Affiliations: Department of Urban and Environmental Sciences &
MOE Laboratory for Earth Surface Process, Peking University, Beijing 100871,
China | Department of Geography and Resource Management, The
Chinese University of Hong Kong, Shatin, New Territories, Hong Kong,
China
Abstract: The long-term temporal and spatial dynamics of marine coastal water
quality in Tolo Harbor, Hong Kong were explored. The Harbor is divided into
three zones represented as Harbor, Buffer, and Channel Subzones. The time range
for the study covers the period from the 1970s to the 1990s. The selected
indicators for the comprehensive assessment of water quality consist of
physical, chemical and biological aspects, including suspended solids (SS),
Secchi disk depth (SD), 5-day biochemical oxygen demand
(BOD_5), total nitrogen (TN), total phosphorus (TP), faecal
coliform, chlorophyll-a (Chl-a), and the number of red tide occurrences. The
results indicated the presence of obvious temporal and spatial trends with
regard to changes in water quality. Spatially, water quality in the Channel
Subzone is the best, while that in the Harbor Subzone is the worst. On a
temporal basis, the average trend from bad to good was 1980s > 1990s >
1970s as indicated by most of the selected water quality indicators. Water
quality during the late 1980s reached its worst level with the lowest SD, the
highest BOD_5, TN, TP, Chl-a concentrations, and the number
of red tide occurrences. These long-term temporal-spatial water quality trends
were also found in other studies of the Tolo Harbor. The large quantity of
pollutants produced as a result of increasing population, industrial and
commercial actives, and urbanization and industrialization trends in both
Shatin and Tai Po seem to be primarily responsible for the changes in marine
coastal water quality.
Keywords: temporal-spatial dynamics, water quality, indicators, pollution load, Tolo Harbor
