For the determination of biodegradable DOC (BDOC), approximately 300mL of filtered water was contained into 500mL precombusted brown glass bottles and incubated in the dark at about selleck 20��C for 30d. The difference of DOC concentrations measured before and after incubation were regarded as the BDOC concentrations.Samples for determining Chl a were filtered through 0.45um cellulose acetate filters, and then the membrane samples were extracted with 90% acetone for 24h. Chl a was determined by using a UV-VIS spectrophotometer (752, UV-2000, Shanghai). The absorbency at wavelength of 663nm, 645nm, 663nm, and 750nm were measured. Chl a was calculated by the following equation +0.1��(D630?D750)]��V1(V��L),(1)where??[15]:C=[11.64��(D663?D750)?2.

16��(D645?D750) D630, D645, D663, and D750 represent the absorbency of 630, 645, 663, and 750nm, respectively. The V1, V, L, and C represent the volume of water samples (L), the thickness of cuvette (cm), and the concentration of chlorophyll a (��g/L), respectively.2.5. Quality Assurance and Quality Control (QA/QC)Procedural blanks and spiked blanks were analyzed with field samples, and surrogate standards (d8-Nap, d10-Acy, d10-Phe, d12-Chry, and d12-Per) were also added to all the samples to monitor procedural performance. Except for Nap, 10.05ng/L of total PAHs was detected on average in water blanks (n = 4), and 17.21ng/L of total PAHs was detected in particle blanks (n = 5). The recoveries of 16 PAHs in spiked blanks (n = 3) varied from 50.9% (Nap) to 122.7% (BgP). Because of the high background values for Nap, total concentrations of PAHs did not include Nap.

Phe was also not considered in the distribution of total PAHs in water and SPM samples due to the possible pollution during the process of experiments. And the reported PAHs concentrations were corrected with the blank values.3. Results and Discussions3.1. Major Properties of WaterThe major aquatic chemical properties in the water samples including pH, conductivity, salinity, dissolved oxygen (DO), concentration of suspended particulate matters (SPM), dissolved organic carbon (DOC), particulate organic matters (POC), chlorophyll a (Chl a), and total PAHs were listed in Tables Tables11 and and2.2. The concentrations of DOC in the Dongjiang River ranged from 1.19mg/L to 13.91mg/L in July 2010. While in April 2011, the DOC concentrations varied from 2.28mg/L to 5.38mg/L in the Dongjiang River and from 2.62 to 4.88mg/L in the Pearl River. In the Dongjiang River, SPM, POC, and Chl a varied from 11 to 53mg/L, from 4.14% to 13.3%, and from 3.11 to 10.1��g/L, respectively in July 2010, while they ranged Dacomitinib from 13.65 to 42.86mg/L, from 1.59% to 9.65%, and from 2.76 to 28.2��g/L in April 2011.