Is terrestrial carbon degradation in stream hyporheic zones stimulated by nutrients?

2020 ◽  
Author(s):  
Katrin Attermeyer ◽  
Astrid Harjung ◽  
Jakob Schelker ◽  
Martin Kainz ◽  
Gabriele Weigelhofer
Keyword(s):  
Hyporheic Zone ◽  
Microbial Respiration ◽  
Hot Spot ◽  
Microbial Activities ◽  
Terrestrial Carbon ◽  
Stream Network ◽  
Respiration Rates ◽  
Carbon Processing ◽  
Carbon Concentrations ◽  
Carbon Degradation

<p>The stream hyporheic zone (HZ) represents the interface between streams and groundwater. Due to the mixing of organic matter and nutrients from groundwater and surface waters it is a hot spot of microbial activities and carbon processing within a stream network. The magnitude of terrestrial carbon degradation by microorganisms in the HZ influences the quantity and biochemical quality of terrestrial carbon as well as greenhouse gas concentrations in streams. One of the factors controlling microbial activities and terrestrial carbon degradation in the HZ are nutrients. However, major knowledge gaps exist regarding the control of nutrients on terrestrial carbon processing in the HZ among different streams.</p><p>We investigated the role of algal DOM (DOM<sub>alg</sub>) and phosphorus (P) on the degradation of soil DOM (DOM<sub>soil</sub>) by hyporheic microorganisms in a lab- and a field-based experiment. In the lab-based experiment, we focused on the influence of different DOM<sub>soil</sub>:DOM<sub>alg</sub> ratios on the DOM degradation at similar carbon concentrations in microcosms mimicking the HZ. One batch was incubated at ambient P concentrations and a second batch at increased P concentrations adapted to the highest levels found in the pure DOM<sub>alg</sub>. We assessed microbial respiration and changes in DOM optical properties to examine quantitative and qualitative changes of the DOM pool. In the field-based experiment, we determined microbial respiration rates of HZ-sediments from 20 streams in Austria with differing ambient nutrient and organic carbon concentrations. The sediments were incubated with DOM<sub>soil</sub>, with and without additional P.</p><p>Results from the lab-based experiment show that microbial respiration in the HZ decreased with increasing soil DOM fractions. When P levels were adapted to DOM<sub>alg</sub> concentrations, microbial respiration rates were comparable between the different DOM mixtures and DOM<sub>soil</sub> was degraded. However, in the field-based experiment, P addition only stimulated microbial respiration rates in one out of 20 HZ-sediments, suggesting that microbial respiration rates are not solely controlled by P.</p><p>In conclusion, nutrient pulses can stimulate microbial activities and thus terrestrial carbon degradation in the HZ. However, when using different stream HZ-sediments, it becomes evident that the nutrient stimulation is not a ubiquitous mechanism and terrestrial carbon degradation in the HZ is controlled by a multitude of factors.</p>

scholarly journals Development and evaluation of ArcGIS based watershed-scale L-THIA ACN-WQ system for watershed management

2017 ◽  
Vol 18 (4) ◽  
pp. 1206-1221
Author(s):  
Jichul Ryu ◽  
Won Seok Jang ◽  
Jonggun Kim ◽  
Gwanjae Lee ◽  
Kwangsik Yoon ◽  
...  
Keyword(s):  
Water Quality ◽  
Watershed Management ◽  
Hot Spot ◽  
Policy Decision ◽  
Curve Number ◽  
Assessment Model ◽  
Quality Model ◽  
Stream Network ◽  
Pollutant Loads ◽  
Model Input

Abstract The Long-term Hydrologic Impact Assessment Model with Asymptotic Curve Number Regression Equation and Water Quality model (L-THIA ACN-WQ) has been developed to simulate streamflow as well as instream water quality using fewer parameters, compared to other watershed models. However, since model input parameters (i.e. hydraulic response unit (HRU) map, stream network, database (DB), etc.) should be built by user manually, it is difficult to use the model for a nonprofessional or environmental policy decision-maker. In addition, it is difficult to analyze model outputs in time and space because the model does not provide geographic information system (GIS) information for the simulation results. To overcome the limitations, an advanced version of L-THIA ACN-WQ system which is based on ArcGIS interface was developed in this study. To evaluate the applicability of the developed system, it was applied to the Banbyeon A watershed in which total maximum daily load (TMDL) has been implemented. The required model input datasets were automatically collected in the system, and stream flow, T-N and T-P pollutant loads were simulated for the watershed. Furthermore, flow duration curve (FDC) and load duration curve (LDC) were generated to analyze hot spot areas in the system through automatic processes included in the system. The system can establish the model input data easily, automatically provide the graphs of FDC and LDC, and provide hot spot areas which indicate high pollutant loads. Therefore, this system can be useful in establishing various watershed management plans.

What controls microbial growth in tropical soils? The role of carbon and phosphorus.

2020 ◽  
Author(s):  
Christian Ranits ◽  
Lucia Fuchslueger ◽  
Leandro Van Langenhove ◽  
Ivan Janssens ◽  
Josep Peñuelas ◽  
...  
Keyword(s):  
Microbial Biomass ◽  
Microbial Communities ◽  
Microbial Growth ◽  
Microbial Respiration ◽  
Tropical Soils ◽  
Microbial Biomass C ◽  
P Availability ◽  
Respiration Activity ◽  
Respiration Rates ◽  
C And N

<p>Tropical forest ecosystems are important components of global biogeochemical cycling. Many tropical rainforests grow in old and highly weathered soils, depleted in phosphorus (P) and net primary productivity in tropical forests is often limited by P availability. It is unclear, however, if heterotrophic microbial communities in tropical soils are also limited by P or rather by carbon (C). Elemental limitations of microorganisms in soil have often been approached by measurements of respiration rates in response to additions of nutrients or carbon. However, it has been argued lately, that microbial growth rather than respiration should be used to assess limitations.</p><p>In this study we therefore ask the question whether the growth of heterotrophic microbial communities in tropical soil is limited by available phosphorus or by carbon. We collected soils from three sites along a topographic gradient (plateau, slope, bottom) differing in soil texture, total and available P concentrations from a well-studied, P-poor region in Nouragues, French Guiana. We incubated these soils in the laboratory with C in the form of cellulose, inorganic phosphorus and with a combination of both, and studied microbial growth by measuring the <sup>18</sup>O incorporation from labelled water into microbial DNA. Moreover, we measured microbial respiration and determined microbial biomass C, N (nitrogen) and P.</p><p>Our results demonstrate that, although microbial biomass C and N was similar in soil collected from all three topographic sites, soil respiration rates were significantly higher in soils from the plateau indicating a more active microbial community. Microbial C and N did not respond to cellulose and inorganic P additions, only microbial P increased significantly when P was added in all soils. Although microbial biomass C was not increased, C and P additions stimulated microbial respiration in clay rich plateau soils. In slope soils microbial communities initially only increased respiration activity in response to P additions, however at the end of the incubation also C showed significant differences in respiration activity, with strongest increases when C and P were added in combination. In sandier bottom soils microorganisms responded with increased activity to C addition, but also here respiration showed strongest increases in response to combined carbon and phosphorus additions. We will discuss these findings in relation to the pattern of gross growth rates in these soils and evaluate the stoichiometric limitations of microbial activity and turnover.</p>

scholarly journals Velocity-amplified microbial respiration rates in the lower Amazon River

2018 ◽  
Vol 3 (3) ◽  
pp. 265-274 ◽  
Author(s):  
Nicholas D. Ward ◽  
Henrique O. Sawakuchi ◽  
Vania Neu ◽  
Diani F. S. Less ◽  
Aline M. Valerio ◽  
...  
Keyword(s):  
Microbial Respiration ◽  
Amazon River ◽  
Respiration Rates

Nutrient cycling in relation to decomposition and organic-matter quality in taiga ecosystems

1983 ◽  
Vol 13 (5) ◽  
pp. 795-817 ◽  
Author(s):  
P. W. Flanagan ◽  
K. Van Cleve
Keyword(s):  
Organic Matter ◽  
Nitrogen Content ◽  
Forest Floor ◽  
Fungal Biomass ◽  
Microbial Respiration ◽  
Black Spruce ◽  
Litter Fall ◽  
Substrate Quality ◽  
Respiration Rates ◽  
Forest Floors

A variety of evergreen and deciduous forests in the taiga of interior Alaska were studied over a 5-year period to examine how the chemical quality of forest-floor organic matter affected its rate of decomposition and mineral cycling within and outside the tree vegetation. Litterbag and respiration studies were used to monitor decomposition. Natural forest-floor substrates and others altered by addition of N, P, and K fertilizer and glucose as a carbon source were studied in the laboratory and field for rates of weight loss and O2 consumption. Forest floors differing in C/N ratios, including those deficient in N, were used to measure substrate quality influences on seedling growth, nutrient content, and tannin content. Microbial (bacteria and fungi) biomass was measured across a range of forest types along with pH, base saturation total pool sizes of N and P, and annual mineralization of organic matter per square metre. Under identical moisture and temperature conditions average respiration rates in evergreen forest-floor L, F, and H substrates were 1.8, 2.8, and 2.0 times less than in the corresponding deciduous forest horizons, respectively. Birch L and F horizons had respiration rates 11.5 times higher than the corresponding black spruce layers. Weight losses in birch L, F, and H horizons were 6, 3, and 2 times higher, respectively, than in the corresponding black spruce substrates. Substrates had a quality-dependent decay rate which did not change when they were relocated within or between sites indicating that measured field climatic differences were not as influential on decay rates as substrate quality components. Fungal biomass was significantly correlated with the quantity of organic matter in all sites (n = 15, r = 0.62) but correlations were better for deciduous (n = 9, r = 0.89), and evergreen (n = 6, r = 0.82) forests separately. Strong correlations exist also between grams of organic matter decayed per square metre per year and fungal biomass (n = 13, r = 0.86), and fungal biomass and grams of N and P mineralized per square metre per year (n = 14, r = 0.95) and (n = 11, r = 0.94, respectively). Seedlings on mineral-deficient substrates produced more tannins than the controls, and seedlings on substrates with widening C/N ratios had successively less tissue with lower N content, and proportionally more roots. Nitrogen content of litter fall in increasingly nitrogen-poor forest floors was correspondingly lower. Nitrogen content of litter fall on N rich forest floors and N fertilized forest floors was proportionately higher. Nitrogen withdrawal in leaves at senescence was inversely correlated with grams N mineralized per square metre per year in forest floors. Fertilization did not influence microbial processes in the field, though lab studies indicated a negative influence of NH4, P, and K on microbial respiration. Glucose added in the laboratory and field markedly increased forest-floor microbial respiration. In vitro glucose-induced increases in respiration were not influenced by addition of ammonium nitrate and were significantly depressed by addition of P and K. In the field, fertilization had no effect on either glucose-induced respiration or microbial biomass.

scholarly journals Experimental desiccation indicates high moisture content maintains hyporheic biofilm processes during drought in temperate intermittent streams

2021 ◽  
Vol 83 (3) ◽  
Author(s):  
Laura E. Coulson ◽  
Jakob Schelker ◽  
Katrin Attermeyer ◽  
Christian Griebler ◽  
Thomas Hein ◽  
...  
Keyword(s):  
Moisture Content ◽  
Hyporheic Zone ◽  
Hot Spot ◽  
Bacterial Respiration ◽  
Dead Cell ◽  
High Moisture Content ◽  
High Moisture ◽  
Drought Duration ◽  
Hyporheic Flow ◽  
Temperate Streams

AbstractDroughts are expected to become more common with climate change resulting in more frequent occurrences of flow intermittency in temperate streams. As intermittency has deleterious effects on fluvial microbial biofilms, there is a need to better understand how droughts affect the microbial functioning and thereby nutrient and organic matter processing in temperate stream ecosystems. Here, the hyporheic zone is of particular importance as it has been shown to be a hot spot for biogeochemical activity under flow intermittence. This study evaluates how drought duration affects microbial biofilm dynamics in the hyporheic zone of intermittent temperate streams. To do so, we used outdoor hyporheic flumes that were subject to periods of drought ranging from 4 to 105 days. Sediment was sampled before and during the drought, and at several occasions after rewetting. Samples were analyzed for extracellular enzymatic activity, bacterial respiration, and bacterial abundances including live to dead cell ratios. The high moisture content remaining in the hyporheic zone of the flumes allowed for the sustained microbial functioning during drought, regardless of drought duration. This can be attributed to cooler temperatures in these climate zones and shading by riparian forests. The high moisture content inhibited the local habitat and community changes that the biofilm might have undergone during more severe desiccation. However, the change in the hyporheic flow regime (flow cessation and resumption) may stimulate microbial processing in these moderate drought conditions. We suggest that the hyporheic zone may act as a buffer against drought and the factors determining this buffer capacity, such as sediment characteristics and climatic regions, need to be analyzed in more detail in future.

scholarly journals Boreal headwater catchment as hot spot of carbon processing from headwater to fjord

2021 ◽  
Author(s):  
F. Clayer ◽  
J.‐E. Thrane ◽  
U. Brandt ◽  
P. Dörsch ◽  
H. A. Wit
Keyword(s):  
Hot Spot ◽  
Carbon Processing ◽  
Headwater Catchment

scholarly journals Biogeochemical cycling at the aquatic–terrestrial interface is linked to parafluvial hyporheic zone inundation history

2017 ◽  
Vol 14 (18) ◽  
pp. 4229-4241 ◽  
Author(s):  
Amy E. Goldman ◽  
Emily B. Graham ◽  
Alex R. Crump ◽  
David W. Kennedy ◽  
Elvira B. Romero ◽  
...  
Keyword(s):  
Microbial Communities ◽  
Reactive Transport ◽  
Hyporheic Zone ◽  
Microbial Respiration ◽  
Co2 Flux ◽  
Biogeochemical Cycling ◽  
Microbial Interactions ◽  
Rrna Gene ◽  
Minor Effect ◽  
Local Conditions

Abstract. The parafluvial hyporheic zone combines the heightened biogeochemical and microbial interactions indicative of a hyporheic region with direct atmospheric/terrestrial inputs and the effects of wet–dry cycles. Therefore, understanding biogeochemical cycling and microbial interactions in this ecotone is fundamental to understanding biogeochemical cycling at the aquatic–terrestrial interface and to creating robust hydrobiogeochemical models of dynamic river corridors. We aimed to (i) characterize biogeochemical and microbial differences in the parafluvial hyporheic zone across a small spatial domain (6 lateral meters) that spans a breadth of inundation histories and (ii) examine how parafluvial hyporheic sediments respond to laboratory-simulated re-inundation. Surface sediment was collected at four elevations along transects perpendicular to flow of the Columbia River, eastern WA, USA. The sediments were inundated by the river 0, 13, 127, and 398 days prior to sampling. Spatial variation in environmental variables (organic matter, moisture, nitrate, glucose,  % C,  % N) and microbial communities (16S and internal transcribed spacer (ITS) rRNA gene sequencing, qPCR) were driven by differences in inundation history. Microbial respiration did not differ significantly across inundation histories prior to forced inundation in laboratory incubations. Forced inundation suppressed microbial respiration across all histories, but the degree of suppression was dramatically different between the sediments saturated and unsaturated at the time of sample collection, indicating a binary threshold response to re-inundation. We present a conceptual model in which irregular hydrologic fluctuations facilitate microbial communities adapted to local conditions and a relatively high flux of CO2. Upon rewetting, microbial communities are initially suppressed metabolically, which results in lower CO2 flux rates primarily due to suppression of fungal respiration. Following prolonged inundation, the microbial community adapts to saturation by shifting composition, and the CO2 flux rebounds to prior levels due to the subsequent change in respiration. Our results indicate that the time between inundation events can push the system into alternate states: we suggest (i) that, above some threshold of inundation interval, re-inundation suppresses respiration to a consistent, low rate and (ii) that, below some inundation interval, re-inundation has a minor effect on respiration. Extending reactive transport models to capture processes that govern such dynamics will provide more robust predictions of river corridor biogeochemical function under altered surface water flow regimes in both managed and natural watersheds.

scholarly journals The Chemical Transformation of the Cellular Toxin INT (2-(4-Iodophenyl)-3-(4-Nitrophenyl)-5-(Phenyl) Tetrazolium Chloride) as an Indicator of Prior Respiratory Activity in Aquatic Bacteria

2019 ◽  
Vol 20 (3) ◽  
pp. 782 ◽  
Author(s):  
Josué Villegas-Mendoza ◽  
Ramón Cajal-Medrano ◽  
Helmut Maske
Keyword(s):  
Microbial Respiration ◽  
Respiratory Activity ◽  
Tetrazolium Salt ◽  
Aquatic Bacteria ◽  
Tetrazolium Chloride ◽  
Respiration Rates ◽  
Consumption Rates ◽  
Marine Microbial Communities

In the ocean, the prokaryote respiration rates dominate the oxidation of organics, but the measurements may be biased due to pre-incubation size filtration and long incubation times. To overcome these difficulties, proxies for microbial respiration rates have been proposed, such as the in vitro and in vivo estimation of electron transport system rates (ETS) based on the reduction of tetrazolium salts. INT (2-(4-Iodophenyl)-3-(4-Nitrophenyl)-5-(Phenyl) Tetrazolium Chloride) is the most commonly applied tetrazolium salt, although it is toxic on time scales of less than 1 h for prokaryotes. This toxicity invalidates the interpretation of the rate of in vivo INT reduction to formazan as a proxy for oxygen consumption rates. We found that with aquatic bacteria, the amount of reduced INT (F; µmol/L formazan) showed excellent relation with the respiration rates prior to INT addition (R; O2 µmol/L/hr), using samples of natural marine microbial communities and cultures of bacteria (V. harveyi) in batch and continuous cultures. We are here relating a physiological rate with the reductive potential of the poisoned cell with units of concentration. The respiration rate in cultures is well related to the cellular potential of microbial cells to reduce INT, despite the state of intoxication.

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