Environmental nitrogen and phosphorus loading and water quality of three culture methods in ponds
不同池塘养殖模式的环境氮磷负荷及其水质特征

In this paper,the environmental nitrogen and phosphorus loading and nitrogen and phosphorus contents in water of two methods of pond culture with feeding(semi-intensive monoculture of shrimps and semi-intensive polyculture of shrimps and crabs),and one method of pond culture without feeding,(extensive polyculture of shrimps and shellfish) were analyzed in the ponds of Haifeng Dongguan Lian’anwei wetland areas.The results showed that in the three culture methods,semi-intensive monoculture of shrimp produced most nutrient discharge into the environment–nitrogen loading of 36.52kg/ hm2 and phosphorus loading of 7.39 kg/ hm2,following by those of semi-intensive polyculture of shrimps and crabs,with nitrogen loading of 1.49kg/ hm2 and phosphorus loading of 0.52 kg/ hm2,and extensive breeding did not discharge but instead,took up 2.47 kg/ hm2 nitrogen and 0.34kg/ hm2phosphorus from water.According to the monthly measurement of the levels of nitrate,nitrite,ammonia,total nitrogen,phosphate,and total phosphorus in seawater from March of 2008 to January of 2009,it indicated that the water quality of semi-intensive monoculture of shrimp was the worst among the three culture methods,followed by semi-intensive polyculture of shrimp and crabs and the extensive polyculture of shrimps and shellfish has the best water.This situation became more significant during the later period of culture.