First, some web links to free online web sites designed for AP Environmental Science or related content:

AP Environmental Science study guides:

Note: I don't endorse any particular guide.  The comments included were found on the publisher's websites.

When it comes to scoring higher on the AP Environmental Science Exam, nobody prepares you better than Smartypants. This comprehensive, efficient study guide pinpoints everything you need to boost your score, from test-taking strategies to a complete review by topic. Features of this study guide include: a focused review of every topic on the AP exam, expert test-taking tips, a realistic full-length practice exam with answer key and thorough explanations, important graphs, charts, and diagrams, and a tune-up of key concepts and vocabulary terms. Compatible with virtually every standard textbook or course on the subject, this invaluable tool is what you need to score your best - and get the college credits you deserve! (excerpted from the site)
Has already been successfully used by thousands of students, worldwide; improving their test scores.
Has three complete practice exams.
Has detailed answer keys with rubrics for all practice exam questions that targets student study efforts to select topics.
Has a comprehensive vocabulary glossary.
Covers the entire course, including laboratory exercises.
Has a supplementary workbook for additional practice and test preparation.

This brand-new Advanced Placement manual is the only book currently on the market that specifically prepares students for the AP Environmental Science Exam. It reviews all important environmental science concepts and problems, including: the flow of energy, its sources, and conversions; the cycling of matter; geology and earth dynamics; the atmosphere, weather, and climate; the biosphere, human history and global distribution; the earth's renewable and nonrenewable resources; measuring environmental quality; global changes; and environmental laws, ethics, and issues. The book's added features include an overview of the test format and test-taking strategies. Two full-length practice tests are presented with questions answered and explained.
 

These books contain a comprehensive review of the AP Environmental Science course. The student workbook includes exercises and three practice exams with both multiple choice and free response questions, while both books cover test taking tips, vocabulary, and a course outline/review. In addition, major concepts and laboratory skills are emphasized and contributions from numerous environmental scientists and teachers are included. Softcover. Study guide, 216 pages. Workbook, 190 pages.