Evangeline
C. Santiago
NPC
from the Philippines
Natural
Sciences Research Institute
University
of the Philippines
The river systems of two important
fish- producing and agricultural provinces in the Philippines were selected
as study areas for the second three-year phase (2002-2005) of UNU Monitoring
project in the Philippines. The monitoring
aims to determine if significant residues of organochlorine pesticides are
present in the river waters and sediments that could potentially contaminate
the fish produced in the provinces. The result of the three - year monitoring
is summarized in the presentation.
The first year monitoring in
Laguna rivers detected traces of BHC, aldrin, trans and cis chlordane,
dieldrin, DDT and endrin aldehyde
in water samples at the levels near the Method Detection Limits during the
first sampling and significant levels of dieldrin (0.03-0.13 ppb) during the
second sampling. Aldrin was
detected in most Pangasinan Rivers at levels (0.063 ppb) higher than the MDL
during the first sampling. During
the second sampling, dieldrin was most significant (0.04-0.09 ppb) in all
Pangasinan sites and endrin aldehyde (0.27 ppb) in one site. Sediments were
analyzed during the first sampling using the EPA procedure (wet sediments dried
with sodium sulfate and extracted by Soxhlet). Endrin, endrin aldehyde,and
endrin ketone were present in highest concentration (89-155ng/g), gamma BHC
(13-18ng/g), methoxychlor (26-41 ng/g) and dieldrin (6-7 ng/g) in the sediments
in Laguna. Sediments in Bay,
The second year monitoring showed
only traces of trans and cis chlordane in most river waters from both provinces
during the first sampling. Traces of dieldrin, p,p’DDT and trans-nonachlor were
detected during the second sampling in addition to the chlordanes. However, the
concentrations detected were all below the MDLs. Using the UNU method for
sediment analysis (extraction of dried sediments by sonication), the first
sampling sediments for Laguna province showed much less OCPs in the sediments
than the concentration obtained the previous year.
The third year monitoring showed
that both water and sediments collected during the two sampling periods
indicated significant contamination with trans and cis chlordanes in both
Laguna/Rizal and in Pangasinan river systems. In some rivers where dieldrin,
endrin , p,p’ DDT and HCB were detected in water, the sediments also showed
contamination of these POPs pesticides. Among the non-POPs pesticides,
endosulfan1, endosulfan2, transnonachlor and endrin ketones were detected in
water and sediment samples. Generally, the concentrations of pesticides in
water are higher in the first sampling than in the second sampling and the
opposite is true with the sediments. Among the rivers in Laguna, Bay,