Nutrient enrichment and N:P ratio decline in a coastal bayeriver system insoutheast China: The need for a dual nutrient (N and P) management strategy
Nengwang Chen, Benrong Peng, Huasheng Hong*, Nicholas Turyaheebwa, Shenghui Cui,Xiujuan Mo
Eutrophication and harmful algal blooms (HAB) have become the primary water quality concerns inChina. A comprehensive analysis was conducted using a dataset obtained from long-term monitoring ofa coastal bayeriver system in southeast China (Xiamen BayeJiulong River Basin), to examine the nutrient[nitrogen (N) and phosphorus (P)] dynamics and the management options. The analysis showed thatincreasing human stresses and external nutrient loads over the past 30 years were the main causes ofwater degradation and eutrophication. A signiﬁcant decline of N:P ratio was observed in both river andestuarine waters since the 1990s due to relatively high P loadings as a consequence of waste dischargesfrom the proliferating husbandry of livestocks and the application of excessive phosphate fertilizers tocash crops. Continued nutrient enrichment and the decline of N:P ratio have changed the nutrientstoichiometry and supply ratio in waters, which have increased the risk of nutrient-enhanced algalbloom. According to the ﬁndings and current knowledge concerning eutrophication and HAB processes,a dual nutrient (N and P) management strategy is necessary for management of water quality in theXiamen BayeJiulong River Basin with a focus on animal wastes in the north Jiulong tributary and over-fertilization in the west Jiulong tributary.