This study was undertaken to determine the fate and fluxes of materials from Arctic estuaries to the coastal zone. The paper is the first of a series addressing questions relating to the physics and chemistry of the region. Three seasonal cruises were undertaken in the Chupa Estuary, White Sea, Russia; in summer (July 1994), autumn (September, 1995) and spring (May/June 1997). The Chupa is a fjord type estuary about 37 km long with several deep troughs, connected by shallow sills, situated south of the Arctic circle on the western shore of Kandalaksha Bay. Vertical profiles were carried out on an axial grid of 10 stations, at spring and neap tidal states, during which measurements were made of salinity, temperature, current speed and direction, the concentration of suspended particulate material (SPM), pH, dissolved oxygen, nutrients (phosphate, silicate, nitrate, nitrite and ammonia) and particulate trace metals in sediments and SPM (Millwardet al., 1999, Estuarine, Coastal and Shelf Science,48,13–25). Additionally, sampling for the hydrodynamic determinants was carried out on diurnal anchor stations at key points in the estuary. Vertical stratification was pronounced, particularly in summer, with sharp gradients in temperature and salinity. A three layer vertical structure was observed with surface (0–5 m) and deep (20–65 m) water layers providing net down-estuary transport while the intermediate (5–20 m) water layer drives net up-estuary transport and advection of more saline waters into the estuary. Strong internal waves were observed in the seaward half of the estuary at certain tidal states. The mechanism for renewal of deep waters in the troughs was investigated, this being considerably slower than in the near surface waters. Evidence of under-saturation of dissolved oxygen was evident in the deep waters of the troughs during the three surveys

The authors wish to express their gratitude to the Royal Society (London) for their support over 4 years through a project grant and to INTAS (Brussels) for their support under Co-operation Agreement Number 1010-CT93-0019. The support and advice given by Dr Alan Morris and Dr Reg Uncles is gratefully acknowledged

12 pages, 11 figures

Peer reviewed