Water chemistry including nutrient concentrations for various forms of N, P, C, as well as suspended sediments and light extinction coefficients, was determined from bi-annual nutrient transects along the Plum Island Sound estuary from the Parker River Dam to the mouth of the sound. Grab samples were taken at 11 sites along a 24 km transect from the mouth of the estuary to as near the dam at the head of the estuary as poosible. These samples have generally been collected in Spring and Fall and are done in conjunction with metabolism transects measuring dissolved oxygen levels. The Spring and Fall transects correspond to the high-flow, pre-growth season and the low-flow, post-growth season, respectively.
General sampling protocol
Semi-annual samplings for nutrients and water quality are conducted in Spring - pre growing season and typically characterized by high river discharge (spring freshet) and Fall - post growing season and generally lower discharge. Sampling times are coordinated with separate surveys done along the same transect measuing oxygen. Grab samples and sonde measurements are taken at 11 stations along a 24Km transect from the mouth of Plum Island Sound up the main stem of the Parker River to as near the dam at the head of the estuary as possible, depending on tide stage at time of sampling. Sampling times are coordinated with separate surveys done along the same transect measuing oxygen using a flow-through sampling technique. (see EST-PR-O2: PIE LTER transects of the Parker River Plum Island Sound Estuary, Massachusetts conducted at dawn and dusk, containing dissolved oxygen, conductivity, temperature, percent saturation, pH, DIC and pCO2 data)
Conductivity (and salinity) and temperature are measured using appropriate probes on a water quality sonde (Hydrolab H20 for 1994-2003; YSI Sonde for 2004-2019). Water quality sondes are backed up by field thermometers and refractometers.
Secchi depth is considered to be the shallowest depth at which the black and white sections of a Secchi disk become indistinguishable.
Water samples for nutrients are collected in acid-washed, 1-liter polycarbonate bottles. Samples are transported to the field lab and filtered within three hours of collection through GF/F filters. Filtered samples are immediately preserved for later analysis of dissolved materials, and filters are preserved for later analysis of particulates.
From 1994 through 2005, samples were taken at designated stations along the transect; latitude and longitude and state plane variables assigned to these stations were fixed. Beginning with the April 2006 transect, samples have been collected in salinity space rather than at fixed station locations (because they are sampled in salinity space, this location will vary depending on the salinity gradient and depending on the tide at which the samples were taken) Beginning in 2008, GPS allowed more precise location of sampling points to be taken at the time of sampling, and state coordinates were no longer included in the dataset. For more details on sampling protocols, contact Nat Weston (firstname.lastname@example.org).
on going data collection
01) updated to EML level 4-5
02) updated data through spring 2007. 9/24/2007
03) added flag data parameters
04) added additional data for 4/15/08
05) added additional flag data parameters
06) updated data through spring 2008, 4/15/08
Version 07: January 24, 2012, updated data and metadata through 2010. Used MarcrosExportEML_HTML (working)pie_excel2007.xlsm 1/18/12 4:51 PM for QA/QC to EML 2.1.0
Version 08: February 21, 2016, Data and metadata updates to comply with importation to Drupal and LTER PASTA. Used MarcrosExportEML_HTML (working)pie_excel2007_Jan2015.xlsm 1/15/15 4:26 PM for QA/QC to EML 2.1.0
Version 09: August 28, 2019, data and metadata updates to comply with importation to DEIMS7 and LTER Data Portal. Used MarcrosExportEML_HTML (working)pie_excel2007_Jun2019.xlsm 6/7/19 12:58 PM for QA/QC to EML 2.1.0
Version 11: March 14, 2022, data and metadata updated through 2019; methods edited for clarity. Used MarcrosExportEML_HTML (working)pie_excel2007_Jun2019.xlsm 6/7/19 12:58 PM for QA/QC to EML 2.1.0