You are here:
ENVIRONMENTAL STRESS AND RECOVERY: THE GEOCHEMICAL RECORD OF HUMAN DISTURBANCE IN NEW BEDFORD HARBOR AND APPONAGANSETT BAY, MASSACHUSETTS (USA)
Citation:
Latimer, J S., W S. Boothman, AND S Jayaraman. ENVIRONMENTAL STRESS AND RECOVERY: THE GEOCHEMICAL RECORD OF HUMAN DISTURBANCE IN NEW BEDFORD HARBOR AND APPONAGANSETT BAY, MASSACHUSETTS (USA). MARINE POLLUTION BULLETIN 313:153-176, (2003).
Description:
To restore and maintain chemical, physical, and biological integrity of the nation's waters, knowledge of the characteristics of unimpaired water bodies and their watersheds is required. The historical reconstruction approach of assessing ecological integrity uses records of human activities coupled with biogeochemical analyses to determine environmental conditions before significant human impact. Comparison of geochemical indicators from two systems (New Bedford Harbor and Apponagansett Bay), which share regional characteristics but have undergone different developmental histories, allowed reconstruction of historical inputs of toxic substances. Concentrations of toxic organic compounds, contaminant and crustal metals, and organic carbon content and isotopic composition were measured in sediment cores. Analyses of 210Pb, 137Cs, and pollen were used to estimate core dating and sedimentation rates. Vertical distributions of the geochemical markers provide an historical record of anthropogenic activities within the respective watersheds that correlates with changes in the nature of local watershed/estuarine activities. Specific contaminants related to the early whaling industry increased significantly above background as early as the late18th century. All contaminants were highly enriched (tens to hundreds times background) in modern New Bedford Harbor sediments. Enrichment began around the turn of the 20th century for all but PCBs, which were first synthesized in the 1930s. An increase in organic carbon content and a shift of carbon isotopes toward a more terrestrial signature illustrates increasing anthropogenic impact in New Bedford as population grew along with the industrial base. Institution of environmental protection measures in the late 20th century was reflected in decreasing concentrations of contaminants, although still substantially enriched above background. A lack of industrial development in Apponagansett Bay resulted in much lower concentrations of the same indicators. This characterization of historical trends was applied to determine whether indicators in sediment cores can be used to establish reference or background stressor conditions. Statistical analyses were performed to determine the depth and characteristics of reference conditions in each location. The similarity of indicators in the deeper, older portion of NBH cores and unimpacted Apponagansett Bay demonstrates that cores may be used to establish reference conditions as successfully as using separate sites judged a priori to represent the reference state. The historical reconstruction approach provides the basis for establishing relationships between environmental stressors and factors that drive the stressors, as well as a framework for the assessment of ecological response(s) to environmental stressors over a range of time and/or exposure scales.