Values of inland fisheries in the Mekong river basin

Asia has the most productive inland fisheries in the world. The fishery sector contributes significantly to the national economies of the region. Inland fisheries also improve food security by providing a source of protein and a livelihood for millions of people in this part of the world, especially the rural poor. The purpose of this report is to provide information on the biological, economic, social and cultural values of river fisheries in the Lower Mekong Basin, and to identify the main impacts of environmental changes on these values. A review of fisheries-related literature, including project reports and gray literature, was undertaken. More than 800 documents were reviewed, and original information was extracted from 270 of them. The analysis identified a large number of localized studies leading to generic conclusions. The report addresses the basin wide issues and studies. It is then organized by nation, namely, the Chinese province of Yunnan, then Laos, Thailand, Cambodia and Vietnam. It first gives an overview of each country’s economic, fisheries and social situation, then details the values documented for river fisheries in each country

Radiocarbon analysis of methane emitted from the surface of a raised peat bog

We developed a method to determine the radiocarbon (14C) concentration of methane (CH4) emitted from the surface of peatlands. The method involves the collection of ~ 9 L of air from a static gas sampling chamber which is returned to the laboratory in a foil gas bag. Carbon dioxide is completely removed by passing the sample gas firstly through soda lime and then molecular sieve. Sample methane is then combusted to CO2, cryogenically purified and subsequently processed using routine radiocarbon methods. We verified the reliability of the method using laboratory isotope standards, and successfully trialled it at a temperate raised peat bog, where we found that CH4 emitted from the surface dated to 195-1399 years BP. The new method provides both a reliable and portable way to 14C date methane even at the low concentrations typically associated with peatland surface emissions

Submarine groundwater discharge: an unseen yet potentially important coastal phenomenon

In collaboration with researchers from Florida State University, Florida Sea Grant introduces an important but poorly known topic: submarine groundwater discharge. Although nearly invisible, submarine groundwater discharge influences coastal systems. This brochure helps explain this important phenomenon. (8pp.

An empirical mathematical model of retentate composition in ultrafiltration of dairy products

Analysis of retentates of milk or whey, ultrafiltered and diafiltered by a pilot batch process with DDS Lab module equipment or (whey only) ultrafiltered by an industrial continuous process showed that nitrogen and ionic contents could not be described mathematically by the use of any value of the retention coefficient K. Analytical data suggested a new concept called segregation for nitrogen and ions in which each of these components consists of a completely permeable fraction and a totally retained fraction that do not exchange. A segregation coefficient Y is then defined as the ratio of the totally retained fraction to the total concentration of the species in the product fed to the equipment. However, this concept does not apply to lactose, where the classic retention concept (K) is retained. The two models are equivalent when K = Y = 0 or K = Y = 1. A first mathematical expression of this model was elaborated for batch ultrafiltration and/or constant volume diafiltration. Another set of equations was established for industrial conditions. These empirical models predict the retentate and permeate composition at any time during processing as well as after drying. The fit of analytical data with computed values was generally fair, with K being 0·1-0·4 in the pilot plant, and 0·1 in the factory. The nitrogen Y value was 0·95 for milk, and 0·85 for whey. In whey, the calcium Y value varied greatly from 0·06-0·71 depending on the pH, citrate content and heat treatment; in milk it was fairly constant at 0·5 at pH 6·7-5·

An Evaluation of Clean the World, Las Vegas Volunteer Program

Background Student evaluation team, AVID Advising, conducted an evaluation of a not for profit organization, Clean the World, Las Vegas Volunteer Program from February 2015 through August 2015. The pre-­‐ valuation consisted of an analysis of the organization’s growth since opening its Las Vegas doors in 2012, staff responsibilities, and their volunteer program. As a result of the pre-­‐ valuation, AVID Advising and Clean the World Las Vegas Manager, Kevin Williams determined an evaluation on the existing volunteer program would be most beneficial to the organization. Purpose The primary purpose of this evaluation is to provide Clean the World, Las Vegas with both short and long term recommendations based on the identified needs of their current volunteer program. Methodology To obtain qualitative and quantitative information about the volunteer program, information was collected via interviews with Clean the World, Las Vegas staff members, found in benchmarks studies, and through surveys ADIV Advising developed and distributed to current volunteers. Findings The volunteer survey respondents were able to provide important critical feedback regarding the volunteer program; survey data and commen

Alpha- and Gammaproteobacterial Methanotrophs Codominate the Active Methane-Oxidizing Communities in an Acidic Boreal Peat Bog

The objective of this study was to characterize metabolically active, aerobic methanotrophs in an ombrotrophic peatland in the Marcell Experimental Forest, Minnesota, USA. Methanotrophs were investigated in the field and in laboratory incubations using DNA-stable isotope probing, expression studies on particulate methane monooxygenase (pmoA) genes, and amplicon sequencing of 16S rRNA genes. Potential rates of oxidation ranged from 14-17 μmol CH4 g dry wt soil-1 d-1. Within DNA-SIP incubations, the relative abundance of methanotrophs increased from 4% in situ to 25-36% after 8 -14 days. Phylogenetic analysis of the 13C-enriched DNA fractions revealed the active methanotrophs were dominated by the genera Methylocystis (Type II; Alphaproteobacteria), Methylomonas, and Methylovulum (Type I; Gammaproteobacteria). In field samples, a transcript-to-gene ratio of 1 to 2 was observed for pmoA in surface peat layers which attenuated rapidly with depth, indicating the highest methane consumption was associated with the 0-10 cm depth interval. Metagenomes and sequencing of cDNA pmoA amplicons from field samples confirmed the dominant active methanotrophs were Methylocystis and Methylomonas. Although Type II methanotrophs have long been shown to mediate methane consumption in peatlands, our results indicate members of the genera Methylomonas and Methylovulum (Type I) can significantly contribute to aerobic methane oxidation in these ecosystems

Control of the Diurnal Pattern of Methane Emission from Emergent Aquatic Macrophytes by Gas Transport Mechanisms

Methane emissions from Typha latifolia (L.) showed a large mid-morning transient peak associated with rising light levels. This peak was also associated with a steep decline in lacunal CH, concentrations near the stem base. This pattern contrasted sharply with emissions from Peltandra virginica (L.) that gradually rose to a peak in the mid-afternoon corresponding to elevated air temperatures. Internal CH4 concentrations within P. virginica stems did not change significantly over the diurnal period. Stomatal conductance appeared to correlate directly with light levels in both plant types and were not associated with peak CH4 emission events in either plant. These patterns are consistent with a convective throughflow and diffusive gas ventilation systems for Typha and Peltandra, respectively. Further effects of the convective throughflow in T. latifolia were evident in the elevated CH4 concentrations measured within brown leaves as contrasted to the near ambient levels measured within live green leaves. Experimental manipulation of elevated and reduced CO2 levels in the atmosphere surrounding the plants and of light/dark periods suggested that stomatal aperture has little or no control of methane emissions from T. latifolia

Greenhouse gas balance over thaw-freeze cycles in discontinuous zone permafrost

Peat in the discontinuous permafrost zone contains a globally significant reservoir of carbon that has undergone multiple permafrost-thaw cycles since the end of the mid-Holocene (~3700 years before present). Periods of thaw increase C decomposition rates which leads to the release of CO2 and CH4 to the atmosphere creating potential climate feedback. To determine the magnitude and direction of such feedback, we measured CO2 and CH4 emissions and modeled C accumulation rates and radiative fluxes from measurements of two radioactive tracers with differing lifetimes to describe the C balance of the peatland over multiple permafrost-thaw cycles since the initiation of permafrost at the site. At thaw features, the balance between increased primary production and higher CH4 emission stimulated by warmer temperatures and wetter conditions favors C sequestration and enhanced peat accumulation. Flux measurements suggest that frozen plateaus may intermittently (order of years to decades) act as CO2 sources depending on temperature and net ecosystem respiration rates, but modeling results suggest that—despite brief periods of net C loss to the atmosphere at the initiation of thaw—integrated over millennia, these sites have acted as net C sinks via peat accumulation. In greenhouse gas terms, the transition from frozen permafrost to thawed wetland is accompanied by increasing CO2 uptake that is partially offset by increasing CH4 emissions. In the short-term (decadal time scale) the net effect of this transition is likely enhanced warming via increased radiative C emissions, while in the long-term (centuries) net C deposition provides a negative feedback to climate warming

Carbon Cycling in Santa Barbara Basin Sediments: A Modeling Study

The primary input of organic matter to almost all marine sediments comes from deposition at the sediment surface. However, in many continental margin settings, reduced carbon can also be added to sediments from below—for example, from “deep” geologic hydrocarbon reservoirs derived from ancient source rocks or from the decomposition of deeply buried gas hydrate deposits. To examine the impact of these two differing reduced carbon inputs on sediment biogeochemistry, a modified reaction-transport model for anoxic marine sediments is described here and applied to data from sediment cores in Santa Barbara Basin to a depth of 4.6 m. Excellent model fits yield results consistent with previous studies of Santa Barbara Basin and other continental margin sediments. These results indicate that authigenic carbonate precipitation in these sediments is not centered around the sulfate-methane transition zone (SMTZ), as is seen in many other sedimentary environments but occurs at shallower depths in the sediments and over a relatively broad depth range. Sulfate profiles are linear between the surface sediments (upper ∼20 cm) and the top of the SMTZ (∼105 cm) giving the appearance of refractory particulate organic carbon (POC) burial and conservative sulfate behavior in this intermediate region. However, model results show that linear profiles may also occur when high rates of sulfate reduction occur near the sediment surface (as organoclastic sulfate reduction [oSR]) and in the SMTZ (largely as anaerobic oxidation of methane) with low, but nonzero, rates of oSR in-between. At the same time, linearity in the sulfate profile may also be related to downward pore-water advection by compaction and sedimentation plus a decrease with depth in sulfate diffusivity because of decreasing porosity. These model-determined rates of oSR and methanogenesis also result in a rate of POC loss that declines near-continuously in a logarithmic fashion over the entire sediment column studied. The results presented further here indicate the importance of a deep methane flux from below on sediment biogeochemistry in the shallower sediments, although the exact source of this methane flux is difficult to ascertain with the existing data