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.