<div><p><strong>Field sampling: </strong>Research cruises were conducted on& R/V Neeskay and R/V Osprey. Water samples were collected using 5-liter Niskin sampling bottles suspended on a 1/4" cable from a hydrographic winch. Immediately after collection, samples were transferred to 4-liter HDPE sample bottles. Sample bottles were rinsed with sample water 3 times before filling. Prior to use, sample bottles were acid washed (48 hours in 5% HCl), followed by multiple rinses with distilled, deionized water. Samples in bottles were stored in a cooler on ice until return to the laboratory. Samples were filtered immediately upon return to the laboratory (usually less than 8 hours after collection). Samples were filtered through pre-combusted Whatman GF/F filters. Filters were retained for particulate Phosphorus (P), stable isotope (particulate Carbon (C) and Nitrogen (N)), and chlorophyll <em>a</em> analyses. At least twice during the field season, field blanks are collected, which consist of clean bottles brought into the field where they are filled with distilled water, followed by analysis for dissolved and particulate phosphorus.</p>
<p><strong>Nutrients:</strong> Samples were collected and analyzed as described in Mosley and Bootsma (2015). Soluble Reactive Phosphorus (SRP) was analyzed using the standard molybdate method and a 10 cm path length in the spectrophotometer. Total Dissolved Phosphorus (TDP) and Particulate Phosphorus (PP) were digested to convert to phosphate, followed by analysis with the standard molybdate method. SRP and TDP were measured within 12 hours of sample filtration.</p>
<p><strong>Chlorophyll <em>a</em></strong>: Samples were collected and analyzed as described in Mosley and Bootsma (2015). Chl <em>a</em> was extracted with a 68:27:5 methanol-acetone-deionized water extraction solvent for 24 hours at -28 degrees Celsius and measured on a Turner Model 10 Series fluorometer, which was calibrated using a chlorophyll extract, the concentration of which was determined spectrophotometrically (Stainton et al. 1977).</p>
<p><strong>CO</strong>₂<strong> / DIC:</strong> Samples for CO2 and Dissolved Inorganic Carbon (DIC) analyses were collected in stoppered 120 mL glass serum bottles. Prior to sampling, bottles were flushed with nitrogen gas and then evacuated, to ensure they contained no CO2. At the time of sampling, a double-ended needle was inserted into the discharge tube of the Niskin bottle while water was flowing out, and the other end of the needle was inserted through the rubber cap of the serum sample bottle, allowing the vacuum in the bottle to draw in the sample water. The bottle was filled approximately 3/4. CO2 and DIC analyses were carried out following the method described by Davies et al. (2003). Briefly, 50 microliter (uL) subsamples are taken from the bottle headspace using a pressure-lok syringe and injected into a gas chromatograph, calibrated with CO2 standard gases. Samples are run in triplicate. Dissolved CO2 is then determined based on the temperature-dependent solubility of CO2, corrected for CO2 lost to the headspace and for the change in inorganic carbon species distribution accompanying the CO2 loss to headspace. Following CO2 analysis, samples are acidified by adding 150 uL of concentrated phosphoric acid, converting all inorganic carbon to CO2, after which the above analysis was repeated to determine total dissolved inorganic carbon concentration. In-lake CO2 concentrations are determined by correcting for any difference between in situ temperature and temperature at time of analysis, which affects the inorganic carbon partitioning coefficients. CO2 samples were measured within 24 hours of collection, and DIC samples were measured within 3 days of collection.</p>
<p><strong>Continuous CO2</strong>: The components of the continuous CO2 monitoring system include a peristaltic pump that forces water through an air-water equilibrator (Membrana mini-module membrane contactor). Reverse-flow air from the equilibrator is pumped through desiccant, after which it flows through an infrared gas analyzer (Li-Cor Li-820) which measures the partial pressure of CO2 normalized to 1 atmosphere. The system also includes a temperature sensor and a WETLabs flow-through fluorometer. The system is controlled by a Campbell CR1000 Controller / Datalogger. Input from a GPS on the ship's upper deck allows all data to be geo-referenced. The system is mounted in the engine room of the Lake Express high-speed ferry, where it draws water from a sea chest that has a residence time of several seconds. Additional details are provided in Zagorski and Bootsma (2006).</p>
<p><strong>Stable isotopes:</strong> Samples for stable isotope (13C:12C and 15N:14N ratios) analyses were collected by filtering lake water samples through GF/F glass fiber filters (nominal pore size = 0.7 to 0.8 micrometers (um)). Following filtration, filters were doused with 5% HCl for ~ 3 minutes to remove any inorganic carbon, followed by rinsing with distilled, deionized water. Filters were then freeze dried and packed in tin foil disks. Samples were then analyzed on an isotope ratio mass spectrometer, following the methods as described in Turschak et al. (2014). After every 12th sample, an acetanilide control was run to ensure instrument calibration.</p>
<p><strong>Dissolved organic carbon:</strong> 25 ml of filtered water was transferred to an amber glass ampule and acidified to a pH of less than 2 by adding 2-3 drops of 1 N hydrochloric acid (HCl), converting all inorganic carbon to CO2, which was then purged from the sample bubbling with carbon-free gas prior to OC analysis. DOC was then measured using the combustion catalytic oxidation method on a total organic carbon analyzer (Shimadzu TOC-L analyzer equipped with an ASI-5000 auto sampler). The analyzer was calibrated with a dilution series of reagent grade potassium hydrogen phthalate in 0.3 molar hydrochloric acid.</p></div>
Lake Michigan Chemistry
<div><p>Water chemistry data, including dissolved and particulate phosphorus, chlorophyll <em>a</em>, carbon dioxide, total dissolved inorganic carbon, and dissolved organic carbon were collected from a Lake Michigan transect between Milwaukee, WI and Muskegon MI from 2017 to 2020.</p></div>
Lake Michigan Chemistry
<div><p><strong>Data Processing:</strong><br />
All nutrient data are stored in a common database. Following analyses, nutrient standard curves are examined to ensure that calibration coefficients are within the range of variability of a long-term (5-year) dataset (±3%). Fluorometer measurements are entered into a spreadsheet containing the fluorometer calibration coefficients, which are used to calculate chlorophyll <em>a</em> and phaeophytin concentrations. The fluorometer is calibrated annually against extracted chlorophyll <em>a</em> standards. CO2 and DIC gas chromatograph measurements are entered into a spreadsheet program that calculates all inorganic carbon species concentrations, as well as pH and carbonate alkalinity. Concentrations are then corrected for any temperature difference between in situ and time of analysis. Stable isotope measurements are stored in a stable isotope database, while DOC measurement data are stored along with nutrient, chlorophyll and inorganic carbon measurements in a chemistry database.</p></div>
737176
Lake Michigan Chemistry
2018-05-18T14:49:50-04:00
2018-05-18T14:49:50-04:00
2024-02-12T15:53:55-05:00
urn:bcodmo:dataset:737176
Versions 1 and 2:
- modified parameter names to conform with BCO-DMO naming conventions;
- re-formatted date to ISO format;
- replaced missing data with nd ("no data");
- updated to version 2 on 2019-05-20.
Version 3:
- converted dates to YYYY-MM-DD format;
- converted times to hh:mm format;
- modified parameter names to conform with BCO-DMO naming conventions;
- removed 'nd' as the missing data identifier (missing data are empty/blank in the final CSV file);
- updated to version 3 on 2023-12-20 as file name "737176_v3_lake_michigan_chemistry.csv".
Lake Michigan water chemistry data, including dissolved and particulate phosphorus, chlorophyll a, carbon dioxide, total dissolved inorganic carbon, and dissolved organic carbon from 2017 to 2020
This dataset provides Lake Michigan water chemistry data collected over several cruises conducted from 2017 to 2020.
Water chemistry and conductivity-temperature-depth (CTD) profiles were measured at several stations in Lake Michigan, ranging in depth from 10 to 55 m, in a region northeast of Milwaukee Harbor. Measurements included soluble reactive phosphorus, total dissolved phosphorus, particulate phosphorus, chlorophyll a, the concentrations and stable isotope ratios of particulate carbon and particulate nitrogen, dissolved carbon dioxide, dissolved total inorganic carbon, and dissolved organic carbon. In addition, continuous lake surface and atmospheric CO2 data were collected in 2019 and 2021 on a Lake Michigan transect between Milwaukee, WI and Muskegon MI. The CO2 and CTD data are provided in separate datasets.
Measurements were made with a CO2 monitoring system mounted on a high-speed ferry that crosses the lake 4 to 6 times daily between May and October. The monitoring system consists of a "wet" box which includes a peristaltic pump that draws water from the ship's sea chest and an equilibrator in which dissolved gases are equilibrated with a recirculating air flow. The air is pumped through a desiccant to remove moisture, after which it flows to a "dry" box where it passes through an infrared gas analyzer. A similar system, without the peristaltic pump or equilibrator, is mounted near the bow of the ship to record atmospheric CO2 concentration.
These chemical measurements have several applications, including: 1) Constructing an annual carbon and nutrient budget for the water column, which is used along with direct measurements of quagga mussel nutrient recycling to assess the role of invasive quagga mussels in the lake's carbon and nutrient cycles; 2) When combined with separate measurements of the vertical structure of water density and currents, to quantify vertical fluxes of dissolved nutrients and inorganic carbon, to determine how carbon and nutrient recycling by profundal quagga mussels may affect plankton production in the euphotic zone; 3) The calibration and validation of physical / biogeochemical models used to better understand how invasive quagga mussel have altered energy flow and nutrient dynamics in the Great Lakes, and guide management decisions with regard to nutrients and fish stocking.
false
Bootsma, H., Liao, Q. (2024) Lake Michigan water chemistry data, including dissolved and particulate phosphorus, chlorophyll a, carbon dioxide, total dissolved inorganic carbon, and dissolved organic carbon from 2017 to 2020. Biological and Chemical Oceanography Data Management Office (BCO-DMO). (Version 3) Version Date 2023-12-20 [if applicable, indicate subset used]. doi:10.26008/1912/bco-dmo.737176.3 [access date]
true
3
10.26008/1912/bco-dmo.737176.3
false
carbon dioxide
Lake Michigan
Quagga mussel
Great Lakes
2023-12-20
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