SO HYBAM / Technics / Samplings

Samplings

During the field campaigns performed to setup the stations, the sampling feasibility was tested at each gauge station, especially:

 

  • to ensure access to the sampling place;
  • to have a clean place to perform the filtrations;
  • to train someone responsible.

Each operator received the equipment needed to sample during a whole year and a document with instructions for sampling and filtration (see framed text), in Spanish or Portuguese language. The equipment consists of:

 

  • a manual vacuum pump;
  • a water proof thermometer – conductivity meter;
  • a 1-litre sampling bottle made of HDPE;
  • 12 filtration kits with : 1 disposable sterilized filtration set with 0.2 µm cellulose acetate filter; one 125 ml bottle made of HDPE for the major elements; one 60 ml bottle made of brown glass for the COD; one 125 ml bottle made of HDPE for the trace elements;
  • aluminum film to package the DOC bottles;
  • adhesive tape to protect the labels and seal the bottles;
  • a cooler to keep the samples and the equipment;
  • 100 l trash bags to unfold on the worktop in order to insure the cleanliness.

The sampling equipment must have been prepared at UnB according to the following procedure:

 

  • sampling bottles for the major elements: HNO3 2N bath during 48h, milli-Q water bath during 48 h, dry in a laminar flow hood;
  • DOC bottles: 8 hours in an oven at 450°C;
  • trace elements bottles: aqua regia on each face and the bottom during 2 h, HNO3 2N N bath during 48h, milli-Q water bath during 48 h, dry in a laminar flow hood;
  • DOC caps and bottles for isotopes : HCl 2N bath during 48h, milli-Q water bath during 48h, dry in a laminar flow hood.

Inside the trace element bottles, 200 µL of supra pure HNO3 are added and in the DOC bottles, 150 µL of supra pure H3PO4 are added.

 

The set filtration filters are first weighted and the weight is reported on a label sticked on the protection bag which is then hermetically closed. All the bottles are labeled with the station name and their future use and placed in plastic bags closed by a zipper.

 

The filtered sample, as the filters, are kept by the operators in insulating compartments in order to prevent them from temperature variation, dust and light. They are regularly sent to Brasília, either through field campaigns opportunity or by mail.

 

Special filtrations for the POC are operated since april 2006 in 6 Brazil located stations: Óbidos , Itaituba, Borba, Manacapuru, Caracarai and Serrinha. To do that, special equipment (filtration sets with GFF filters first pyrolyzed at 480° C) is provided to the operators in order to perform a specific filtration of 300 ml for the DOC.

Sampling procedures for major and trace elements in water.

The 10th of every month, hands cleaned, collect water at the sampling place in the one-liter-bottle first cleaned up three times with the river water.

 

Stop the motor and place the boat against the current to avoid contamination of the collected water with gasoline or steam.

 

To avoid mixing with surface water, open the bottle underwater. Take pH and temperature measurement and empty the bottle.

 

Collect water again in the same way and close the bottle underwater.

 

Put the bottle in a plastic bag and keep it away from direct sunlight and/or motor steam.

 

Prepare the filtration place to turn it clean and well organized.

 

Wash one's hands with soap.

 

Install the manual pump on a new disposable filtration system.

 

Pour 150 ml of sampled water in the upper part of the filtration set and vacuum the system by operating the pump.

 

Remove the manual pump and throw the filtered water away.

 

Connect the pump again. Pour 100 ml of sampled water in the upper part of the filtration set and vacuum the system by operating the pump.

 

Remove the pump and pour the 100 ml filtered water in a "major elements" labeled-bottle, fill out label with date and water level.

 

Connect the pump again. Pour 10 ml of sampled water in the upper part of the filtration set and vacuum the system by operating the pump.

 

Remove the pump and pour 60 ml filtered water in a "carbon" labeled-bottle, fill out label with date and water level, put transparent adhesive tape and pack the bottle with an aluminum foil.

 

Connect the pump again. Pour 100 ml of sampled water in the upper part of the filtration set and vacuum the system by operating the pump.

 

Remove the pump and pour the 100 ml of filtered water in a "trace elements" labeled-bottle, fill out label with date and water level.

 

Connect the pump again.

 

Put the three bottles together in a plastic bag and close the zipper. Note down the station name, the date and the water level on the plastic bag.

 

Put the disposable filtration system into its own bag and note down the date and the water level on the plastic bag.