87mg/L, from 4.05% to 14.6%, and from 16.2 to 48.3��g/L.The POC distribution shows a similar pattern with the distribution of chlorophyll a (Figure 3), indicating that phytoplankton plays an important role in POC pool. Gemcitabine buy Besides, the concentrations of BDOC illustrate a linear and positive relationship with the initial DOC concentrations (Figure 2), suggesting that DOC was highly biodegradable within the time scale of the incubation (1 month). Chl a concentrations were also related to the PAHs concentrations (Figure 3), which indicated that PAHs can be easily absorbed by algae in the SPM. It was also implied that algae was the dominant composition of POC and governed the distribution of particulate PAHs. An increasing phytoplankton biomass and growth rate was reported to increase the air-water transfer of PAHs [16].

New phytoplankton production contributed to substantially longer times for air-water equilibrium, and the depletion of the dissolved phase by phytoplankton uptake prevented the equilibrium of air and water phases. The gas phase supports the concentrations of organic pollutants such as PAHs in atmospherically driven environments. Increased air-water exchange followed by phytoplankton uptake also seemed to be two of the most relevant processes increasing the vertical flux in the water column [17].Figure 2Correlations of DOC with BDOC of PAHs in Pearl River Delta.Figure 3Relationship between Chl a and POC and between particulate PAHs (S-PAHs) and Chl a.3.2. Concentrations of PAHs in the Water, SPM, Fish, Lipid Samples 3.2.1.

PAHs in the Water Samples PAHs in the water and SPM samples were listed in Figure 4. For the water samples, PAHs showed obviously seasonal variation in the Dongjiang River. They were higher in summer, ranging from 16.56 to 34.27ng/L with an average of 25.63ng/L, than in spring, ranging from 11.11 to 65.21ng/L with an average of 25.15ng/L.Figure 4Spatial distribution of total PAHs in the riverine surface water and the SPM samples from the Pearl River Delta (except for Nap and Phe). Individual PAHs also showed considerable variances among the samples (Figure 5). For all the water samples, low molecular weight PAHs were the dominate compounds. Brefeldin_A The percentage of 3 and 4-ring PAHs ranged from 42.06% to 81.09% with an average of 65.38%. Acenaphthylene, fluorene, fluoranthene, and pyrene were the major constituents of PAHs in the water samples.Figure 5The composition of PAHs in (a) water samples and (b) suspended particular matters samples (both except for Nap and Phe).PAHs in the water samples are compared with those of other investigations (Table 3).