Pelorus Sound is typical of New Zealand coastal locations, i.e. there is a semi-diurnal tide modulated on a spring-neap cycle, generated by the superposition of M2 (lunar, semi-diurnal) and S2 (solar, semi-diurnal) tidal constituents. Other tidal constituents, notably N2 (semi-diurnal, generated by the ellipticity of the moon’s orbit), introduce further modulation, meaning that the spring-neap cycle is not exactly repeated. The tidal range varies between at neap and at spring. (These values are calculated from a sea level time series, July 1997 – February 1998, at Pelorus Sound entrance.) The propagation of this tidal signal into Pelorus Sound has not been well
Issues relating to biofuels ecosystems including rainforest in South America. In forest ecosystems, these effects themselves will undermine the climate benefits of alternative fuels, in addition to representing a major threat to global biodiversity. Although biofuels are generally considered to improve net carbon output, biodiesel and other fuels do produce local air pollution, including nitrogen oxides, the principal cause of smog. Issues relating to biofuels There are various social, economic, environmental and technical issues with biofuel production and use, which have been discussed in the popular media and scientific journals. These include: the effect of moderating oil prices, the "food vs fuel" debate, poverty