采油平台改建鱼礁海域沉积物再悬浮对磷的吸附—解吸

发布时间：2018-08-20 20:28

【摘要】：沉积物-水界面上磷的吸附解吸是海域磷素迁移转化的重要方式并且直接影响海水中磷的浓度和富营养化水平。埕岛采油平台改建鱼礁海域人工鱼礁的投放和退役采油平台铸铁的腐蚀形成了研究区独特的沉积物环境。本文通过等温吸附解吸的方法模拟固体浓度、pH和针铁矿含量对沉积物-水界面上的磷吸附解吸的影响,主要探讨了影响因素对吸附量、EPCo等重要吸附参数产生的作用。采用修正的Langmuir、 Freundlich以及线性回归的方法对等温吸附实验结果进行拟合,并对其在EPC0计算方面的作用进行比较。最后,结合退役采油平台海域投礁后期调查与实验所得规律,判断退役采油平台海域磷酸盐浓度的变化趋势,对富营养化水平作出预估。主要结论如下： (1)固体浓度升高,EPCo值随之增大,说明在一定程度上固体浓度升高有利于沉积物中磷的释放,但EPC0值整体上仍小于海域底层海水磷浓度,表明沉积物主要表现为对磷的吸附作用。因此研究海域中的项目施工引起的悬浮物浓度增大不会改变沉积物磷汇的作用。 (2)研究海域表层沉积物对磷的吸附量随pH在6.5～8.5之间的小幅度增大表现为先增大后减小,在略偏碱性范围内(pH值为7.71时)出现最大吸附量。小幅度的pH变化对吸附参数的影响较小,等温吸附实验显示偏酸或偏碱都会使磷倾向于吸附,但这种作用十分微弱。 (3)针铁矿含量增大对吸附的影响显著。针铁矿含量增大,PAC与NAP的增大说明针铁矿特殊的表面性质使沉积物更易于固定水中的磷,而表现为吸附解吸磷的能力同时增强；EPC0轻微减小,Kp明显增大,说明从表观上来看沉积物易于吸附磷。 (4)通过对比固体浓度、pH和针铁矿含量对吸附产生的影响,并结合海域中影响因子的变化空间,推出固体浓度是该海域中磷吸附解吸的最主要的影响因子。在人力物力有限的条件下,可着重研究固体浓度对吸附产生的影响,以从整体上把握变化趋势。 (5)对EPC0的分析表明,固体浓度为沉积物-水界面磷吸附解吸的最主要的影响因子；沉积物组成即针铁矿含量的升高对EPC0未表现出明显影响,但针铁矿的添入与否对EPCo有一定程度的影响。拟合数据表明,修正后的Langmuir和Freundlich可以较可靠的计算EPC0值,但吸附量与初始浓度做线性回归的方法出现较大的偏差,不适合计算本研究区域沉积物磷吸附的EPC0值。 (6)调查显示,海域磷酸盐与固体浓度表现出较为一致的变化规律,表明固体浓度是沉积物-水界面磷吸附解吸的重要影响因子。悬浮沉积物可以吸附水体中的磷酸盐,是海水中磷的汇。总体上不会因为固体浓度的增大,导致海水中磷浓度的突然升高,但也不排除极端状况下,固体浓度的大幅升高引起的磷释放。退役采油平台海域整体上不会因为沉积环境的变化而导致磷的大量释放引起海域富营养化,但也存在局部富营养水平偏高的可能。
[Abstract]:Adsorption and desorption of phosphorus on the sediment-water interface is an important way of phosphorus transport and transformation in the sea area and directly affects the concentration and eutrophication of phosphorus in the sea water. Adsorption and desorption methods simulate the effects of solid concentration, pH and goethite content on phosphorus adsorption and desorption at the sediment-water interface. The effects of influencing factors on adsorption capacity, EPCo and other important adsorption parameters are discussed. The experimental results of isothermal adsorption are fitted by modified Langmuir, Freundlich and linear regression methods. Finally, the change trend of phosphate concentration in the area of decommissioned platforms is judged and the eutrophication level is predicted by combining the investigation and experimental results of the decommissioned platforms.
(1) With the increase of solid concentration, the EPCo value increases, which indicates that the increase of solid concentration is beneficial to the release of phosphorus from sediments to a certain extent, but the EPC0 value is still lower than the phosphorus concentration in the bottom seawater, indicating that the sediments mainly show phosphorus adsorption. Changing the role of phosphorus in sediments.
(2) The adsorption capacity of phosphorus on the surface sediments of the sea area increases first and then decreases with the small increase of pH between 6.5 and 8.5, and the maximum adsorption capacity appears in the slightly alkaline range (pH 7.71). The small change of pH has little effect on the adsorption parameters, and isothermal adsorption experiments show that both acidic and alkaline can make phosphorus tend to adsorption. But this effect is very weak.
(3) The increase of goethite content and PAC and NAP indicated that the special surface properties of goethite made the sediments more easily to fix phosphorus in water, and the adsorption and desorption capacity of goethite increased at the same time. EPC0 decreased slightly and Kp increased significantly, indicating that the sediments were easy to adsorb phosphorus from the surface.
(4) By comparing the effects of solid concentration, pH and goethite content on adsorption and combining with the changing space of influencing factors in the sea area, it is deduced that the solid concentration is the most important influencing factor of phosphorus adsorption and desorption in the sea area. Grasp the trend of change.
(5) The analysis of EPC0 shows that the solid concentration is the most important factor affecting the adsorption and desorption of phosphorus at the sediment-water interface; the elevation of goethite content in sediments has no obvious effect on EPC0, but the addition of goethite has some effect on EPCo. The fitting data show that the modified Langmuir and Freundlich can be compared. Reliable calculation of EPC0 value, but the method of linear regression between adsorption capacity and initial concentration is not suitable for calculating the EPC0 value of phosphorus adsorption in sediments of this study area.
(6) The results show that the concentration of phosphate and solids in the sea area shows a relatively consistent change law, indicating that the solid concentration is an important factor affecting the adsorption and desorption of phosphorus at the sediment-water interface. The sudden increase of phosphorus content in the decommissioned oil platforms will not lead to the eutrophication of the sea area as a whole because of the change of sedimentary environment, but there is also the possibility of high local eutrophication.
【学位授予单位】：青岛大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：X55

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