scholarly journals Partitioning Inorganic Carbon Fluxes from Paired O2 - CO2 Gas Measurements in a Neotropical Headwater Stream, Costa Rica

2021 ◽  
Author(s):  
Nicholas S. Marzolf ◽  
Gaston E. Small ◽  
Diana Oviedo-Vargas ◽  
Carissa N. Ganong ◽  
John H. Duff ◽  
...  
Keyword(s):  
Costa Rica ◽  
Headwater Streams ◽  
Headwater Stream ◽  
Sensor Data ◽  
Stream Metabolism ◽  
Temperate Streams ◽  
C Cycle ◽  
Terrestrial Inputs ◽  
Gas Measurements ◽  
The Tropics

Abstract The role of rivers and streams in the global carbon (C) cycle remains unconstrained, especially in headwater streams where CO2 evasion (FCO2) to the atmosphere is high. Stream C cycling is understudied in the tropics compared to temperate streams, and tropical streams may have among the highest FCO2 due to higher temperatures, continuous organic matter inputs, and high respiration rates both in-stream and in surrounding soils. In this paper, we present paired in-stream O2 and CO2 sensor data from a headwater stream in a lowland rainforest in Costa Rica to explore temporal variability in ecosystem processes. Further, we estimate groundwater CO2 inputs (GWCO2) from riparian well CO2 measurements and assess all fluxes to examine the relative contributions of sinks and sources of dissolved inorganic C (DIC) to a headwater stream. Paired O2 - CO2 data reveal stream CO2 supersaturation driven by groundwater CO2 inputs and large in-stream production of CO2. Areal fluxes in our study reach show FCO2 is supported by both GWCO2 inputs and in-stream metabolism and the seasonality in GWCO2 reflects the hydrology of the site. Using a mass balance approach, we show FCO2 is the dominant loss of DIC from the stream, greater than dissolved exports, and is sustained by both internal production of DIC and terrestrial inputs of DIC. Our results underscore the importance of tropical headwater streams as large contributors of greenhouse gases to the atmosphere among inland waters and show of this C derives from both in-stream and terrestrial sources.

scholarly journals Rapid Loss of Dissolved CO2 From a Subtropical Steep Headwater Stream

2021 ◽  
Vol 9 ◽  
Author(s):  
Chun Ngai Chan ◽  
Cheuk Lam Tsang ◽  
Frederick Lee ◽  
Boyi Liu ◽  
Lishan Ran
Keyword(s):  
Carbon Dioxide ◽  
Headwater Streams ◽  
Stream Water ◽  
Narrow Channel ◽  
Headwater Stream ◽  
Small Water ◽  
Water Surface Area ◽  
Air Temperatures ◽  
C Cycle ◽  
Groundwater Source

High-gradient headwater streams are major participants in the carbon (C) cycle because of their capabilities of emitting a significant amount of carbon dioxide (CO2). Notwithstanding, their CO2 emissions have been largely overlooked in previous studies owing to their small water surface area and are sometimes strenuous to be measured because of their narrow channel widths and strong turbulence. This study examined the spatial and seasonal variabilities of CO2 dynamics of a subtropical steep headwater stream fed by groundwater. Our study found that the pH and dissolved oxygen exhibited a general increasing trend away from the source of the headwater whereas the partial pressure of carbon dioxide (pCO2) showed a downward trend. The stream water pCO2 in the upper reach was found to be higher than the ambient level by 19–114 times, with an average drop of >70% at just 9.2 m from the groundwater source, demonstrating the potentially large emission of CO2 into the atmosphere within this short distance. Additionally, the sampling works conducted further downstream revealed that the CO2 derived from groundwater could almost completely dissipate within approximately half a kilometer downstream of the source. The concentrations of dissolved organic carbon and pCO2 were also lower during the period with lower air temperatures in the headwater stream, indicating temperature-dependent metabolism and decomposition of organic matter in soil might modulate the C dynamics in the headwater stream, although the rapid gas exchange along the stream remained the determinative factor. Our findings reassert that headwater streams are an essential source of CO2 and disregarding them from the studies of greenhouse gas emissions of inland waters would underestimate their potency to influence the global C cycle.

scholarly journals Detección de la presencia del ácaro (Aculops lycopersici) causante del bronceamiento del tomate (Lycoprsicon esculentum) en El Salvador, América Central

2016 ◽  
Vol 2 ◽  
pp. 49
Author(s):  
Leopoldo Serrano Cervantes
Keyword(s):  
Costa Rica ◽  
El Salvador ◽  
Central America ◽  
Taxonomic Identification ◽  
Review Of Literature ◽  
Plant Mortality ◽  
Tomato Plants ◽  
Aculops Lycopersici ◽  
The Tropics ◽  
First Time

In October 1989, microscopic specimens of (acaros) with symptoms of browning and plant mortality in young and older tomato plants from various locations in El Salvador were sent tó the entomologist Ing. Ronald Ochoa from Costa Rica. lng. Ronald Ochoa is associated with the Diagnostics Network of the Centro Agronomico Tropical de Investigation y Enseñanza (CATlE) based in Turrialba, Costa Rica. Microscopic examination of this material confirmed the taxonomic identification as Aculops lycopersici (Acariformes: Eriophyidae), suspected since May 1988 with the first observation and collection of samples. Abrief review of literature and a phone conversation with the specialist who identified the material, permits reporting for the first time of the presence of this species in El Salvador. This finding is a warning about this pest which could be apotential problem in the tropics of Central America. This paper discusses personal observations of some of the characteristics, habits and appearances of this species, small experiments, and it includes a review of literature pertinent to this subject

scholarly journals Slow Recovery of Headwater-Stream Fishes Following a Catastrophic Poisoning Event

2021 ◽  
Vol 12 (2) ◽  
pp. 362-372
Author(s):  
Mary Freeman ◽  
Duncan Elkins ◽  
Peter Maholland ◽  
Zachary Butler ◽  
Maxwell Kleinhans ◽  
...  
Keyword(s):  
At Risk ◽  
Fish Species ◽  
Headwater Streams ◽  
Local Population ◽  
Fish Fauna ◽  
Headwater Stream ◽  
Fish Kill ◽  
Slow Recovery ◽  
Stream Biota ◽  
Road Crossing

Abstract Accidental spills of chemicals and other pollutants can decimate populations of stream-dwelling species. Recovery from such accidents can be relatively fast and complete when the affected stream reaches can be recolonized from upstream and downstream sources. However, faunal recoveries from accidental spills that extirpate populations from entire headwater streams have not been extensively documented, and understanding resilience of headwater-stream biota is relevant for assessing threats to at-risk species. We assessed recovery of fish populations in a 5.7-km-long headwater stream in the southeastern United States following a complete, or nearly complete, fish-kill caused by a chemical spill near the source of the stream. We sampled for fishes at five stream locations, two downstream and three upstream from a perched, culverted road-crossing located 2.4 km upstream from the stream mouth, over a period of 18.5 mo following the poisoning event. We observed 11 fish species, representing ≤65% of the fish species expected based on occurrences in nearby tributary streams. In postpoisoning sampling, only three of these taxa were observed upstream of the culvert; all 11 species, including the federally threatened Cherokee Darter Etheostoma scotti, were found downstream of the culvert but were mostly represented by a few, large individuals. In contrast, dead individuals of at least eight taxa including the Cherokee Darter were observed upstream of the culvert at the time of the fish-kill. These observations provide evidence of slow recovery of a headwater fish fauna, and especially upstream of a barrier to fish movement, where the recolonization sources are primarily downstream. Additional case studies may reveal whether this result applies generally to headwater streams. Slow recovery could make species that primarily inhabit or maintain greatest abundances in headwaters, including multiple at-risk fishes, particularly vulnerable to the threat of accidental spills that result in local population extirpation.

scholarly journals Lagged effects regulate the inter-annual variability of the tropical carbon balance

2020 ◽  
Vol 17 (24) ◽  
pp. 6393-6422
Author(s):  
A. Anthony Bloom ◽  
Kevin W. Bowman ◽  
Junjie Liu ◽  
Alexandra G. Konings ◽  
John R. Worden ◽  
...  
Keyword(s):  
Data Model ◽  
Climatic Variability ◽  
Model Framework ◽  
Tropical Ecosystem ◽  
Annual Variations ◽  
Annual Variability ◽  
C Balance ◽  
C Cycle ◽  
Lagged Effects ◽  
The Tropics

Abstract. Inter-annual variations in the tropical land carbon (C) balance are a dominant component of the global atmospheric CO2 growth rate. Currently, the lack of quantitative knowledge on processes controlling net tropical ecosystem C balance on inter-annual timescales inhibits accurate understanding and projections of land–atmosphere C exchanges. In particular, uncertainty on the relative contribution of ecosystem C fluxes attributable to concurrent forcing anomalies (concurrent effects) and those attributable to the continuing influence of past phenomena (lagged effects) stifles efforts to explicitly understand the integrated sensitivity of a tropical ecosystem to climatic variability. Here we present a conceptual framework – applicable in principle to any land biosphere model – to explicitly quantify net biospheric exchange (NBE) as the sum of anomaly-induced concurrent changes and climatology-induced lagged changes to terrestrial ecosystem C states (NBE = NBECON+NBELAG). We apply this framework to an observation-constrained analysis of the 2001–2015 tropical C balance: we use a data–model integration approach (CARbon DAta-MOdel fraMework – CARDAMOM) to merge satellite-retrieved land-surface C observations (leaf area, biomass, solar-induced fluorescence), soil C inventory data and satellite-based atmospheric inversion estimates of CO2 and CO fluxes to produce a data-constrained analysis of the 2001–2015 tropical C cycle. We find that the inter-annual variability of both concurrent and lagged effects substantially contributes to the 2001–2015 NBE inter-annual variability throughout 2001–2015 across the tropics (NBECON IAV = 80 % of total NBE IAV, r =  0.76; NBELAG IAV = 64 % of NBE IAV, r = 0.61), and the prominence of NBELAG IAV persists across both wet and dry tropical ecosystems. The magnitude of lagged effect variations on NBE across the tropics is largely attributable to lagged effects on net primary productivity (NPP; NPPLAG IAV 113 % of NBELAG IAV, r = −0.93, p value < 0.05), which emerge due to the dependence of NPP on inter-annual variations in foliar C and plant-available H2O states. We conclude that concurrent and lagged effects need to be explicitly and jointly resolved to retrieve an accurate understanding of the processes regulating the present-day and future trajectory of the terrestrial land C sink.

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