This study aims to understand the influence of external forcing (i.e. climate, human influences) changes on the inputs of terrigenous materials from the Kaoping River as well as the biogeochemical responses of carbon and nutrients to riverine fluxes in the Kaoping coastal zone. The Kaoping River exhibits contrasting patterns in water discharge and material fluxes between wet and dry seasons. In general, river discharge is about 12 times higher in the wet season than in the dry season. Riverine fluxes of terrigenous materials (DOC¡BPOC¡BDSi¡BDIN¡BDIP¡BTDN and TDP) are about 3 to 10 times higher in the wet season than in the dry season. Consequently, distribution patterns of carbon, nutrients and hydrochemical parameters are significant difference among four seasons in the Kaoping coastal zone. Distributions of DOM (dissolved organic matter), POM (particulate organic matter) and nutrients in the Kaoping coastal zone show that the highest concentration is generally found in the area close to the Kaoping estuary, and the concentration decreases with the distance away from the land. The riverine fluxes also affect the ratios of DOC/TOC and £GPOC/£GPN in the coastal zone. The characteristics of DIN and DIP distributions and their ratios imply that the primary productivity may be largely limited by nitrogen (DIN < 1£gM¡AN/P < 10) rather than phosphorus (DIP < 0.2£gM¡AN/P < 30) in the Kaoping coastal zone. The occurring probability of nitrogen limitation varies from season to season during the study period, roughly ranging from 4% to 42% (winter, summer > spring, autumn). The GP (gross production) ranges from 708-19819 mg C m-2 d-1 in spring, from 2451-16230 mg C m-2 d-1 in summer, and from 844-5549 mg C m-2 d-1 in winter. The DCR (dark community respiration) ranges from 970-6284 mg C m-2 d-1 in spring, from 861-12418 mg C m-2 d-1 in summer, and from 997-5781 mg C m-2 d-1 in winter. Both GP and DCR display the highest value in summer, indicating the significant influence of terrigenous fluxes on biological production and respiration during summer. Meanwhile, correlations are significantly positive between GP (DCR) and temperature and nutrients, but significantly negative between GP (DCR) and salinity, also indicating the impacts of terrigenous inputs on GP and DCR. In the Kaoping coastal zone, the BCD (bacterial carbon demand) is about 15% GP and 64% GP, respectively, in winter and summer, inplying that the contribution of GP to BCD is more important in winter than in summer. Judging from the ratio of GP/DCR in different seasons and sampling stations, we conclude that the study area near the Kaoping estuary is likely to be autotrophic throughout the study period, the other stations are also likely to be autotrophic during summer. Nevertheless, the offshore stations appear to be heterotrophic during the winter season.

This study investigates the distributions of trace metals and their controlling mechanisms in the Kaoping coastal zone. Concentrations of most dissolved metals were generally lower in the wet season than in the dry season in the Kaoping Estuary, showing clearly the effects of river discharge rate and water residence time on metal distributions. Dissolved trace metals (Fe, Mn, Zn, Cu, Cd and Pb) behaved non-conservatively with addition in the estuary. Nevertheless, dissolved Pb was apparently removed from the estuary in the wet season. Particulate Al and Fe were derived mainly from continental weathering and their transports through the estuary depend highly on the distribution of total suspended matter (TSM). During the dry season, the occurrence oxygen-deficit condition in the low salinity region and possible pollution from the San-Wei fishery harbor likely determined the distributions and solid-solution partitions of Mn, Zn, Cu, Cd and Pb in the estuary. Distributions of dissolved trace metals in the Kaoping coastal zone were significantly influenced by terrestrial inputs from the Kaoping River. Seasonal variations were attributed largely from the mixing between river water and sea water in the mixing layer and sediment resuspension from canyon bed. The column integrated dissolved and particulate metals were generally higher in the summer season than in other seasons. The difference was especially pronounced in nearshore stations. Concentrations of dissolved Mn, Zn, Cu and Pb increased generally with depth, reflecting the effects of resuspension and lateral transport of bottom sediment. Dissolved Zn and Cu concentrations correlated well with dissolved Mn concentration, but particulate Zn and Cu correlated poorly with particulate Al, implying that distributions of Zn and Cu were controlled by terrestrial inputs and biogeochemical processes in the Kaoping Canyon. Positive and negative correlations are found between dissolved Cd and nutrients (N+N¡Aorthophosphate) and between dissolved Cd and dissolved organic carbon (DOC), respectively, indicating that Cd is a nutrient-type metal and controlled biogeochemically in the Kaoping Canyon. Specific events such as typhoon and earthquake influenced significantly the distributions of trace metals in the Kaoping coastal zone. The integrated suspended-matter and suspended-metal concentrations showed an order magnitude higher during the typhoon season than in the normal summer season. Under the influence of earthquake, the TSM values of the bottom waters were much higher (2-7 folds) during the post- earthquake cruise (Jan/2007) than in the normal season (Jan/2006). Meanwhile, particulate Al, Fe, and Mn can increase up to 2- to 10-folds after earthquake in the bottom layer of canyon. Metal enrichment factor (EF) is an indicator of metal pollution. The EFs show an order magnitude higher in the dry season than in the wet season both in the estuary and canyon. Such seasonal patterns clearly indicate the impacts of local and river inputs on metal distributions in the estuary and canyon.