in the treatment performance of subsurface effluent disposal areas. Monitoring changes in these properties permit improved prediction of the treatment potential of a soil. The changes within soil properties of the disposal area due to effluent application were found to be directly related to the subsurface drainage characteristics including permeability, clay content and clay type. The major controlling soil physical and chemical attributes were found to be moderate drainage, significant soil cation exchange capacity and dominance of exchangeable Ca or exchangeable Mg over exchangeable Na, low exchangeable Na, clay type and a minimum depth of 0.4m of potential unsaturated soil before encountering a restrictive horizon. The study confirmed that both the physical properties and chemistry of the soil can be valuable predictive tools for evaluating the long term operation of sewage effluent disposal systems