Investigation into the Distribution of Ballast Water Tracers in Coastal Waters
Abstract
The assessment of compliance by ships with mandatory ballast water exchange (BWE) is limited by the difficulty of verifying whether BWE was implemented. Previous research indicates that concentrations in ballast water of barium, phosphorous and manganese and chromophoric dissolved organic matter (CDOM) can be robust tracers of BWE. The current study examined the seasonal and spatial variability of BWE tracers in Pacific rim ports and the adjacent seas, using the north Pacific as a model system to examine whether it would be possible to set universal thresholds for tracer concentrations in ballast water that can consistently and effectively discriminate tanks that have undergone BWE from tanks that have not. Surveys were conducted in eight port systems in North America and Asia and along perpendicular and coastwise transects off the US Pacific coast. CDOM decreased rapidly with increasing distance from land, whereas barium, phosphorous, and manganese exhibited more seasonally and regionally variable trends. CDOM tracers could usually discriminate between port (<0.2 nautical miles (nmi) from land) and oceanic samples, but not necessarily between BWE performed in coastal (0.2nmi to 100 nmi from land) versus oceanic (>100nmi from land) locations. This result has important implications for verifying BWE performed according to state legislation, which allows BWE as close as 50 nautical miles from land.
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 01, 2009
- Accession Number
- ADA530080
Entities
People
- C. M. Brown
- D. Sparks
- G. Ruiz
- Geoffrey B. Smith
- J. Boehme
- K. Murphy
- M. Novle
- T. Mullady
Organizations
- United States Coast Guard Research & Development Center