Thursday 25 May, 2017

IMA: Toxic ammonia levels above acceptable limit

A 2016 report from the Institute of Marine Affairs (IMA) says the coastal areas off the Point Lisas Industrial Estate and the Caroni River have toxic ammonia levels exceeding acceptable limits.

Data provided shows waters in the Gulf of Paria with a maximum level of 9.05 µM, almost nine times the USEPA 1995 acceptable limit of 1.43 µM for the protection of aquatic life, while Point Lisas Bay measured a maximum of 7.63 µM. Levels at the Caroni river recorded a maximum of 9.05 µM.

“Poor water quality is noted at major rivers receiving land-based discharge such as Diego Martin, Maraval, Caroni, Madame Espagnole, Couva, Guaracara, Cipero and Godineau. The Gulf of Paria receives excessive pollution loading from agriculture, industrial, and domestic sources. This has resulted in several hot spot areas characterised primarily by elevated levels of suspended solids, nutrients and hydrocarbons,” the report said.

“Dissolved dispersed petroleum hydrocarbon (DDPH) concentrations above 10.0 parts per billion (ppb) are found close to oil and gas operations on the west coast whereas concentrations less than 1.0 ppb are considered ambient and are found in other areas away from petroleum sources.”

The report noted elevated levels of >100.0 ppm of hydrocarbons off Pointe-a-Pierre, La Brea and Granville, as well as in the waters off Port of Spain and Chaguaramas, “likely due to accidental spills from shipping activity”.

(Photo: Clean-up of Petrotrin oil spill in 2013)

The IMA added that the presence of heavy metals was also noted in the Gulf of Paria off the West Coast of Trinidad.

“Many anthropogenic activities occur on this coast and in its associated watersheds. These include manufacturing, light and heavy industries such as plants producing iron and steel, iron carbide, power, gas, ammonia, fertiliser, urea and methanol, liquid natural gas, cement, petroleum refining, oil and gas exploration and production as well as shipyard and yachting activities and extensive agriculture.”

However, the IMA said temperature, pH and dissolved oxygen concentration in coastal waters are generally within the USEPA (1995) acceptable limits for the protection of aquatic life as well as the Trinidad and Tobago water pollution rules.

The data was gathered under the IMA’s ongoing monitoring and research projects using standardised scientific methods.