US Long-Term Ecological Research Network

North Temperate Lakes LTER: Groundwater Chemistry 1984 - current

Abstract
Water chemistry is measured annually in 11 monitoring wells to characterize regional groundwater chemistry in the Trout Lake area. The chemical parameters measured include pH, conductivity, total alkalinity, dissolved inorganic and organic carbon, total nitrogen, nitrate, ammonia, total phosphorus, calcium, magnesium, sodium, potassium, chloride, sulfate, iron, manganese, total silica and dissolved reactive silica. Chemical data are available at a quarterly sampling frequency for some years. In addition (see related data set - Groundwater Level), water levels in 37 monitoring wells are measured several times per year. The wells are scattered throughout the Trout Lake hydrological basin and the data are used to calibrate and test regional groundwater flow models. Sampling Frequency: annually - with some earlier data from quarterly sampling Number of sites: 11
Dataset ID
10
Date Range
-
Maintenance
ongoing
Metadata Provider
Methods
Ammonium, Nitrate, Nitrit Samples for ammonium and nitrate or nitrite are collected together with a peristaltic pump and tubing and in-line filtered (through a 0.40 micron polycarbonate filter) into new, 20 ml HDPE plastic containers with conical caps. The samples are stored frozen until analysis, which should occur within 6 months. The samples are analyzed for ammonium (and nitrateornitrite) simultaneously by automated colorimetric spectrophotometry, using a segmented flow autoanalyzer. Ammonium is determined by utilizing the Berthelot Reaction, producing a blue colored indophenol compound, where the absorption is monitored at 660 nm. The detection limit for ammonium is approximately 3 ppb and the analytical range for the method extends to 4000 ppb. The detection limit for nitrateornitrite is approximately 2 ppb and the analytical range for the method extends to 4000 ppb. Method Log: Prior to January 2006 samples, ammonium was determined on a Technicon segmented flow autoanalyzer. From 2006 to present, ammonium is determined by an Astoria-Pacific Astoria II segmented flow autoanalyzer. Chloride, Sulfate Samples for chloride and sulfate are collected together with a peristaltic pump and tubing and in-line filtered (through a 0.40 micron polycarbonate filter) into new, 20 ml HDPE plastic containers with conical caps. The samples are stored refrigerated at 4 degrees Celsius until analysis, which should occur within 6 months. The samples are analyzed for chloride (and sulfate) simultaneously by Ion Chromatography, using a hydroxide eluent. The detection limit for chloride is approximately 0.01 ppm and the analytical range for the method extends to 100 ppm. The detection limit for sulfate is approximately 0.01 ppm and the analytical range for the method extends to 60 ppm. Method Log: Prior to January 1998 samples, chloride was determined on a Dionex DX10 Ion Chromatograph, using a chemical fiber suppressor. From 1998 to 2011, chloride was determined by a Dionex model DX500, using an electro-chemical suppressor. From January 2011 until present, chloride is determined by a Dionex model ICS 2100 using an electro-chemical suppressor. Calcium, magnesium, sodium, potassium, iron, and manganese Samples for calcium analysis (as well as dissolved nitrogen and phosphorus, magnesium, sodium, potassium, iron, and manganese) are collected together with a peristaltic pump and tubing and in-line filtered (through a 40 micron polycarbonate filter) into 120 ml LDPE bottles and acidified to a 1percent HCl matrix by adding 1 ml of ultra pure concentrated HCl to 100 mls of sample. For every sample acidification event, three acid blanks are created by adding the same acid used on the samples to 100 mls of ultra pure water supplied from the lab. Once acidified, the samples are stable at room temperature until analysis, which should occur within one year. Until acidification, the samples should be refrigerated at 4 degrees Celsius. Calcium, as well as magnesium, sodium, potassium, iron, and manganese are analyzed simultaneously on an optical inductively-coupled plasma emission spectrophotometer (ICP-OES). The acidified samples are directly aspirated into the instrument without a digestion. Calcium is analyzed at 317.933 nm and at 315.887 nm and viewed axially for low-level analysis and radially for high level analysis. The detection limit for calcium is 0.06 ppm with an analytical range of the method extends to 50 ppm. The detection limit for iron is 0.02 ppm with an analytical range of the method extends to 20 ppm. The detection limit for magnesium is 0.03 ppm with an analytical range of the method extends to 50 ppm. The detection limit for manganese is 0.01 ppm with an analytical range of the method extends to 2 ppm. The detection limit for potassium is 0.06 ppm with an analytical range of the method extends to 10 ppm. The detection limit for sodium is 0.06 ppm with an analytical range of the method extends to 50 ppm. Method Log: Prior to January 2002, calcium, magnesium, sodium, potassium, iron, and manganese were determined on a Perkin-Elmer model 503 Atomic Absorption Spectrophotometer. Lanthanum at a 0.8percent concentration was added as a matrix modifier to suppress chemical interferences. From January 2002 to present, samples are analyzed for calcium on a Perkin-Elmer model 4300 DV ICP. Inorganic and organic carbon Samples for inorganic and organic carbon are collected together with a peristaltic pump and tubing and in-line filtered, if necessary, (through a 0.40 micron polycarbonate filter) into glass, 24 ml vials (that are compatible with the carbon analyzer autosampler), and capped with septa, leaving no head space. The samples are stored refrigerated at 4 degrees Celsius until analysis, which should occur within 2-3 weeks. The detection limit for inorganic carbon is 0.15 ppm, and the analytical range for the method is 60 ppm. The detection limit for organic carbon is 0.30 ppm and the analytical range for the method is 30 ppm. Method Log: Prior to May 2006 samples, inorganic carbon was analyzed by phosphoric acid addition on an OI Model 700 Carbon Analyzer. From May 2006 to present, inorganic carbon is still analyzed by phosphoric acid addition, but on a Shimadzu TOC-V-csh Total Organic Carbon Analyzer. Method Log: Prior to May 2006 samples, organic carbon was analyzed by heated persulfate digestion on an OI Model 700 Carbon Analyzer. From May 2006 to present, Organic carbon is analyzed by combustion, on a Shimadzu TOC-V-csh Total Organic Carbon Analyzer. Dissolved reactive silicon Samples for silicon are collected with a peristaltic pump and tubing and in-line filtered (through a 40 micron polycarbonate filter) into 120 ml LDPE bottles and acidified to a 1percent HCl matrix by adding 1 ml of ultra pure concentrated HCl to 100 mls of sample. For every sample acidification event, three acid blanks are created by adding the same acid used on the samples to 100 mls of ultra pure water supplied from the lab. Once acidified, the samples are stable at room temperature until analysis, which should occur within one year. Until acidification, the samples should be refrigerated at 4 degrees Celsius. Dissolved reactive silica is determined by the Heteropoly Blue Method and the absorption is measured at 820 nm. The detection limit for silicon is 6 ppb and the analytical range is 15000 ppb. Method Log These determinations were performed manually using a Bausch and Lomb Spectrophotometer from the beginning of the project until April 1984. From 1984 through 2005, dissolved reactive silicon was determined on a Technicon Auto Analyzer II. From January 2006 to present, samples are run on an Astoria-Pacific Astoria II Autoanalyzer. total and dissolved nitrogen and phosphorus Samples for total and dissolved nitrogen and phosphorus analysis are collected together with a peristaltic pump and tubing and in-line filtered, when necessary, (through a 40 micron polycarbonate filter) into 120 ml LDPE bottles and acidified to a 1percent HCl matrix by adding 1 mL of ultra pure concentrated HCl to 100 mls of sample. For every sample acidification event, three acid blanks are created by adding the same acid used on the samples to 100 mls of ultra pure water supplied from the lab. Once acidified, the samples are stable at room temperature until analysis, which should occur within one year. Until acidification, the samples should be refrigerated at 4 degrees Celsius. The samples must first be prepared for analysis by adding an NaOH–Persulfate digestion reagent and heated for an hour at 120 degrees C and 18-20 psi in an autoclave. The samples are analyzed for total nitrogen and total phosphorus simultaneously by automated colorimetric spectrophotometry, using a segmented flow autoanalyzer. Total nitrogen is determined by utilizing the automated cadmium reduction method, as described in Standard Methods, where the absorption is monitored at 520 nm. The detection limit for total and dissolved nitrogen is approximately 21 ppb and the analytical range for the method extends to 2500 ppb. The detection limit for total phosphorus is approximately 3 ppb and the analytical range for the method extends to 800 ppb. Method Log: Prior to January 2006 samples, total nitrogen was determined on a Technicon segmented flow autoanalyzer. From 2006 to present, total nitrogen is determined by an Astoria-Pacific Astoria II segmented flow autoanalyzer. pH We sample at the deepest part of the lake using a peristaltic pump and tubing, monthly during open water and approximately every five weeks during ice cover. We collect two types of pH samples at each sampling depth: one in 20ml vials with cone cap inserts to exclude all air from the vial, and one in 125ml bottles to be air equilibrated before analysis. The depths for sample collection are based on thermal stratification: top and bottom of the epilimnion, mid thermocline, and top, middle,and bottom of the hypolimnion. During mixis we sample at the surface, mid water column, and bottom. We analyze for pH the same day that samples are collected, keeping them cold and dark until just before analysis. Samples are warmed to room temperature in a dark container, and the air equilibrated samples are bubbled with outside air for at least 15 minutes prior to measurement. We measure pH using a Radiometer combination pH electrode and Orion 4Star pH meter. Protocol Log: 1981-1988 -- used a PHM84 Research pH meter. 1986 -- began analyzing air equilibrated pH. 1988 - July 2010 -- used an Orion model 720 pH meter.</p>
Short Name
NTLGW02
Version Number
23

North Temperate Lakes LTER: Chemical Limnology of Primary Study Lakes: Nutrients, pH and Carbon 1981 - current

Abstract
Parameters characterizing the nutrient chemistry of the eleven primary lakes (Allequash, Big Muskellunge, Crystal, Sparkling, and Trout lakes, unnamed lakes 27-02 [Crystal Bog] and 12-15 [Trout Bog], Mendota, Monona, Wingra, and Fish) are measured at multiple depths throughout the year. These parameters include total nitrogen, total dissolved nitrogen, nitrite+nitrate-N, ammonium-N, total phosphorus, total dissolved phosphorus, dissolved reactive phosphorus (only in the southern lakes and not in Wingra and Fish after 2003), bicarbonate-reactive filtered and unfiltered silica (both discontinued in 2003), dissolved reactive silica, pH, air equilibrated pH (discontinued in 2014 in the northern lakes and in 2020 in the southern lakes), total alkalinity, total inorganic carbon, dissolved inorganic carbon, total organic carbon, dissolved organic carbon, and total particulate matter (only in the northern lakes in this data set; total particulate matter in southern lakes starting in 2000 is available in a separate dataset). Sampling Frequency: Northern lakes- monthly during ice-free season -- every 5 weeks during ice-covered season. Southern lakes- Southern lakes samples are collected every 2-4 weeks during the summer stratified period, at least monthly during the fall, and typically only once during the winter, depending on ice conditions. Number of sites: 11
Dataset ID
1
Date Range
-
DOI
10.6073/pasta/cc6f0e4d317d29200234c7243471472a
Maintenance
ongoing
Metadata Provider
Methods
Inorganic and organic carbon: Samples for inorganic and organic carbon are collected together with a peristaltic pump and tubing and in-line filtered, if necessary, (through a 0.40 micron polycarbonate filter) into glass, 24 ml vials (that are compatible with the carbon analyzer autosampler), and capped with septa, leaving no head space. The samples are stored refrigerated at 4 degrees Celsius until analysis, which should occur within 2-3 weeks. The detection limit for inorganic carbon is 0.15 ppm, and the analytical range for the method is 60 ppm. The detection limit for organic carbon is 0.30 ppm and the analytical range for the method is 30 ppm. Method Log: Prior to May 2006 samples, inorganic carbon was analyzed by phosphoric acid addition on an OI Model 700 Carbon Analyzer. From May 2006 to present, inorganic carbon is still analyzed by phosphoric acid addition, but on a Shimadzu TOC-V-csh Total Organic Carbon Analyzer. Method Log: Prior to May 2006 samples, organic carbon was analyzed by heated persulfate digestion on an OI Model 700 Carbon Analyzer. From May 2006 to present, Organic carbon is analyzed by combustion, on a Shimadzu TOC-V-csh Total Organic Carbon Analyzer. Dissolved reactive silica Samples for silica are collected with a peristaltic pump and tubing and in-line filtered (through a 45 micron polycarbonate filter) into 120 ml LDPE bottles and acidified to a 1percent HCl matrix by adding 1 ml of ultra pure concentrated HCl to 100 mls of sample. For every sample acidification event, three acid blanks are created by adding the same acid used on the samples to 100 mls of ultra pure water supplied from the lab. Once acidified, the samples are stable at room temperature until analysis, which should occur within one year. Until acidification, the samples should be refrigerated at 4 degrees Celsius. Dissolved reactive silica is determined by the Heteropoly Blue Method and the absorption is measured at 820 nm. The detection limit for silica is 6 ppb and the analytical range is 15000 ppb. Method Log These determinations were performed manually using a Bausch and Lomb Spectrophotometer from the beginning of the project until April 1984. From 1984 through 2005, dissolved reactive silica was determined on a Technicon Auto Analyzer II. From January 2006 to present, samples are run on an Astoria-Pacific Astoria II Autoanalyzer. total and dissolved nitrogen and phosphorus Samples for total and dissolved nitrogen and phosphorus analysis are collected together with a peristaltic pump and tubing and in-line filtered, when necessary, (through a 45 micron polycarbonate filter) into 120 ml LDPE bottles and acidified to a 1percent HCl matrix by adding 1 mL of ultra pure concentrated HCl to 100 mls of sample. For every sample acidification event, three acid blanks are created by adding the same acid used on the samples to 100 mls of ultra pure water supplied from the lab. Once acidified, the samples are stable at room temperature until analysis, which should occur within one year. Until acidification, the samples should be refrigerated at 4 degrees Celsius. The samples must first be prepared for analysis by adding an NaOH–Persulfate digestion reagent and heated for an hour at 120 degrees C and 18-20 psi in an autoclave. The samples are analyzed for total nitrogen and total phosphorus simultaneously by automated colorimetric spectrophotometry, using a segmented flow autoanalyzer. Total nitrogen is determined by utilizing the automated cadmium reduction method, as described in Standard Methods, where the absorption is monitored at 520 nm. The detection limit for total and dissolved nitrogen is approximately 21 ppb and the analytical range for the method extends to 2500 ppb. The detection limit for total phosphorus is approximately 3 ppb and the analytical range for the method extends to 800 ppb. Method Log: Prior to January 2006 samples, total nitrogen was determined on a Technicon segmented flow autoanalyzer. From 2006 to present, total nitrogen is determined by an Astoria-Pacific Astoria II segmented flow autoanalyzer.
Short Name
NTLCH01
Version Number
52

Microbial Observatory at North Temperate Lakes LTER Alkaline Phosphatase Activity in Lake Mendota 2000 - 2001

Abstract
Parameters characterizing the alkaline phosphatase activity of Lake Mendota. Samples were collected at one station in the deepest part of each lake from an integrated sample of the epilimnion.Sampling Frequency: fortnightly during ice-free season - every 6 weeks during ice-covered seasonNumber of sites: 1
Core Areas
Dataset ID
45
Date Range
-
Metadata Provider
Methods
BEFOREHAND prepare MUF-P substrate. Dissolve 180.04 mg of MUF-P in 120.0 mL total fresh Nanopure water to get 5 mM solution. Aliquot 1 mL each into thirty microcentrifuge tubes. Store in freezer. These aliquots will be thawed as needed.BEFOREHAND prepare borate buffer by dissolving 4.7675 g in 250 mL Nanopure water.PREPARE MUF standards the day before and store in cold room. Standards are prepared as follows: Prepare 5 mM MUF by adding 158.56 mg MUF in 100 mL. Vortex. Dilute 0.120 mL of 5 mM MUF in 15.0 mL total to get 40 uM solution. Prepare solutions for working standards as follows. Vortex solutions before dilutions.MUF Concentration (nM) - Preparation:0 -- 0 mL of 200 nM in 10 mL.10 -- 0.5 mL of 200 nM in 10 mL.50 -- 2.5 mL of 200 nM in 10 mL.100 -- 5 mL of 200 nM in 10 mL.200 -- 75 mL of 200 nM in 10 mL.THAW MUF-P substrate the day before in cold room.LABEL scintillation vials day before sampling. For substrate need one vial labelled 100 uM. For lake water sample need 9 vials. Three replicates samples are run for each of three size fractions. The three size fractions are less than 0.2 um water, less than 1 um water and less than 70 um (field filtered) water.DAY of sampling, filter borate buffer solution through a 0.2 um syringe filter. Dilute 0.300 mL of 5 mM MUF-P solution in 15.0 mL total Nanopure water to get 100 uM solution. Vortex MUF-P before aliquoting to samples.TURN on fluorometer to warm up (10 minutes) and set filters to 365 nm excitation, 460 nm emmission. Aliquot 10 mL of lake water into appropriate 20 mL scintillation vials labelled the day before.PERFORM measurement in room with fluorometer in the dark. First run the standard curve. If the standard curve does not appear to be linear, make new standards before running samples. If standard curve is good, add 0.010 mL of 100 uM MUF-P substrate to each ten mL sample for a final concentration of 100 nM. Note time when you spiked the samples.BEGIN immediately aliquoting 3.0 mL of sample each to glass test tubes. Aliquot all nine test ubes before adding borate buffer. Add 1.0 mL borate buffer to test tubes and mix. Note fluorescence. Continue with next sample. Do less than70, less than1 and less than 0.2 um replicates together to make more comparable (i.e. less than70 um replicate 1, less than 1 um replicate 1, less than 0.2 um replicate 1, less than 70 um replicate 2, etc.). Note time when finisihed running all initial samples. Put rest of samples in incubator.REPEAT measurements of sample for final time point thirty to sixty minutes later. Note time when you begin aliquoting 3 mL of samples to test tubes. Note time when final samples have all be run.
NTL Themes
Short Name
MOACT1
Version Number
5

Little Rock Lake Experiment at North Temperate Lakes LTER: Nutrients 1996 - 2000

Abstract
The Little Rock Acidification Experiment was a joint project involving the USEPA (Duluth Lab), University of Minnesota-Twin Cities, University of Wisconsin-Superior, University of Wisconsin-Madison, and the Wisconsin Department of Natural Resources. Little Rock Lake is a bi-lobed lake in Vilas County, Wisconsin, USA. In 1983 the lake was divided in half by an impermeable curtain and from 1984-1989 the northern basin of the lake was acidified with sulfuric acid in three two-year stages. The target pHs for 1984-5, 1986-7, and 1988-9 were 5.7, 5.2, and 4.7, respectively. Starting in 1990 the lake was allowed to recover naturally with the curtain still in place. Data were collected through 2000. The main objective was to understand the population, community, and ecosystem responses to whole-lake acidification. Funding for this project was provided by the USEPA and NSF. Parameters characterizing the nutrient chemistry of the treatment and reference basins of Little Rock Lake are measured at one station in the deepest part of each basin at the top and bottom of the epilimnion, mid-thermocline, and top, middle, and bottom of the hypolimnion. These parameters include total nitrogen, total dissolved nitrogen, nitrate, ammonia, total phosphorus, total dissolved phosphorus, dissolved reactive phosphorus, bicarbonite-reactive filtered and unfiltered silica, dissolved reactive silica, total inorganic carbon, dissolved inorganic carbon, total organic carbon, dissolved organic carbon, and total particulate matter. Sampling Frequency: varies - Number of sites: 2
Dataset ID
246
Date Range
-
Maintenance
completed
Metadata Provider
Methods
Inorganic and organic carbonSamples for inorganic and organic carbon are collected together with a peristaltic pump and tubing and in-line filtered, if necessary, (through a 0.40 micron polycarbonate filter) into glass, 24 ml vials (that are compatible with the carbon analyzer autosampler), and capped with septa, leaving no head space. The samples are stored refrigerated at 4 degrees Celsius until analysis, which should occur within 2-3 weeks.The detection limit for inorganic carbon is 0.15 ppm, and the analytical range for the method is 60 ppm.The detection limit for organic carbon is 0.30 ppm and the analytical range for the method is 30 ppm.Method Log: Prior to May 2006 samples, inorganic carbon was analyzed by phosphoric acid addition on an OI Model 700 Carbon Analyzer. From May 2006 to present, inorganic carbon is still analyzed by phosphoric acid addition, but on a Shimadzu TOC-V-csh Total Organic Carbon Analyzer.Method Log: Prior to May 2006 samples, organic carbon was analyzed by heated persulfate digestion on an OI Model 700 Carbon Analyzer. From May 2006 to present, Organic carbon is analyzed by combustion, on a Shimadzu TOC-V-csh Total Organic Carbon Analyzer.Dissolved reactive siliconSamples for silicon are collected with a peristaltic pump and tubing and in-line filtered (through a 40 micron polycarbonate filter) into 120 ml LDPE bottles and acidified to a 1percent HCl matrix by adding 1 ml of ultra pure concentrated HCl to 100 mls of sample. For every sample acidification event, three acid blanks are created by adding the same acid used on the samples to 100 mls of ultra pure water supplied from the lab. Once acidified, the samples are stable at room temperature until analysis, which should occur within one year. Until acidification, the samples should be refrigerated at 4 degrees Celsius.Dissolved reactive silica is determined by the Heteropoly Blue Method and the absorption is measured at 820 nm.The detection limit for silicon is 6 ppb and the analytical range is 15000 ppb.Method Log These determinations were performed manually using a Bausch and Lomb Spectrophotometer from the beginning of the project until April 1984. From 1984 through 2005, dissolved reactive silicon was determined on a Technicon Auto Analyzer II. From January 2006 to present, samples are run on an Astoria-Pacific Astoria II Autoanalyzer.total and dissolved nitrogen and phosphorusSamples for total and dissolved nitrogen and phosphorus analysis are collected together with a peristaltic pump and tubing and in-line filtered, when necessary, (through a 40 micron polycarbonate filter) into 120 ml LDPE bottles and acidified to a 1percent HCl matrix by adding 1 mL of ultra pure concentrated HCl to 100 mls of sample. For every sample acidification event, three acid blanks are created by adding the same acid used on the samples to 100 mls of ultra pure water supplied from the lab. Once acidified, the samples are stable at room temperature until analysis, which should occur within one year. Until acidification, the samples should be refrigerated at 4 degrees Celsius.The samples must first be prepared for analysis by adding an NaOH&ndash;Persulfate digestion reagent and heated for an hour at 120 degrees C and 18-20 psi in an autoclave.The samples are analyzed for total nitrogen and total phosphorus simultaneously by automated colorimetric spectrophotometry, using a segmented flow autoanalyzer. Total nitrogen is determined by utilizing the automated cadmium reduction method, as described in Standard Methods, where the absorption is monitored at 520 nm.The detection limit for total and dissolved nitrogen is approximately 21 ppb and the analytical range for the method extends to 2500 ppb.The detection limit for total phosphorus is approximately 3 ppb and the analytical range for the method extends to 800 ppb.Method Log: Prior to January 2006 samples, total nitrogen was determined on a Technicon segmented flow autoanalyzer. From 2006 to present, total nitrogen is determined by an Astoria-Pacific Astoria II segmented flow autoanalyzer.
Short Name
LRNUTR1
Version Number
4

North Temperate Lakes LTER: Northern Highlands Stream Chemistry Survey 2006

Abstract
We compared regional patterns in lake and stream biogeochemistry in the Northern Highlands Lake District (NHLD), Wisconsin, USA to ask how regional biogeochemistry differs as a function of the type of ecosystem considered (i.e., lakes versus streams); if lake-stream comparisons reveal regional patterns and processes that are not apparent from studies of a single ecosystem type; and if characteristics of streams and lakes scale similarly. Fifty-two streams were sampled using a stratified random design to determine regional distribution of 21 water chemistry variables during summer baseflow conditions.Sampling Frequency: once per site Number of sites: 52
Contact
Core Areas
Dataset ID
254
Date Range
-
Maintenance
completed
Metadata Provider
Methods
Site SelectionBecause lakes are a dominant feature of the region and stream characteristics could potentially differ based on their hydrologic connections to lakes, we classified streams into three categories as a function of their hydrologic connections to lakes. The first category was streams that had no lakes within the drainage network upstream of the sampling location. The second category was streams that originated from headwater lakes (i.e., no stream inlet but a stream outlet) and the headwater lake was the only lake in the drainage network above the sampling location. The final category had at least a single drainage lake (i.e., a lake with both stream inlet(s) and outlet) in the drainage network above the sampling location. We then used these categories to select sampling sites using a stratified random design for a variety of chemical and physical characteristics.All streams identified on 1:24,000 7.5 inch USGS topographical maps that crossed access points were selected as potential sampling locations and assigned to one of the three stream types. A stream could be classified by more than a single category depending on the sampling location within the drainage network. However, a single drainage network was never sampled more than once to ensure sample independence. Of the 500 possible sampling locations, 52 sites were selected and sampled.SamplingAll streams were sampled 7-10 channel widths upstream of an access point to minimize any influences caused by culverts and other features. Water samples were collected from the center of the channel using a peristaltic pump. Stream discharge was measured after Gore (2007) using cross sectional area and water velocity.Chemical AnalysesAll samples for both studies were collected and processed following the North Temperate Long Term Ecological Research (NTL-LTER) protocols (http://lter.limnology.wisc.edu). Filtering was done in the field using an in-line 0.45 μm membrane filter. All samples were stored on ice and returned to the laboratory where they were preserved according to NTL-LTER protocols. Acid neutralizing capacity (ANC) was determined by Gran titration (APHA 2005). DOC was measured on a Shimadzu TOC-V carbon analyzer. Total nitrogen and phosphorus (unfiltered, TN and TP; filtered, TDN and TDP), nitrate+nitrite (NO3-N), and ammonium (NH4-N) were quantified with an Astoria-Pacific segmented flow auto-analyzer. Soluble reactive phosphorus (SRP) in streams was measured colormetrically on a Beckman DU-800 spectrophotometer (APHA 2005). Anions (Cl- and SO4 2-) were measured using a Dionix DX-500 ion chromatograph and cations (Ca, Mg, Na, K, Fe, K, and Mn) on a Perkin Elmer ICP mass spectrometerDissolved inorganic carbon (DIC) and pH were quantified differently in the lakes and stream data sets. For the lakes data, DIC was determined with a Shimadzu TOC-V carbon analyzer, whereas DIC for the streams dataset was determined by headspace equilibration of acidified water samples in the field and direct measurement of carbon dioxide (CO2) gas on a Shimadzu gas chromatograph (Cole et al. 1994). pH measurements for the lakes dataset were quantified on non-air equilibrated samples in the lab with a Accumet 950 pH meter while direct measurements were taken in the field for the streams dataset using a hand-held Orion model 266 pH meter that was allowed to equilibrated about 20 min in the center for the stream channel.Several variables presented in this study were determined from calculations based on measured values. In streams, dissolved organic nitrogen and phosphorus (DON and DOP, respectively) were determined by the difference between inorganic nutrients and total dissolved nutrients (e.g., DOP = TDP-SRP). We were unable to determine DON in lakes due to the lack of inorganic nitrogen data. It was assumed that DOP approximately equals TDP in lakes because dissolved inorganic phosphorus concentrations in the region are typically below detection limits in the epilimnion during the summer months and consequently not quantified (NTL-LTER unpublished data).
Short Name
LOTTIG2
Version Number
19

Landscape Position Project at North Temperate Lakes LTER: Chemical Limnology 1998 - 2000

Abstract
Parameters characterizing the chemical limnology and spatial attributes of 51 lakes were surveyed as part of the Landscape Position Project. Parameters are measured at or close to the deepest part of the lake. The following parameters are measured one meter from the surface and two meters from the bottom of the lake: pH, total phosphorus, total nitrogen, total silica. The following parameters are measured one meter from the surface: dissolved organic carbon, total organic carbon, dissolved inorganic carbon, total inorganic carbon, spectrophotometric absorbance (color scan), major anions and cations, alkalinity. Sampling Frequency: once for conservative parameters (major ions, carbon, color, alkalinity); monthly for one summer for other parameters (chlorophyll, nitrogen, phosphorus, pH, silica, temperature, dissolved oxygen, and conductivity) Number of sites: 51Allequash Lake, Anderson Lake, Arrowhead Lake, Beaver Lake, Big Lake, Big Crooked Lake, Big Gibson Lake, Big Muskellunge Lake, Boulder Lake, Brandy Lake, Crampton Lake, Crystal Lake, Diamond Lake, Flora Lake, Heart Lake, Ike Walton Lake, Island Lake, Johnson Lake, Katherine Lake, Kathleen Lake, Katinka Lake, Lehto Lake, Little Crooked Lake, Little Muskie, Little Spider Lake, Little Sugarbush Lake, Little Trout Lake, Lower Kaubeshine Lake, Lynx Lake, McCullough Lake, Mid Lake, Minocqua Lake, Muskesin Lake, Nixon Lake, Partridge Lake, Randall Lake, Round Lake, Sanford Lake, Sparkling Lake, Statenaker Lake, Stearns Lake, Tomahawk Lake, Trout Lake, Upper Kaubeshine Lake, Verna Lake, Ward Lake, White Birch Lake, White Sand Lake, Wild Rice Lake, Wildcat Lake, Wolf Lake, Vilas County, WI, Iron County, WI, Oneida County, WI, Gogebic County, MI, USA
Dataset ID
91
Date Range
-
Maintenance
completed
Metadata Provider
Methods
Chloride, SulfateSamples for chloride and sulfate are collected together with a peristaltic pump and tubing and in-line filtered (through a 0.40 micron polycarbonate filter) into new, 20 ml HDPE plastic containers with conical caps. The samples are stored refrigerated at 4 degrees Celsius until analysis, which should occur within 6 months. The samples are analyzed for chloride (and sulfate) simultaneously by Ion Chromatography, using a hydroxide eluent.The detection limit for chloride is approximately 0.01 ppm and the analytical range for the method extends to 100 ppm.The detection limit for sulfate is approximately 0.01 ppm and the analytical range for the method extends to 60 ppm.Method Log: Prior to January 1998 samples, chloride was determined on a Dionex DX10 Ion Chromatograph, using a chemical fiber suppressor. From 1998 to 2011, chloride was determined by a Dionex model DX500, using an electro-chemical suppressor. From January 2011 until present, chloride is determined by a Dionex model ICS 2100 using an electro-chemical suppressor.Calcium, silicon, magnesium, sodium, potassium, iron, and manganeseSamples for calcium analysis (as well as dissolved nitrogen and phosphorus, silicon, magnesium, sodium, potassium, iron, and manganese) are collected together with a peristaltic pump and tubing and in-line filtered (through a 40 micron polycarbonate filter) into 120 ml LDPE bottles and acidified to a 1percent HCl matrix by adding 1 ml of ultra pure concentrated HCl to 100 mls of sample. For every sample acidification event, three acid blanks are created by adding the same acid used on the samples to 100 mls of ultra pure water supplied from the lab. Once acidified, the samples are stable at room temperature until analysis, which should occur within one year. Until acidification, the samples should be refrigerated at 4 degrees Celsius.Calcium, as well as magnesium, sodium, potassium, iron, and manganese are analyzed simultaneously on an optical inductively-coupled plasma emission spectrophotometer (ICP-OES). The acidified samples are directly aspirated into the instrument without a digestion. Calcium is analyzed at 317.933 nm and at 315.887 nm and viewed axially for low-level analysis and radially for high level analysis.The detection limit for calcium is 0.06 ppm with an analytical range of the method extends to 50 ppm.The detection limit for iron is 0.02 ppm with an analytical range of the method extends to 20 ppm.The detection limit for magnesium is 0.03 ppm with an analytical range of the method extends to 50 ppm.The detection limit for manganese is 0.01 ppm with an analytical range of the method extends to 2 ppm.The detection limit for potassium is 0.06 ppm with an analytical range of the method extends to 10 ppm.The detection limit for sodium is 0.06 ppm with an analytical range of the method extends to 50 ppm.Method Log: Prior to January 2002, Calcium, magnesium, sodium, potassium, iron, and manganese were determined on a Perkin-Elmer model 503 Atomic Absorption Spectrophotometer. Lanthanum at a 0.8percent concentration was added as a matrix modifier to suppress chemical interferences. From January 2002 to present, samples are analyzed for calcium on a Perkin-Elmer model 4300 DV ICP.Dissolved reactive silica is determined by the Heteropoly Blue Method and the absorption is measured at 820 nm.The detection limit for silicon is 6 ppb and the analytical range is 15000 ppb.Method Log These determinations were performed manually using a Bausch and Lomb Spectrophotometer from the beginning of the project until April 1984. From 1984 through 2005, dissolved reactive silicon was determined on a Technicon Auto Analyzer II. From January 2006 to present, samples are run on an Astoria-Pacific Astoria II Autoanalyzer.
Short Name
LPPCHEM1
Version Number
9

Lake Mendota Phosphorus Entrainment at North Temperate Lakes LTER 2005

Abstract
This dataset contains total (TP) and soluble reactive phosphorus (SRP) data collected in Lake Mendota during the summer of 2005 between 6/28/2005 and 10/14/2005 as well as high-resolution temperature data for that same time period . The phosphorus data were taken at five different locations where buoys were deployed. The buoys were deployed with HOBO temperature data loggers attached at 2 - 4 m intervals. Similarly the phosphorus samples were collected at 2 - 4 m intervals throughout the water column. The position of the five buoys changed a few times during the summer in an effort to monitor circulation patterns due to different wind directions and speeds. Manuscript using this dataset: Kamarainen, A.M., H. Yuan, C. Wu, S.R. Carpenter. 2009. One-dimensional and three-dimensional approaches converge on similar estimates of phosphorus entrainment in Lake Mendota. Limnology and Oceanography Methods 7:553-567 Sampling frequency: Water temperature: generally 1 min; some at 5 min. TP and SRP: approximately at 2 weeks intervals Number of sites: 12
Core Areas
Dataset ID
258
Date Range
-
Maintenance
completed
Metadata Provider
Methods
Kamarainen, A.M., H. Yuan, C. Wu, S.R. Carpenter. 2009. One-dimensional and three-dimensional approaches converge on similar estimates of phosphorus entrainment in Lake Mendota. Limnology and Oceanography Methods 7:553-567
Short Name
KAMWT05
Version Number
15

Lake Wingra Exclosure Experiment at North Temperate Lakes LTER: Nutrients 2005 - 2008

Abstract
Starting in late summer 2005, Wisconsin Dept of Natural Resources (WDNR), Dane County, Friends of Lake Wingra (FOLW), and NTL-LTER initiated a 3-year experiment in Lake Wingra to test the response of the native macrophyte community to clearer water produced from a major carp reduction program. This demonstration-scale experiment includes the construction of a 1.0-hectare rectangular carp exclosure with its solid vinyl walls extending from the lake shoreline to a water depth of 2.9 meters. NTL-LTER conducts the routine limnological monitoring of the lake and exclosure and is leading the science evaluation of potential lake restoration activities. The exclosure experiment was terminated in the fall of 2008. The exclosure was removed from Lake Wingra at that time. Sampling is done both within the exclosure and at a control site located nearby in the littoral zone. The sample location within the exclosure is equidistant from the side walls and approximately 75 meters from the shore in a water depth of approximately 2.5 meters. The control site sample location is approximately 75 meters west of the exclosure sample site at the same approximate distance from shore and water depth. Samples are taken at the same time and on the same schedule as the NTL-LTER limnological sampling on Lake Wingra, e.g., biweekly spring through summer, every 4 weeks in the fall, and once during the winter depending on ice conditions. Parameters measured within the exclosure and at the control site include water temperature, dissolved oxygen, secchi depth and chlorophyll-a. Additional parameters measured only within the exclosure include total Kjeldahl nitrogen, nitrate + nitrite nitrogen, ammonia nitrogen, total phosphorus, dissolved reactive phosphorus and dissolved reactive silica. Parameters characterizing the nutrient chemistry are measured at the surface within the exclosure in Lake Wingra. These parameters include total Kjeldahl nitrogen, nitrate + nitrite nitrogen, ammonia nitrogen, total phosphorus, dissolved reactive phosphorus and dissolved reactive silica. Total nitrogen is calculated by adding Kjeldahl nitrogen and nitrate/nitrite. Ammonia nitrogen is already included in the Kjeldahl nitrogen value. Sampling Frequency: generally bi-weekly during ice-free season from late March or early April through early September, then every 4 weeks through late November. Number of sites: 1
Core Areas
Dataset ID
191
Date Range
-
Maintenance
completed
Metadata Provider
Methods
Samples for nitrateornitrite and ammonium are collected together with a peristaltic pump and tubing and in-line filtered (through a 40 micron polycarbonate filter) into new, 20 ml HDPE plastic containers with conical caps. The samples are stored frozen until analysis, which should occur within 6 months. The samples are analyzed for nitrateornitrite (and ammonium) simultaneously by automated colorimetric spectrophotometry, using a segmented flow autoanalyzer. Nitrateornitrite is determined by utilizing the automated cadmium reduction method, as described in Standard Methods, where the absorption is monitored at 520 nm.The detection limit for nitrateornitrite is approximately 2 ppb and the analytical range for the method extends to 4000 ppb.Ammonium is determined by utilizing the Berthelot Reaction, producing a blue colored indophenol compound, where the absorption is monitored at 660 nm.The detection limit for ammonium is approximately 3 ppb and the analytical range for the method extends to 4000 ppb.Method Log: Prior to January 2006 samples, nitrateornitrite was determined on a Technicon segmented flow autoanalyzer. From 2006 to present, nitrateornitrite is determined by an Astoria-Pacific Astoria II segmented flow autoanalyzer.Samples for total and dissolved phosphorus and nitrogen analysis are collected together with a peristaltic pump and tubing and in-line filtered, when necessary, (through a 40 micron polycarbonate filter) into 120 ml LDPE bottles and acidified to a 1percent HCl matrix by adding 1 mL of ultra pure concentrated HCl to 100 mls of sample. For every sample acidification event, three acid blanks are created by adding the same acid used on the samples to 100 mls of ultra pure water supplied from the lab. Once acidified, the samples are stable at room temperature until analysis, which should occur within one year. Until acidification, the samples should be refrigerated at 4 degrees Celsius.The samples must first be prepared for analysis by adding an NaOH&ndash;Persulfate digestion reagent and heated for an hour at 120 degrees C and 18-20 psi in an autoclave.The samples are analyzed for total nitrogen and total phosphorus simultaneously by automated colorimetric spectrophotometry, using a segmented flow autoanalyzer. Total phosphorus is determined by forming a phosphoantimonylmolybdenum complex and the absorption is monitored at 880 nm.The detection limit for total phosphorus is approximately 3 ppb and the analytical range for the method extends to 800 ppb.Method Log: Prior to January 2006 samples, total phosphorus was determined on a Technicon segmented flow autoanalyzer. From 2006 to present, total phosphorus is determined by an Astoria-Pacific Astoria II segmented flow autoanalyzer.
Short Name
FOLWEXNU
Version Number
23

Zooplankton of Small Lakes and Wetland Ponds in Wisconsin - North Temperate Lakes LTER 1996

Abstract
We sampled zooplankton communities from 54 small water bodies distributed throughout Wisconsin to evaluate whether a snap-shot of zooplankton community structure during early spring could be used for the purpose of differentiating lakes from wetlands. We collected a single set of zooplankton and water chemistry data during a one-month time window (synchronized from south to north across the state) from an open water site in each basin as a means to minimize and standardize sampling effort and to minimize cascading effects arising from predator-prey interactions with resident and immigrant aquatic insect communities. We identified 53 taxa of zooplankton from 54 sites sampled across Wisconsin. There was an average of 6.83 taxa per site. The zooplankton species were distributed with a great deal of independence. We did not detect significant correlations between number of taxa and geographic region or waterbody size. There was a significant inverse correlation between number of taxa and the concentration of calcium ion, alkalinity and conductivity. One pair of taxa, Lynceus brachyurus and Chaoborus americanus, showed a significant difference in average duration of sites of their respective occurrence. All other pairs of taxa had no significant difference in average latitude, waterbody surface area, total phosphorus, total Kjeldahl nitrogen, alkalinity, conductivity, calcium ion, sulfate, nitrate, silicate or chloride. Taxa were distributed at random among the sites - there were no statistically significant pairs of taxa occurring together or avoiding each other. Multivariate analysis of zooplankton associations showed no evidence of distinct associations that could be used to distinguish lakes from wetlands. Zooplankton community structure appears to be a poor tool for distinguishing between lakes and wetlands, especially at the relatively large scale of Wisconsin (dimension of about 500 km). The data suggest that a small body of water in Wisconsin could be classified as a wetland if it persists in the spring and summer for only about 4 months, and if it is inhabited by Lynceus brachyurus, Eubranchipus bundyi, and if Chaoborus americanus and Chydorus brevilabris are absent. Schell, Jeffery M., Carlos J. Santos-Flores, Paula E. Allen, Brian M. Hunker, Scott Kloehn, Aaron Michelson, Richard A. Lillie, and Stanley I. Dodson. 2001. Physical-chemical influences on vernal zooplankton community structure in small lakes and wetlands of Wisconsin, U.S.A. Hydrobiologia 445:37-50 Number of sites: 54
Creator
Dataset ID
224
Date Range
-
Maintenance
completed
Metadata Provider
Methods
Schell, Jeffery M., Carlos J. Santos-Flores, Paula E. Allen, Brian M. Hunker, Scott Kloehn, Aaron Michelson, Richard A. Lillie, and Stanley I. Dodson. 2001. Physical-chemical influences on vernal zooplankton community structure in small lakes and wetlands of Wisconsin, U.S.A. Hydrobiologia 445:37-50
Short Name
DODSON3
Version Number
25
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