Guangdong has promised to join forces with Hong Kong to clean up the air over the increasingly industrialised Pearl River Delta. Two studies - one on acid rain and the other on nitrogen dioxide and smog pollution - are expected to be launched in the middle of the year. Guangdong will fund and carry out the acid rain study, and Hong Kong will finance and be responsible for the other project. In a document to be tabled before the Legco environmental affairs panel meeting on Friday, the Planning, Environment and Lands Bureau says both sides have secured funding for the studies. At Friday's meeting, Works Bureau officials will brief legislators on a programme to refill the seabed at south Tsing Yi, north Lantau and east Tung Lung Chau. Mud and sand have been dredged from the seabed for building and reclamation projects, and now the Government wants to reinstate the seabed to original levels, using uncontaminated mud. A $29.2 million monitoring programme is planned to ensure water quality and ecology are not affected.