A complete list of all protocols can be found here:
http://arc.lternet.edu/streams/arctic-lter-streams-protocol

Summary of Site Locations:

Kuparuk River:
In 1983, phosphorus addition through dripping began at the site designated as 0.0k. Stations downstream of 0.0k have positive numbers and upstream have negative numbers. The reach upstream of the phosphorus addition has remained the reference reach for the duration of this dataset. Downstream of the original phosphorus addition was the fertilized reach.  In 1985, the phosphorus dripper moved to 0.59k, creating a recovery reach from 0.0k to 0.59k. In 1996, the dripper was moved downstream to 1.4k, creating a recovery reach between 0.6k and 1.39k. The historic recovery reach from 0k to 0.59k had not been fertilized for 11 years, so it was then considered part of the reference reach after 1996. In 2011, an additional phosphoric acid dripper was placed at 0k to fertilize the area of stream from 0k to 1.4k. These areas became known as the "Re-Fert" zones. The stream reach above the historic dripper from 1985 to 1996 (0k to 0.59k) became known as Re-Fert 1, and the once fertilized reach from the 1985 to 1996 dripper (0.6k to 1.39k) became known as Re-Fert 2. Fertilization of the Kuparuk concluded at the end of 2016. All sites downstream of the 0k dripper are considered "Recovery" sites from 2017-present. Reach information can be found in data for specific time periods. A table is provided below for various stations. The 0k riffle is about 75 meters downstream of the actual "0k" deployment location of the dripper. Therefore, the actual dripper location should be known at -0.075k.

+-----------------+-----------------+-----------------+-----------------+-----------------+

| Kuparuk Station |    1983-1984    |    1985-1995    |    1996-2010    | 2011-Present    |

+-----------------+-----------------+-----------------+-----------------+-----------------+

| -0.47           | Reference       | Reference       | Reference       | Reference       |

| -0.3            | Reference       | Reference       | Reference       | Reference       |

| -0.177          | Reference       | Reference       | Reference       | Reference       |

| -0.075          | DRIPPER IS HERE |                 | Reference       | DRIPPER IS HERE |

| 0               | Fertilized      | Recovery A      | Reference       | Re-Fert 1       |

| 0.3             | Fertilized      | Recovery A      | Reference       | Re-Fert 1       |

| 0.56            | Fertilized      | Recovery A      | Reference       | Re-Fert 1       |

| 0.59            | Fertilized      | DRIPPER IS HERE |                 |                 |

| 0.74            | Fertilized      | Fertilized      | Recovery B      | Re-Fert 2       |

| 1               | Fertilized      | Fertilized      | Recovery B      | Re-Fert 2       |

| 1.39            | Fertilized      | Fertilized      | Recovery B      | Re-Fert 2       |

| 1.4             | Fertilized      | Fertilized      | DRIPPER IS HERE | DRIPPER IS HERE |

| 1.5             | Fertilized      | Fertilized      | Fertilized      | Fertilized      |

| 1.8             | Fertilized      | Fertilized      | Fertilized      | Fertilized      |

| 2               | Fertilized      | Fertilized      | Fertilized      | Fertilized      |

| 2.5             | Fertilized      | Fertilized      | Fertilized      | Fertilized      |

| 3               | Fertilized      | Fertilized      | Fertilized      | Fertilized      |

| 4               | Fertilized      | Fertilized      | Fertilized      | Fertilized      |

| 5.5             | Fertilized      | Fertilized      | Fertilized      | Fertilized      |

| Hershey Creek   | Tributary       | Tributary       | Tributary       | Tributary       |

+-----------------+-----------------+-----------------+-----------------+-----------------+

Oksrukuyik Creek:
In 1990, reference sampling took place throughout various stations on the Oksrukuyik. From 1991 to 1992, phosphorus was added at 0k. In 1993, both Nitrogen and Phosphorus were added at 0k. Fertilization came to an end in 1997, leaving a recovery reach downstream of 0k and a reference reach upstream of 0k.  A table is provided below for various stations.

Imnavait Creek:
Stations A and AA are upstream of the access road. Station B is just downstream of the road. Station C is about 250m downstream from the access road. Station D is just upstream of the footbridge of the Weintraub boardwalk. Station E is about 50m upstream of the Haul Road.

Toolik River TK:
Toolik River Thermokarst (TK) first became active in 2004. It is this year that the Arctic LTER started some sampling. From 2009-2011 the ARCSS/TK project used this site as one of their main sampling locations. Upon this projects completion, the Arctic LTER continued to sample about two times a year. The Toolik River TK location has five sampling sites. TK Above is a sampling location above the thermokarst feature, about forty meters above the headwall. TK Mid was sampled just below the main thermokarst feature. TK Low is located below the thermokarst, approximately 200 meters before the small stream flowing from the thermokarst flows into the Toolik River. Toolik River REF is located about forty meters upstream of where the thermokarst water track enters the river. Toolik River IMP is located about twenty five meters downstream of where the water track enters the river.

Toolik River TK-4:
In 2014, a "gurgler" named Toolik River TK-4 formed upstream of the Toolik River reference reach for the main thermokarst. A new station was sampled just upstream of the old access road to measure reference conditions before this thermokarst.

Toolik Inlet:
1st riffle upstream of the Toolik Boardwalk Bridge crossing.

I-minus-2 TK:
I-minus-2 Thermokarst (TK) first became active in 2005. It is this year that the Arctic LTER started some sampling. From 2009-2011 the ARCSS/TK project used this site as one of their main sampling locations. Upon this projects completion, the Arctic LTER continued to sample about two times a year. The I-minus-2 TK location has five sampling sites. The main thermokarst track named TK High is located above the main thermokarst and joins with another water track named TK High Side, which is not affected by the thermokarst. Once these two channels join, they flow through the most heavily impacted portion of the thermokarst. Downstream of the thermokarst, there is another sampling location named TK Low. On the main stream of I-minus-2, there is a sampling location about twenty five meters before the confluence of the stream and the impacted water track named I-minus-2 REF, and about thirty five meters downstream of the confluence named I-minus-2 IMP.

Burn Sites:
The Anaktuvuk River region, which burned in 2007, is one of the largest tundra fires recorded on the North Slope. This site has been called “The Burn”, and has been extensively researched. The LTER Burn project, active from 2008 to 2011, sampled numerous rivers throughout the Burn. The Arctic LTER has maintained four main sampling locations upon the completion of this study, including the North River, South River, and both the Reference and Impacted streams of the Valley of the Thermokarst (VTK).

Burn Reference Sites:
Located outside of the Burn, these sites were sampled lightly during the main Burn campaign and once in 2014. New sites were added in 2014.

Caterpillar Creek TK:
A new thermokarst discovered when flying to the Burn in 2014. This site includes a reference site (REF) before the feature, impacted site (IMP) about 150 meters downstream of the feature, and a site at the outlet of the thermokarst impacted water track (TK Low).

Roche Moutonnee Creek:
Riffle located at the USGS gauging station upstream of the Dalton Highway crossing. Benthic samples are collected slightly downstream of the gauging station. Samples taken at site "DS" were collected approximately 50 meters downstream of the road crossing.

Trevor Creek:
Sampling site approximately 200 meters upstream of the Dalton Highway crossing.

Summary of Site Analysis Methods:

Alkalinity:
Alkalinity is the measurement of the Acid Neutralizing Capacity (ANC) of a water sample.  Alkalinity is usually reported in units of milliequivalents per liter of sample (meq/L).  In Toolik area waters, ANC is due primarily to HCO3, CO3-2, OH-, and certain organic bases.  Of these, HCO3 is usually by far the most important species.  We are interested in measuring alkalinity for a couple of reasons.  When coupled with a measurement of pH, alkalinity can be used to compute total dissolved inorganic carbon (needed for primary production measurements), and the partial pressure CO2 gas in the water (useful for atmosphere-water interaction studies).  In waters which have a near-neutral pH (most of the Toolik area), alkalinity correlates well with the total concentration of dissolved ions, and hence can be useful in categorizing the overall ionic state of a water sample.  Also, when used as a long-term monitoring tool, it can detect acidic impacts on lakes and rivers.  Alkalinity is usually measured by titrating a water sample with a strong acid.  The alkalinity is a measurement of the amount (equivalents) of acid needed to exactly neutralize the original ANC of the water sample.  There are two common methods of performing this titration; both are based on monitoring pH as acid is added to a water sample.  The procedure outlined below is based on the “Gran” methodology.  In the Gran method, a series of pH measurements are made.  The alkalinity is determined by an analysis of the rate at which pH changes in response to acid additions.  In practice, the alkalinity is computed with a computer program written for this purpose. Samples were run at the Marine Biological Laboratory (MBL) 2010 and prior. All samples analyzed after 2010 were analyzed at the University of Vermont Rubensten Ecosystem Science Laboratory (RESL) in Burlington, VT including some backlog samples from previous years.

Ammonium:
Indolphenol Blue with a Technicon Autoanalyzer (Used 1983-1999):
In order to detect the low levels of ammonium found in most unfertilized stream reaches and lakes, it was necessary to use a manual method at Toolik.  A blue compound, indolphenol blue, is formed by the reaction of ammonium, hypochlorite, and phenol.  The color is intensified by nitroprusside.  A spectrophotometer read these samples at a 630nm wavelength with a 5cm light path capacity. Reference Citations: R.G. Wetzel and G.E. Likens. 1979.  Limnological Methods.  Saunders. Philadelphia.  APHA.  1985.  Standard Methods.  Boyd.  Albany.

Holmes et al 1999 OPA Method (Used 1999-2014):
Fluorescence is produced by the reaction of OPA with ammonium.  Fluorometry is sensitive and simple so it seems to be a good way to measure ammonium, particularly at low levels.  Details of methods, reagents, etc are given in Holmes et al. 1999 (CJFAS 56:1801-1808). All samples were analyzed at Toolik Field Station.
R.M. Holmes, A. Aminot, r. Kerouel, B.A. Hooker, and B.J. Peterson. 1999. A simple and precise method for measuring ammonium in marine and freshwater ecosystems. Can. J. Fish. Aquat. Sci. 56: 1-8.

Salicylate Method on Lachat (Used 2013-Present):
After heating, sample water reacts with salicylate and hypochlorite in an alkaline phosphate buffer. An emerald green color is produced which is proportional to the ammonia concentration. The color is intensified by the addition of sodium nitroprusside and read by the spectrophotometer at a 660nm wavelength. Lachat QuikChem Method 10-107-06-2O. All samples were shipped frozen and analyzed at the University of Vermont Rubensten Ecosystem Science Laboratory (RESL) in Burlington, VT

Anions:
Samples were analyzed on a Dionex Ion Chromatograph for sulfate and chloride ions. Ion chromatography is a form of liquid chromatography which analyzes concentrations of anions by how they interact with a resin. Anions interact with this resin differently based on their molecular makeup. Samples pass through a pressurized chromatographic column where anions are absorbed by column constituents. As the eluent, a liquid that extracts ions, runs through the column, ions begin separating from the column. Concentrations of certain ions (such as Cl-1 and SO4) are determined by their retention time as they are separated from the column. Samples were run at the Marine Biological Laboratory (MBL) 2010 and prior. All samples analyzed after 2010 were analyzed at the University of Vermont Jeffords Laboratory in Burlington, VT including some backlog samples from previous years.

Cations:
Cation analysis used the method from  Rains, Theodore, C.  1984.  Atomic Absorption Spectrometry.  Water Analysis, Vol II Edited by Roger A. Minear and Lawrence H. Keith.  An Absorption/Emission Spectrophotometer was used at the Marine Biological Laboratory (MBL) 2010 and prior. All samples analyzed after 2010 were analyzed at the University of Vermont Jeffords Laboratory with a Absorption/Emission Spectrophotometer in Burlington, VT including some backlog samples from previous years.

Chlorophyll:
Sestonic chlorophyll a was sampled by filtering stream water through a 47mm filter. Benthic/Epilithic chlorophyll a was sampled by filtering a small amount of scrubbate through a 47mm filter.  The filters were returned to the lab, frozen from 1-7 days, and placed in 10ml of 90% buffered acetone and extracted for 24 hours. The samples were then read on a Turner 111 (1990-1991) and Turner 450 (1992-1997), TurnerDesigns 10AU (1998-2009) Fluorometers.
Epilithic chlorophyll was sampled using either a "2x2" or "whole rock" scrubbing method.
2x2 method: Epilithic chlorophyll was sampled three times on rocks from riffles. Using a plastic 35mm slide mount to partition a known area, the algae was scraped from the rock surface with a brass brush. The brushed area of the rock, the brush and slide holder were then rinsed and the slurry collected and brought up to a volume of 56 ml.  Five rocks were sampled from each riffle station.
Whole rock method: Whole rock samples were also collected from riffles.  The upper surface of rocks fitting into an area of 546cm^2 ( +/- 18cm) (363 cm2 ( +/- 18cm) in 1996) were scrubbed with a brass brush.   The slurry was brought to a volume of 1 L.The samples were returned to the lab where they were filtered through a GF/C or GF/F glass fiber filter.
Entire rock method: Same as whole rock but entire rocks were scrubbed, not just the top of the rock.
Reference Citations: R.G. Wetzel and G.E. Likens. 1979.  Limnological Methods. Saunders. Philadelphia.
Notes:  In 2004 several adjustments were made to the protocol from 2003. Extraction took place at approximately 4C using chilled acetone. A multipoint curve was analyzed using a chl a stock std. A Turner Designs solid standard could then be utilized as a check. GF/F 25mm filters were used. Additionally, chl a was corrected for pheophytin following EPA 445 and data is reported in corrected chl a. For more information please reference the chlorophyll protocol available on the Arctic LTER website.

Dissolved Organic Carbon:
The TOC-L uses carrier gas, which is used to supply oxygen at 150mL/min to the combustion tube filled with oxidation catalyst. This tube is heated to 680 degrees C and samples are burned in the combustion tube to form carbon dioxide. The carrier gas, containing the carbon dioxide created from the combustion, flows into a dehumidifier, where it is cooled and dehydrated. The gas then goes through a halogen scrubber before it reaches the cell of a non-dispersive infrared NDIR gas analyzer. This analyzer detects the carbon dioxide, and the analog detection signal of the NDIR forms a peak. The area of this peak is measured by a data processor, and the peak’s area is proportional to the concentration of the TC in the sample. All samples were acidified and run at the Marine Biological Laboratory (MBL) 2010 and prior. All samples analyzed after 2010 were analyzed at the University of Vermont Rubensten Ecosystem Science Laboratory (RESL) in Burlington, VT including some backlog samples from previous years.

Nitrate / Nitrite:
Samples are passed through a copperized cadmium column to reduce nitrate to nitrite.  The nitrite (both original and reduced nitrate) are determined by diazotizing with sulfanilamide and coupling with N-(1-napthyl)-ethylenediamine dihydrochloride to form a highly colored azo dye which is measured colorimetrically. All samples were frozen and run at the Marine Biological Laboratory (MBL) 2010 and prior using the Lachat Method 31-107-04-1C. All samples 2011 and after were shipped frozen and analyzed at the University of Vermont Rubensten Ecosystem Science Laboratory (RESL) in Burlington, VT using method 31-107-04-1E. Many of the Kuparuk ISCO samples from 2017 were analyzed on a SEAL AA3 segmented flow analyzer at RESL due to technical issues with the Lachat in 2018.

Particulate Carbon and Nitrogen:
Particulate samples were collected by filtering water through an ashed GF/F filter and drying for 24 hours at 60oC. The  FlashEA elemental analyzer uses a combustion method to convert the sample elements to the simple gases (CO2, H2O, and N2). The sample is first oxidized in a pure oxygen environment; the resulting gases are then controlled to exact conditions of pressure, temperature, and volume. Finally, the product gases are separated. Then, under steady-state conditions, the gases are measured as a function of thermal conductivity. A known standard is first analyzed to calibrate the analyzer in micrograms. The calibration factor is then used to determine unknowns. All quantitation is performed on a weight percent basis, using a gravimetric technique. The systems uses a steady state, wavefront chromatographic approach to searate the measured gases. This approach involves separating a continuous homogenized mixture of gases through a chromatographic column. As the gases elute, each gas separates as a steady state step, with each subsequent gas added to the previous one. Consequently, each step becomes the reference for the subsequent signal.

Particulate Phosphorus:
Particulate samples were collected by filtering water through an ashed GF/F filter and drying for 24 hours at 60oC. Particulate matter collected on a glass fiber filter is ignited at low temperature to destroy organic matter.  The ignited filter is heated with dilute HCl, which extracts the phosphorus and converts it to ortho-phosphate.  The phosphorus is then analyzed by a version of the soluble reactive phosphorus method.

Soluble Reactive Phosphorus:
The method used for soluble reactive phosphorus determination is based on Parsons et al. 1984. It involves the reaction of phosphorus with molybdate, ascorbic acid, and trivalent antimony. The molybdic acids are reduced to a blue-colored complex which is then read for absorbance on a UV spectrophotometer. A 1 cm cell is used in the spectrophotometer. From 1983 to 1996 samples were analyzed with a Technicon Autoanalyzer II at Toolik. From 1997 to 2014 samples were analyzed at Toolik Field Station with a Spectrophotometer. The same method is used from 2014 to present, but samples are shipped frozen from Toolik to the Rubensten Ecosystem Science Laboratory (RESL) in Burlington, VT. Many of the Kuparuk ISCO samples from 2017 were analyzed on a SEAL AA3 segmented flow analyzer in tandem with the nitrate analysis of those samples.
Parsons, T.R., Maita, Y., Lalli, C.M.,  1984.  A manual of chemical and biological methods for seawater analysis.  Pergamon Press, New York.  pp. 173.

Total Dissolved Nitrogen:
TDN was analyzed from 1994 to 2004 with a persulfate digestion on a Lachat. Starting in 2005, all samples were analyzed (including some backlog samples) using a TOC-L with a TNM-L addition. This instrument uses carrier gas, which is used to supply oxygen at 150mL/min to the combustion tube filled with oxidation catalyst. To detect TN, the sample also goes through a combustion tube at 720 degrees C. The sample decomposes at this temperature to become nitrogen monoxide. The carrier gas carries the nitrogen monoxide to a dehumidifier, where it is dehydrated. Then it enters a chemiluminescence gas analyzer, where the nitrogen monoxide is detected. The detection signal from the analyzer generates a peak which are proportional to the concentration of the TN in the sample. All samples were acidified and run at the Marine Biological Laboratory (MBL) 2010 and prior. All samples analyzed after 2010 were analyzed at the University of Vermont Rubensten Ecosystem Science Laboratory (RESL) in Burlington, VT including some backlog samples from previous years.

Total Dissolved Phosphorus:
The determination of total dissolved phosphorus is done by liberating organic phosphorus as inorganic phosphate through oxidation by persulfate. The total phosphate can then be determined using the molybdate method. Slightly different concentrations of reagent are used for this method. Please use caution when using TDP values from 1994-2003 for Recovery and Fertilized reaches, since these were never re-run. All samples were acidified and run at the Marine Biological Laboratory (MBL) 2010 and prior. All samples analyzed after 2010 were analyzed at the University of Vermont Rubensten Ecosystem Science Laboratory (RESL) in Burlington, VT including some backlog samples from previous years.
***Data Note***
Reference TDP samples were rerun for 1994-2003 on December 4, 2007 at the MBL by EBS. Some runs from 1994-2003 had poor check standards and/or blanks when they were originally run. Reference samples re-run in 2007 were of much higher quality