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 dam to the mouth of the estuary. 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 in April and the low-flow, post-growth season in September.
EXPERIMENTAL DESIGN AND METHODS:
For all dates during 1994, samplings were made within 2 hours of high tide, except for samples that have a station designation of "low", which were collected within 2 hours of low tide. For all other dates, samples were collected Salinity was measured using a refractometer or calculated from conductivity. Conductivity was measured using a Hydrolab H2O probe with a Scout 2 Water Quality Data System. Temperature was measured using the Hydrolab H2O probe or a field thermometer. Conductivity and temperature have also been measured using a YSI Sonde probe since 2004. A secchi disk was used to obtain the secchi depth, which was considered to be the shallowest depth at which black and white sections of the disk were indistinguishable. During 1994, approximately 10 liters of water were collected in an HDPE carboy. 1 liter polycarbonate bottles were used for later water collections. In the lab, the water was filtered through a GFF filter within 3 hours of collection, and preserved immediately for later analysis of dissolved materials, and filters preserved for later analysis of particulate materials. For details on analytical procedures, see Analytical Methods.
NOTES AND COMMENTS:
Samples for NH4 analysis were filtered and preserved in the field, immediately upon collection, for all transects from 3/94 to 8/94. For the July 11, 2000 transect, water samples for nutrient analysis were collected at specific salinities, rather than at the designated stations. For the September 11, 2001 transect, water samples for nutrient analysis were collected at specific salinities corresponding to the water masses in which the metabolism measurements were made during the dusk transect on September 10, 2001. Sampling at specific salinities has been done consistently since the April 2006 transect. Contact Chuck Hopkinson (firstname.lastname@example.org) for more details on sampling. Starting in 2008, we recorded the actual location at which the nutrients were sampled (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 for each transect. Sites are measured using GPS and state coordinates no longer included in database.
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