Explain how human activities can cause an imbalance in biogeochemical cycling and lead to problems such as cultural eutrophication and fish killing

Biogeochemcal cycling refers to the cyclic movement and turn over of the essential elements  of living matter. Due to various human activities, most of these cycles have been thrown out of balance. Alteration in biogeochemical cycle together with climate changes leads to various problems such as destruction of biodiversity, food security, eurtrophication, etc. The killing of fish in water bodies occurs, when the fish do not have enough oxygen to breath as a result of eutrophication. Eutrophication refers to the excessive richness of a body of water which result in dense plant growth that takes oxygen away from the water body. 

Wetlands form where water and land meet. a lake with a wetland fringe can fill in with decayed plant and animal material to become a wet meadow. a pond can fill in to become a bog or fen. sediment can fill in a river marsh to become a swamp.flooding of coastal lowlands from rising sea levels has created broad coastal marshes that are protected from wave action by barrier islands or reefs. coastal wetlands also form when rivers deposit sediment as they reach the ocean. plants then take root and hold the soil firm against the forces of tides and waves.