Abstract:
Trinidad and Tobago is a fast-developing country and industrial growth can impact negatively
sometimes by increasing the chance of pollution if proper measures are not obeyed. Caroni River
and its major tributaries flow through the most urbanized and industrialized part of this country
and perhaps this increases the opportunity of polluting the river basin and its catchment area. Till
now, no detail assessment has been carried out in this area to measure the accumulation indices
and associated risks. This study is one of the initial efforts to investigate and the distribution and
potential sources of heavy metal pollutants (Cr, Ni, Cu, Zn, As and Pb) in sediments and water
from the Caroni River system. The degree of metal contamination is compared with the global
standards (International Sediment Quality Guidelines, ISQG and Water Quality Guideline,
IWQG). Results from the study revealed that the concentration (in Ug/L): Cr (5.07-6.85), Ni
(5.23-9.38), Cu (4.56-10.11), Zn (2.13-60.91), As (3.97-5.7) and Pb (4.04-9.92). Profiles of these
metals in the river bed sediment samples (Cr: 4.17-12.69, Ni: 5.0-26.86, Cu: 4.28-46.94, Zn:
49.22-161.4, As: 5.24-12.7 and Pb: 3.55-42.43; in Ug/g) were below international Probable
Effects Levels (PELs) at all locations, but some metal levels were above the international
Threshold Effect Levels (TELs) in a few occasions (Ni, Cu, Zn and As). The geoaccumulation
index order for the river sediments is As>Pb>Zn>Cu>Ni>Cr. This study also revealed that these
higher concentration can be attributed to effluents from small-scale industries, unnoticed
irrigation processes, and domestic wastes. Though it would be too early to make predictions,
especially before more detailed study, the San Juan, St. Joesph and Arouca Rivers (three
important tributaries of the Caroni River) were found to be the most polluted, and Cu, Pb, Zn and As were the most abundant metals in the study area. It is recommended that appropriate
measures are taken by the relevant authorities to mitigate the problems at this early stage. |
