Pollution in Guangdong's coastal waters continued to worsen last year, mainly in the Pearl River Delta, which affected offshore water quality in Hong Kong.
The steady deterioration of water quality along the province's coast had not let up, said Li Lei, a spokesman for Guangdong's Oceanic and Fisheries Administration, in Guangzhou yesterday.
Guangdong's "Oceanic Environment Report 2012", published yesterday, said about 6.5 per cent of the province's offshore water was rated "poorer than category four" - the most polluted - last year. That was about a percentage point more than in 2011.
"Most of category four water is concentrated in the Pearl River estuary, with inorganic nitrogen and active phosphate being the main pollutants," Li said.
The report said 910,000 tonnes of pollutants generated on land had been discharged into Guangdong's coastal waters last year. It said 26,000 tonnes of pollutants found at 28 monitored dumping spots had exceeded permissible pollution-discharge standards by 34 per cent.
Li said 16 red tides occurred in Guangdong last year, the most in five years. The province sees about 10 a year on average.
"The red tides were mainly spotted in the waters of the Pearl River, Daya Bay, Dapeng Bay [known as Mirs Bay in Hong Kong] and waters around Zhanjiang [in the south of the province]," he said.
Li said the problem of pollutants being dumped into the ocean had not been contained and posed a threat to marine life.
The report also named four major industrial polluters found among the province's 82 monitored discharge stations.
The heaviest polluter was state-owned Guangzhou Paper Group, followed by Jialian Leather (China), Jiangmen City Hongjie Fine Chemical and Guangdong Zhanhua Corporation Group.
Professor Ho Kin-chung, dean of the school of science and technology at The Open University of Hong Kong, said offshore water quality in Hong Kong's western and southern waters had worsened due to the consistently high pollution found in the Pearl River every year.
"Water around Tuen Mun, northern Lantau Island as well as Stanley, Clear Water Bay and Lamma Island has worsened as a result," Ho said.
The deterioration had been particularly obvious in southern Hong Kong over the past decade, with total nitrogen rising consistently when the Pearl River was at its dirtiest, he said.