Natural waterscapes are a frequent subject of traditional Chinese ink art, but for Gu Wenda they serve as material as well. Last month, Gu gathered around 1,500 schoolchildren to the Shenzhen Conference and Exhibition Center, where they painted 1,500 meters of rice paper using green algae as part of the performance project A Story of Qinglu Shanshui. “I believe this is a historical break for Chinese painting, using the ecological pigment,” says the New York and Shanghai-based artist. The resulting work will be reproduced on the façade of the Ping’an International Finance Center, and shown this month at Shanghai’s M21 Museum during Gu’s solo exhibition, which will also feature another mass performance by schoolchildren. The algae blooms that plague China’s waterways come from industrial and agricultural pollution, and while “the government spends so much money to clean up algae,” says Gu, a solution “must start from education, or it will be endless.” But his chosen collaborators required the artist to make some creative compromises: “The kids are not allowed to touch polluted water, so we switched to [edible] algae from a lab.”