Pollution with ammonia came from the sea

GEORGE TOWN: Penang is not just dealing with illegal dumpsites on land.

Scientists found that someone is illegally dumping waste a few kilometres from the shore.

A vast amount of an unknown waste containing ammonia and nitrate levels that are toxic to fish was traced up to about 7km from Penang island’s northern shore.

Scientists from Universiti Sains Malaysia’s Centre for Marine and Coastal Studies (Cemacs) and Universiti Malaya’s Institute of Ocean and Earth Studies were checking pollution parameters on Tuesday and at each testing point, they collected water samples which were later tested in the lab.

“We could not believe it. The nutrient data showed that as we went further out to sea, the nitrate and ammonia levels got higher.

“It is unnatural, ” said Cemacs director Professor Datuk Dr Aileen Tan, adding that her team retested each sample to be sure.

This, she said, showed that the tens of thousands of fishes that died in Teluk Bahang between Saturday and Tuesday suffered from pollution that came from high seas.

Prof Tan said the exact form of the waste was unknown but it would have to be organic, based on the ammonia and nitrate content.

At the shore, Cemacs found that the ammonia level in the seawater was 0.07mg/L but at 7km away, it rose to 0.9mg/L.

“We don’t know if it gets higher further out because we were chasing the low dissolved oxygen level that killed all the fish around us.

“The dissolved oxygen levels were back to the usual of 5mg/L to 6mg/L at 7km from shore but we are now surprised that the ammonia and nitrate levels were higher out there, ” she said yesterday.

Prof Tan explained that ammonia was toxic to fish even at low concentrations while nitrates were food for phytoplankton.

When planktonic life becomes extreme, it contributes to low dissolved oxygen levels over a vast area, which causes fish to die.

Test results for fish and sediment samples, including possible heavy metal content, will be known next week, she added.

Asked if the unknown waste could be dredged material, Prof Tan said it was “possible”.

The only dredging taking place at the time of the mass deaths of fish was at North Butterworth Container Terminal (NBCT).

The state government on Tuesday ordered an investigation of the dredging operations after a fisherman lodged a police report on Monday about seeing the dredger leaving the harbour waters with a thick sediment plume trailing behind it.

The dredger’s task was to suck up sediment off NBCT – an annual job to keep the sea deep enough for vessels to dock – carry it six nautical miles (11km) from Teluk Bahang and dump its load there.

Using Internet-based ship tracking portals, it was shown that this specific dredger passed by Teluk Bahang a few kilometres from shore on its journey to the dumping zone approved by Department of Environment (DoE).

Prof Tan said she could not say for certain if the pollution was from dredged material illegally dumped too close to Penang.

“The problem is that we don’t have baseline data.

“If we had been taking measurements around Penang long term, we would know better.

“This is the first time we measured the dissolved oxygen and nutrient data at 7km from Penang, ” she said, adding that the research cost of tracing the pollution was bearing heavily on Cemacs and the scientists themselves.

At a press conference, state environment committee chairman Phee Boon Poh announced that the state has allocated a budget for a taskforce to gather long-term baseline data to be used in all investigations by bodies such as Cemacs, DOE and Fisheries Department.

He said authorities were investigating the cause of the extremely low amount of dissolved oxygen in the sea that killed all the wild and farmed fish.

“There could be many factors such as the area being a dead zone with low current flow.

“Overpopulation and feeding in the fish cages might also lead to an increase in hydrogen sulphide as the uneaten food decays, leading to growth of jellyfishes and algae blooms, which further take up oxygen.

“We are looking into shifting the cages to spread them out at deeper waters where there is more current, ” he said.