Measurement of primary production and community respiration in oligotrophic lakes using the Winkler method

1998 ◽  
Vol 55 (5) ◽  
pp. 1078-1084 ◽  
Author(s):  
Richard Carignan ◽  
Anne-Marie Blais ◽  
Chantal Vis
Keyword(s):  
Primary Production ◽  
Detection Method ◽  
Gross Primary Production ◽  
Community Respiration ◽  
Oligotrophic Lakes ◽  
Respiration Rates ◽  
Precision Level ◽  
Winkler Method ◽  
End Point Detection ◽  
Point Detection

The precision of the Winkler method can reach 2 µg ·L-1 if a potentiometric end-point detection method if used and if minor modifications to standard protocols are made. The major sources of variability encountered at this precision level are due to the gradual decrease (1-3 µg ·L-1 ·h-1) in apparent O2 which occurs after reagent addition and to thermal expansion and contraction of the samples during storage. These sources of error can, however, be easily minimized or eliminated. The precision of the proposed protocols for Winkler determinations and metabolic rate measurements allows the detection of gross primary production and community respiration rates as low as 0.7 mg C ·m-3 ·h-1 after 4-h incubations. The methods are therefore adequate for metabolic studies in oligotrophic lakes, where epilimnetic production and respiration rates range between 5 and 50 mg C ·m-3 ·h-1.

scholarly journals Consequences of respiration in the light on the determination of production in pelagic systems

2007 ◽  
Vol 4 (1) ◽  
pp. 105-114 ◽  
Author(s):  
O. Pringault ◽  
V. Tassas ◽  
E. Rochelle-Newall
Keyword(s):  
Primary Production ◽  
Dark Respiration ◽  
Gross Primary Production ◽  
Community Respiration ◽  
Metabolic Balance ◽  
Net Community Production ◽  
Respiration Rates ◽  
Seawater Samples ◽  
Community Production

Abstract. Oxygen microprobes were used to estimate Community Respiration (R), Net Community Production (NCP) and Gross Primary Production (GPP) in coastal seawater samples. Using this highly stable and reproducible technique to measure oxygen change during alternating dark and light periods, we show that respiration in the light could account for up to 640% of respiration in the dark. The light enhanced dark respiration can remain elevated for several hours following a 12 h period of illumination. Not including Rlight into calculations of production leads to an underestimation of GPP, which can reach up to 650% in net heterotrophic systems. The production: respiration (P:R) ratio is in turn affected by the higher respiration rates and by the underestimation of GPP. While the integration of Rlight into the calculation of P:R ratio does not change the metabolic balance of the system, it decreases the observed tendency, thus net autotrophic systems become less autotrophic and net heterotrophic systems become less heterotrophic. As a consequence, we propose that efforts have to be focused on the estimation and the integration of Rlight into the determination of GPP and R for a better understanding of the aquatic carbon cycle.

Signal analysis of the end point detection method based on motor current

2003 ◽  
Vol 66 (1-4) ◽  
pp. 472-479 ◽  
Author(s):  
Sang-Yong Kim ◽  
Chang-Jun Park ◽  
Yong-Jin Seo
Keyword(s):  
Signal Analysis ◽  
Detection Method ◽  
Motor Current ◽  
End Point ◽  
End Point Detection ◽  
Point Detection

scholarly journals Magnetic Separation Methods for the Detection ofMycobacterium aviumsubsp.paratuberculosisin Various Types of Matrices: A Review

2017 ◽  
Vol 2017 ◽  
pp. 1-15 ◽  
Author(s):  
Marketa Husakova ◽  
Radka Dziedzinska ◽  
Iva Slana
Keyword(s):  
Magnetic Separation ◽  
Mycobacterium Avium ◽  
Food Chain ◽  
Dairy Products ◽  
Detection Method ◽  
Animal Health ◽  
Initial Matrix ◽  
Crucial Step ◽  
End Point Detection ◽  
Point Detection

The main reasons to improve the detection ofMycobacterium aviumsubsp.paratuberculosis(MAP) are animal health and monitoring of MAP entering the food chain via meat, milk, and/or dairy products. Different approaches can be used for the detection of MAP, but the use of magnetic separation especially in conjunction with PCR as an end-point detection method has risen in past years. However, the extraction of DNA which is a crucial step prior to PCR detection can be complicated due to the presence of inhibitory substances. Magnetic separation methods involving either antibodies or peptides represent a powerful tool for selective separation of target bacteria from other nontarget microorganisms and inhibitory sample components. These methods enable the concentration of pathogens present in the initial matrix into smaller volume and facilitate the isolation of sufficient quantities of pure DNA. The purpose of this review was to summarize the methods based on the magnetic separation approach that are currently available for the detection of MAP in a broad range of matrices.

Novel End-point Detection Method by Monitoring Shear Force Oscillation Frequency for Barrier Metal Polishing in Advanced LSI

2009 ◽  
Vol 1157 ◽  
Author(s):  
Xun Gu ◽  
Takenao Nemoto ◽  
Yasa Adi Sampurno ◽  
Jiang Cheng ◽  
Sian Nie Theng ◽  
...  
Keyword(s):  
Oscillation Frequency ◽  
Shear Force ◽  
Detection Method ◽  
Spectral Amplitude ◽  
Fast Fourier Transformation ◽  
Silicon Dioxide Film ◽  
End Point ◽  
End Point Detection ◽  
Barrier Metal ◽  
Point Detection

AbstractA novel end-point detection method based on a combination of shear force and its spectral amplitude was proposed for barrier metal polishing on copper damascene structures. Under some polishing conditions, the shear force changed significantly with polished substrate. On the other hand, the change in shear force was insignificant under certain polishing conditions. Therefore, a complementary end-point detection method by monitoring oscillation frequency of shear force was proposed. It was found that the shear force fluctuated in unique frequencies depending on polished substrates. Using Fast Fourier Transformation, the shear force data was converted from time domain to frequency domain. The amplitude of spectral frequencies corresponding to the rotational rate of wafer carrier and platen was monitored. Significant frequency amplitude changes were observed before, during and after the polished layer transition from barrier film to silicon dioxide film. The results indicated that a combination of shear force and its spectral amplitude analyses provided effective end-point detection for barrier CMP process.

Evaluation of a Toxicant on the Metabolism of Model Stream Communities

1976 ◽  
Vol 33 (12) ◽  
pp. 2740-2746 ◽  
Author(s):  
Alan W. Maki ◽  
Howard E. Johnson
Keyword(s):  
Primary Production ◽  
Net Primary Production ◽  
Gross Primary Production ◽  
Benthic Communities ◽  
Exposure Period ◽  
Community Respiration ◽  
Metabolic Rates ◽  
Stream Communities ◽  
Time Period

The effects of a toxicant, the lampricide TFM (3-trifluoromethyl-4-nitrophenol), on the metabolism of benthic communities were studied in a series of six indoor model streams resembling typical woodland streams. Each artificially illuminated stream consisted of a 4-m pool section and a 4-m riffle section.A specially developed in situ stream respirometer was used for measurements of net primary production and community respiration in pool and riffle communities. Pretreatment levels of gross primary production ranged during summer, fall, and early winter from 10.7 to 79.0 mg O2∙m−2∙h−1 and were suppressed by 25–50% during exposure to 9.0 mg/liter TFM. Community respiration ranged from 10.5 to 36.2 mg O2∙m−2∙h−1 during the same time period and was increased 3–50% by the 9.0 mg/liter lampricide treatment. Calculated photosynthesis to respiration (P:R) ratios proved to be sensitive indicators of the influence of the toxicant. The stream communities demonstrated a capacity to adjust to the toxicant influence as evidenced by the rapid return of metabolic rates to pretreatment levels following the exposure period.

Pharmaceuticals and personal care products alter growth and function in lentic biofilms

2015 ◽  
Vol 12 (3) ◽  
pp. 301 ◽  
Author(s):  
Lawton Shaw ◽  
Chuyen Phung ◽  
Michael Grace
Keyword(s):  
Primary Production ◽  
Ecosystem Respiration ◽  
Gross Primary Production ◽  
Personal Care Products ◽  
Algal Growth ◽  
Biologically Active ◽  
Community Respiration ◽  
Personal Care ◽  
Ecological Processes ◽  
And Function

Environmental context Pharmaceuticals and personal care products are routinely found in waters discharged from treatment plants and in surrounding aquatic ecosystems. Despite the widespread occurrence of these biologically active agents, there is limited understanding of their potential effects on key ecosystem processes such as primary production, ecosystem respiration and algal growth. This paper examines the effects of five common pharmaceuticals on the rates of these fundamental processes. Abstract Pharmaceutical diffusing substrates were used to study in situ responses of aquatic biofilms in an urbanised lentic ecosystem to five pharmaceutical and personal care products (PPCPs; caffeine, cimetidine, ciprofloxacin, diphenhydramine and metformin). The pharmaceutical diffusing substrates consisted of porous biofilm substrates placed atop a mass of agar amended with 2.5mM of the PPCP compound of interest. Over 21 days, biofilms growing on the substrata were exposed to slow diffusion of the PPCP through the agar and porous substrate. Algal biomass was suppressed by exposure to diphenhydramine (–81%) and ciprofloxacin (–50%). Gross primary production was completely suppressed by diphenhydramine exposure but stimulated by caffeine (+39%) and cimetidine (+46%). For heterotroph biofilms, community respiration was suppressed by exposure to diphenhydramine (–24%). To characterise PPCP exposure, rates of diffusion from the pharmaceutical diffusing substrates were measured at 10, 20 and 30°C. Diffusion was Fickian for all compounds and all temperatures. Diffusion coefficients, D, were in the range 1.5×10–10 to 1.1×10–9m2s–1. From diffusion data, average release rates over 21 days were typically 30–50ngmin–1cm–2 at 20°C. The results show that PPCPs can dramatically affect rates of key ecological processes, and the relationship between release rate and ambient concentration of PPCPs is discussed.

scholarly journals Ocean acidification decreases plankton respiration: evidence from a mesocosm experiment

2016 ◽  
Author(s):  
K. Spilling ◽  
A. J. Paul ◽  
N. Virkkala ◽  
T. Hastings ◽  
S. Lischka ◽  
...  
Keyword(s):  
Primary Production ◽  
Ocean Acidification ◽  
Community Composition ◽  
Carbon Fixation ◽  
Plankton Community ◽  
Community Respiration ◽  
Carbon Export ◽  
High Co2 ◽  
Respiration Rates ◽  
Co2 Levels

Abstract. Anthropogenic carbon dioxide (CO2) emissions are reducing the pH in the world's oceans. The plankton community is a key component driving biogeochemical fluxes, and the effect of increased CO2 on plankton is critical for understanding the ramifications of ocean acidification on global carbon fluxes. We determined the plankton community composition and measured primary production, respiration rates and carbon export (defined here as carbon sinking out of a shallow, coastal area) during an ocean acidification experiment. Mesocosms (~ 55 m3) were set up in the Baltic Sea with a gradient of CO2 levels initially ranging from ambient (~ 240 μatm), used as control, to high CO2 (up to ~ 1330 μatm). The phytoplankton community was dominated by dinoflagellates, diatoms, cyanobacteria and chlorophytes, and the zooplankton community by protozoans, heterotrophic dinoflagellates and cladocerans. The plankton community composition was relatively homogenous between treatments. Community respiration rates were lower at high CO2 levels. The carbon-normalized respiration was approximately 40 % lower in the high CO2 environment compared with the controls during the latter phase of the experiment. We did not, however, detect any effect of increased CO2 on primary production. This could be due to measurement uncertainty, as the measured total particular carbon (TPC) and combined results presented in this special issue suggest that the reduced respiration rate translated into higher net carbon fixation. The percent carbon derived from microscopy counts (both phyto- and zooplankton), of the measured total particular carbon (TPC) decreased from ~ 26 % at t0 to ~ 8 % at t31, probably driven by a shift towards smaller plankton (< 4 μm) not enumerated by microscopy. Our results suggest that reduced respiration lead to increased net carbon fixation at high CO2. However, the increased primary production did not translate into increased carbon export, and did consequently not work as a negative feedback mechanism for increasing atmospheric CO2 concentration.

Short-term coherency between gross primary production and community respiration in an algal-dominated reef flat

Coral Reefs ◽  
2010 ◽  
Vol 30 (1) ◽  
pp. 53-58 ◽  
Author(s):  
J. L. Falter ◽  
M. J. Atkinson ◽  
D. W. Schar ◽  
R. J. Lowe ◽  
S. G. Monismith
Keyword(s):  
Primary Production ◽  
Reef Flat ◽  
Gross Primary Production ◽  
Community Respiration ◽  
Short Term
Sign in / Sign up

Export Citation Format

Share Document