Fluxo de CO2 em Ambientes Aquáticos. Estudo de Caso em Caxiuanã, Portel, Pará

Abstract

The increase of Carbon Dioxide (CO) concentration in the atmosphere, considered as one of the main greenhouse gases, has encouraged studies on the Global Carbon Cycle. This work proposal aims to characterize the CO flux in the Caxiuanã region, whose magnitude is still unknown, the contribution of this flux in the carbon cycle, as well as the physical-chemical and chemical characterization of surface water. In the field five (5) sampling points were selected, three (3) in the Curuá River, one (1) in the Caxiuanã River and one (1) in the Caxiuanã Bay, where pH values, electrical conductivity, dissolved oxygen and carbon dioxide flux are being measured in situ. Surface water is also being collected for chemical characterization (alkalinity, chloride, sulfate, ammonia and metals - Na, K, Ca and Mg). The collections are monthly and were started in January of this year, the period of heaviest rainfall. The data presented in this work correspond to the first collection. At the points sampled in the Curuá River the CO2 flux presented an increasing form from source to mouth (RCu01= O,53j.1mol.m2 .S-I; RCu02=4,J 6j.1 mol.m-'.s-I; RCu03=5,77 j.lmol.m2 .s-I ); in the Caxiuanã river the flow was greater than the third point of the Curuá river (RCx= 5,84 umol .m -2 .s-I ), a justifiable fact since the Curuá river is a tributary of the Caxiuanã river, the flow in the Caxiuanã bay was negative, contrary to expectations (BC=-O,28j.1 mol.m-'-.\--I), which would characterize, taking into account its area, the water body of the region as a carbon absorber, contrary to the existing literature that attributes the Amazon rivers as carbon exporters to the atmosphere (RICHEY, 2002), this data still needs to be ratified, since only the first campaign was considered. For the values of the physical-chemical measurements and chemical determinations there was agreement with the values presented by Furch (1984).