Methods and systems for measurements of gross primary production

Abstract

Described herein are methods and systems useful for real-time high-resolution measurements of gross primary production (GPP).

Description

METHODS AND SYSTEMS FOR MEASUREMENTS OF GROSS PRIMARY PRODUCTIONCROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims priority to U.S. Provisional Patent Application No. 63 / 551,177, filed February 8, 2024, the contents of which are hereby incorporated by reference herein.STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0002] This invention was made with government support under Federal Grant no. OCE-2123198 awarded by the National Science Foundation. The Government has certain rights in the invention.FIELD OF THE DISCLOSURE

[0003] The field of the disclosure relates generally to methods and systems useful for real-time high-resolution measurements of gross primary production (GPP).BACKGROUND

[0004] Aquatic (marine and freshwater) photosynthesis by primary producers such as phytoplankton is responsible for approximately 50% of the primary production on Earth over geological timescales, and supports the biological carbon pump that removes CO2 from the atmosphere.

[0005] The aquatic primary producers constitute only 1% of the Earth’s photosynthetic biomass, which points to a biomass turnover for these organisms as compared to terrestrial primary producers. Algal blooms, including harmful algal blooms (HABs) can pose a significant threat to coastal ecosystems by leading to a reduction of the dissolved oxygen in the water with organic matter decomposition. Cultural eutrophication, caused by human activities such as agriculture, urbanization, and wastewater discharge, exacerbates algal blooms by overloading aquatic ecosystems with nutrients like nitrogen and phosphorus.It is crucial to be able to predict and follow the progression of algal blooms to protect aquatic ecosystems.

[0006] However, currently available methods to study primary production have important shortcomings such as relying on long incubations, having low throughput, or having theoretical limitation in measuring precise and accurate magnitude of gross primary production.

[0007] Thus, there is an ongoing need for improved methods and systems for measuring photosynthesis in aquatic ecosystems.BRIEF DESCRIPTION OF THE DISCLOSURE

[0008] In one aspect, the present disclosure is directed to a method including: extracting O2 from a fluid source; reacting the extracted O2 with a reactant in a reaction vessel to produce an oxygen-containing product; and analyzing oxygen isotopes of the oxygen- containing product with an analyzer.

[0009] In another aspect, the present disclosure is directed to a system including: a reaction vessel configured to react a reactant with O2 extracted from a fluid source to produce an oxygen-containing product; and an analyzer configured to analyze oxygen isotopes of the oxy gen-containing product.

[0010] In still another aspect, the present disclosure is directed to a system including: a reaction vessel configured to react a reactant with O2 extracted from a fluid source to produce an oxygen-containing product, wherein the reaction vessel comprises a catalyst contained in the reaction vessel; and an analyzer configured to analyze oxygen isotopes of the oxygen-containing product.BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 depicts an exemplary explanatory scheme of a system in accordance with the present disclosure.

[0012] Figure 2 depicts an exemplary schematic diagram of a system in accordance with the present disclosure including a sample testing system (top) and a standard testing system (bottom).

[0013] Figure 3 depicts an exemplary explanatory scheme of the aquatic gross primary production (GPP) that can be measured by the triple oxygen isotope method in accordance with the present disclosure.

[0014] Figure 4 depicts an exemplary schematic diagram of a system in accordance with the present disclosure.

[0015] Figure 5 depicts an Allan deviation curve obtained by different integration intervals for the measurements with the system in accordance with the present disclosure.

[0016] Figure 6 depicts a method for data correction via calibration in accordance with the present disclosure.

[0017] Figure 7 depicts measurements made at the Duke Marine lab, including a calibration curve plotted vs. DI-IRMS (left) and the calibrated data (right), in accordance with the present disclosure.

[0018] Figure 8 depicts measurements made at the Duke pond, including a calibration curve plotted vs. DI-IRMS (left) and the calibrated data (right), in accordance with the present disclosure.DETAILED DESCRIPTION OF THE DISCLOSURE

[0019] Described herein is a method and system useful for real-time high- resolution measurements of gross primary production (GPP).

[0020] In many embodiments, the method includes: extracting O2 from a fluid source; reacting the extracted O2 with a reactant in a reaction vessel to produce an oxygencontaining product; and analyzing oxygen isotopes of the oxygen-containing product with an analyzer.

[0021] Generally, the method may be performed by any suitable system known in the art that facilitates the method.

[0022] In many embodiments, the system includes a reaction vessel configured to react a reactant with O2 extracted from a fluid source to produce an oxygen-containingproduct; and an analyzer configured to analyze oxygen isotopes of the oxygen-containing product.

[0023] In some embodiments, the system does not include a catalyst. In these embodiments, the reaction vessel is configured to react a reactant with O2 in a combustion reaction (e.g., combusting carbon and O2 to produce CO2). In some embodiments, the reaction vessel comprises a combustion module.

[0024] In some embodiments, the system comprises a reaction vessel comprising a reaction module configured to produce the oxygen-containing product. In these embodiments, the reaction vessel may be any vessel that produces an appropriate sample for the analyzer.

[0025] In some embodiments, the system includes a reaction vessel configured to react a reactant with O2 extracted from a fluid source to produce an oxygen-containing product, wherein the reaction vessel comprises a catalyst contained in the reaction vessel; and an analyzer configured to analyze oxygen isotopes of the oxygen-containing product.

[0026] In some embodiments, the method is capable of measuring gross primary production in a fluid source. In some embodiments, the system is capable of measuring gross primary production in the fluid source.

[0027] The fluid source includes any suitable fluid source known in the art that facilitates the method and system. In some embodiments, the fluid source comprises a liquid, a gas, or a combination thereof. In some embodiments, the fluid source comprises a mixture of water and more than 50 percent other fluids or solids.

[0028] In some embodiments, the fluid source comprises water, freshwater, brackish water, and / or seawater. In some embodiments, the fluid source is selected from the group consisting of a fluid source including freshwater, a fluid source including seawater, a lake, a pond, a river, a stream, a canal, an estuary, a sea, an ocean, a reservoir, a man-made fluid source, and combinations thereof. In some embodiments, the fluid source includes another substance. In some embodiments, the fluid source does not include another substance. In some embodiments, the other substance does not comprise water.

[0029] The reactant includes any suitable reactant known in the art that facilitates the method and system. In some embodiments, the reactant is selected from the group consisting of hydrogen-containing reactants, H2, carbon-containing reactants, carbon (C), and combinations thereof.

[0030] The oxygen-containing product includes any suitable oxygen-containing product known in the art that facilitates the method and system. In some embodiments, the oxy gen-containing product is selected from the group consisting of H2O, CO2, and combinations thereof.

[0031] The oxygen isotopes include any suitable oxygen isotopes known in the art that facilitate the method and system. In some embodiments, the oxygen isotopes of the oxy gen-containing product include at least one of16O,17O, and18O. In some embodiments, the oxygen isotopes of the oxygen-containing product include at least two of16O,17O, and18O. In some embodiments, the oxygen isotopes of the oxygen-containing product include160,17O, and18O.

[0032] In some embodiments, the oxygen isotopes of the oxygen-containing product are analyzed for a ratio between two or more of the oxygen isotopes. In some embodiments, GPP is estimated by analyzing the ratio of17O and18O and16O with reference to a standard.

[0033] As used herein, the term “continuous” means an analysis performed without interruption (unless for maintenance or calibration) and in real-time or near real-time over a single time interval. In this context, real-time means results representing GPP for the chosen averaging time and within the response time limits of the system and method.

[0034] In some embodiments, the method includes continuously analyzing the oxygen isotopes. In some embodiments, the system is configured to continuously analyze the oxygen isotopes. In these embodiments, the oxygen isotopes are continuously analyzed and averaged over a time interval. In some embodiments, the oxygen isotopes are analyzed for a time interval greater than about 360 minutes. In some embodiments, the oxygen isotopes are analyzed for a time interval in a range between about 1 minute and about 360 minutes. In some embodiments, the oxygen isotopes are analyzed for a time interval in a range between about 1 minute and about 300 minutes. In some embodiments, the oxygenisotopes are analyzed for a time interval in a range between about 1 minute and about 240 minutes. In some embodiments, the oxygen isotopes are analyzed for a time interval in a range between about 1 minute and about 180 minutes. In some embodiments, the oxygen isotopes are analyzed for a time interval in a range between about 1 minute and about 120 minutes. In some embodiments, the oxygen isotopes are analyzed for a time interval in a range between about 1 minute and about 90 minutes. In some embodiments, the oxygen isotopes are analyzed for a time interval in a range between about 1 minute and about 60 minutes. In some embodiments, the oxygen isotopes are analyzed for a time interval in a range between about 1 minute and about 30 minutes. In some embodiments, the oxygen isotopes are analyzed for a time interval in a range between about 1 minute and about 15 minutes.

[0035] Analyzing oxygen isotopes of the oxygen-containing product with an analyzer includes any suitable analyzing means known in the art that facilitates the method and system. In some embodiments, analyzing oxygen isotopes of the oxygen-containing product with an analyzer includes analyzing oxygen isotopes of the oxygen-containing product with a technique selected from the group consisting of laser spectroscopy, laser absorption spectroscopy, cavity ringdown laser absorption spectroscopy, mass spectroscopy, and combinations thereof. Cavity ringdown laser absorption spectroscopy refers to one or more of cavity ring-down spectroscopy (CRDS), cavity enhanced absorption spectroscopy, cavity enhanced spectroscopy, laser ring-down spectroscopy, ringdown spectroscopy, cavity decay spectroscopy, or cavity-based absorption spectroscopy.

[0036] As used herein, the term “high resolution” means measurements with a high throughput as compared to what is pragmatically allowed using the discrete method. In some embodiments, the term “high resolution” means collection of at least 1 data point per day. In some embodiments, the term “high resolution” means collection of at least 10 data points per day. In some embodiments, the term “high resolution” means collection of at least 24 data points per day. In some embodiments, the term “high resolution” means collection of at least 48 data points per day. In some embodiments, the term “high resolution” means collection of at least 96 data points per day. In some embodiments, the term “high resolution” means collection of at least 240 data points per day. In some embodiments, the term “high resolution” means collection of at least 480 data points per day. In some embodiments, the term “high resolution” means collection of more than 480 data points per day.

[0037] The reaction vessel includes any suitable reaction vessel known in the art that facilitates the method and system. In some embodiments, the reaction vessel is in a form selected from the group consisting of tubing, pipes, capillaries, boxes, and combinations thereof.

[0038] In some embodiments, the reaction vessel includes a catalyst contained in the reaction vessel. In some embodiments, the reaction vessel includes a catalyst stabilized in the reaction vessel. In some embodiments, the reaction vessel includes a catalyst coated on walls of the reaction vessel. In some embodiments, the reaction vessel includes a catalyst selected from the group consisting of platinum (Pt), catalysts supported on carbon (C), catalysts supported on aluminum (Al), Pt / C catalysts, Pd / C catalysts, and combinations thereof.

[0039] The reaction vessel includes any suitable wall material known in the art that facilitates the method and system. In some embodiments, the reaction vessel includes a wall material that is not chemically reactive with the reactant. In some embodiments, the reaction vessel includes a wall material selected from the group consisting of fluoropolymers, polytetrafluoroethylene (PTFE), stainless steel, quartz wool, quartz tube, and combinations thereof.

[0040] Extracting O2 from a fluid source includes any suitable extracting means known in the art that facilitates the method and system. In some embodiments, the O2 is dissolved in the fluid source. In some embodiments, the O2 is not dissolved in the fluid source. In some embodiments, the O2 is extracted from the fluid source by a technique selected from the group consisting of displacing the O2 in the fluid source with a carrier gas such as N2, heating the fluid source, reducing the atmospheric pressure of the fluid source, spraying, spraying the fluid source in a container through which the carrier gas passes, using a bubble column, using a membrane contactor, using a showerhead equilibrator, and combinations thereof.

[0041] In some embodiments, the system further includes a gas extractor to extract the O2 from the fluid source. In some embodiments, the gas extractor is an extractor that extracts dissolved O2 from the fluid source. In some embodiments, the gas extractor is a degasser that degasses dissolved O2 from the fluid source. In some embodiments, when the source is a gas, gas extraction is not necessary and / or performed.

[0042] Generally, the method includes any suitable further processing steps and processing elements known in the art that facilitate the method and system.

[0043] In some embodiments, the method further includes drying the extracted O2. In some embodiments, the method further includes drying the mixture of the extracted O2 and the carrier gas. In some embodiments, the method further includes drying the extracted O2 to water content in a range acceptable for the analyzer. In some embodiments, the method further includes drying the extracted O2 to water content less than about 1000 ppm. In some embodiments, the method further includes drying the extracted O2 to water content less than about 500 ppm. In these embodiments, drying means reducing the water content as much as possible. In some embodiments, drying is achieved with a drier selected from the group consisting of Drierite drying columns, Nafion membranes, desiccants, and combinations thereof.

[0044] In some embodiments, the system further includes a dryer.

[0045] In some embodiments, the method further includes calibrating the analyzer. In some embodiments, the method further includes calibrating the analyzer with a standard selected from the group consisting of internal standards, external standards, and combinations thereof. In some embodiments, the method further includes calibrating the analyzer includes at least one calibration step selected from the group consisting of analyzing air or other standard gases, removing the impact of fractionation (e.g., by lines, catalyst, splitter, etc.), removing the impact of fractionation by air equilibration in water, and calibrating the data using discrete samples measured by isotope ratio mass spectrometry (DI- IR.MS).

[0046] In some embodiments, the method further includes calibrating the analyzer with calibration gases instead of by discrete sample calibration. In some embodiments, a first air calibration removes bias from fractionation. In some embodiments, a last calibration by discrete samples is replaced by gas to correct for span and bias of the data.

[0047] Generally, the method and system may be utilized in any suitable environment known in the art that facilitates the method and system.

[0048] In some embodiments, the method is carried out over a fluid source or next to a fluid source. In some embodiments, the method is carried out within a fluid source.

[0049] In some embodiments, the system is positioned over a fluid source or next to a fluid source. In some embodiments, the system is positioned within a fluid source.

[0050] In some embodiments, the method is carried out on a station located next to the fluid source. In some embodiments, the system is located on a station located next to the fluid source.

[0051] In some embodiments, the method is carried out on a vessel floating on or in a fluid source (e.g., a boat or submarine). In these embodiments, the method analyzes underway water (i.e., water under the vessel).

[0052] In some embodiments, the system is located on a vessel floating on or in a fluid source (e.g., a boat or submarine). In these embodiments, the system analyzes underway water (i.e., water under the vessel).

[0053] In some embodiments, at least one of the reaction vessel and the analyzer are stationary during use. In some embodiments, at least one of the reaction vessel and the analyzer are in motion during use.

[0054] In some embodiments, the system is stationary during use. In some embodiments, the system is in motion during use.

[0055] One particular aspect of the present disclosure is a method for underway high-resolution measurements of GPP using cavity ring down spectroscopy. The disclosed method, which can be referred to as Gross Oxygen Production by Triple Isotope Cavity ringdown laser Absorption Spectroscopy (GOPTICAS), can be used for higher frequency observations than logistically possible at this time. GOPTICAS is based on measurements of the triple isotopes of dissolved oxygen by cavity ringdown laser absorption spectroscopy (CRDS). A schematic explanatory scheme of a GOPTICAS system is shown in Figure 1. An exemplary representation of a GOPTICAS system is shown in Figure 2. The triple isotopes of oxygen capture the unique isotopic fingerprint of photosynthetically derived oxygen. Such measurements have traditionally been conducted by dual inlet isotope ratio mass spectroscopy (DI-IRMS), which only allows discrete sampling of seawater with a highcost per sample and a low throughput. By contrast, GOPTICAS allows for underway high- resolution observations (e.g., 30 minutes measurement interval) with similar precision of <9 ppm, but with a significantly reduced cost per sample and a higher throughput. Such realtime observations allow for situational awareness for adaptive sampling, which is not possible when the samples are analyzed after deployment.

[0056] In the particularly disclosed continuous method, underway water is sparged with N2 gas to extract the oxygen in a customized bubble-column-contactor. The stripped oxygen stream is dried with a Drierite column and catalytically combusted with H2 to H2O in a custom-built catalytic reactor, with the produced H2O analyzed on a CRDS analyzer. The isotopic values are calibrated with two gas mixtures with known isotopic ratios. Test results indicate that GOPTICAS can produce results with accuracy and precision comparable to the traditional DI-IRMS method for GPP calculations. Hence, GOPTICAS has the potential to be used for ground-truthing and calibrating satellite productivity observations, ultimately improving the understanding of climate-ecosystem interactions in a myriad of aquatic ecosystems.EXAMPLES

[0057] Without further elaboration, it is believed that one skilled in the art using the preceding description can utilize the present disclosure to its fullest extent. The following Examples are, therefore, to be construed as merely illustrative, and not limiting of the disclosure in any way whatsoever. It is understood that any numerical range recited herein includes all values from the lower value to the upper value. For example, if a range is stated as 10-50, it is intended that values such as 12-30, 20-40, or 30-50, etc., are expressly enumerated in this specification. These are only examples of what is specifically intended, and all possible combinations of numerical values between and including the lowest value and the highest value enumerated are to be considered to be expressly stated in this application.

[0058] Example 1. Measuring continuous high resolution GPP using triple oxygen isotope method.

[0059] Oxygen present in the surface ocean has two endmembers: atmosphere and photosynthetic pool. The atmospheric oxygen equilibrates with water following Henry’s law(other processes contribute to air-sea O2 exchange, including bubble injection). Photosynthetic oxygen is produced by primary producers through the water splitting mechanism. The water splitting mechanism splits H2O molecules of the aquatic water and produces O2. The dissolved oxygen is consumed by respiration and in chemical oxidation of reduced solutes. The two end-members of oxygen at the ocean surface, atmospheric oxygen, and oxygen derived from the photosynthetic splitting of water, have distinct isotopic signatures.

[0060] The methods to measure primary production can be based on measuring inorganic carbon consumed by photosynthetic organisms or oxygen produced by photosynthetic organisms. This example focuses on an oxygen-based method called the triple oxygen isotope method. The triple oxygen isotope method can be used to estimate GPP in the ocean, as depicted in Figure 3.

[0061] This method uses the following facts to estimate the amount of photosynthetically produced O2:

[0062] 1) Photosynthesis does not fractionate the oxygen isotopes. In the fractionation process, one oxygen isotope is favored more and the other isotopic ratios are then enriched. The fractionation can be mass independent (a function of isotopes masses) or mass independent (not a function of isotope masses). Because photosynthesis generally does not fractionate, the isotopic signatures of produced O2 are substantially similar to the isotopic ratios of oxygen in the background aquatic water. That is, the dissolved oxygen is consumed by respiration and in and chemical oxidation of reduced solutes. The two end-members of oxygen at the ocean surface, atmospheric oxygen and oxygen derived from the photosynthetic splitting of water, have distinct isotopic signatures.

[0063] 2) Respiration does fractionate, but in a predictable mass-dependent way. Thus, the impacts of respiration can be excluded by using a composite tracer that is not sensitive to respiration. This tracer is called A17O. A17O ~ 817O - A618O. A is approximately 0.518 for aquatic GPP measurements.

[0064] 3) Because the atmosphere is well-mixed, the isotopic signature of atmospheric oxygen is generally constant on Earth.

[0065] 4) The triple oxygen isotope uses the composite tracer A17O that is not impacted by mass dependent fractionation of the respiration process, it is possible to distinguish between the photosynthetic and atmospheric sources of O2 to then estimate the GPP by estimating the advected O2 from atmosphere based on gas transfer velocity.

[0066] Gross primary production for sample water may be calculated by the following equation:

[0067] In these calculations, A17Op=249 ppm and is associated with the photosynthetic endmember of O2 from photosynthesis dissolved in aquatic water and 17Oeq=8 ppm and is associated with atmospheric endmember of O2 present from air dissolved in aquatic water, k is oxygen gas exchange efficiency in m.d'1. Generally, k is a value on an order of magnitude of several m.d'1.

[0068] The triple oxygen isotope method is an established method, and a conventional tool for triple oxygen isotope measurements is dual-inlet mass spectroscopy. This tool is expensive and highly complicated, with a low throughput for results. Dual inlet mass spectroscopy (DI-IRMS) only allows measurements for discrete samples that can be highly time-consuming because of the time-consuming nature of sample bottle preparation, analysis, and cleaning for the appropriate protocol.

[0069] Cavity Ring Down laser absorption Spectroscopy (CRDS) uses a laser to estimate isotopic ratios of oxygen in CO2 or H2O that can be used for either continuous or discrete measurements of liquid or gases. It is not possible to measure oxygen isotopes in diatomic molecules by commercially available analyzers and these can only measure oxygen in H2O or CO2. For example, commercially available CRDS systems that measure the oxygen isotopes in H2O are available from companies such as Picarro, Inc. and commercially available CRDS systems that measure oxygen isotopes in CO2 are available from companies such as Aerodyne Research, Inc., LI-COR Biosciences, and Los Gatos Research, Inc.

[0070] In this example, a prototype system that uses a commercially available analyzer to measure oxygen isotopes of dissolved O2 in H2O is provided. Because thisanalyzer is limited to measuring the oxygen isotopes of H2O molecules, a custom-made catalyst has been devised to combust the dissolved O2 in the water with H2 sourced from a H2 generator to produce water vapor, which is then fed to the analyzer to perform isotopic measurements.

[0071] The custom-made catalyst of this example is a 1 / 8" OD fluoropolymer (e.g., PTFE) tubing internally coated with a catalytic powder (e.g., a commercial powder like TEC10E50E including 50wt% of Pt on high surface area carbon). The tubing is coated by adding about 1 gram of the catalytic powder in a 2.2 m length of tube by using a 1 / 4" to 1 / 8" Swagelok union as a funnel. Half of the catalyst is placed from one side and distributed inside the tube by shaking the tube. Then the other half of the catalyst is placed in the tube from the opposite side of the tube and distributed in the tube by shaking. The excess catalyst is washed using a 4-5 L / min flow of dry air or N2 one time from each side to ensure that the sample gas flow (<0.1 L / min flow rate) cannot wash the catalyst downstream to contaminate the instrument. Finally, 0.1 m of the tube is cut from either side to yield a final 2m length catalyst-coated tubing. The efficiency of the catalyst was found to be above 94%.

[0072] There are several unique aspects of the present approach. First, the system includes a setup that enables measurements of GPP in a continuous fashion, in-situ, and with high precision. Another aspect is the method by which the catalysts are made. A Pt / C powder is placed inside a 1 / 8” PTFE tube, flushed with high velocity air, and used for lower velocities. Although PTFE tubes are considered non-stick, the powder is fine enough to be stable for these applications. Yet another aspect is the method by which the dissolved gases are extracted from the seawater. A sparger produces very fine bubbles to purge the aquatic water with N2 gas that displaces >65% of the gases from the dissolved phase to the overhead vapor. The overhead vapor is dried using a Drierite drying column and sent to the catalyst and then to the analyzer.

[0073] A schematic diagram is depicted in Figure 4.

[0074] To calibrate the readings of the CRDS analyzer, ambient air with known isotopic values is used.

[0075] Figure 5 shows the obtained Allen deviation for the measurements for different averaging periods. For GPP measurements, a precision of 9 ppm can be obtainedby averaging times of over 20 minutes (based on the shown Allan curve). A precision of 10 ppm is achieved around 14 minutes. A precision of 4 ppm is achieved around 90 minutes.

[0076] The results are provided in Table 1.

[0077] Table 1. The averages of 30-minute means for an uncalibrated 120-hour dataset (the same dataset that was used for the Allan curve of Figure 5).

[0078] Data correction via calibration may be achieved by the method shown in Figure 6. First, the reference is changed from CRDS’s to air. Second, the impact of fractionation by lines, catalyst, splitter, etc., is removed. Third, the impact of fractionation by air equilibration in water is removed. Fourth, the data are calibrated using discrete samples measured by DI-IRMS.

[0079] This method was tested once at the Duke Marine Lab, and once at the Duke retention pond. The results are shown in Figures 7-8, respectively. These figures plot calibration curves vs. DI-IRMS in the left panels and the calibrated data for the three deployments in the right panels. The calibration equation in the left panel was used to calibrate the date obtained in the step 3 of Fig. 6. The isotopic values are reported in reference to air standard.

[0080] To investigate the accuracy of the method, discrete samples of water were taken and analyzed using a conventional dual inlet mass spectrometer (DI-IRMS). The results indicate that the disclosed method (GOPTICAS) produces results in the same order of magnitude.

[0081] It was found that the isotopic values measured using CRDS are sensitive to the concentration of analyzed H2O (the result of O2 and H2 combustion). Therefore, it isessential to prevent large fluctuations in H2O value by maintaining a relatively stable extraction of O2.

[0082] Conclusions.

[0083] Disclosed herein are methods and systems useful for real-time high- resolution measurements of GPP.

[0084] Particularly disclosed herein are methods and systems for real-time high- resolution measurements of GPP using cavity ring down spectroscopy. These methods and systems are capable of a A17O precision of < 10 ppm every 30 minutes, which allows for high resolution datasets.

[0085] Definitions.

[0086] Definitions and methods described herein are provided to better define the present disclosure and to guide those of ordinary skill in the art in the practice of the present disclosure. Unless otherwise noted, terms are to be understood according to conventional usage by those of ordinary skill in the relevant art.

[0087] To facilitate the understanding of the embodiments described herein, a number of terms are defined below. The terms defined herein have meanings as commonly understood by a person of ordinary skill in the areas relevant to the present disclosure. Terms such as "a," "an," and "the" are not intended to refer to only a singular entity, but rather include the general class of which a specific example may be used for illustration. The terminology herein is used to describe specific embodiments of the disclosure, but their usage does not delimit the disclosure, except as outlined in the claims.

[0088] In some embodiments, numbers expressing quantities of ingredients, properties such as molecular weight, reaction conditions, and so forth, used to describe and claim certain embodiments of the present disclosure are to be understood as being modified in some instances by the term “about.” In some embodiments, the term “about” is used to indicate that a value includes the standard deviation of the mean for the device or method being employed to determine the value. In some embodiments, the numerical parameters set forth in the written description and attached claims are approximations that vary depending upon the desired properties sought to be obtained by a particular embodiment. In someembodiments, the numerical parameters are be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of some embodiments of the present disclosure are approximations, the numerical values set forth in the specific examples are reported as precisely as practicable. The numerical values presented in some embodiments of the present disclosure may contain certain errors necessarily resulting from the standard deviation found in their respective testing measurements. The recitation of ranges of values herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range. Unless otherwise indicated herein, each individual value is incorporated into the specification as if it were individually recited herein.

[0089] In some embodiments, the terms “a” and “an” and “the” and similar references used in the context of describing a particular embodiment (especially in the context of certain of the following claims) are construed to cover both the singular and the plural, unless specifically noted otherwise. In some embodiments, the term “or” as used herein, including the claims, is used to mean “and / or” unless explicitly indicated to refer to alternatives only or to refer to the alternatives that are mutually exclusive.

[0090] The terms “comprise,” “have” and “include” are open-ended linking verbs. Any forms or tenses of one or more of these verbs, such as “comprises,” “comprising,” “has,” “having,” “includes” and “including,” are also open-ended. For example, any method that “comprises,” “has” or “includes” one or more steps is not limited to possessing only those one or more steps and may also cover other unlisted steps. Similarly, any composition or device that “comprises,” “has” or “includes” one or more features is not limited to possessing only those one or more features and may cover other unlisted features.

[0091] All methods described herein are performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g. “such as”) provided with respect to certain embodiments herein is intended merely to better illuminate the present disclosure and does not pose a limitation on the scope of the present disclosure otherwise claimed. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the present disclosure.

[0092] Groupings of alternative elements or embodiments of the present disclosure disclosed herein are not to be construed as limitations. Each group member is referred to and claimed individually or in any combination with other members of the group or other elements found herein. One or more members of a group are included in, or deleted from, a group for reasons of convenience or patentability. When any such inclusion or deletion occurs, the specification is herein deemed to contain the group as modified thus fulfilling the written description of all Markush groups used in the appended claims.

[0093] The systems described herein can be implemented in hardware, software, firmware, or combinations of hardware, software and / or firmware. In some examples, the systems described in this specification may be implemented using a non-transitory computer readable medium storing computer executable instructions that when executed by one or more processors of a computer cause the computer to perform operations. Computer readable media suitable for implementing the systems described in this specification include non-transitory computer-readable media, such as disk memory devices, chip memory devices, programmable logic devices, random access memory (RAM), read only memory (ROM), optical read / write memory, cache memory, magnetic read / write memory, flash memory, and application-specific integrated circuits. In addition, a computer readable medium that implements a system described in this specification may be located on a single device or computing platform or may be distributed across multiple devices or computing platforms.

[0094] All of the compositions and / or methods disclosed and claimed herein may be made and / or executed without undue experimentation in light of the present disclosure. While the compositions and methods of this disclosure have been described in terms of the embodiments included herein, it will be apparent to those of ordinary skill in the art that variations may be applied to the compositions and / or methods and in the steps or in the sequence of steps of the method described herein without departing from the concept, spirit, and scope of the disclosure. All such similar substitutes and modifications apparent to those skilled in the art are deemed to be within the spirit, scope, and concept of the disclosure as defined by the appended claims.

[0095] This written description uses examples to disclose the disclosure, including the best mode, and also to enable any person skilled in the art to practice the disclosure,including making and using any devices or systems and performing any incorporated methods. The patentable scope of the disclosure is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.

Claims

WHAT IS CLAIMED IS:

1. A method comprising: extracting O2 from a fluid source; reacting the extracted O2 with a reactant in a reaction vessel to produce an oxygencontaining product; and analyzing oxygen isotopes of the oxygen-containing product with an analyzer.

2. The method of claim 1, wherein the method is capable of measuring gross primary production in the fluid source.

3. The method of claim 1 , wherein the fluid source is selected from the group consisting of a fluid source comprising freshwater, a fluid source comprising salt water, a lake, a pond, a river, a stream, a canal, an estuary, a sea, an ocean, a reservoir, a man-made fluid source, and combinations thereof.

4. The method of claim 1, wherein the reactant is selected from the group consisting of hydrogen-containing reactants, H2, carbon-containing reactants, C, and combinations thereof.

5. The method of claim 1, wherein the oxygen-containing product is selected from the group consisting of H2O, CO2, and combinations thereof.

6. The method of claim 1, wherein the oxygen isotopes of the oxygen-containing product comprise at least one of16O,17O, and18O.

7. The method of claim 1, wherein the oxygen isotopes are continuously analyzed.

8. The method of claim 1, wherein the reaction vessel comprises a catalyst contained in the reaction vessel, wherein the reaction vessel comprises a combustion module, or wherein the reaction vessel comprises a reaction module configured to produce the oxy gen-containing product.

9. The method of claim 1 , wherein the reaction vessel comprises a catalyst selected from the group consisting of platinum (Pt), catalysts supported on carbon (C), catalystssupported on aluminum (Al), Pt / C catalysts, Pd / C catalysts, and combinations thereof.

10. The method of claim 1, wherein the reaction vessel comprises a wall material selected from the group consisting of fluoropolymers, polytetrafluoroethylene (PTFE), stainless steel, quartz wool, quartz tube, and combinations thereof.

11. The method of claim 1, wherein the O2 is extracted from the fluid source by a technique selected from the group consisting of displacing the O2 in the fluid source with a carrier gas, heating the fluid source, reducing the atmospheric pressure of the fluid source, spraying, spraying the fluid source in a container through which the carrier gas passes, using a bubble column, using a membrane contactor, using a showerhead equilibrator, and combinations thereof.

12. The method of claim 1, further comprising drying the extracted O2.

13. The method of claim 1, wherein the analyzing oxygen isotopes of the oxygencontaining product with an analyzer comprises analyzing oxygen isotopes of the oxy gen-containing product with a technique selected from the group consisting of laser spectroscopy, laser absorption spectroscopy, cavity ringdown laser absorption spectroscopy, mass spectroscopy, and combinations thereof.

14. The method of claim 1, further comprising calibrating the analyzer.

15. A system comprising: a reaction vessel configured to react a reactant with O2 extracted from a fluid source to produce an oxygen-containing product; and an analyzer configured to analyze oxygen isotopes of the oxygen-containing product.

16. The system of claim 15, wherein the system is capable of measuring gross primary production in the fluid source.

17. The system of claim 15, wherein the system is configured to continuously analyze the oxygen isotopes.

18. The system of claim 15, further comprising a drier to dry the extracted O2.

19. The system of claim 15, further comprising an extractor to extract the O2 from the fluid source.

20. A system comprising: a reaction vessel configured to react a reactant with O2 extracted from a fluid source to produce an oxygen-containing product, wherein the reaction vessel comprises a catalyst contained in the reaction vessel; and an analyzer configured to analyze oxygen isotopes of the oxygen-containing product.

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