闽江口营养盐生物地球化学过程研究

Research the Biogeochemical Processes of Nutrients in Minjiang Estuary

对2007年在闽江口的全潮观测数据分析表明,在河口过程,悬沙、无机氮、硅与潮汐的变化相反,表现出涨潮时降低,落潮时升高的变化特征;而水位、盐度与潮汐的变化相一致;磷与潮汐的变化不明显,磷酸盐缓冲机制受到悬沙与水相互作用的控制.闽江口水体中硅酸盐、磷酸盐、无机氮浓度范围分别为0.63～9.00 mg.L-1、0.013～0.075 mg.L-1和0.33～4.24mg.L-1,因受农业、工业和人类生活的影响,观测的无机氮含量较20多年前有大幅上升的趋势.闽江口无机氮、硅浓度与盐度呈显著负相关.研究表明闽江口无机氮、磷、硅营养盐生物地球化学过程中,无机氮、硅在闽江口过程主要是保守性行为,磷则是非保守性行为.陆源冲淡水给闽江口补充了丰富的无机氮、硅营养盐,而陆源冲淡水与海水中磷含量差别不大,硅∶氮∶磷比值表明闽江口磷是浮游植物的限制性因子.

The variations in the concentration and distribution of nutrients and influencing factors in the Minjiang Estuary with a tidal cycle were investigated based on the data obtained during field observations in May 2007.The results showed the suspended sediment,dissolved inorganic nitrogen and silicate were opposite to the change of tidal,while the water level and salinity were consistent with tidal.The buffer mechanism of phosphate was controlled by suspended sand and water.The concentrations of silicate,phosphate and inorganic nitrogen were ranged 0.63-9.00 mg/L,0.013-0.075 mg/L,0.33-4.24 mg/L respectively.The contents of dissolved inorganic nitrogen in water mass increased remarkably comparing 1980s because of agriculture,industry and living.The research indicated that the nitrate and silicate were conservative,but phosphate was non-conservative in the biogeochemical processes of nutrients in Minjiang Estuary.The diluted water carried abundant inorganic nitrogen、silicate nutrients to Minjiang Estuary and thus phosphate was similar between diluted water and sea water.Based on the results of nutrient ratios,it was suggested that phosphate was a limiting factor for phytoplankton growth in the Minjiang Estuary.