Benjamin Hagedorn
California State University, Long Beach
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Featured researches published by Benjamin Hagedorn.
Waste Management | 2016
Benjamin Hagedorn; Henry B. Kerfoot; Mark Verwiel; Bruce Matlock
In this study, a multi-tracer approach was applied to a complex, methane-impacted site in Southern California to (1) distinguish between natural gas and landfill gas (LFG)-derived methane impacts at site perimeter gas probes, (2) estimate the relative age of the LFG at these probes, and (3) document natural attenuation trends during a 3-year monitoring period. Relationships between methane and ethane values suggest that at the majority of probes, methane is from LFG and not from natural gas and that the relative contribution of LFG methane at these probes has increased over the monitoring period. To evaluate whether LFG is attenuating in the subsurface, the relative age of LFG was estimated by comparing readily degraded VOCs that are major constituents in LFG (toluene in this case) with those resistant to degradation (Freons). Time-series data trends are consistent with several probes being impacted by fresh LFG from recent releases that occurred after the update of the local LFG collection and control system (LFGCCS). Data further indicate some probes to be only affected by legacy LFG from a past release that occurred prior to the LFGCCS update and that, because of a lack of oxygen in the subsurface, had not been fully degraded. The outlined attenuation evaluation methodology is potentially applicable to other sites or even groundwater contaminants; however, the assessment is limited by the degree of homogeneity of the LFG source composition and non-LFG-derived toluene inputs to the analyzed samples.
Geosciences Journal | 2014
Benjamin Hagedorn; Alan Mair; Suzanne Tillery; Aly I. El-Kadi; Kyoochul Ha; Gi-Won Koh
Volcanic islands can be characterized by remarkable surface air temperature variability. The distribution of weather stations in these settings, however, is typically too sparse to reliably describe temperature patterns which can complicate regional-scale hydrologic analyses. Here, a simple method is presented to estimate near surface air temperatures for such a setting (Jeju Island, Republic of Korea). The method utilizes temperature lapse rates (TLR; the change in temperature with elevation) which are computed for Tmin, Tave, and Tmax for two distinct hemispheres: the more arid northern flanks and the more humid southern flanks of the central orographic divide. Computed TLRs vary greatly with season and location relative to the orographic divide and, unlike in continental mountainous settings, are generally highest for Tmin in winter. Cross-validation results indicate a good match between modeled and measured values particularly for high altitude stations that are characterized by highest precipitation rates. Because temporally changing TLRs perform better than the often applied theoretical constant environmental lapse rate of 6.5 °C/km, monthly mean TLRs compiled from temperature data from Jeju Island are presented here as proxies for surface air temperature simulation efforts in similar settings for which only limited climatic data are available.
Geochimica et Cosmochimica Acta | 2011
Nils Moosdorf; Jens Hartmann; Ronny Lauerwald; Benjamin Hagedorn; S. Kempe
Journal of Hydrology | 2011
Benjamin Hagedorn; Aly I. El-Kadi; Alan Mair; Robert B. Whittier; Kyoochul Ha
Chemical Geology | 2011
Benjamin Hagedorn; Ian Cartwright; Massimo Raveggi; Roland Maas
Journal of Hydrology | 2015
Benjamin Hagedorn
Journal of Hydrology | 2013
Alan Mair; Benjamin Hagedorn; Suzanne Tillery; Aly I. El-Kadi; Stephen M. Westenbroek; Kyoochul Ha; Gi-Won Koh
Hydrogeology Journal | 2013
Aly I. El-Kadi; Suzanne Tillery; Robert B. Whittier; Benjamin Hagedorn; Alan Mair; Kyoochul Ha; Gi-Won Koh
Chemical Geology | 2015
Benjamin Hagedorn; Robert B. Whittier
Environmental Science: Processes & Impacts | 2013
Henry B. Kerfoot; Benjamin Hagedorn; Mark Verwiel