Ocean debris

R. V. Grace, Oceanic Debris Observations in the Indian Ocean Whale Sanctuary and Eastern Mediterranean Sea, Report to International Whaling Commission Scientific Committee SC/46/0, Puerto VaUarta, Mexico, 1994. 

Food packaging and food service plastics have the shortest service lifetime of any plastic product manufactured and end up in the waste or litter at a much faster rate compared to other plastic products. Packaging therefore has implications on sustainable development for several reasons. First, being a high-volume-use sector, plastic packaging produces waste that can end up in urban litter and even as ocean debris (see Chapter 10). There is no efficient mechanisms to collect, recycle, or dispose of most plastic litter. Secondly, some of the primary plastic packaging is used in contact with food or beverages, and the possibility of additives (and residual monomer)... 

Common types of plastics found as ocean debris are listed along with their densities in Table 10.1. Those denser than seawater (p 1.025 g/cm ) will sink and invariably end up in the marine sediment. The long-term fate of even the floating plastics, however, will be the same. A surface biofilm of bacteria and diatoms develops... 

TABLE 10.1 Plastics Commonly Found in Ocean Debris... 

Debris and What We Can Do About It The report presented ocean debris data recorded by nearly 400,000 volunteers in 104 countries and 42 US states (Ocean Conservancy s International Coastal Cleanup 2010). In 2008, approximately 73% of cleanups were performed on ocean beaches and 27% were completed on inland waterways and lakes. 

A report in 2009 from Ocean Conservancy found that the source of the debris items is mostly related to human recreational activities and smoking (Ocean Conservancy s International Coastal Cleanup 2010). The world averages for the sources of marine debris demonstrate that 61 % of the items that collected were related to shoreline and recreational activities, 31 % of the items were related to smoking, 5% related to ocean and waterway activities, 2% to dumping activities, and 1% to medical and personal hygiene activities. In North America, the sources of ocean debris were similar to the world averages. The sources of marine debris by region are listed in Table 2.5. 

Table 2.5 lists the sources of marine debris around the world. Littering from shoreline and recreational activities is the primary source of ocean debris in the world that accounts for approximately 61% of the worldwide marine debris items. Smoking activities contribute to approximately 31% of the worldwide marine debris items. The source of marine debris from smoking can be attributed to smokers who are on or near the beaches around the world. Very little ocean debris is caused by dumping from ocean vessels or of medical and personal hygiene products. 

The predominant sources of marine debris around the world are from smoking activities and littering dvuing shoreline and recreational activities. Very little ocean debris is caused by dumping from ocean vessels or of medical and personal hygiene products. 

Over the past decade, plastic debris has become a common feature of beaches and coastal waters adjoining populated areas of Europe (36-38), the Mediterranean (39-41), North and Central America (42-44) and New Zealand (45). Plastics are also present in the open ocean both near the major shipping lanes and in the most remote regions of the world (the Arctic (46), the Benguela Current (47), the Cape Basin area of the South Atlantic (48), the Humboldt Current in the South Pacific (49), and the Antarctic (50, 51). 

Estuaries exhibit physical and chemical characteristics that are distinct from oceans or lakes. In estuaries, water renewal times are rapid (10 to 10 years compared to 1 to 10 years for lakes and 10 years for oceans), redox and salinity gradients are often transient, and diurnal variations in nutrient concentrations can be significant. The biological productivity of estuaries is high and this, coupled with accumulation of organic debris within estuary boundaries, often produces anoxic conditions at the sediment-water interface. Thus, in contrast to the relatively constant chemical composition of the... 

Broecker and Li (1970) and Broecker (1974) found that the 14C/12C ratio in the deep ocean was 84 percent of this ratio in the pre-bomb surface ocean. Assuming that surface carbon (dissolved and falling debris) is the only source of deep ocean carbon, calculate the residence time tc of this element in the deep-ocean. The 14C decay constant is 1.2 x 10 4a 1. 

Using the rock cycle as an example, we can compute the turnover time of marine sediments with respect to river input of solid particles from (1) the mass of solids in the marine sediment reservoir (1.0 x 10 g) and (2) the annual rate of river input of particles (1.4 X lO g/y). This yields a turnover time of (1.0 x 10 " g)/(14 x lO g/y) = 71 X lo y. On a global basis, riverine input is the major source of solids buried in marine sediments lesser inputs are contributed by atmospheric feUout, glacial ice debris, hydrothermal processes, and in situ production, primarily by marine plankton. As shown in Figure 1.2, sediments are removed from the ocean by deep burial into the seafloor. The resulting sedimentary rock is either uplifted onto land or subducted into the mantle so the ocean basins never fill up with sediment. As discussed in Chapter 21, if all of the fractional residence times of a substance are known, the sum of their reciprocals provides an estimate of the residence time (Equation 21.17). 

The unique chemical composition of cosmogenous debris has provided some insight into why approximately 70% of the species of organisms on Earth were driven extinct over a relatively short time interval approximately 66 million years ago. Evidence for this mass extinction has been observed in marine sediments throughout all the ocean basins. In a contemporaneous layer deposited at the end of the Cretaceous period, the hard parts of many species of marine plankton abruptly vanished from the sedimentary record. This sedimentary layer is also characterized by a large enrichment in the rare element iridium. 

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