Details and Metadata

Printer-friendly version     View XML version    Download Ecological Metadata Language file


Methods

The methods followed in the creation of the dataset, including description of field, laboratory and processing steps, and quality control procedures

Current Methods


  • Started: 2012-05-01

    From summer 2004 to spring of 2013 sampling was done on an event basis with co-located wet-only precipitation collectors; An Aerochemetrics (ACM) and a N-CON Systems (N-CON). Precipitation was collected in the morning after every precipitation event with both ACM and N-CON collectors. Lids open in response to precipitation.

  • Deposition collection
    Started: 2004-07-27

    A special collector was designed for MDN which is a modification of the wet-only deposition collector used by NADP for other observations. The modifications include replacing the collection bucket with a smaller insulated sampling chimney.

  • Sampler processes
    Started: 2004-07-27

    The lower portion of the sampler is enclosed and insulated. A small space heater is used to maintain the winter temperature between 10 and 15 °C to prevent samples from freezing. Heat from the interior rises up the chimney to warm the collection funnel which melts ice and snow on contact with the funnel. A ventilation fan pulls filtered air through the sampler during warm weather to moderate the inside temperatures.

  • Mercury sampling train
    Started: 2004-07-27

    The mercury sampling train consists of an approximately 128-mm diameter, borosilicate glass funnel, an acid-cleaned, wide-bore (3-mm) capillary tube, and a 2-liter, borosilicate glass bottle. The capillary tube is connected to the funnel by a ground glass fitting. The opposite end of the capillary tube is expanded to form a sphere with a diameter slightly larger than the mouth of the sample bottle. A small hole in the sphere allows water to drain into the sample bottle.


  • Started: 2004-07-27

    Sample bottles are pre-charged with 20.0 mL of dilute (0.12 M) hydrochloric acid as a preservative to prevent microbial action and provides sufficient chloride ion to complex mercury in solution and prevent conversion to and loss of Hg0


  • Started: 2004-07-27

    The field operators receive a pre-cleaned sampling train each week. Every Tuesday, the exposed sampling train is removed using clean techniques and returned to the MDN laboratory, Frontier Global sciences, Inc. in Seattle, WA (Hg Analytical Laboratory, "HAL"), along with the sample bottle containing any collected precipitation.


  • Started: 2004-07-27

    All operators wear plastic gloves when handling the sampling train and follow special procedures to avoid contaminating the sample. Any overflow from the bottle is collected and measured to determine the total precipitation amount, but it is not included with the sample sent to the lab.

  • Precipitation monitoring
    Started: 2004-07-27

    Each site is also equipped with a weighing-bucket rain gauge that provides a continuous record of rainfall amounts. Rainfall is recorded to the nearest 0.01 in. The rain gauge also monitors the precipitation sampler, recording whether the sampler was properly open during wet periods and closed during dry periods.

Past Methods (No longer in use)


  • Started: 2005-08-01
    Ended: 2012-05-01

    During spring 2013 the sampling frequency changed from event based to the weekly composite sampling that is typical of the network. Precipitation collected over course of one week. Sampling period is Tuesday to Tuesday.

Dataset Fields

Detailed documentation of the fields comprising the dataset, including the type of measurement, units where applicable, and any controlled vocabularies or code lists present in the data


Field Name Caption Description Additional Information
SITEIDSite ID

Site identification code

Measurement type: Nominal
DATEONDate On

Date and time that sample collection began

Measurement type: DateTime
Date/Time Format:
DATEOFFDate Off

Date and time that sample collection ended

Measurement type: DateTime
Date/Time Format:
RGPPTPrecipitation

Precipitation amount as measured by rain gauge

Measurement type: Ratio
Units:
SVOLSample Volume

Volume of the sample analyzed

Measurement type: Ratio
Units:
SUBPPTCalculated Precipitation

Precipitation amount, equal to gauge precipitation or, when absent, calculated from bottle catch volume

Measurement type: Ratio
Units:
HGCONCMercury Concentration

Concentration of mercury measured in the sample

Measurement type: Ratio
Units:
HGDEPMercury Deposition

Deposition of mercury derived from the precipitation and concentration data

Measurement type: Ratio
Units:
SAMPLETYPESample Type

Measurement type: Nominal
QRQuality Code

Qualtiy assurance code, including invalid data (QR = C)

Measurement type: Nominal
NOTESLab Notes

Notes attached by lab

Measurement type: Nominal
YRMONTHSample Year-Month

Month and year of sample

Measurement type: DateTime
Date/Time Format:
DATEMODDate Mod

Unknown

Measurement type: DateTime
Date/Time Format:

Sampling Equipment

Equipment and software used to collect data, including how that equipment was used.

Current Equipment

  • Precipitation collector
    Started: 2004-07-27

    Aerochemetrics (ACM) automated precipitation collector.

  • Automated precipitation collector
    Started: 2005-08-01

    N-CON Systems (N-CON) automated precipitation collector.

  • Precipitation collector
    Started: 2005-08-01

    N-CON Systems (N-CON) automated precipitation collector.

Site Characteristics

The spatial extent of the dataset site coverage, and descriptions of the spatial extent and context for the data collection

  • Site Description

    West slope of Mount Mansfield in an open field at the Proctor Maple Research Center. Site has a west aspect and an 8% slope

    Minimum Altitude: 399 meter

    Maximum Altitude: 399 meter