Ferreira M. M. C., Faria C. G., Paes E. T., “OCEANOGRAPHIC DISTRIBUTION OF NORTHERN SÃO PAULO COAST, A CHEMOMETRIC STUDY”.  Budapest, Hungary, 21-23/ 08/1997: CC'97 Conferentia Chemometrica, Book of Abstracts, Lec14(1997). Oral L14 - Keynote Lecture.

      OCEANOGRAPHIC DISTRIBUTION OF NORTHERN SÃO PAULO
                               COAST: A CHEMOMETRIC STUDY

        Ferreira¹, Márcia M. C.; Faria¹, Cristiano G. and Paes², Eduardo T.

          ¹Instituto de Química, UNICAMP Campinas - SP - BRAZIL  13083-970
               ² Dept. de Biologia Marinha, UFF Niterói - RJ - BRAZIL 24220-970
 

    The northern coast of São Paulo state is a rich and interesting environment which
has attracted attention from geologists and oceanographists.  The  data set  analyzed
here  was  collected  in  this region  (between  parallels  23⁰15'  and  24⁰25')  in  two
different seasons: summer (December 85 and 86) and  winter (July 86 and 87). The
samples were collected  in different stations and  at different depths.  The  chemical
analysis  included  temperature, salinity, saturated oxygen,  nitrate,  nitrite, nitrogen,
phosphate,  silicate  and  chlorophyll  concentrations.

Scatter plots of temperature versus salinity show that this region  is bathed  by three
water bodies with distinct  physico-chemical  characteristics: The  Central  Southern
Atlantic (CSA) with  lower  temperatures  and  salinity; Coastal waters,  with  higher
temperatures and salinity and Tropical waters with high salinity. It can be seen from
all plots that there are  not much variations  from winter to summer  samplings.

    Principal Component Analysis  and  Hierarchical Cluster Analysis  (HCA)  in  the
autoscaled data, reveal  a depth  gradient.  The samples corresponding  to  CSA  are
grouped  in  a  distinct class  as shown  by  the  scores of  first Principal Component
(PC1) and HCA. The loadings indicate that the variables which loads heavily in PC1
are temperature, phosphate, nitrate, nitrogen  and  nitrite concentrations.  It  is  clear
from  the analysis  that waters from CSA  are rich in  nutrients.

    During summer, and in a much smaller intensity during the winter, some samples
can  be  found which  are originated  from depths inferior  to 50 m  (euphotic zone),
inside  the CSA class. This  is an evidence  of meandering formation, resulted  from
oceanic streams which are directly related to the ressurgence phenomena where cold
waters throw  a great amound of nutrients  in  the euphotic zone.

    It can be concluded from this study that nitrate and phosphate concentrations are
as  important  as  temperature  and  salinity,  which  are  usually  taken  as  the  sole
characterization  of  ocean  water  bodies.
 
 

                         Lec14