The Guajará Bay, a river-dominated coastal system, is the main recipient of natural
and sewage drainages from the Belém city (Pará, Brazil). Particulate matter has an
important role as base of food chain in aquatic environments (the organic fraction),
and also serves as an adsorptive surface for pollutants. One way to detect and
assess the impacts of pollutants in the environment is through the use of biomarkers.
A set of antioxidant enzymes, including glutathione-S-transferase (GST), plays a
significant function in cellular detoxification and has been used as stress biomarkers.
In this work, we determined the concentration of total proteins and GST activities in
the particulate matter during the wet and dry seasons at four stations along the
urbanized margin of the Guajará Estuary: Mangal das Garças Ecological Park (P1),
the fishery market Ver-o-peso (P2), Val de Cães Airport (P3) and the mouth of
Maguari river (P4). Samples of particulate matter were collected along horizontal
hauls using a plankton net (40 µm). The seasonal variation of the hydrochemical
parameters temperature, salinity, conductivity, pH and redox potential was also
considered. Student’s t test indicated statically significant differences in the GST
activity for the sampling stations and between rainy and dry seasons. The abiotic
variables reflect a significant marine influence in the Guajará Estuary during the dry
season. The sampling sites P2 and P3 presented an enhanced enzymatic activity
during both seasons, which seems to be linked to an environmental pressure caused
by sewage contamination and other sources of pollution. Highest GST activity was
also observed during dry season, possibly due to a decrease in the dilution of
sewage effluents. Ongoing complementary studies involving plankton species
identification will help the interpretation of the results and also to elucidate the use of
GST as biomarker in the assessment of the water quality of the bay.
|
