http://lod.bco-dmo.org/id/dataset/990899 eng; USA utf8 dataset Highest level of data collection, from a common set of sensors or instrumentation, usually within the same research project Biological and Chemical Oceanography Data Management Office (BCO-DMO) Unavailable 508-289-2009 WHOI MS#36 Woods Hole MA 02543 USA info@bco-dmo.org http://www.bco-dmo.org Monday - Friday 8:00am - 5:00pm For questions regarding this resource, please contact BCO-DMO via the email address provided. pointOfContact 2025-12-31 ISO 19115-2 Geographic Information - Metadata - Part 2: Extensions for Imagery and Gridded Data ISO 19115-2:2009(E) Mercury, methylmercury, nutrients, and physicochemical measurements from water column samples collected in the Gulf of Maine and Penobscot Estuary during several cruises in 2023 and 2024 2026-01-12 publication 2026-01-12 revision Woods Hole Oceanographic Institution (WHOI BCO-DMO) 2026-03-25 publication https://doi.org/10.26008/1912/bco-dmo.990899.1 Robert P. Mason University of Connecticut principalInvestigator Vivien F. Taylor Dartmouth College principalInvestigator Biological and Chemical Oceanography Data Management Office (BCO-DMO) Unavailable 508-289-2009 WHOI MS#36 Woods Hole MA 02543 USA info@bco-dmo.org http://www.bco-dmo.org Monday - Friday 8:00am - 5:00pm For questions regarding this resource, please contact BCO-DMO via the email address provided. publisher Cite this dataset as: Taylor, V. F., Mason, R. P., Smith, S., Inman, H. (2026) Mercury, methylmercury, nutrients, and physicochemical measurements from water column samples collected in the Gulf of Maine and Penobscot Estuary during several cruises in 2023 and 2024. Biological and Chemical Oceanography Data Management Office (BCO-DMO). (Version 1) Version Date 2026-01-12 [if applicable, indicate subset used]. doi:10.26008/1912/bco-dmo.990899.1 [access date] Gulf of Maine Hg Dataset Description: Methods and Sampling: &lt;p&gt;&lt;strong&gt;Description:&lt;/strong&gt;&lt;br /&gt; Total mercury, methylmercury, and ancillary variable data were collected in the Gulf of Maine along the Gulf of Maine North Atlantic Time Series (GNATS) transect and on a transect in the Penobscot Estuary and River. Sampling took place over four cruises on the R/V Endeavor (April 2023, August 2023, November 2023, April 2024), and two separate trips in a small boat to sample further upstream in the Penobscot River (September 2023, May 2024). 21 stations were sampled in total, with multiple depths (up to 6) extending throughout the water column at all stations except for the shallow Penobscot River stations.&lt;/p&gt; &lt;p&gt;This dataset includes bulk and particulate total mercury and monomethylmercury, dissolved organic carbon, particulate organic carbon and nitrogen, chlorophyll-a, phaeopigments, nitrate, phosphate, silicate, fluorescence indices (including the freshness index, BIX, and HIX), and components identified during Parallel Factor (PARAFAC) analysis. The percentage of methylated mercury (bulk methylmercury/bulk total mercury), percentage of particulate methylated mercury (particulate methylmercury/particulate total mercury), and percentage of each PARAFAC component are also included. The dataset also includes salinity, temperature, and dissolved oxygen data from the sensors on the CTD, as well as the calculated apparent oxygen utilization. Nutrient data in August in the Gulf of Maine was replaced with data supplied by the Canada Department of Fisheries and Oceans (DFO) from a transect similar to the GNATS transect, which occurred in September 2023.&lt;/p&gt; &lt;p&gt;&lt;strong&gt;Methods &amp;amp; Sampling:&lt;/strong&gt;&lt;br /&gt; During the four cruises, samples were collected using a trace metal clean rosette with Go-Flo bottles. During the August 2023 cruise, the trace metal clean rosette and winch system suffered a technical issue that was unable to be resolved, thus Stations 3, 4, 6, 7, and 10-15 were collected with the same Go-Flo bottles attached to a non-trace metal clean, Seabird rosette. Water samples were collected over the side of a small watercraft for the Penobscot River sites, taken either by hand or via Go-Flo bottles. Bulk water samples were collected in 2-liter (L) acid-cleaned Teflon bottles and then brought into a trace metal clean van (or laminar flow hood for the Penobscot River sites) for typically immediate, but if not same-day, filtering and subsampling.&lt;/p&gt; &lt;p&gt;&lt;strong&gt;Bulk Methylmercury&lt;/strong&gt; samples were preserved with sulfuric acid (0.5%) and kept cold until analysis. They were analyzed on a Tekran 2700 Automated Methylmercury Analysis System following standard techniques (Hammerschmidt and Fitzgerald, 2006). Briefly, bulk MeHg samples were digested overnight with sulfuric acid, buffered with acetate buffer, followed by the addition of ascorbic acid, neutralized with potassium hydroxide, and ethylated using sodium tetraethylborate. Once on the Tekran 2700, samples were purged with argon, and the Hg species were trapped on a Tenax trap. Upon heating the trap, the Hg species were released and underwent gas chromatographic separation prior to decomposition of the Hg species to elemental Hg for cold vapor atomic fluorescence detection. Samples were run within 6 months of collection at the University of Connecticut Avery Point.&lt;/p&gt; &lt;p&gt;&lt;strong&gt;Particulate methylmercury&lt;/strong&gt; was filtered through a pre-weighed and pre-combusted (400 degrees Celsius (°C), 15-18 hours), 0.45-micrometer (μm) pore-size, quartz fiber filter using a vacuum pump and frozen until analysis. Filters were freeze-dried for 7 days, weighed, and then digested in 4.5 N nitric acid overnight in a 60°C water bath, buffered with acetate buffer, neutralized with potassium hydroxide, and ethylated using sodium tetraethylborate, where the sample then underwent the same process on the Tekran 2700 as described above. The remaining digest - 3 milliliters (mL) out of 7 mL total - was frozen and preserved within 1 week for THg analysis by diluting to 10 mL with DI water, adding bromine monochloride, and storing in the dark at room temperature. Filters were run within 1 year of collection at the University of Connecticut Avery Point.&lt;/p&gt; &lt;p&gt;&lt;strong&gt;Bulk total mercury&lt;/strong&gt; samples were filled with no headspace and kept cold until analysis on a Tekran 2600 following EPA method 1631, refined by Hammerschmidt and Fitzgerald (2006). Briefly, both particulate and bulk samples were digested overnight with bromine chloride, reduced with hydroxylamine hydrochloride to remove excess reductant, oxidized with stannous chloride to form elemental Hg, and run using cold vapor atomic fluorescence spectrometry. Samples were run within 6 months of collection at the University of Connecticut Avery Point.&lt;/p&gt; &lt;p&gt;&lt;strong&gt;Particulate total mercury&lt;/strong&gt; was analyzed using the same filter as for particulate methylmercury and run using the method described above. Filters were run within 1 year of collection at the University of Connecticut Avery Point.&lt;/p&gt; &lt;p&gt;&lt;strong&gt;Chlorophyll-a and phaeopigments&lt;/strong&gt; were collected by filtering 100 mL of sample through a 25-millimeter (mm), 0.7 μm pore-size glass fiber filter using a vacuum pump and immediately covering with tin foil and freezing. The filters were pre-combusted (450°C, 2 hours) for the April 2024 cruise and 2024 Penobscot river samples only. Samples were analyzed using EPA method 445. Briefly, the filters were digested overnight in 90% acetone and run in dimmed light with and without hydrochloric acid acidification using a Trilogy Fluorometer. Samples were only collected for the shallowest 3 to 4 depths at each station for all cruises except April 2023 because the chlorophyll-a was found to be below the limit of detection (LOD) at depth during the April 2023 cruise. The bottom depths for chlorophyll-a were replaced with ½ the LOD, based on the CTD fluorescence scans, which confirmed the lack of chlorophyll-a at depth. Phaeopigment data at depth were left blank due to inability to confirm or deny the lack of phaeopigments at depth. Chlorophyll and phaeopigment concentrations were calculated using equations based on the EPA method 445. Some phaeopigment values came back negative; these samples were assumed to contain no phaeopigments. Samples were run within 1 month of collection, except for in April 2023 where they were run within 3 months of collection at the University of Connecticut Avery Point.&lt;/p&gt; &lt;p&gt;&lt;strong&gt;Particulate organic carbon and nitrogen&lt;/strong&gt; samples were collected by filtering 200 mL (300 mL in November 2023) of sample through a 25 mm, 0.7 μm pore-size, pre-combusted (450°C, 2 hours) glass fiber filter using a vacuum pump and immediately covering with tin foil and freezing. POC/N filters were saturated with hydrochloric acid for 4 to 12 hours, allowed to dry overnight in the hood, and dried at 45°C for at least 3 days in the oven. Filters were weighed and re-dried for a couple of hours to ensure the drying process was complete and kept in a sealed desiccator until analysis (within 1 year of collection). Samples were run on a Fisons NA 1500 series 2 elemental analyzer by Costech Analytical Technologies using procedures based on the EPA method 440. Several samples did not have any peaks associated with nitrogen; these samples were replaced with ½ the LOD. Samples were processed within 14 months of collection at the University of Connecticut Avery Point.&lt;/p&gt; &lt;p&gt;&lt;strong&gt;Dissolved organic carbon&lt;/strong&gt; samples were filtered through a 25 mm, 0.7 μm pore-size, pre-combusted (450°C, 2 hours) glass fiber filter and were frozen until analysis. Samples were acidified to 0.5% with hydrochloric acid and analyzed with a Shimadzu TOC analyzer within seven months of collection at the University of Connecticut Avery Point.&lt;/p&gt; &lt;p&gt;&lt;strong&gt;Nitrate, phosphate, and silicate &lt;/strong&gt;samples were filtered through a 25 mm, 0.7 μm pore-size glass fiber filter and were frozen until analysis. Filters were pre-combusted (450°C, 2 hours) for the April 2024 cruise and Penobscot river trip only. Samples were analyzed via standard colorimetric methods using a Shimadzu UV-1900i Spectrophotometer (Hansen &amp;amp; Koroleff, 1999). Samples were analyzed within approximately one year of collection at Dartmouth College. Results from April 2023 and August were not included due to concerns about data quality. August data was replaced with data from a cruise by DFO from September 27th to the 29th, 2023, which followed a transect close to the GNATS transect (Figure S1 of Smith et al. 2026). Data was substituted if it was collected from within 15 meters of this study’s depths.&lt;/p&gt; &lt;p&gt;&lt;strong&gt;Dissolved organic matter&lt;/strong&gt; samples were filtered through a 25 mm, 0.7 μm pore-size, pre-combusted (450°C, 2 hours) glass fiber filter and were frozen until analysis (they were defrosted for short periods to obtain a subsample for DOC analysis). Samples were run using a Cary Eclipse Fluorescence Spectrophotometer (excitation: 220-550 nanometer (nm)), emission: 300-700 nm, slit width: 5 nm, increment by 5 nm, PMT voltage: 800, scan speed: 900 nm/minute) within 14 months of collection at the University of Connecticut Avery Point. Absorbance scans were run using a Shimadzu UV-1900i Spectrophotometer from a wavelength of 200 to 700 nm within 18 months of collection at Dartmouth College. Only samples from the upper 30 meters of the water column were analyzed. Data was processed by Urban Wünsch (Technical University of Denmark) using Parallel Factor (PARAFAC) analysis to obtain fluorescence indices and PARAFAC components.&lt;/p&gt; &lt;p&gt;&lt;strong&gt;Salinity, temperature, and dissolved oxygen&lt;/strong&gt; were collected using either the CTD or a hand-held Sonde (for the Penobscot River sites).&lt;/p&gt; &lt;p&gt;&lt;strong&gt;Apparent Oxygen Utilization&lt;/strong&gt; was calculated using the equation and constants from Garcia &amp;amp; Gordon (1992).&lt;/p&gt; &lt;p&gt;Hg data was blank and spike corrected and ancillary variables were blank-subtracted, with the exception of the nutrient data. THg and MeHg bulk samples were run in triplicate. For the other variables, triplicate samples were collected at varying stations and depths throughout the cruises. Any data below the limit of detection (LOD) was replaced with the LOD. The LOD was defined as 3 times the standard deviation of the blanks. A table with the average QA/QC parameters is included (Table 1, see Supplemental File, &quot;990899_v1_Table_1.pdf&quot;).&lt;/p&gt; Funding provided by NSF Division of Ocean Sciences (NSF OCE) Award Number: OCE-2148407 Award URL: https://www.nsf.gov/awardsearch/show-award?AWD_ID=2148407 Funding provided by NSF Division of Ocean Sciences (NSF OCE) Award Number: OCE-2148683 Award URL: https://www.nsf.gov/awardsearch/show-award?AWD_ID=2148683 completed Robert P. Mason University of Connecticut 860-405-9129 Department of Marine Sciences Groton CT 06340 USA Robert.mason@uconn.edu pointOfContact Vivien F. Taylor Dartmouth College 603-646-3318 Dept. of Earth Sciences Hanover NH 03755 USA Vivien.F.Taylor@Dartmouth.edu pointOfContact asNeeded Dataset Version: 1 Unknown Cruise_ID Cruise_Name Date_Time_UTC Latitude_N Longitude_W WaterColumn_Depth Station_Num Sample_ID Sample_Depth_m Temp Salinity Oxygen AOU Bulk_THg pTHg Bulk_MeHg pMeHg Percent_MeHg Percent_pMeHg DOC PON POC Chl_a Pha NOx PO4 SiO4 Freshness_Index BIX HIX PercentC1 PercentC2 PercentC3 PercentC4 PercentC5 PercentC6 C1 C2 C3 C4 C5 C6 Fisons NA 1500 series 2 elemental analyzer Go-Flo bottles Sea-Bird Electronics Model 19/33 V2 plus Sea-Bird Electronics Model 19/33 V2 plus Cary Eclipse Fluorescence Spectrophotometer Tekran 2600 cold vapor atomic fluorescence spectrometer Tekran 2700 Automated Methylmercury Analysis System Shimadzu TOC analyzer Trilogy Fluorometer Shimazdu UV-1900i Spectrophotometer YSI – EXO2 theme None, User defined Cruise identfier cruise name ISO_DateTime_UTC latitude longitude depth_w station sample identification depth water temperature at measurement depth salinity dissolved Oxygen Apparent Oxygen Utilization total mercury methylmercury dissolved organic Carbon particulate organic nitrogen particulate organic Carbon (POC) chlorophyll a total phaeopigment nitrate plus nitrite reactive phosphorus (PO4) Silicate, Si(OH)4, silicic acid No BCO-DMO term featureType BCO-DMO Standard Parameters Elemental Analyzer GO-FLO Bottle Sea-Bird SBE 19plus V2 SEACAT CTD Sea-Bird SBE 33 Carousel Deck Unit Spectrophotometer Tekran 2600 Automated Total Mercury Analyzer series Tekran Model 2700 Automated Methyl Mercury Analysis System Total Organic Carbon Analyzer Turner Designs Trilogy fluorometer UV Spectrophotometer-Shimadzu YSI EXO multiparameter water quality sondes instrument BCO-DMO Standard Instruments otherRestrictions otherRestrictions Access Constraints: none. Use Constraints: Please follow guidelines at: http://www.bco-dmo.org/terms-use Distribution liability: Under no circumstances shall BCO-DMO be liable for any direct, incidental, special, consequential, indirect, or punitive damages that result from the use of, or the inability to use, the materials in this data submission. If you are dissatisfied with any materials in this data submission your sole and exclusive remedy is to discontinue use. Collaborative Research: The effects of terrestrial organic matter inputs on coastal mercury cycling, methylmercury production and bioaccumulation https://osprey.bco-dmo.org/project/896019 Collaborative Research: The effects of terrestrial organic matter inputs on coastal mercury cycling, methylmercury production and bioaccumulation <p><em>NSF Award Abstract:</em><br /> Climate change will influence the delivery of contaminants, organic matter, and nutrients from land to the coastal ocean. This is because higher rainfall and warming increase runoff from land to coastal waters. Runoff also influences coastal algal blooms. These changes are expected to alter the distribution of mercury in the water and impact its availability for biological uptake. Mercury is a potent toxin. Its uptake into the food web contaminates fish and seafood and affects human health. This project will study how organic matter delivered from land to coastal waters affects mercury concentrations in seawater and in the food webs of the Gulf of Maine. The Gulf of Maine is one of the largest and most important coastal fishing grounds in the United States. This project will measure the concentration and isotopes of mercury on samples collected from research cruises under different algal bloom conditions and river flows. Lab experiments will be used to study how land-derived organic matter affects mercury accumulation in plankton. The project will provide research experiences for four undergraduate students in a STEM field. Training will be provided to a PhD student and a postdoctoral fellow. Findings from the project will provide critical information about the effect of climate change on mercury levels in marine waters and food webs. This information is needed for achieving the goals of the Minamata Convention, a global treaty for reducing mercury emissions to the environment.</p> <p>This project will examine the effects of climate change on terrestrial organic matter and mercury concentrations in Gulf of Maine waters. Specifically, the scientists will study the complex and often competing processes that influence: 1) mercury cycling and distribution; 2) the formation of methylmercury; and 3) methylmercury uptake to microplankton. Terrestrial organic matter plays an important role in transferring mercury from watersheds to coastal and offshore waters. It also controls the formation of methylmercury in water by providing a microenvironment that promotes the methylation of mercury by microbes, which represents the first step for uptake of methylmercury into seafood. However, some plankton can directly use organic matter as a food source (so-called “mixotrophs”) and can bioaccumulate methylmercury during feeding. Mixotrophs can dominate microplankton assemblages in coastal waters at some times of the year, and previous studies have not explored the impact of this feeding mode on methylmercury uptake at the base of the food web. This project will study the effects of organic matter dynamics on mercury and methylmercury cycling and bioaccumulation through 1) field surveys and shipboard experiments in the Gulf of Maine, where delivery of terrestrial organic matter is increasing, and 2) through laboratory microcosm experiments using autotrophic and mixotrophic microplankton taxa under contrasting carbon acquisition modes and organic matter characteristics and concentrations. This work will also apply novel mercury and methylmercury-specific isotope analyses and measures of organic matter quality to increase understanding of mercury cycling in coastal environments. This research will fill important gaps in predicting the effects of environmental changes on marine methylmercury levels, providing critical information to mitigating mercury emissions and methylmercury exposures, and for predicting changes in mercury levels in seafood in the future.</p> <p>This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.</p> Mercury in the Gulf of Maine largerWorkCitation project eng; USA oceans -69.7678 -66.43346 43.4715 44.60633 2023-04-04 2024-05-07 Gulf of Maine and the Penobscot River estuary 0 BCO-DMO catalogue of parameters from Mercury, methylmercury, nutrients, and physicochemical measurements from water column samples collected in the Gulf of Maine and Penobscot Estuary during several cruises in 2023 and 2024 Biological and Chemical Oceanography Data Management Office (BCO-DMO) Unavailable 508-289-2009 WHOI MS#36 Woods Hole MA 02543 USA info@bco-dmo.org http://www.bco-dmo.org Monday - Friday 8:00am - 5:00pm For questions regarding this resource, please contact BCO-DMO via the email address provided. pointOfContact http://lod.bco-dmo.org/id/dataset-parameter/991283.rdf Name: Cruise_ID Units: unitless Description: <p>Official cruise identifier. I.e. EN699 = R/V Endeavor cruise number 699. &quot;NA&quot; represents samples taken from a small boat, not the R/V Endeavor.</p> http://lod.bco-dmo.org/id/dataset-parameter/991284.rdf Name: Cruise_Name Units: unitless Description: <p>Month and year of the cruise. This is how the cruise is referenced in the publication.</p> http://lod.bco-dmo.org/id/dataset-parameter/991285.rdf Name: Date_Time_UTC Units: unitless Description: <p>Date and time (UTC) when the CTD was deployed for each station.</p> http://lod.bco-dmo.org/id/dataset-parameter/991286.rdf Name: Latitude_N Units: decimal degrees Description: <p>Latitude of the sample station.</p> http://lod.bco-dmo.org/id/dataset-parameter/991287.rdf Name: Longitude_W Units: decimal degrees Description: <p>Longitude of the sample station.</p> http://lod.bco-dmo.org/id/dataset-parameter/991288.rdf Name: WaterColumn_Depth Units: meters (m) Description: <p>Depth of the seafloor at each station.</p> http://lod.bco-dmo.org/id/dataset-parameter/991289.rdf Name: Station_Num Units: unitless Description: <p>Station number.</p> http://lod.bco-dmo.org/id/dataset-parameter/991290.rdf Name: Sample_ID Units: unitless Description: <p>Identifying number for each sample. The first digits are the station number, followed by two zeros, followed by the position in the water column. 1 represents surface samples, and 6 represents the deepest sample. Ex: 7002 represents station 7, the 2nd sample from the surface. Samples with a &quot;P&quot; at the end were collected in the Penobscot River, not during the R/V Endeavor cruises.</p> http://lod.bco-dmo.org/id/dataset-parameter/991291.rdf Name: Sample_Depth_m Units: meters (m) Description: <p>Depth that the sample was collected.</p> http://lod.bco-dmo.org/id/dataset-parameter/991292.rdf Name: Temp Units: Degrees Celsius (°C) Description: <p>Water temperature.</p> http://lod.bco-dmo.org/id/dataset-parameter/991293.rdf Name: Salinity Units: Practical Salinity Units (psu) Description: <p>Salinity of water.</p> http://lod.bco-dmo.org/id/dataset-parameter/991294.rdf Name: Oxygen Units: micromoles per kilogram (µmol/kg) Description: <p>Concentration of dissolved oxygen in the water.</p> http://lod.bco-dmo.org/id/dataset-parameter/991295.rdf Name: AOU Units: micromoles per kilogram (µmol/kg) Description: <p>Calculated apparent oxygen utilization in the water.</p> http://lod.bco-dmo.org/id/dataset-parameter/991296.rdf Name: Bulk_THg Units: picomoles (pM) Description: <p>Unfiltered concentration of total mercury in water.</p> http://lod.bco-dmo.org/id/dataset-parameter/991297.rdf Name: pTHg Units: picomoles (pM) Description: <p>Particulate total mercury in water.</p> http://lod.bco-dmo.org/id/dataset-parameter/991298.rdf Name: Bulk_MeHg Units: picomoles (pM) Description: <p>Unfiltered concentration of methylmercury in water.</p> http://lod.bco-dmo.org/id/dataset-parameter/991299.rdf Name: pMeHg Units: picomoles (pM) Description: <p>Particulate methylmercury in water.</p> http://lod.bco-dmo.org/id/dataset-parameter/991300.rdf Name: Percent_MeHg Units: unitless (percent) Description: <p>Percentage of bulk methylmercury in bulk total mercury. I.e. Bulk_MeHg/Bulk_THg.</p> http://lod.bco-dmo.org/id/dataset-parameter/991301.rdf Name: Percent_pMeHg Units: unitless (percent) Description: <p>Percentage of particulate methylmercury in particulate total mercury. I.e. pMeHg/pTHg.</p> http://lod.bco-dmo.org/id/dataset-parameter/991302.rdf Name: DOC Units: micromolar (µM) Description: <p>Dissolved organic carbon in water.</p> http://lod.bco-dmo.org/id/dataset-parameter/991303.rdf Name: PON Units: micrograms per Liter (µg/L) Description: <p>Particulate organic nitrogen in water.</p> http://lod.bco-dmo.org/id/dataset-parameter/991304.rdf Name: POC Units: micrograms per Liter (µg/L) Description: <p>Particulate organic carbon in water.</p> http://lod.bco-dmo.org/id/dataset-parameter/991305.rdf Name: Chl_a Units: micrograms per Liter (µg/L) Description: <p>Chlorophyll-a in water.</p> http://lod.bco-dmo.org/id/dataset-parameter/991306.rdf Name: Pha Units: micrograms per Liter (µg/L) Description: <p>Phaeopigments in water.</p> http://lod.bco-dmo.org/id/dataset-parameter/991307.rdf Name: NOx Units: micromolar (µM) Description: <p>Nitrate and nitrite in water.</p> http://lod.bco-dmo.org/id/dataset-parameter/991308.rdf Name: PO4 Units: micromolar (µM) Description: <p>Phosphate in water.</p> http://lod.bco-dmo.org/id/dataset-parameter/991309.rdf Name: SiO4 Units: micromolar (µM) Description: <p>Silicate in water.</p> http://lod.bco-dmo.org/id/dataset-parameter/991310.rdf Name: Freshness_Index Units: unitless Description: <p>Freshness Index.</p> http://lod.bco-dmo.org/id/dataset-parameter/991311.rdf Name: BIX Units: unitless Description: <p>Biological Index.</p> http://lod.bco-dmo.org/id/dataset-parameter/991312.rdf Name: HIX Units: unitless Description: <p>Humification Index.</p> http://lod.bco-dmo.org/id/dataset-parameter/991313.rdf Name: PercentC1 Units: unitless (percent) Description: <p>Percentage of PARAFAC component 1. I.e. C1/Sum of all components.</p> http://lod.bco-dmo.org/id/dataset-parameter/991314.rdf Name: PercentC2 Units: unitless (percent) Description: <p>Percentage of PARAFAC component 2. I.e. C2/Sum of all components.</p> http://lod.bco-dmo.org/id/dataset-parameter/991315.rdf Name: PercentC3 Units: unitless (percent) Description: <p>Percentage of PARAFAC component 3. I.e. C3/Sum of all components.</p> http://lod.bco-dmo.org/id/dataset-parameter/991316.rdf Name: PercentC4 Units: unitless (percent) Description: <p>Percentage of PARAFAC component 4. I.e. C4/Sum of all components.</p> http://lod.bco-dmo.org/id/dataset-parameter/991317.rdf Name: PercentC5 Units: unitless (percent) Description: <p>Percentage of PARAFAC component 5. I.e. C5/Sum of all components.</p> http://lod.bco-dmo.org/id/dataset-parameter/991318.rdf Name: PercentC6 Units: unitless (percent) Description: <p>Percentage of PARAFAC component 6. I.e. C6/Sum of all components.</p> http://lod.bco-dmo.org/id/dataset-parameter/991319.rdf Name: C1 Units: unitless Description: <p>PARAFAC component 1.</p> http://lod.bco-dmo.org/id/dataset-parameter/991320.rdf Name: C2 Units: unitless Description: <p>PARAFAC component 2.</p> http://lod.bco-dmo.org/id/dataset-parameter/991321.rdf Name: C3 Units: unitless Description: <p>PARAFAC component 3.</p> http://lod.bco-dmo.org/id/dataset-parameter/991322.rdf Name: C4 Units: unitless Description: <p>PARAFAC component 4.</p> http://lod.bco-dmo.org/id/dataset-parameter/991323.rdf Name: C5 Units: unitless Description: <p>PARAFAC component 5.</p> http://lod.bco-dmo.org/id/dataset-parameter/991324.rdf Name: C6 Units: unitless Description: <p>PARAFAC component 6.</p> GB/NERC/BODC > British Oceanographic Data Centre, Natural Environment Research Council, United Kingdom Biological and Chemical Oceanography Data Management Office (BCO-DMO) Unavailable 508-289-2009 WHOI MS#36 Woods Hole MA 02543 USA info@bco-dmo.org http://www.bco-dmo.org Monday - Friday 8:00am - 5:00pm For questions regarding this resource, please contact BCO-DMO via the email address provided. pointOfContact https://doi.org/10.26008/1912/bco-dmo.990899.1 download onLine dataset &lt;p&gt;&lt;strong&gt;Description:&lt;/strong&gt;&lt;br /&gt; Total mercury, methylmercury, and ancillary variable data were collected in the Gulf of Maine along the Gulf of Maine North Atlantic Time Series (GNATS) transect and on a transect in the Penobscot Estuary and River. Sampling took place over four cruises on the R/V Endeavor (April 2023, August 2023, November 2023, April 2024), and two separate trips in a small boat to sample further upstream in the Penobscot River (September 2023, May 2024). 21 stations were sampled in total, with multiple depths (up to 6) extending throughout the water column at all stations except for the shallow Penobscot River stations.&lt;/p&gt; &lt;p&gt;This dataset includes bulk and particulate total mercury and monomethylmercury, dissolved organic carbon, particulate organic carbon and nitrogen, chlorophyll-a, phaeopigments, nitrate, phosphate, silicate, fluorescence indices (including the freshness index, BIX, and HIX), and components identified during Parallel Factor (PARAFAC) analysis. The percentage of methylated mercury (bulk methylmercury/bulk total mercury), percentage of particulate methylated mercury (particulate methylmercury/particulate total mercury), and percentage of each PARAFAC component are also included. The dataset also includes salinity, temperature, and dissolved oxygen data from the sensors on the CTD, as well as the calculated apparent oxygen utilization. Nutrient data in August in the Gulf of Maine was replaced with data supplied by the Canada Department of Fisheries and Oceans (DFO) from a transect similar to the GNATS transect, which occurred in September 2023.&lt;/p&gt; &lt;p&gt;&lt;strong&gt;Methods &amp;amp; Sampling:&lt;/strong&gt;&lt;br /&gt; During the four cruises, samples were collected using a trace metal clean rosette with Go-Flo bottles. During the August 2023 cruise, the trace metal clean rosette and winch system suffered a technical issue that was unable to be resolved, thus Stations 3, 4, 6, 7, and 10-15 were collected with the same Go-Flo bottles attached to a non-trace metal clean, Seabird rosette. Water samples were collected over the side of a small watercraft for the Penobscot River sites, taken either by hand or via Go-Flo bottles. Bulk water samples were collected in 2-liter (L) acid-cleaned Teflon bottles and then brought into a trace metal clean van (or laminar flow hood for the Penobscot River sites) for typically immediate, but if not same-day, filtering and subsampling.&lt;/p&gt; &lt;p&gt;&lt;strong&gt;Bulk Methylmercury&lt;/strong&gt; samples were preserved with sulfuric acid (0.5%) and kept cold until analysis. They were analyzed on a Tekran 2700 Automated Methylmercury Analysis System following standard techniques (Hammerschmidt and Fitzgerald, 2006). Briefly, bulk MeHg samples were digested overnight with sulfuric acid, buffered with acetate buffer, followed by the addition of ascorbic acid, neutralized with potassium hydroxide, and ethylated using sodium tetraethylborate. Once on the Tekran 2700, samples were purged with argon, and the Hg species were trapped on a Tenax trap. Upon heating the trap, the Hg species were released and underwent gas chromatographic separation prior to decomposition of the Hg species to elemental Hg for cold vapor atomic fluorescence detection. Samples were run within 6 months of collection at the University of Connecticut Avery Point.&lt;/p&gt; &lt;p&gt;&lt;strong&gt;Particulate methylmercury&lt;/strong&gt; was filtered through a pre-weighed and pre-combusted (400 degrees Celsius (°C), 15-18 hours), 0.45-micrometer (μm) pore-size, quartz fiber filter using a vacuum pump and frozen until analysis. Filters were freeze-dried for 7 days, weighed, and then digested in 4.5 N nitric acid overnight in a 60°C water bath, buffered with acetate buffer, neutralized with potassium hydroxide, and ethylated using sodium tetraethylborate, where the sample then underwent the same process on the Tekran 2700 as described above. The remaining digest - 3 milliliters (mL) out of 7 mL total - was frozen and preserved within 1 week for THg analysis by diluting to 10 mL with DI water, adding bromine monochloride, and storing in the dark at room temperature. Filters were run within 1 year of collection at the University of Connecticut Avery Point.&lt;/p&gt; &lt;p&gt;&lt;strong&gt;Bulk total mercury&lt;/strong&gt; samples were filled with no headspace and kept cold until analysis on a Tekran 2600 following EPA method 1631, refined by Hammerschmidt and Fitzgerald (2006). Briefly, both particulate and bulk samples were digested overnight with bromine chloride, reduced with hydroxylamine hydrochloride to remove excess reductant, oxidized with stannous chloride to form elemental Hg, and run using cold vapor atomic fluorescence spectrometry. Samples were run within 6 months of collection at the University of Connecticut Avery Point.&lt;/p&gt; &lt;p&gt;&lt;strong&gt;Particulate total mercury&lt;/strong&gt; was analyzed using the same filter as for particulate methylmercury and run using the method described above. Filters were run within 1 year of collection at the University of Connecticut Avery Point.&lt;/p&gt; &lt;p&gt;&lt;strong&gt;Chlorophyll-a and phaeopigments&lt;/strong&gt; were collected by filtering 100 mL of sample through a 25-millimeter (mm), 0.7 μm pore-size glass fiber filter using a vacuum pump and immediately covering with tin foil and freezing. The filters were pre-combusted (450°C, 2 hours) for the April 2024 cruise and 2024 Penobscot river samples only. Samples were analyzed using EPA method 445. Briefly, the filters were digested overnight in 90% acetone and run in dimmed light with and without hydrochloric acid acidification using a Trilogy Fluorometer. Samples were only collected for the shallowest 3 to 4 depths at each station for all cruises except April 2023 because the chlorophyll-a was found to be below the limit of detection (LOD) at depth during the April 2023 cruise. The bottom depths for chlorophyll-a were replaced with ½ the LOD, based on the CTD fluorescence scans, which confirmed the lack of chlorophyll-a at depth. Phaeopigment data at depth were left blank due to inability to confirm or deny the lack of phaeopigments at depth. Chlorophyll and phaeopigment concentrations were calculated using equations based on the EPA method 445. Some phaeopigment values came back negative; these samples were assumed to contain no phaeopigments. Samples were run within 1 month of collection, except for in April 2023 where they were run within 3 months of collection at the University of Connecticut Avery Point.&lt;/p&gt; &lt;p&gt;&lt;strong&gt;Particulate organic carbon and nitrogen&lt;/strong&gt; samples were collected by filtering 200 mL (300 mL in November 2023) of sample through a 25 mm, 0.7 μm pore-size, pre-combusted (450°C, 2 hours) glass fiber filter using a vacuum pump and immediately covering with tin foil and freezing. POC/N filters were saturated with hydrochloric acid for 4 to 12 hours, allowed to dry overnight in the hood, and dried at 45°C for at least 3 days in the oven. Filters were weighed and re-dried for a couple of hours to ensure the drying process was complete and kept in a sealed desiccator until analysis (within 1 year of collection). Samples were run on a Fisons NA 1500 series 2 elemental analyzer by Costech Analytical Technologies using procedures based on the EPA method 440. Several samples did not have any peaks associated with nitrogen; these samples were replaced with ½ the LOD. Samples were processed within 14 months of collection at the University of Connecticut Avery Point.&lt;/p&gt; &lt;p&gt;&lt;strong&gt;Dissolved organic carbon&lt;/strong&gt; samples were filtered through a 25 mm, 0.7 μm pore-size, pre-combusted (450°C, 2 hours) glass fiber filter and were frozen until analysis. Samples were acidified to 0.5% with hydrochloric acid and analyzed with a Shimadzu TOC analyzer within seven months of collection at the University of Connecticut Avery Point.&lt;/p&gt; &lt;p&gt;&lt;strong&gt;Nitrate, phosphate, and silicate &lt;/strong&gt;samples were filtered through a 25 mm, 0.7 μm pore-size glass fiber filter and were frozen until analysis. Filters were pre-combusted (450°C, 2 hours) for the April 2024 cruise and Penobscot river trip only. Samples were analyzed via standard colorimetric methods using a Shimadzu UV-1900i Spectrophotometer (Hansen &amp;amp; Koroleff, 1999). Samples were analyzed within approximately one year of collection at Dartmouth College. Results from April 2023 and August were not included due to concerns about data quality. August data was replaced with data from a cruise by DFO from September 27th to the 29th, 2023, which followed a transect close to the GNATS transect (Figure S1 of Smith et al. 2026). Data was substituted if it was collected from within 15 meters of this study’s depths.&lt;/p&gt; &lt;p&gt;&lt;strong&gt;Dissolved organic matter&lt;/strong&gt; samples were filtered through a 25 mm, 0.7 μm pore-size, pre-combusted (450°C, 2 hours) glass fiber filter and were frozen until analysis (they were defrosted for short periods to obtain a subsample for DOC analysis). Samples were run using a Cary Eclipse Fluorescence Spectrophotometer (excitation: 220-550 nanometer (nm)), emission: 300-700 nm, slit width: 5 nm, increment by 5 nm, PMT voltage: 800, scan speed: 900 nm/minute) within 14 months of collection at the University of Connecticut Avery Point. Absorbance scans were run using a Shimadzu UV-1900i Spectrophotometer from a wavelength of 200 to 700 nm within 18 months of collection at Dartmouth College. Only samples from the upper 30 meters of the water column were analyzed. Data was processed by Urban Wünsch (Technical University of Denmark) using Parallel Factor (PARAFAC) analysis to obtain fluorescence indices and PARAFAC components.&lt;/p&gt; &lt;p&gt;&lt;strong&gt;Salinity, temperature, and dissolved oxygen&lt;/strong&gt; were collected using either the CTD or a hand-held Sonde (for the Penobscot River sites).&lt;/p&gt; &lt;p&gt;&lt;strong&gt;Apparent Oxygen Utilization&lt;/strong&gt; was calculated using the equation and constants from Garcia &amp;amp; Gordon (1992).&lt;/p&gt; &lt;p&gt;Hg data was blank and spike corrected and ancillary variables were blank-subtracted, with the exception of the nutrient data. THg and MeHg bulk samples were run in triplicate. For the other variables, triplicate samples were collected at varying stations and depths throughout the cruises. Any data below the limit of detection (LOD) was replaced with the LOD. The LOD was defined as 3 times the standard deviation of the blanks. A table with the average QA/QC parameters is included (Table 1, see Supplemental File, &quot;990899_v1_Table_1.pdf&quot;).&lt;/p&gt; Specified by the Principal Investigator(s) - Imported original file &quot;GoM_Penobscot_Data.xlsx&quot; into the BCO-DMO system. - Marked &quot;NaN&quot; and &quot;nd&quot; as missing data identifiers (missing data are empty/blank in the final CSV file). - Replaced &quot;15:37.30&quot; with &quot;15:37:30&quot; in the Date_Time_UTC column. - Converted the Date_Time_UTC column to ISO 8601 format. - Saved the final file as &quot;990899_v1_gulf_of_maine_hg.csv&quot;. Specified by BCO-DMO Data Managers asNeeded 7.x-1.1 Biological and Chemical Oceanography Data Management Office (BCO-DMO) Unavailable 508-289-2009 WHOI MS#36 Woods Hole MA 02543 USA info@bco-dmo.org http://www.bco-dmo.org Monday - Friday 8:00am - 5:00pm For questions regarding this resource, please contact BCO-DMO via the email address provided. pointOfContact Fisons NA 1500 series 2 elemental analyzer Fisons NA 1500 series 2 elemental analyzer PI Supplied Instrument Name: Fisons NA 1500 series 2 elemental analyzer PI Supplied Instrument Description:Used to measure particulate organic carbon and nitrogen. Instrument Name: Elemental Analyzer Instrument Short Name: Instrument Description: Instruments that quantify carbon, nitrogen and sometimes other elements by combusting the sample at very high temperature and assaying the resulting gaseous oxides. Usually used for samples including organic material. Community Standard Description: http://vocab.nerc.ac.uk/collection/L05/current/LAB01/ Go-Flo bottles Go-Flo bottles PI Supplied Instrument Name: Go-Flo bottles Instrument Name: GO-FLO Bottle Instrument Short Name:GO-FLO Instrument Description: GO-FLO bottle cast used to collect water samples for pigment, nutrient, plankton, etc. The GO-FLO sampling bottle is specially designed to avoid sample contamination at the surface, internal spring contamination, loss of sample on deck (internal seals), and exchange of water from different depths. Community Standard Description: http://vocab.nerc.ac.uk/collection/L05/current/30/ Sea-Bird Electronics Model 19/33 V2 plus Sea-Bird Electronics Model 19/33 V2 plus PI Supplied Instrument Name: Sea-Bird Electronics Model 19/33 V2 plus Instrument Name: Sea-Bird SBE 19plus V2 SEACAT CTD Instrument Short Name:Sea-Bird SEACAT 19 Plus V2 Instrument Description: Self-contained self-powered CTD profiler. Measures conductivity, temperature and pressure (Digiquartz sensor) in both profiling (samples at 4 scans/sec) and moored (sample rates of once every 5 seconds to once every 9 hours) mode. Available in plastic or titanium housing with depth ranges of 600m and 7000m respectively. Miniature submersible pump provides water to the conductivity cell. Compared to the previous 19plus, the V2 incorporates an electronics upgrade and additional features, with six differentially amplified A/D input channels, one RS-232 data input channel, and 64 MB FLASH memory. Sea-Bird Electronics Model 19/33 V2 plus Sea-Bird Electronics Model 19/33 V2 plus PI Supplied Instrument Name: Sea-Bird Electronics Model 19/33 V2 plus Instrument Name: Sea-Bird SBE 33 Carousel Deck Unit Instrument Short Name:SBE 33 Instrument Description: The rack-mountable SBE 33 provides power and real-time data acquisition and control for an SBE 32 Carousel Water Sampler that has the SBE 33 interface option installed in its pylon. The SBE 33 is compatible with all Carousel sizes - full size, compact, and sub-compact. When powered and controlled by the SBE 33, the Carousel can be used: - with an SBE 19, 19plus, 19plus V2, 25, 25plus, or 49 CTD - without a CTD - with a Neil Brown Mk III CTD (requires optional interface for both SBE 32 and 33) The SBE 33 can also provide power and real-time data acquisition and control for the smaller SBE 55 ECO Water Sampler used with an SBE 19, 19plus, 19plus V2, 25, 25plus, or 49 CTD, or no CTD. See http://www.seabird.com/sbe33-deck-unit for further details. Cary Eclipse Fluorescence Spectrophotometer Cary Eclipse Fluorescence Spectrophotometer PI Supplied Instrument Name: Cary Eclipse Fluorescence Spectrophotometer PI Supplied Instrument Description:Produced excitation emission matrixes for dissolved organic matter. Instrument Name: Spectrophotometer Instrument Short Name:Spectrophotometer Instrument Description: An instrument used to measure the relative absorption of electromagnetic radiation of different wavelengths in the near infra-red, visible and ultraviolet wavebands by samples. Community Standard Description: http://vocab.nerc.ac.uk/collection/L05/current/LAB20/ Tekran 2600 cold vapor atomic fluorescence spectrometer Tekran 2600 cold vapor atomic fluorescence spectrometer PI Supplied Instrument Name: Tekran 2600 cold vapor atomic fluorescence spectrometer PI Supplied Instrument Description:Used to measure bulk and particulate total mercury. Instrument Name: Tekran 2600 Automated Total Mercury Analyzer series Instrument Short Name:Tekran 2600 Instrument Description: The Tekran 2600 is a total Mercury (Hg) analysis system that can measure sub-picogram quantities of mercury in water, soil, vegetation, and other sample matrices. The system utilizes a Cold Vapour Atomic Fluorescence Spectroscopy (CVAFS) detector. The 2600-IVS (In-Vial Sparging) model is reconfigured for direct in-vial sparging sample introduction, and the 2600-NG (Natural Gas) model is designed for the analysis of gas phase sample cartridges. The system is capable of multiple method configurations: Dual stage gold preconcentration (EPA Method 1631); Direct measurement without preconcentration (EPA Method 245.7); Air sample analysis on gold traps (EPA Compendium Method IO-5); and Natural gas analysis on gold traps (ASTM D-6350, ISO 6978). It has a guaranteed minimum detection limit of < 0.05 nanograms per liter (ng/L). In clean room environments, with low mercury blanks, minimum detection limits as low as 0.02 ng/L are achievable. See: https://www.tekran.com/products/laboratory/tekran-model-2600-automated-total-mercury-analysis-system/ Tekran 2700 Automated Methylmercury Analysis System Tekran 2700 Automated Methylmercury Analysis System PI Supplied Instrument Name: Tekran 2700 Automated Methylmercury Analysis System PI Supplied Instrument Description:Used to measure bulk and particulate methylmercury samples. The instrument incorporates gas chromatography and cold vapor atomic fluorescence detection. Instrument Name: Tekran Model 2700 Automated Methyl Mercury Analysis System Instrument Short Name:Tekran 2700 Instrument Description: The Tekran 2700 is a fully integrated Gas Chromatography Cold-Vapor Atomic Fluorescence Spectrophotometer (GC-CVAFS) automated Methyl Mercury analysis system. The 2700 can analyze distilled waters, extracted or distilled tissues and solids, and allows direct analysis of suitable water samples. The system is pre-programmed to run EPA Method 1630, however it offers complete method customization including: GC column temperature ramping; programmable analysis cycle settings; high temperature purge cycles; and choice of trap and GC column. It can also interface with ICP-MS or other analytical instruments. The sample analysis cycle is less than 7 minutes per sample. It has a minimum detection limit of 0.002 nanograms per liter (ng/L). The system has IR trap heating and active cooling. See: https://www.tekran.com/products/laboratory/tekran-model-2700-automated-methyl-mercury-analysis-system/ Shimadzu TOC analyzer Shimadzu TOC analyzer PI Supplied Instrument Name: Shimadzu TOC analyzer PI Supplied Instrument Description:Used to measure dissolved organic carbon. Instrument Name: Total Organic Carbon Analyzer Instrument Short Name:TOC analyzer Instrument Description: A unit that accurately determines the carbon concentrations of organic compounds typically by detecting and measuring its combustion product (CO2). See description document at: http://bcodata.whoi.edu/LaurentianGreatLakes_Chemistry/bs116.pdf Community Standard Description: http://vocab.nerc.ac.uk/collection/L05/current/LAB04/ Trilogy Fluorometer Trilogy Fluorometer PI Supplied Instrument Name: Trilogy Fluorometer PI Supplied Instrument Description:Used to measure chlorophyll-a and phaeopigments. Instrument Name: Turner Designs Trilogy fluorometer Instrument Short Name:Turner Trilogy Instrument Description: The Trilogy Laboratory Fluorometer is a compact laboratory instrument for making fluorescence, absorbance, and turbidity measurements using the appropriate snap-in application module. Fluorescence modules are available for discrete sample measurements of various fluorescent materials including chlorophyll (in vivo and extracted), rhodamine, fluorescein, cyanobacteria pigments, ammonium, CDOM, optical brighteners, and other fluorescent compounds. Shimazdu UV-1900i Spectrophotometer Shimazdu UV-1900i Spectrophotometer PI Supplied Instrument Name: Shimazdu UV-1900i Spectrophotometer PI Supplied Instrument Description:Used to measure nitrate, inorganic phosphate, and silicate. Also used to measure dissolved organic matter fluorescence. Instrument Name: UV Spectrophotometer-Shimadzu Instrument Short Name:UV Spectrophotometer-Shimadzu Instrument Description: The Shimadzu UV Spectrophotometer is manufactured by Shimadzu Scientific Instruments (ssi.shimadzu.com). Shimadzu manufacturers several models of spectrophotometer; refer to dataset for make/model information. Community Standard Description: http://vocab.nerc.ac.uk/collection/L05/current/LAB20/ YSI – EXO2 YSI – EXO2 PI Supplied Instrument Name: YSI – EXO2 Instrument Name: YSI EXO multiparameter water quality sondes Instrument Short Name:YSI EXO Instrument Description: Comprehensive multi-parameter, water-quality monitoring sondes designed for long-term monitoring, profiling and spot sampling. The EXO sondes are split into several categories: EXO1 Sonde, EXO2 Sonde, EXO3 Sonde. Each category has a slightly different design purpose with the EXO2 and EXO3 containing more sensor ports than the EXO1. Data are collected using up to four user-replaceable sensors and an integral pressure transducer. Users communicate with the sonde via a field cable to an EXO Handheld, via Bluetooth wireless connection to a PC, or a USB connection to a PC. Typical parameter specifications for relevant sensors include dissolved oxygen with ranges of 0-50 mg/l, with a resolution of +/- 0.1 mg/l, an accuracy of 1 percent of reading for values between 0-20 mg/l and an accuracy of +/- 5 percent of reading for values 20-50 mg/l. Temp ranges are from-5 to +50 degC, with an accuracy of +/- 0.001 degC. Conductivity has a range of 0-200 mS/cm, with an accuracy of +/-0.5 percent of reading + 0.001 mS/cm and a resolution of 0.0001 - 0.01 mS/cm.