The effects of three sulfonylurea herbicides and their degradation products on the green algae Chlorella pyrenoidosa

The effects of three sulfonylurea herbicides, metsulfuron-methyl, chlorsulfuron and bensulfuron, and their main degradation products on the green algae (Chlorella pyrenoidosa) were studied through 96-hour algae growth inhibition tests and organic nitrogen bioavailability tests. Experimental results indicated that, the acute toxicity of these sulfonylurea herbicides was much higher (about 2 or 3 orders) than their corresponding degradation products, and nitrogen of the degradation products could be used by the algae as the only nitrogen source to stimulate their growth in the order .