Continuous Flow Analysis Techniques Research Articles

Contribution of white grubs (Scarabaeidae: Coleoptera) to N2O emissions from tropical soils

Soil biological processes that produce greenhouse gases, such as N2O, are more intense in tropical soils because of the warm and humid climate; however, the role played by the wide diversity of fauna in these soils in soil N2O production is still poorly understood. This study attempts to assess the role of scarabaeid grubs (Coleoptera), a major faunal group in tropical soils, in emissions of atmospheric N2O. It was hypothesized that (i) the guts of these grubs are important sites of N2O-genesis, since they present environmental conditions (anoxia, high labile C and N mineral contents) that are suitable for N2O production; and (ii) rates of N2O emissions will vary according to the density of gut microbial communities that are involved in N2O emission (i.e. ammonia-oxidizers and denitrifiers). Through laboratory microcosm experiments, in vitro emissions of N2O were determined directly from live grubs of different scarabaeid species (collected from tropical soils of Madagascar and Mexico) and from their surrounding parent soils. Quantitative PCR was used to determine the abundance of the total bacterial community (using the 16S rRNA gene) as well as the ammonia-oxidizing (bacterial AOB and archaeal AOA) and denitrifying (nirK, nirS and nosZ) microbial communities in the grub guts and surrounding soils. The mineral N contents of grub guts and parent soils were also determined using a continuous flow analysis technique. All of the studied grub species emitted significantly higher N2O than the parent soils and presented a high gut ammonium to nitrate ratio (16:1). Their guts harbor a higher density of total bacterial (4.5-fold) and nitrite reductase (nirK) genes (1.5-fold) than the parent soils. However, with the exception of nirK, the relative and absolute abundances of all ammonia-oxidizer and denitrifier genes were higher in soils than in the grub gut environment. The average gene abundance of AOA was 10-fold higher than that of its bacterial counterpart (AOB). Emission of N2O from grubs correlated significantly with the gene abundance of their gut ammonia-oxidizers (AOA and AOB) and denitrifiers (nirS), but not with mineral N contents. Based on average biomass values, these scarabaeid grubs are estimated to contribute between 0.2 and 1.8% of total soil N2O emissions in tropical areas.

A refined TALDICE-1a age scale from 55 to 112 ka before present for the Talos Dome ice core based on high-resolution methane measurements

Abstract. A precise synchronization of different climate records is indispensable for a correct dynamical interpretation of paleoclimatic data. A chronology for the TALDICE ice core from the Ross Sea sector of East Antarctica has recently been presented based on methane synchronization with Greenland and the EDC ice cores and δ18Oice synchronization with EDC in the bottom part (TALDICE-1). Using new high-resolution methane data obtained with a continuous flow analysis technique, we present a refined age scale for the age interval from 55–112 thousand years (ka) before present, where TALDICE is synchronized with EDC. New and more precise tie points reduce the uncertainties of the age scale from up to 1900 yr in TALDICE-1 to below 1100 yr over most of the refined interval and shift the Talos Dome dating to significantly younger ages during the onset of Marine Isotope Stage 3. Thus, discussions of climate dynamics at sub-millennial time scales are now possible back to 110 ka, in particular during the inception of the last ice age. Calcium data of EDC and TALDICE are compared to show the impact of the refinement to the synchronization of the two ice cores not only for the gas but also for the ice age scale.

Autonomous Environmental Water Quality Monitoring—The Future of Continuous Flow Analysis

Biochemist and hospital laboratory supervisor Leonard Skeggs’ burst of insight in the early 1950s that ‘. . .[manually intensive clinical] analyses could be done in a continuously flowing stream’[1] launched, and to a large extent defined, the field of automated clinical diagnostic testing for the quarter century that followed. Segmented analytical streams, in which air bubbles enhance within-segment mixing and minimize between-segment mixing, are the hallmark of Skeggs’ continuous flow (CF) analysis concept.[2] In 1975, Jaromir Ruzicka and Elo Hansen demonstrated the feasibility of performing CF analysis in non-air-segmented analytical streams.[3] This new approach to CF analysis, which they named flow injection analysis (FIA), launched a new wave of research and development directed primarily at bench-top analysis and environmental, industrial and pharmaceutical process monitoring applications. As described in this Research Front, CF analysis technology that has accrued over the past half century is well poised to meet global water quality monitoring needs in the present century. Terrestrial, estuarine and coastal waters are adversely impacted by substantial anthropogenic nutrient loads they receive from fertilized cropland runoff, confined animal feeding operation discharges, and municipal sewage outfalls. Globally burgeoning nutrient loads promote unsightly eutrophication and occasional ‘fish kills’ in freshwater regimes, and their entry into estuaries and gulfs at the terminus of major river systems drives a reduced dissolved oxygen condition known as hypoxia,[4] which threatens shallowwater fisheries in coastal areas. Excessive nutrient inputs into coastal waters can also trigger blooms of harmful algal species whose toxins are concentrated in fish and shellfish consumed by marine mammals and humans. In the United States, for example, the Chesapeake Bay Foundation identified nitrogen and phosphorus as ‘the Bay’s two primary pollutants’ in its 2004 State of the Bay report.[5] In light of the global proliferation of nutrients-as-contaminants, articles included in this Research Front, including a review of nutrient monitoring by CF analysis techniques,[6] and papers

Continuous flow analysis of mercury using a chalcogenide glass ion-selective electrode

A commercial Hg chalcogenide glass ion-selective electrode (ISE) has been characterized using scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy, and the compositional data have been used in the fabrication of our own Hg ISE. It is shown that continuous flow analysis (CFA) is suitable for rapid determinations of ultratrace levels of mercury in saline media when used in conjunction with an extrapolation method that predicts the steady-state potential of the Hg ISE by using the initial data following a stepwise change in aHg2+. The CFA technique yields a near-Nernstian response of 28 mV per decade change in aHg2+ in Hg buffers in the range 10−18 to 10−12 M Hg2+. It is shown that the repeatability of the CFA technique in seawater is ±0.03 pHg units, and a seawater matrix effect causes a significant offset and apparent error in the response of the Hg ISE relative to Hg buffer standards. Standard addition CFA may be used to compensate for the seawater matrix interference. © 2000 John Wiley & Sons, Inc. Lab Robotics and Automation 12:194–199, 2000

Continuous flow analysis of iron (III) in seawater using a chalcogenide glass ion-selective electrode

Continuous flow analysis (CFA) is suitable for rapid and reliable determination of free FeIII in organic-free, UV-oxidized seawater when used in conjunction with an extrapolation method that predicts the steady-state potentials of an FeIII chalcogenide glass ion-selective electrode (ISE) by using initial data associated with a step-wise change in aFe3+. It is shown that the CFA technique yields a Nernstian response of a 30 mV per decade change in aFe3+ in saline citrate buffers in the range of 10−22 to 10−1 M Fe3+. Validation of the CFA technique in organic-free, UV-oxidized seawater has demonstrated that the response of the FeIII ISE is internally consistent with the well-known inorganic speciation equilibria occurring in natural seawater. © 1999 John Wiley & Sons, Inc. Lab Robotics and Automation 11: 284–288, 1999

The influence of nitrogen and potassium supply on the ammonium content of maize (Zea mays L.) leaves including a comparison of measurements made in vivo and in vitro

Maize seedlings were grown on either nitrate or ammonium, at two different potassium levels, and the growth analysis revealed that ammonium supply reduced shoot dry matter particularly under conditions of limited potassium supply. The ammonium content of the leaves was determined in vitro, using continuous flow analysis of plant extracts, and in vivo using 14N nuclear magnetic resonance (NMR) spectroscopy. The conventional continuous flow analysis procedure was modified by the inclusion of a gas dialysis step across a PTFE membrane and control experiments showed that this provided an effective method for avoiding the overestimation of the ammonium content of leaf tissue extracts, by eliminating interference from amino acids and amides. Excellent agreement was obtained between the non-invasive NMR method and the modified continuous flow analysis technique, and it was concluded that leaf ammonium levels are unlikely to affect growth in plants grown with an adequate potassium supply.

Comparison of continuous flow analysis techniques: A laboratory exercise

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTComparison of continuous flow analysis techniques: A laboratory exerciseC. L. M. Stults , Paul R. Kraus , S. K. Ratanathanawongs , Chas. J. Patton , and S. R. Crouch Cite this: J. Chem. Educ. 1989, 66, 12, 1060Publication Date (Print):December 1, 1989Publication History Received3 August 2009Published online1 December 1989Published inissue 1 December 1989https://doi.org/10.1021/ed066p1060RIGHTS & PERMISSIONSArticle Views95Altmetric-Citations4LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (2 MB) Get e-Alerts Get e-Alerts

A multi-parameter extension of temperature/salinity diagram techniques for the analysis of non-isopycnal mixing

The technique of water mass analysis based on temperature-salinity curves is extended to more than three water masses (or water masses defined by temperature-salinity curves rather than points) by including one or more additional parameters and solving the equations of linear mixing without additional assumptions. The oceanographical significance of the result is studied by means of examples. It is shown that the method is particularly useful for investigations of mesoscale mixing as observed in frontal zones where interleaving and intrusions are commonly observed, and that it can be used for obtaining bulk estimates of the impact of non-isopycnal, small-scale mixing events on the mesoscale fields. Possible parameters are discussed and sources of errors reviewed. Examples are used to show that major nutrients can be used as parameters to detect non-isopycnal mixing although limitations in the historical data and low data accuracy lead to considerable error bounds at present. It is argued that introduction of continuous flow analysis techniques and continuous vertical profiling in marine chemistry will greatly improve the potential of the method.