• Address:
  705 Spear Street
  South Burlington, Vermont 05403
  United States of America
  
  Phone: (802) 391-4135
  Email: femc@uvm.edu
  Website: www.uvm.edu/femc

Measure the concentration and deposition of mercury in precipitation as part of the mercury deposition network (MDN).

• Label: Site ID

• Description: Site identification code

• Storage Type: text

• Measurment Type: nominal

• Label: Date Off

• Description: Date and time that sample collection ended

• Storage Type: datetime

• Measurment Type: datetime
• String Format: M/D/YYYY hh:mm

• Label: Date On

• Description: Date and time that sample collection began

• Storage Type: datetime

• Measurment Type: datetime
• String Format: M/D/YYYY hh:mm

• Label: Precipitation

• Description: Precipitation amount as measured by rain gauge

• Storage Type: decimal

• Measurment Type: ratio
• Precision: 0.01
• Unit: milliliters
• Number Type: whole

• Label: Sample Volume

• Description: Volume of the sample analyzed

• Storage Type: decimal

• Measurment Type: ratio
• Precision: 0.1
• Unit: milliliters
• Number Type: whole

• Label: Calculated Precipitation

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

• Storage Type: decimal

• Measurment Type: ratio
• Precision: 0.01
• Unit: milliliters
• Number Type: whole

• Label: Mercury Concentration

• Description: Concentration of mercury measured in the sample

• Storage Type: decimal

• Measurment Type: ratio
• Precision: 0.01
• Number Type: whole

• Label: Mercury Deposition

• Description: Deposition of mercury derived from the precipitation and concentration data

• Storage Type: decimal

• Measurment Type: ratio
• Precision: 0.01
• Unit: nanograms per square meter
• Number Type: whole

• Label: Sample Type

• Description: Type of sample collected (wet, dry, invalid or unknown)

• Storage Type: text

• Measurment Type: nominal

• Custom List: Codes for Sample Types

• Label: Quality Code

• Description: Qualtiy assurance code, A=fully qualified, no problems; B=valid data with minor problems; C= invalid data, -=unknown

• Storage Type: text

• Measurment Type: nominal

• Label: Lab Notes

• Description: Notes attached by lab

• Storage Type: text

• Measurment Type: nominal

• Custom List: MDN Sample Problem Codes
• Code: e
• Definition: extended sample time (> 8 days)

• Label: Sample Year-Month

• Description: Month and year of sample

• Storage Type: int

• Measurment Type: interval
• Number Type: integer

• Label: Date Mod

• Description: Unknown

• Storage Type: datetime

• Measurment Type: datetime
• String Format: M/D/YYYY hh:mm

• Weekly Sampling
  • Started: 2012-10-29
    
  • Method Description: During the fall of 2012 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.
  Instrumentation: N-CON and ACM

• Deposition collection
  • Started: 2004-07-27
    
  • Method Description: 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
    
  • Method Description: 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
    
  • Method Description: 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.

• Sample bottle prep
  • Started: 2004-07-27
    
  • Method Description: 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

• Sample collection
  • Started: 2004-07-27
    
  • Method Description: 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.

• Handling and overflow
  • Started: 2004-07-27
    
  • Method Description: 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
    
  • Method Description: 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.

• Overview of event based Hg sampling
  • Started: 2004-07-27
    Ended: 2012-10-29
    
  • Method Description: 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.
  • Instrumentation: NCON and ACM

• Started: 2004-07-27
  Ended: 2016-01-19
• Sampling Description: Aerochemetrics (ACM) automated precipitation collector.
• Frequency: Weekly

• Started: 2005-08-01
  Ended: 2012-10-29
• Sampling Description: N-CON Systems (N-CON) automated precipitation collector.
• Frequency: Event based

• Started: 2012-10-29
  Ended: 2015-03-03
• Sampling Description: N-CON Systems (N-CON) automated precipitation collector.
• Frequency: Weekly