Introduction to the Gulf of Maine Contaminated Sediments Database

Organics Tables

The organics section of the Database includes three parts: (1) General Organics; (2) Polychlorinated Biphenyls (PCBs) and Pesticides; and (3) Polyaromatic Hydrocarbons (PAHs). Approximately 3,443 samples are compiled that have analysis of one or more organic contaminants. Lists of the parameters included in this section of the Database can be found under Database Structure.

Each table contains entries for every sample in the "Unique Identification Number" (Unique ID) and "Source of Reference" fields. This allows the user to also access information on the samples from other tables in the database. The data tables contain columns for the source of the data, the year of the publication or data collection, the analytical laboratory, the methods used, any replicates for laboratory quality control, 127 chemical parameters, as well as qualifier and detection limit fields (See Parameter Listing).

Each table is an Excel version 4.0 document. The General Organics table uses 1.4 MB of hard disk space and has 10 different parameters for general organic contaminants. The PCBs and Pesticides table uses 4.9 MB of hard disk space and records 30 different PCB congeners, including six Arochlors, as well as 39 pesticide parameters. The table of PAHs uses 5.4 MB of hard disk space and has 48 PAH parameters.

These tables can be used independently to assess the quality of the data in each field by examining the qualifiers given with each analysis. It is VITAL that this quality assurance step be taken by the user prior to using the data for scientific and interpretive purposes! 79% of the samples include information regarding methodology; however, the reported methods vary widely. Generally in environmental chemistry, accurate quantitation at low concentration levels is difficult, due to a variety of confounding factors that include the lack of pure standard reference material, separation techniques in which there are co-eluting compounds, , interfering co-extracted materials, and so forth. Consequently, comparison of separate data sets should be carried out with extreme caution.

Before downloading the organics data, please read Organic Contaminant Analysis: In flux with time (Farrington and Tripp), which discusses how one must use caution when merging datasets for which methods that are in flux.

Once the user is satisfied with the selection of appropriate data, the organic contaminant data tables may be used in conjunction with information from the station table (e.g. latitude and longitude data) to illustrate and study the distribution of the samples and their concentrations. Examples of plots and graphs that describe the organics data in the Contaminated Sediments Database for the Gulf of Maine are displayed here

View plots and graphs of selected organic parameters.