This study focused on the monitoring of water in the Bolonha reservoir, with a focus on
obtaining the Trophic State Index (IET) during the rainy and less rainy period of the year
2016. The site is located on the grounds of the Utinga State Park (PEUT), which is located at
Avenida João Paulo II, s / n - Curió Utinga, in the municipality of Belém-PA. The reservoir
has an elongated shape, approximately 577,127 m² of the area and 1,954,000 cubic meters of
water volume; its maximum depth is around 7.64 m. The objective of this research was to
evaluate the IET of the Bolonha reservoir from the quantification of the total phosphorus and
transparency variables and the application of descriptive, analytical and multivariate statistics,
and it was possible to observe the distinct variations in the analysis periods. The methodology
of the work consisted in the accomplishment of composite and straightforward field
collections, to a point, located at the entrance of the ETA Bolonha capture, before the grating.
When a seasonal comparison between less rainy and rainier periods was carried out, using the
Mann Whitney hypothesis tests, it was possible to observe that pH, alkalinity, accurate color,
total phosphorus and dissolved oxygen did not show a significant difference between the
analyzed periods. The other variables as visible color, total suspended solids, turbidity, and
IET, presented substantial differences between rainier and less rainy periods. The presence of
phosphorus is evident in both periods. The Mann Whitney test revealed that there was a
significant difference of the phosphorus fractions between wetter and less rainy periods,
through the ρ values. The test showed that the phosphorus fractions analyzed presented
significant differences (p <0.05) lower than the significance level of 5%. Through the analysis
of the main component for phosphorus fractionation, it was possible to observe the formation
of two distinct elements for each period (rainy and less rainy), which together explained 93%
and 92.6% of the variability of the data. The IET was calculated for Bolonha, which allowed
to classify the Bolonha reservoir as a eutrophic environment, both in the rainy season and in
the less wet period.
|
