A: The impact hypothesis is deemed to be invalid.
B: The hypothesis is valid and proven, and no further research is required.
C: The impact hypothesis is believed to be valid but further study is required to examine and monitor the appropriateness of the hypothesis.
D: The hypothesis is valid, but impact poses little threat to the ecosystem so further study is unnecessary.
Of 59 impact hypotheses evaluated, four were categorized as A and 14 as B-these were found not worth testing; 14 were categorized as D and found valid and already verified. The remaining 27 hypotheses were classified as C, indicating that they were assumed valid but further investigations were recommended for validation. As an example, Table 4.5-5 shows the impact hypotheses examined with respect to a few components of the VECs, benthic vertebrates, marine, estuarine and anadromous fish in the case (specific activity) of summer operation with container vessels in the NSR.
Various methods have been developed for qualitative assessment of vulnerability and semi-quantitative evaluation of environmental impact. The application of these methods in the environmental assessment and planning system depends on the accuracy and resolution of the database. Generally, semi-quantitative methods are applied where high-resolution data are available; otherwise qualitative methods are chosen. Figure 4.5-5 shows a flowchart for an environmental assessment and planning system and the principle procedures. To examine impact hypotheses and estimate the impact significance, a standard method called the ESSA method is used. This method introduces scaled parameters for indications of the potential impact level, which are spatial scale, temporal scale and perturbation magnitude. Each of the parameters consists of three levels, given scores from 1 to 3, as shown in Table 4.5-6. The multiplication of the three parameters yields 27 different values and they are grouped into three classes, relating to the corresponding level of the potential impact levels; low, medium or high potential impact. For example, as shown in Figure 4.5-6, INSROP GIS was applied to assess the potential impact level of noise and disturbance from navigation (the impact factor) on ivory gulls (the VEC). Most INSROP GIS data are unsuitable for quantitative evaluations as shown in Table 4.5-6, and in many cases, the distributions are given only at relative level.
4.5.5 Environmental regulations
As our understanding improves of the extent of environmental pollution and its future impact, people of all nations and regions are coming to realize how important it is to reduce and eliminate wherever possible the pollution that attends human activity. Because the ocean covers 70% of the earth's surface, marine pollution is a particularly critical issue of global significance. The sources of marine pollution are found on land and in the air as well as at sea; pollution from ships accounts for a relatively low 12% of the total (Kuribayashi, 1999). Nonetheless, the Arctic Ocean in which the NSR lies is unusually vulnerable to pollution, and its exceptionally harsh environment aggravates the danger of accidents.