【作者】 王波；

【导师】 高会旺； 游奎；

【作者基本信息】 中国海洋大学 ， 环境科学， 2007， 硕士

【摘要】 近年来贝类养殖区大规模养殖生物死亡事件频发,这引起人们对近岸养殖环境的关注。了解贝类养殖海区的水质变化和分布规律,是评价海区环境状况的主要工作,也是进行海区规划和管理的基础和前提。在典型养殖区域建立贝类养殖的水质模型,可以对养殖海域水质全局变化趋势和分布规律有一个更系统更全面的认识,从而更有针对性的管理和规划海水养殖的发展,使海水养殖业得到可持续发展。本文应用美国普林斯顿海洋模型(POM)研究了桑沟湾的水动力特征,为养殖污染物的扩散转移提供动力场。计算结果表明,桑沟湾的潮流以往复流为特征,湾口的流速比湾内的流速大,最大流速为55cm/s。桑沟湾余流较弱,湾内大部分区域只有2-3cm/s。湾内南部有一个逆时针方向的小涡,湾内北部余流呈顺时针方向流出桑沟湾。湾内余流大体属于南进北出型。在潮流模拟的基础上,本文建立了水质模型。基于对贝类养殖的环境影响分析,对筏式养殖的无机营养盐污染负荷量进行了估算。以径流输入污染物的浓度分布作为背景场,以扇贝排泄所产生的与滞留在养殖区的无机氮的差值作为养殖源强,得到了整个海区的污染物的分布。研究结果表明,扇贝养殖对无机营养盐的贡献很大。湾北大部分地区超过三类海水水质标准,南部的非养殖区低于国家的二类水质标准。湾内污染物浓度分布南低北高是由桑沟湾余流场和养殖区位置决定的。以建立的水质模型为工具,研究了减少养殖密度和调整养殖区位置对水质的影响。对降低现有养殖密度50%和减少现有养殖面积50%两种方法进行了对比。采用前一种方法的计算结果比较好,无机氮平均浓度可降为原来的57%。停止养殖活动700天后,湾内的无机氮浓度平均水平降为原来的一半。说明现有养殖密度过大,养殖污染超过海域的物理自净能力。桑沟湾内平均海水半交换周期41.7天,交换时间从湾口向湾底逐渐增长。根据余流和海水半交换时间分布规律,以桑沟湾现有的养殖规模和密度把养殖区调整到湾的东北部,会使湾内的污染物浓度降低30%。这是受余流形态和距湾口位置双重因素影响的结果。本文利用水质模型重现了养殖海域的水体运动规律和养殖污染物浓度分布特征;预测了养殖面积、养殖密度和养殖位置的改变对周围海域水质的影响,为政府有关部门进行海域水质管理和贝类养殖规划提供了科学依据。同时也为中国浅海贝类养殖海域的水质污染研究和贝类养殖模式的优化研究等提供了有价值的参考。更多还原

【Abstract】 The frequent marine aquaculture disease attracts more and more attention to marine cultivation. The distributions and variations of pollutants are the main point of valuing environmental quality and the base of environmental programming and managemenet. A model applied in a typical area of scallop cultivation will help us understand the water quality thouroughly and systemally and support the development of marine cultivation.In this paper, the Princenton Ocean Model (POM) is applied to Sanggou Bay in order to simulate the hydrodynamic field. The model results show that the character of tidal current in Sanggou Bay is go-back flow; the speed at mouth is greater than inside; the maximum is about 55cm/s. The residual current in the bay is weak, 3cm/s in most of the study area. There is a small counter-clockwise eddy in the south and a clockwise current flowing out of the bay in the north. In the bay mouth, the residual current shows outward in north while inward in south.Based the simulation of tidal current, a water quality model is established. The pollutant load due to scallop cultivation is calculated according to the result of interrelated research. With the runoff and cultivation load taken into account , the distribution of the pollutant concentration is obtained. The study shows: scallop cultivation makes great contribution to the inorganic nutrients concentration. In most of the north the concentration is above Class Three of the water quality standard, in the south the non-farming region is below Class Two. This pattern is owing to the residual current and the location of cultured zone.In the final part of the paper, the impact of reduce cultivation density and of adjust location are studied by numerical experiments. Comparison of the two methods (halving scallop density or cultured area respectively), the result of former is better and the inorganic nitrogen average concentration may reduce to 57%. The inorganic nitrogen concentration will reduce to half after stoping farming 700 days.This shows that the existing cultivation density oversizes and the cultivation pollution surpasses the physical self purification capacity of the area. The average half-life time of seawater is 41.7 days, gradually increases from the mouth to the head. Adjusting the cultivation area to the northeast, the average DIN concentration will reduce 30%, which is the result of the influence about the shape of residual current and about the location.In this paper, the physical characteristic and the distribution of DIN are simulated by a water quality model, the effect on water quality is forecasted through the adjustment of cultivation structure. The result of this paper can give an evidence for water quality management and scallop cultivation planning, simultaneously provide the valuable reference for the research of water quality in marine aquaculture zone and for the research of the optimization on the structure of shellfish culture.更多还原