THE Hong Kong Shipowners' Association has circulated among members the new four-part Environment Code issued by the International Chamber of Shipping (ICS). ''Since Hong Kong is one of the leading maritime centres, we want our members to take the lead in helping to protect the environment,'' association director Michael Farlie said. Part One of the code highlights the environment performance of the industry, placing its contribution to marine and atmospheric pollution in the context of overall pollution from human activities and comparing its energy efficiency with other modes of transport. Part Two lists 10 principles of environmental management and Part Three lists prime sources of pollution and gives background information on the environmental concerns surrounding these sources. It also details elements of international regulation, recommendations and codes of practice upon which companies need to focus. Brief comment is also provided in areas where future environmental protection requirements are being discussed. Part Four contains recommended management standards to be incorporated into company environmental plans to address the sources of pollution introduced in part three. ''Economic growth, efficient marine transportation, safety, and protection of the environment must go hand in hand if the shipping industry is to prosper and to achieve the recognition it deserves,'' ICS chairman Juan Kelly says in the foreword. It is estimated that land-based discharge (including sewage, industrial effluent, and urban and river run-off) and atmospheric input from land industry account for about 77 per cent of the marine pollution generated from human activities. By contrast, according to ICS, maritime transport is responsible for only about 12 per cent of the total. Between 1985 and 1991, world seaborne trade rose more than 23 per cent, from about 13 billion tonne miles to more than 17 billion tonne miles. The carriage of oil and petroleum products has had a marked influence on this increase, rising by about 33 per cent from about five billion tonne miles to more than 7.5 billion tonne miles. According to the ICS, the amount of oil entering the sea from marine transport has diminished over the years. Estimates by the US National Academy of Sciences show that oil discharged from shipping sources fell from 1.47 million tonnes in 1981 to 568,800 tonnes in 1989, down more than 60 per cent. Mr Kelly points out that advances have been made in the design of oily water separating equipment for space bilges and oil tanker discharges and for the monitoring and control of the discharge of those mixtures. ''These technological advances have allowed international regulation to be adopted, reducing the permitted operational discharge of oil effluent from machinery space bilges from 100 part per million to 15 parts per million. Similarly, the amount of oil entering the sea as a result of accidental pollution from shipping has shown a declining trend since the mid-1970s, according to the ICS. By the end of the 1980s, the average number of major oil spills each year had dropped to one-third of that witnessed in the previous decade. According to the chamber, shipping will remain an efficient and one of the least environmentally damaging modes of transport, responsible for carrying more than 80 per cent of world trade by volume. ''One expression of the industry's safety record is that using the number of ship losses recorded in 1991, a ship loss occurs once every 122 billion tonne miles of cargo carried,'' the ICS says.