| To investigate the temporal and spatial variations of nitrogen and phosphrous status in the Qinhuai River, the total dissolved nitrogen(TN), nitrate(NO3-), ammonium(NH4+), dissolved organic nitrogen(DON), total dissolved phosphrous(TP), chloride(Cl-), sulfate(SO42-). dissolved organic carbon(DOC) and other basic physicochemical indexes were monitored with continuous year-round measurements from June2010to December2012. The year-round source of nitrate in the Qinhuai River was determined by using the15N isotope of nitrate from April2011to March2012. Moreover, the Coliforms and Fecal Coliforms were analyzed once every three months for one year. These results together with the above mentioned Cl-, SO42-measurements and local field survey were combined to distinguish the nitrogen sources and thus deduce the phosphrous sources. Results showed that the Qinhuai River was polluted seriously in terms of nitrogen and phosphrous, and that the concentrations of both nitrogen and phosphrous showed highly spatial and temporal variations; the main sources of nitrogen and phosphrous were from manure and sewage.The interannual average TN concentrations in the traditionally managed agricultural area, intensively managed agricultural area, and urban area were2.10,3.79, and6.71mg·L-respectively. The spatial variations of TN concentrations indicated that the urban area and intensively managed agricultural area, rather than the traditionally managed agricultural area, were the major sources for TN in the river water, the TN contribution of traditionally managed agricultural area was small, other nitrogen in the river water showed the similar spatial patterns with those of TN. The average concentrations of NH4+were high in urban area and intensively managed agricultural area where manure and sewage pollutions were serious. As for the interannual variations of nitrogen concentrations, while the concentration of TN in river was increased, the NO3-, DON concentrations of traditionally managed agricultural area and urban area and the DON concentration of intensively managed agricultural showed increasing tendency, and the NH4+concentration had a declining tendency among the three area.The temporal variations of TN and DIN were influenced by rainfall and air temperature, showing that during the high rainfall and temperature period, the nitrogen concentration of the river was low; and during the low rainfall and temperature period, the corresponding nitrogen concentration in the water was high. The concentrations of TN and NH4+were influenced by rainfall and air temperature markedly, but the NO3-concentration was markedly influenced only by air temperature. The temporal variations of the DON concentration were low, and its concentration had no significant correlations with rainfall and air temperature. In terms of the monthly average of nitrogen concentration, the NO3-, NH4+, and DON accounted for46.27%,30.94%, and22.79%, respectively of the TN. Therefore, the main nitrogen composition of the river water was NO3-, followed by NH4+and DON.The average TP concentrations of the river water in the traditionally managed agricultural area, intensively managed agricultural area, and urban area were0.08,0.16,0.30mg·L-1, respectively. The TP of Qinhuai River mainly came from the urban area and intensively managed agricultural area while the traditionally managed agricultural area had least contribution. The TP showed similar variation tendency with the TN. As for the TP interannual variations, the TP concentration had a increasing tendency in traditionally managed agricultural area, intensively managed agricultural area and the urban area, thus the TP pollution condition in Qinhuai River became gradually serious. Through the correlation of average TP concentration in river and rainfall, air temperature, we found that the TP concentration was influenced markedly by air temperature, but not by the rainfall. The TP of river had a higher concentration in autumn and winter as compared to that in summer.The NO3-/Cl-value for spring, summer, autumn, winter were0.17,0.15,0.07, and0.12, respectively, and the average NO3-/Cl-value for all the seasons was low due to mixing of manure, sewage, filed, rainfall and other nitrogen sources. The ratio of NO3-/Cl-and the concentration of Cl-concentration of the Qinhuai River were concentrated, and the river water had high Cl-concentration, as well as the input of the fields, manure and sewage had high Cl-concentration. Consequently, we deduced the main NO3-sources were the manure and sewage, the seasonal input of fields was also a important NO3-source. Using the NO3/Cl-value and the seasonal variations, we could deduce the species of nitrogen sources in different seasons in the Qinhuai River. The Coliforms and Fecal Coliforms results showed that the Qinhuai River was polluted seriously by manure and sewage and that the urban area and intensively managed agricultural area had a serious pollution by manure and sewage, and the traditionally managed agricultural area had little influence by manure and sewage. The results showed that the main nitrogen sources of the Qinhuai River water were manure and sewage, and manure and sewage also were main NH4sources.The average value of δ15N-NO3-for spring, summer, autumn, winter in Qinhuai River were11.44‰(n=48),9.78%o (n=54),9.76%o(n=48), and11.86%o(n=32), respectively. According the δ15N-NO3-value of different NO3-sources and the δ15N-NO3-value of seasonal distribution in river water, the main NO3-sources of the Qinhuai River were manure and sewage which varied with the different seasons. There were45.8%,83.3%,68.8%, and96.9%samples came from manure and sewage sources in spring, summer, autumn, and winter, respectively. Duing the warm seasons including spring, summer, and autumn, the fertilizer, rainfall, and soil sources with low δ5N-NO3-values showed a great input, and there were43.8%and31.3%samples came from fertilizer, rainfall,and soil sources in spring and autumn, respectively, while only16.7%in summer due to the rainfall dilution effect.The main nitrogen form in the Qinhuai River was NO3-, the following was NH4+, the main NO3-and NH4+sources were manure and sewage, the NK4+, NO3-, DON were significant correlation from sources, combining the results of survey in local, the main TN sources of the Qinhuai River were manure and sewage. The TP and TN had similar spatial variations, showing that the TP and the TN had a same origin. Consequently, the TP sources of the Qinhuai River were manure and sewage. |
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