(a) How is the 'Law of the Sea' relevant to the management of marine mineral resources ? (10 marks) (b) Explain the causes and…

(a) Law of the Sea and marine mineral resources (10 marks)

The UN Convention on the Law of the Sea (UNCLOS, 1982) divides the ocean into zones with different ownership of minerals.

• Territorial sea (12 nautical miles) and contiguous zone (24 nm): full sovereignty in the first.
• Exclusive Economic Zone (200 nm): sovereign rights over living and non-living resources, including seabed minerals and hydrocarbons.
• Continental shelf: rights up to 200 nm, extendable to about 350 nm on submission to the Commission on the Limits of the Continental Shelf.
• Area: seabed beyond national jurisdiction, the "common heritage of mankind", administered by the International Seabed Authority (Kingston), which licenses exploration of nodules, sulphides and crusts and shares benefits.

India ratified UNCLOS in 1995, has an EEZ of over two million km², holds an ISA contract for polymetallic nodules in the Central Indian Ocean Basin, and another for polymetallic sulphides on the Indian Ocean ridges.

(b) Causes and impacts of sea-level rise (10 marks)

Causes.

• Global (climatic): thermal expansion of warming ocean water and melting of glaciers and the Greenland and Antarctic ice sheets, which add water.
• Local (relative rise): land subsidence from groundwater extraction, sediment compaction in deltas, and tectonic movement.

The global mean rate has risen from about 1.5 mm per year in the twentieth century to nearly 4 mm per year at present, and the sea has risen about 20 cm since 1900.

Impacts.

• Physical: coastal inundation, erosion, stronger storm surges, and saline intrusion into aquifers and river deltas.
• Ecological: loss of mangroves, coral reefs and wetlands.
• Socio-economic: displacement, damage to ports, cities and farmland, and loss of livelihood. Low islands, such as the Maldives and Lakshadweep, the Sundarbans and cities such as Mumbai and Kolkata are especially exposed.

(c) Prospecting methods for metallic mineral deposits (10 marks)

Prospecting proceeds from reconnaissance to detailed work, using four groups of methods.

• Geological: regional and detailed mapping, study of outcrops, gossans, float and indicator minerals, and rock and structure controls, followed by pits and trenches.
• Geochemical: analysis of soil, stream sediment, rock, water and plants for the ore metals and pathfinder elements, to trace dispersion haloes and anomalies.
• Geophysical: magnetic surveys (magnetite, chromite), gravity (dense massive ores), electrical resistivity and induced polarisation (disseminated sulphides), self-potential and electromagnetic methods (conductive sulphides), and radiometric surveys (uranium).
• Drilling and sub-surface: core drilling and borehole logging to test anomalies, prove depth and grade, and estimate reserves.

Remote sensing supports the early stages by mapping structure and alteration zones.

(d) Causes of groundwater and surface-water pollution (10 marks)

Surface water.

• Point sources: domestic sewage and industrial effluent discharged into rivers and lakes.
• Diffuse sources: agricultural runoff with nitrate, phosphate and pesticides, urban runoff, and solid waste.
• Mining, acid mine drainage, oil spills, thermal discharge and sediment load.

Groundwater.

• Leachate from landfills, septic tanks, fertiliser and industrial lagoons, with nitrate as the common pollutant.
• Mining and over-pumping, which draw saline or polluted water into aquifers.
• Geogenic contamination, which dominates the Indian problem: fluoride from fluoride-bearing minerals in Rajasthan, Andhra Pradesh, Telangana and Karnataka, and arsenic from reduced alluvial sediments of the Ganga–Brahmaputra plains in West Bengal and Bihar, along with iron, uranium and salinity.

Groundwater pollution is slow to appear and hard to reverse, whereas surface pollution is fast and visible.

(e) Environmental cost of urbanisation and sustainability (10 marks)

Environmental costs.

• Land: loss of farmland, wetlands and forests, and the building of impervious surfaces that raise runoff and flood risk (Chennai 2015).
• Air: vehicles and industry cause pollution, and the urban heat island effect.
• Water: large demand, groundwater depletion, less recharge, and polluted sewage.
• Geology: land subsidence from groundwater withdrawal, construction on hazard-prone slopes and floodplains, and sand and stone mining.
• Waste: large volumes of solid, construction and sewage waste.

Ensuring sustainability.

• Master planning and zoning, using geological hazard maps and preserving green space and wetlands.
• Rainwater harvesting, artificial recharge, and recycling of wastewater.
• Public transport, waste segregation and recycling, and efficient use of construction materials.
• Strong local governance, enforcement and public participation, with geoscientific input into planning.