Li Y, WZ Cao, CX Su, HS Hong.Marine Pollution Bulletin, 2011. 63: 249-254.

The natural process of eutrophication is accelerated by human activities worldwide that interrupt nutrient biogeochemical cycles. Three algal bloom events have been monitored in the northern tributary of the Jiulong River since 2009. The inflection points in a robust locally-weighted regression analysis (LOESS) of the relationship between TN and TP concentrations in the river water, and a TN:TP comparison with nutrient source loadings, suggested that both external loading and internal nutrient cycling contributed to these algal blooms. Nutrient release from the sediments may have played an important role in regulating the nutrients in the overlying water column. In particular, excessive nutrient inputs from various sources and ubiquitous river damming caused further accumulation of the nutrient loading. In-situ autochthonous primary production was enhanced in this relatively stable “river’’ to ‘‘lake’’ water body. Thus, attention must be paid to the effects of river damming and the consequent internal nutrient release.

Fig. 5 Relationship between mean TN and TP concentrations (mg L^-1) in river water (dots) and the TN:TP in terrestrial nutrient loadings (lines) in the northern Jiulong watershed. TN and TP concentrations were analyzed during the algal blooms in 2009 and the first 3 months of 2010. The TN:TP of runoff from unfertilized fields, precipitation and eutrophic lake sediment are cited from Loehr (1974), Allen et al. (1968) and Fukushima et al. (1991), whilst the other ratios were values from the northern Jiulong watershed.