4.3.3 Total Phosphorus
The total phosphorus dissolved in water in T1 (Figure 3E), was higher
than those recommended by CONAMA Resolution 20/86, which is 0.025 mg
l-1), compared to T2 (Figure 3F). The values of phosphorus recorded in
T2 were 0.10, 0.16 and 0.16 mg l-1, in the months of February, October,
and December, respectively, were below the values of 0.21, 0.13 and 0,
21 mg l-1, except for October. The values observed in T1 were higher
than those recorded in T2, except for the peaks recorded in December
2010 and October 2009, and 2012, which reached more than 0.30 mg l-1,
even below the peaks that occurred in T1 in 2001, 2002, 2003 and 2005,
which reached 0.50 mg l-1, in December 2005 (Figure 3E).
These values are lower than the ones obtained by Donadio et al.
(2005), who evaluated the water quality in a watershed in Taquaritinga,
SP, where the predominant soil is the Ultisol, and the average values
of phosphorus in the water, in the driest period of the year, was 1.58
mg l-1 and, for the rainy season, was 4.32 mg l-1.
Pinheiro et al. (2014) assessed soil use and occupation, and its
relation to water quality, in two sub-areas of Rio Duas Mamas watershed
in Santa Catarina, documenting phosphorus content of 27.3 and 41.6 mg
l-1 , which are higher than the results found in the present study. This
may be explained by the fact that, in SW2, there were banana plantations
and annual crops, despite the large percentage of remaining natural
forest, in both cases.