A common question: where to begin your search? With a popular source on your topic, or a scholarly source?.
Here are a few ways you may want to approach this.
Maybe you start with Chemistry World, C&EN Global Enterprise, or another popular resource that covers science news. These often highlight recent journal articles on topic being covered. You may find these articles helpful for your essay, or provide a launching point to find related articles.
Maybe you started with a topic search in Web of Science and found an interesting article: Emergent constraint on Arctic Ocean acidification in the twenty-first century. You go to Nature to read the article and decide to use it. Now you want to find a popular source on your topic. There are several approaches you can take: