四周 (sì zhōu) is a spatial noun meaning 'all around, on every side' — it emphasizes the immediate area encircling a central point. It's more concrete and localized than 周围 (zhōu wéi), which is the general, everyday word for 'surroundings'. 四处 (sì chù) adds a sense of movement or scattering ('in all directions'), while 环境 (huán jìng) refers to the broader environment or circumstances.