Andrew S. Mehring

Andrew S. Mehring
University of Louisville | UL · Department of Biology

Ph.D.

About

33
Publications
8,982
Reads
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589
Citations
Additional affiliations
September 2018 - present
Estación Biológica de Doñana (EBD-CSIC)
Position
  • Fellow
January 2018 - July 2018
University of California, San Diego
Position
  • Researcher
July 2013 - December 2017
University of California, San Diego
Position
  • PostDoc Position

Publications

Publications (33)
Article
Full-text available
Because of their abundance and high emissions rates, small reservoirs (< 0.01 km²) can be important emitters of the greenhouse gases carbon dioxide and methane. However, emissions estimates from small reservoirs have lagged those of larger ones, and efforts to characterize small reservoir emissions have largely overlooked variations in emissions pa...
Article
Full-text available
The urbanization process substantially alters every aspect of the soil environment. In this study, we compared soil microclimate, chemistry, and physical characteristics of unmanaged natural soils with managed soils of three common urban land uses (stormwater natural treatment systems, ornamentally landscaped areas, and lawns) across three Universi...
Article
Full-text available
Decomposition of coarse detritus (e.g., dead organic matter larger than ~1 mm such as leaf litter or animal carcasses) in freshwater ecosystems is well described in terms of mass loss, particularly as rates that compress mass loss into one number (e.g., a first‐order decay coefficient, or breakdown rate, “k”); less described are temporal changes in...
Article
Full-text available
Decomposing organic matter forms a substantial resource base, fueling the biogeochemical function and secondary production of most aquatic ecosystems. However, detrital N (nitrogen) and P (phosphorus) dynamics remain relatively unexplored in aquatic ecosystems relative to terrestrial ecosystems, despite fundamentally linking microbial processes to...
Article
Full-text available
Nitrogen (N) in urban runoff is often treated with green infrastructure including biofilters. However, N fates across biofilters are insufficiently understood because prior studies emphasize low N loading under laboratory conditions, or use “steady-state” flow regimes over short time scales. Here, we tested field scale biofilter N fates during simu...
Article
Full-text available
Natural treatment systems (NTS) for stormwater have the potential to provide a myriad of ecosystem services to society. Realizing this potential requires active collaboration among engineers, ecologists and landscape planners and begins with a paradigm shift in communication whereby these groups are made aware of each other's perceptions about NTS...
Article
Leaf-cutting ants of the genus Atta are widely distributed throughout the American tropics and subtropics and rival other herbivores in the consumption of surrounding foliage. Although numerous studies have been conducted on the role these insects play in herbivory and organic matter dynamics, only a handful of studies have examined their impacts o...
Article
The maintenance of stormwater biofilter vegetation is conducted under local guidelines, which often include seasonal pruning. However, the effects that pruning has on water quality improvement remain unknown. This study used experimental columns to investigate the effects of pruning on effluent concentrations of nitrogen, phosphorus, and metals whe...
Article
Full-text available
U.S. public university campuses are held directly responsible for compliance with many of the same federal- and state-level environmental regulations as cities, including stormwater management. While operating as ‘cities within cities’ in many respects, campuses face unique constraints in achieving stormwater regulatory compliance. To compare the a...
Article
As the proportion of the human population living in cities continues to increase, understanding the factors affecting urban biodiversity is crucial to enhancing conservation efforts, urban ecosystem function, and human wellbeing. Here we present the results of the first comparative study of belowground invertebrate communities in urban soils (lawns...
Article
Constructed stormwater wetlands provide a host of ecosystem services, including potentially pathogen removal. We present results from a multi-wetland study that integrates across weather, chemical, microbiological and engineering design variables in order to identify patterns of microbial contaminant removal from inlet to outlet within wetlands and...
Article
Full-text available
Although aquatic ecologists and biogeochemists are well aware of the crucial importance of ecosystem functions, i.e., how biota drive biogeochemical processes and vice-versa, linking these fields in conceptual models is still uncommon. Attempts to explain the variability in elemental cycling consequently miss an important biological component and t...
Article
Full-text available
One of the goals of urban ecology is to link community structure to ecosystem function in urban habitats. Pollution-tolerant wetland invertebrates have been shown to enhance greenhouse gas (GHG) flux in controlled laboratory experiments, suggesting that they may influence urban wetland roles as sources or sinks of GHG. However, it is unclear if the...
Article
Green infrastructure (also referred to as low impact development, or LID) has the potential to transform urban stormwater runoff from an environmental threat to a valuable water resource. In this paper we focus on the removal of fecal indicator bacteria (FIB, a pollutant responsible for runoff-associated inland and coastal beach closures) in stormw...
Article
Catchment urbanization perturbs the water and sediment budgets of streams, degrades stream health and function, and causes a constellation of flow, water quality and ecological symptoms collectively known as the urban stream syndrome. Low-impact development (LID) technologies address the hydrologic symptoms of the urban stream syndrome by mimicking...
Article
Natural treatment systems such as rain gardens aim to overcome the negative effects of urbanization on water quality, availability, and freshwater and marine ecosystem integrity by mimicking the natural water cycle in urban planning and design. While soils in these systems are inhabited by a diverse array of invertebrates, the soil macrofauna is ig...
Article
Organic matter may sequester nutrients as it decomposes, increasing in total N and P mass via multiple uptake pathways. During leaf litter decomposition, microbial biomass and accumulated inorganic materials immobilize and retain nutrients, and therefore, both biotic and abiotic drivers may influence detrital nutrient content. We examined the relat...
Article
Full-text available
We assessed the key role of aquatic fungi in modifying coarse particulate organic matter ( CPOM ) by affecting its breakdown rate, nutrient concentration and conversion to fine particulate organic matter ( FPOM ). Overall, we hypothesised that fungal‐mediated conditioning and breakdown of CPOM would be accelerated when nutrient concentrations are i...
Article
Full-text available
Current design of bioretention systems is intended to intercept and retain stormwater, enhance infiltration, and remove organic particulates, nutrients, pathogens, metals, and other contaminants using natural processes that derive from the interactions of water, soil, microbes, plants, and animals. Most bioretention systems function as isolated pat...
Article
Full-text available
Many North American blackwater rivers exhibit low dissolved O2 (DO) that may be the result of benthic respiration. We examined how tree species affected O2 demand via the quantity and quality of litter produced. In addition, we compared areal estimates of surface leaf-litter microbial respiration to sediment O2 demand (SOD) and ecosystem respiratio...
Article
[1] The Little River (LR) in southern Georgia, U.S., has experienced lengthening droughts since monitoring began in 1972. We evaluated the impacts of drought on riverine carbon cycling using a 9 year data set of dissolved organic carbon (DOC) coupled with laboratory experiments in the LR, as well as long-term data sets in three additional rivers wi...
Article
We used in situ and laboratory mesocosm experiments to test the effects of red maple (Acer rubrum), white oak (Quercus alba), and northern red oak (Q. rubra) leaf litter on microbial biomass and detritivore (Limnephilus indivisus) growth, survival, and organic matter processing in temporary forest ponds. Fungal biomass was highest in red maple leaf...
Article
Full-text available
We examined benthic algal response to nutrient enrichment by nitrogen (N), phosphorus (P), and N + P in mangrove wetlands of The Bahamas, to test the hypothesis that human impacts (fragmentation) on these ecosystems altered nutrient limitation, thereby changing the frequency and/or magnitude at which ecological synergies occurred. Fragmentation occ...
Article
Full-text available
Eighty-one species of butterfl ies and two-hundred and thirty-seven spe-cies of moths were identifi ed from Fort Indiantown Gap, a National Guard training facility in south-central Pennsylvania. The Lepidoptera found here include the last remaining population of Speyeria idalia idalia (eastern regal fritillary), as well as the rare Callophrys irus...
Conference Paper
Dissolved oxygen (DO) levels in the Little River, a tributary within the Suwannee River basin of southern Georgia, regularly drop below 1 mg L-1. This requires the development of total maximum daily load (TMDL) management and implementation plans for watersheds drained by these water body segments. However, potential site-specific factors influenci...
Article
Full-text available
Dissolved oxygen (DO) levels in the Little River, a tributary within the Suwannee River basin of southern Georgia, regularly drop below 1 mg L-1. A budget of coarse particulate organic matter (CPOM) dynamics and the oxygen demand generated by associated microbial respiration is being developed for third- and fifth-order reaches of the Little River....
Article
Full-text available
Thesis (M.S.)--Shippensburg University of Pennsylvania, 2003. Includes bibliographical references (leaves 63-69).

Questions

Questions (2)
Question
I frequently measure benthic fluxes of greenhouse gases, and I'm looking for options to speed up the process of measuring concentrations of GHGs dissolved in water.
Does anyone have experience with the Dissolved Gas Extraction System (DGEU) made by Los Gatos Research (LGR), or similar devices for extracting dissolved gases from water? I'm looking for quick assessments of their effectiveness.
Thanks!
Andrew
Question
I am currently using both Picarro CRDS (G2508) and LGR OA-ICOS (UGGA) greenhouse gas analyzers to measure flux rates, and I would like to convert units from ppm to mg/m3, using the following formula:
mg/m3 = (ppmv)(12.187)(MW) / (273.15 + °C)
where: mg/m3 = milligrams of gas per cubic meter of air ppmv = ppm by volume (i.e., volume of gas per 1 million volumes of air) MW = molecular weight of the gas °C = temperature in degrees C
However, I am not certain which temperature to use in the conversion. It seems to me that internal chamber temperature (reported in both analyzers) would make more sense than external (ambient) air temperature.
Can anyone offer any insight?
Thanks!
Andrew

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