**4.1 Methods and preliminary biogeochemistry results of transect T2**

In the North and the South Channel in Amapá, sampling of water quality was conducted with i) quarterly and ii) in the Channel North monthly frequency (Brito, 2010). Quarterly collections are used to obtain vertically and horizontally integrated samples for the calculation of dissolved and particulate loads in the water column with the use of 15 to 20 metre boats. The monthly samples are used for seasonal interpolation and are obtained from the surface and 60% of water depth. The measures routine collected are used to derive parameters relating to the ion and nutrient system, carbonates, organic material, water discharge and suspended sediment.

The depth and surface samples are obtained by immersion pumps, where water is then pumped into a graduated cylinder of 2 litters, which is flooded for at least three times prior to sampling and the overflow is maintained during the procedures sampling.

Transect T2 (Table 1) defines the main flow of the river to the north of the island of Marajo. As sea water never passes the dividing line at the mouth of the river in front of the city of Macapá (Nikieme et al., 2007), this is considered a final a purely fluvial compounent of the river.


Table 1. Geographical coordinates of sampling sites

Challenges and Solutions for Hydrodynamic and Water Quality in Rivers in the Amazon Basin 79

Table 2. Preliminary results and physical-chemical in Transect T2, in the North Channel

(two water sampling).

The graduated cylinder 2 liters are removed aliquots with syringes of 60 mL for routine analysis of chemical parameters Na +, K +, Ca2+, Mg2 +, Al, Si, Cl - , SO4 2-, NO2 -, NO3 -, NH4+, PO43-, total nitrogen and dissolved organic carbon (DOC). Chemical parameters for the samples are filtered using cellulose acetate filters with pore size 0.45 micrometres in bottles of high density polyethylene capacity of 60 mL containing 6 mg of thymol as a preservative. For DOC, samples are filtered in triplicate using glass fiber filters preheated (500 °C for 5 hours) GFF type with pore size 0.7 mm, in glass vials of 25 mL, also preheated. Samples are preserved with 25 mL of HCl 50%.

In situ measurements (meter used) are: electrical conductivity (Amber Science 2052); pH and temperature (Orion 290A plus), and dissolved oxygen (DO) with the YSI 55 meter.

To fill the collection tube, using the same technique of overflow, ten bottles of glass BOD (Biochemical Oxygen Demand) of 60 mL for measurements of respiration rates are used. Of these, five bottles are preserved with 0.5 mL of manganous sulfate and 0.5 mL of sodium azide and five bottles are incubated in coolers containing water from the river, staying in the dark for 24 hours.

To measure the concentration of suspended sediment in the water, are filled with twenty gallons of polyethylene-liter and transported to the laboratory for further processing to separate the coarse particles (up to 63 µm) of fine particles (between 0 and 63 µm, 45 µm) samples.

The sampling parameters of fecal coliform and Escherichia coli, coliform, sterile bags are made directly from the collector tube connected to the pump.

During the sampling process, a phytoplankton net (63μm mesh) is submerged in the side of the boat to collect coarse sediments. At the end of sampling, the content network is rinsed polycarbonate flask of 250 ml wide mouth and preserved with 250 mL of HCl 50%. To measure the isotopic composition of carbon and nitrogen.

To measure the concentration of dissolved CO2, water is pumped through a closed plexiglass tube in which a small part is filled with air, this air is pumped out of the pipe to a device called a CO2 analyzer IRGA (InfraRed Gas Analyzer ) Licor LI820 model, after passing through the analyzer back to the air pipe to reach the equilibrium (Cole et al, 1994. With modifications). Expected to balance the flow of air, so it made measurements of CO2 dissolved in water for 5 minutes.

The flux measurements of CO2 in surface water are made by the same method, but instead of the plexiglass tube to balance the flow of CO2 it uses a static camera that is floating on the surface of the river connected to tubes to circulate air to the IRGA for 5 minutes.

In addition, samples are collected to characterization of phytoplankton for identification and determination of density.

Table 2 shows the preliminary results of some parameters obtained in the first gathering held in the channel north, following Brito (2010):

With preliminary data observed, we cannot make qualitative and quantitative analysis representative. But we can highlight some features of the river, such as the harmony of the data of surface and depth, the good condition of dissolved oxygen in water, acid pH which is a characteristic of the Amazonian rivers, the presence of considerable amounts of iron in water, low water hardness, the presence of nutrients in the water and the high level of carbon dioxide dissolved in water (mass transfer through air-water interface).


Table 2. Preliminary results and physical-chemical in Transect T2, in the North Channel (two water sampling).

The graduated cylinder 2 liters are removed aliquots with syringes of 60 mL for routine

PO43-, total nitrogen and dissolved organic carbon (DOC). Chemical parameters for the samples are filtered using cellulose acetate filters with pore size 0.45 micrometres in bottles of high density polyethylene capacity of 60 mL containing 6 mg of thymol as a preservative. For DOC, samples are filtered in triplicate using glass fiber filters preheated (500 °C for 5 hours) GFF type with pore size 0.7 mm, in glass vials of 25 mL, also preheated. Samples are

In situ measurements (meter used) are: electrical conductivity (Amber Science 2052); pH and temperature (Orion 290A plus), and dissolved oxygen (DO) with the YSI 55

To fill the collection tube, using the same technique of overflow, ten bottles of glass BOD (Biochemical Oxygen Demand) of 60 mL for measurements of respiration rates are used. Of these, five bottles are preserved with 0.5 mL of manganous sulfate and 0.5 mL of sodium azide and five bottles are incubated in coolers containing water from the river, staying in the

To measure the concentration of suspended sediment in the water, are filled with twenty gallons of polyethylene-liter and transported to the laboratory for further processing to separate the coarse particles (up to 63 µm) of fine particles (between 0 and 63 µm, 45 µm)

The sampling parameters of fecal coliform and Escherichia coli, coliform, sterile bags are

During the sampling process, a phytoplankton net (63μm mesh) is submerged in the side of the boat to collect coarse sediments. At the end of sampling, the content network is rinsed polycarbonate flask of 250 ml wide mouth and preserved with 250 mL of HCl 50%. To

To measure the concentration of dissolved CO2, water is pumped through a closed plexiglass tube in which a small part is filled with air, this air is pumped out of the pipe to a device called a CO2 analyzer IRGA (InfraRed Gas Analyzer ) Licor LI820 model, after passing through the analyzer back to the air pipe to reach the equilibrium (Cole et al, 1994. With modifications). Expected to balance the flow of air, so it made measurements of CO2

The flux measurements of CO2 in surface water are made by the same method, but instead of the plexiglass tube to balance the flow of CO2 it uses a static camera that is floating on the

In addition, samples are collected to characterization of phytoplankton for identification and

Table 2 shows the preliminary results of some parameters obtained in the first gathering

With preliminary data observed, we cannot make qualitative and quantitative analysis representative. But we can highlight some features of the river, such as the harmony of the data of surface and depth, the good condition of dissolved oxygen in water, acid pH which is a characteristic of the Amazonian rivers, the presence of considerable amounts of iron in water, low water hardness, the presence of nutrients in the water and the high level of carbon dioxide dissolved in water (mass transfer through air-water

surface of the river connected to tubes to circulate air to the IRGA for 5 minutes.

made directly from the collector tube connected to the pump.

measure the isotopic composition of carbon and nitrogen.

, NH4 +,

analysis of chemical parameters Na +, K +, Ca2+, Mg2 +, Al, Si, Cl -, SO42-, NO2-, NO3-

preserved with 25 mL of HCl 50%.

dissolved in water for 5 minutes.

held in the channel north, following Brito (2010):

determination of density.

interface).

meter.

samples.

dark for 24 hours.

Challenges and Solutions for Hydrodynamic and Water Quality in Rivers in the Amazon Basin 81

Fig. 4. Velocity and dispersion of pollutants in natural runoff - in the coast of the cities of

Macapá and Santana. Representation of a semi-diurnal tidal cycle.
