Can you get the morning off work on Thursday or Friday this week? If so, do so, and head along to the Isle of Dogs. The Thames21 charity is appealing for volunteers to help clean up the particularly trash-prone stretch of the river in the Island Gardens area. Plastic bags are a real menace in these parts - over 30,000 were collected here last year by Thames21 volunteers. If you want to help, they'll provide the wellies, training and encouragement to get you started. All you need to do is get to Newcastle Draw Dock, off Saunders Ness Road, E14 any time between 8 and 11.30 tomorrow, or 8.30 and 11 on Friday. As well as doing your bit for London's environment, the 'deep clean' also offers the chance to explore the Thames foreshore. An especially low tide coupled with a closing of the Thames Barrier mean that the site will be accessible for longer than normal, and to a lower depth. See you there.