Study On Spatial Distributions And Influencing Factors Of Nutrients In The Typical Intertidal Zones Of China

14 typical intertidal zones including big estuary area(river runoff>500 million m3/a):Yellow River estuary(Shandong,Dongying),Chongming Island(Shanghai,Chongming Island),Min river esturary(Fujian,Fuzhou),the Pearl River estuary(Guangdong,Zhuhai);small estuary area(river runoff<500 million m3/a):Daliao river estuary(Liaoning,Yingkou),Jian River estuary(Tianjin,Hangu),Dagu River estuary(Shandong,Qingdao),Southern Hangzhou Bay(Zhejiang,Cixi)and the Jiulong River estuary(Fujian,Xiamen),and non-estuarine area includ the Beidai river beaches(Heibei,Qinhuangdao),Sishili Bay(Shandong,Yantai),Suzhou shoal(Jiangsu,Yancheng),Yingluo bay(Guangxi,Beihai)and Dongzhai Harbor(Hainan,Haikou)were chosen.Based on the intertidal sediment types,development characteristics,regional distribution and human activities in the study.Nutrient concentrations together with temperature,salinity,pH of sediment interstitial water and overlying water and sediment grain size were analyzed.Combined with human activities,the main influencing factors to nutrient spatial distribution were studied.The main conclusions were as follows:In the interstitial water,concentration of TDN ranged from 47.7 to 178.1?mol/L;DON ranged from 10.2 to 98.4?mol/L;DIN ranged from 29.5 to 151.5?mol/L.,NH4-N ranged from 7.4 to 140.3?mol/L,NO3-N ranged from 0.78 to 43.4?mol/L,NO2-N ranged from 0.29 to 11.8?mol/L.Daliao River estuary,Yellow River estuary,Dagu River,Min River estuary,Jiulong River estuary and Pearl River estuary showed higher concentrations,Beidai River beaches,Chongming Island and southern Hangzhou Bay showed olwer concentration.The PO4-P concentration range of the fourteen interstitial zones was 0.38-2.9?mol/L.Daliao River estuary,Sishili Bay,Jiulong River estuary,Yingluo Bay and Dongzhai Harbor showed higher concentrations,which Yellow River estuary,the Suzhou shoal,Chongming Island and Southern Hangzhou Bay showing lower concentrations.SiO3-Si concentrations ranged from 17.8 to 100.0?mol/L,which Dagu River eatuary,Chongming Island,Min River estuary,Jiulong River estuary and the Pearl River estuary stations showing higher concentrations,and the Beidai River beaches and Sishili Bay stations showing lower concentrations.For the overlying water.,except for the Jian River estuary,the concentrations of nitrogen in estuarine zones were higher than those in non-estuary area.TDN concentration ranged from 15.4 to 123.7?mol/L;DON was in the range of 7.34-58.3?tmol/L;DIN ranged from 6.28 to 67.3?mol/L,NH4-N was in the range of 3.14-23.2?mol/L;NO3-N ranged from 0.14 to 47.1?mol/L,NO2-N ranged from 0.05 to 10.4?mol/L.Daliao River estuary,Dagu River estuary,Chongming Island,Southern Hangzhou Bay,Min River estuary,Jiulong River estuary and Pearl River estuary stations had a high concentration of nitrogen,but the Beidai River beaches,Sishili Bay,Suzhou shoal,Yingluo Bay stations were low.The concentrations of PO4-P was in the range of 0.14-3.3?mol/L,Daliao River estuary,Dagu River estuary,Jiulong River estuary and Dongzhai Harbor stations had a high concentration,but the Beidai River Beach,Jian River estuary and the Yellow River estuary,Sishili Bay,Suzhou shoal and Chongming Island stations were low;The concentration of SiO3-Si ranged between 4.70 and 58.7?mol/L,Daliao River estuary,Chongming Island,the Southern Hangzhou Bay,Min River estuary and Jiulong estuary had a high concentration,the Beidai River beaches,Yellow River estuary and Sishili Bay were low.The nutrient concentration of the interstitial water were higher than that in the overlying water.Nutrient concentrations of the intertidal zone and the the overlying water influenced each other.DIN,DON and SiO3-Si released from interstitial water to the overlying water due to the high concentration.Daliao River estuary,Dagu River estuary,Min River estuary,Pearl River estuary and the Jiulong River estuary were more obvious.Sediment grain size was an important factor related to nutrient concentration,which might explain the low nutrients concentrations of Beidai River beaches,and Sishili Bay.Overlying water temperature,salinity and pH value also showed influence on the interstitial water.The concentration of DIN and DON in the interstitial water were effected by temperature;PO4-P in the Beidai River beaches effected by the input of freshwater;PO4-P in the interstitial water of by overlying water was influenced by temperature and influence of freshwater input in Sishili Bay;In Yingluo Bay,freshwater input had a certain influence on the PO4-P in the interstitial water;PO4-P was influenced by overlying water temperature in Dongzhai Harbor.In this study,we did not see the effect of pH value and chlorophyll a on the nutrient of interstitial water,which need add other comprehensive actual environment factors.In the estuary area,the concentration of DIN in interstitial water in Daliao River estuary,JIan River estuary,Chongming Island were mainly influenced by population density,but in Yellow River estuary,Dagu River estuary,Southern Hangzhou Bay influenced by discharge wastewater.In Daliao River estuary,Yellow River estuary and Southern Hangzhou River estuary,DON were effected by mariculture area,but in Jian River estuary,Dagu River estuary,Chongming Island,Min River estuary,Jiulong River estuary and Pearl River estuary affected by farmland area.Te concentration of PO4-P in inerstitial water in Daliao River estuary was influenced by overlying water,Jian River estuary and Pearl River estuary affected by farmland area,Yellow River estuary,Dagu River estuary,Chongming Island,Southern Hangzhou River Bay,Min River estuary and Jiulong River estuary effected by chlorophyll a.The concentration of SiO3-Si in interstitial water in Jian River estuary and Pearl River estuary were influenced by discharge wastewater,but other stations influenced by sediment grain size.In the non-estuary area,in the Beidai River beaches,Sishili Bay and Suzhou shoal,the DIN in interstitial water were influenced by discharge wastewater,mariculture area in Yingluo Bay,chlorophyll a in Dongzhai Haobor.The concentration of DON in interstitial water was influenced by farmland area in Dongzhai Harbor,other stations influenced by sediment grain size.Chlorophyll a mianly influenced to the PO4-P in interstitial water,and sediment grain size influenced to the SiO3-Si in interstitial water in the non-estuary area.