Geochemical characteristics of contaminated surficial sediments in Halifax Harbour: impact of waste discharge

Abstract

Analyses of 274 surface sediment samples collected from Halifax inlet between 1986 and 1990 permit assessment of the chemical environmental quality of this major east coast Canadian harbour. Contamination of the marine sediments is due to discharge of untreated sewage and industrial waste directly into the harbour, and leaching of solid waste deposits on land. Concentrations of total Cu, Pb, Zn, Hg, and Cd in the uppermost 2 cm of sediments on the sea floor ranks Halifax Harbour among the most contaminated marine areas in the industrialized world. Statistical factor analysis has been used to identify five types of sediments based on sedimentological and geochemical characteristics. The dominant factor type accounts for 41% of the chemical variance and represents sediments that are highly contaminated with metals and organics derived from sewage effluents and waste deposits. More than 50% of the total Cu, Zn, and Pb in the sediments is potentially reactive as reducible or oxidizable metal.A simple two-layer estuarine circulation model has been used to assess the significance of dissolved metal sources and sinks in the harbour. The contribution to sediment contamination from dissolved metal inputs is relatively minor, with more than 88% of the potentially reactive Cu, Zn, Pb, and Hg being directly associated with particulate deposition. However, the model suggests that high proportions of the dissolved annual inputs of Zn (40% of 5.5 t), Pb (100% of 1.3 t), Hg (100% of 0.02 t), and Mn (89% of 19.6 t) are taken up by the bottom sediments.Future environmental quality management of Halifax Harbour should take into consideration the geochemical stability of sediments. New sewage treatment facilities may reduce the loading of contaminants, but some remobilization of metals from sediments may reduce long-term improvements in contaminant levels in the water column.

An Empirical Assessment of Marine Debris, Seawater Quality and Littering in Ghana

“…For fishing and boating, the levels of coliform are within the acceptable range. Water quality results for this study is comparable to that in the Halifax harbour where raw sewage has been discharged for more than 200 years [48]. Bacterial contamination is pervasive throughout the harbour, and the waterfronts along Halifax and Dartmouth are aesthetically poor owing to particulates, floatables, and odour [49].…”

Simulating the three-dimensional circulation and hydrography of Halifax Harbour using a multi-nested coastal ocean circulation model

“…1. The annual mean discharge from the Sackville River is relatively small (∼5 m 3 s −1 , Buckley and Winters 1992) and accounts for about one third of the total freshwater inflow to the Harbour. The monthly mean discharge of the Sackville River (red dots, Fig.…”

“…The locations and values (Fig. 1) of fluvial and sewage effluents in Halifax Harbour are taken from Buckley and Winters (1992). Buoyancy forcing is implemented in submodel L5 using the approach of Yang et al (2007).…”

“…Bedford Basin is approximately 6 km long, 4 km wide and has a maximum depth of about 71 m. It is connected to the Inner Harbour by the Narrows which is about 500 m wide, 3 km long and features a shallow sill with a minimum mean depth of about 20 m. The Sackville River, which is the only major fresh water river in the region, discharges into the northern end of Bedford Basin and, as will be shown, is an important contributor to the overall mean circulation. Raw sewage and wastewater have been discharged into Halifax Harbour for more than 200 years, which has had negative effects on the reputation of the Harbour, and has created serious economic and environmental problems (Wilson 2000;Buckley and Winters 1992;Fournier 1990).…”

Trace elements levels in sediments of the Czech part of the Elbe river

“…This statistical tool is based on the selective matrix coefficient and thus yielded the relationships amongst the elements that can be described in terms of the correlation coefficients (Pavoni et al 1988;Buckley and Winters 1992). The data was transformed to the corresponding points in multi-dimensional space by extracting the eigenvectors and eigenvalues from the variance-covariance matrix ( Table 2).…”