IELTS Writing Task 1:-- The diagram shows nitrogen sources and concentration levels in the groundwater of a coastal city.

Answer

The diagram reveals nitrogen sources and density levels in the groundwater of a seaside/coastal city/ coastal vicinity.

It is clear from the diagram that in the natural conditions, lightning oxides nitrogen and vegetation/ plants fix it. Domestic and market garden refill nitrogen in the soil through fertilizers and domestic waste/household waste/ household rubbish. Industries contributes in the nitrogen cycle by adding up it through leakage from storage tanks and waste water ponds. Lastly, nitrogen in the waste disposal/landfill is absorbed by soil and enriches soil with it.

The diagram further reveals that, the groundwater flows from East to West directions passing near to the salt water interface reaching to its destination sea and gets discharged into it from groundwater discharge zone. Reduction in ammonia occurs through two processes, in first process, ammonia is absorbed by soil particles and second is ammonia degassing. The heaviest concentration of nitrogen is below the landfills followed closely by industries while it is less near the sea. 

Overall, waste disposal supply/release maximum nitrogen in groundwater than other sources but density beneath landfills is more.

Vocabulary

Concentration - density

Seaside- coastal

Area- vicinity

Vegetation- Plants

Domestic- household

Waste - Rubbish