In a dated core from the Northwest Arm of Halifax Harbour, pollutant hydrocarbon concentrations have increase 100-fold since about 1900 (15–20 cm depth). Aliphatic contaminants characteristic of sewage and urban runoff have had a steady, exponential growth overtime, while aromatic hydrocarbon combustion products are currently declining slightly from a subsurface maximum around 1950 (5–10 cm depth). Present levels of these compounds are among the highest reported in the literature. Similarly, contamination of sediments by the metals Cu, Zn, Pb, and Hg has also increased from 1890 to 1970, with maximum levels among the highest reported from other urban and industrialized coastal marine areas in the world. In contrast, the concentrations of natural product hydrocarbons such as squalene and perylene have not changed significantly in this century.
Common properties of hydrocarbon combustion products and Brayton cycle
