Ferrying of iron ore mined in Goa’s hinterland towards the Mormugao Port Trust via river barges is affecting the quality of water and consequently the riverine ecosystems, a study conducted by the National Institute of Oceanography has concluded.

A research report released recently by the Goa-based National Institute of Oceanography (NIO) reveals high iron and other metal content including aluminum and manganese content in the Mandovi (North Goa) and Zuari (South Goa) rivers and credits saying that it is because of mining and related activities in the State.

“Since ore handling ie, loading in barges, transporting and reloading at the port or mid-stream in giant ships, is done in an open system and one would expect abundant spilled-over ore material into the estuaries (of the two rivers),” the paper jointly authored by Indian and Chinese researchers reads.

“Stations (for collecting samples) of Mandovi, where ore deposits are stored on the shore, exhibit high Fe (iron), Mn (manganese), and middle REE (rare earth elements) — and heavy REE-enriched REE patterns. Canal stations exhibit highest concentrations of major and trace metals. High metal/Al (aluminum) ratios occur at stations in the upstream of Zuari and at the confluence of canal in the Mandovi estuary. Enrichment factors of metals indicate that Mn is significantly polluted while other metals are moderately polluted,” their final report reads.

The paper comes at a time when mining is banned by the Supreme Court on account of illegalities among which was the allegations of improper and incomplete Environment Impact Assessment studies commissioned by the mining companies.

The data, however, has been complied when mining was rampant and production was at its highest. All ore mined in Goa is transported from mines to jetties by trucks and from there to the port via river barges.

“Mandovi has 37 loading points with 1,500 trips of barges per year while Zuari has 20 loading points with 1,800 trips per year. Ore transport through rivers increases annually from 14 million tonnes,” the report states, while establishing the quantum of ore transported using the river ways.

“Shipbuilding industries on the shores of both rivers may have contributed to the trace metals,” the report states, adding that in some areas in the two rivers pollution had reached “significant” levels.

The report was aimed at studying the biochemistry of suspended particulate matter including clay and run of sediments in the two estuaries.

Most of the State’s economic activity is surrounding the two river estuaries both of which converge round the State’s capital of Panjim.

Along these estuaries lie industries such as iron-pellet making factory and shipbuilding are located on the shores of the Zuari estuary.

The report, ‘Geochemistry of the suspended sediment in the estuaries of the Mandovi and Zuari rivers, Central west coast of India’, is authored by Pratima M Kessarkar, R Shynu, V Purnachandra Rao, Tanuja Narvekar of the NIO and Feng Chong and Jing Zhang of the Shanghai-based State Key laboratory of Estuarine and Coastal Research.

Pollution of Goa rivers due to iron ore deposition on their beds and along its course and plastic and other affluent have already been flagged as a concern for Goa.

Dr Baban Ingole, a fish scientist at the NIO had earlier cautioned that over-fishing as well as pollution leading to increased acidity in the water was leading to the dissolving of the shells of clams as well as an increase in the number of jelly fish along Goa’s rivers and coastline could lead to a fish famine in the future.

The State known for its beach tourism, has also come under pressure after a recent report by the oceanography institute established that swimming in Goa’s water’s was unsafe owing to high concentrations of coliform bacteria especially in summer.

“This is primarily due to excessive land run-off containing raw sewage and fecal debris that supports the proliferation of coliform bacteria… There were hardly any samples that had counts of bacteria that would be considered safe,” said a report released by NIO scientist N Ramiah, along with his co-scientists.