In this task, we ask you to rewrite a sentence in simple English without changing its general meaning. Essentially, you want to make the sentence easier to read by using simpler words, utilizing more straightforward sentence structures, and omitting non-essential information etc.

In marine sediments the biological production of methane , also termed methanogenesis , is generally confined to where sulfates are depleted , below the top layers .
In marine sediments methane is produced when sulfates are low .

The Nymphalidae are the largest family of butterflies with more than 6,000 species distributed throughout most of the world , belonging to the superfamily Papilionoidea .
The Nymphalidae is the largest family of butterflies , with about 6,000 species .

The Chinese Canadian community is the largest ethnic group of Asian Canadians , consisting approximately 40 % of the Asian Canadian population .

Chinese Canadians make up 40 % of Asian Canadian people .