近年来网箱养殖业飞速发展,但养殖活动对区域环境的影响,尤其影响范围的研究还鲜见报道.海南省澄迈县马袅湾海域有较大规模的网箱养殖鱼类生产,本文选取马袅湾网箱养殖区为研究区域,分别于2019年3月(春季)、7月(夏季)、10月(秋季)、12月(冬季)进行现场调查与采样,检测并分析了沉积物中总氮(TN)、总磷(TP)和总有机碳(TOC)等指标的含量与时空变化,并建立TN、TP和TOC分别与距网箱养殖区距离的拟合方程,初步估算了网箱养殖活动对表层沉积物的辐射影响范围.结果显示,马袅湾海域表层沉积物TN、TP平均含量分别在113.48～1 265.10 mg/kg与287.90～760.05 mg/kg之间,TOC含量为0.03％～1.14％,四个季节表层沉积物环境整体优良.TN受季节变化影响较显著,夏季较低,秋、冬季节有增加趋势,TN在春、秋、冬季都存在不同程度的富集现象;TP含量随季节上下波动,秋季呈现一定程度的富集;TOC含量也随季节上下变动,但没有出现富集现象.空间分布上,马袅湾表层沉积物TN、TP和TOC含量在养殖区(S区)和养殖邻近区(A区)含量高,对照区(B、C)含量低;从地理位置看,整体呈北部湾口含量高,南部湾底含量低,可能受东北和西南向往复水流影响,将养殖残饵或者代谢废物带出了马袅湾.马袅湾表层沉积物TN、TP、TOC含量随养殖区距离变化拟合结果较为类似,在距养殖区(A区)0～1 km的范围内TN、TP、TOC含量增加;而在距离网箱养殖区1～3 km的空间范围内开始降低.由此,马袅湾网箱养殖对表层沉积物TN、TP、TOC影响范围约为1 km.
Impact of cage culture on regional surface sediment of Maniao Bay
In recent years,the cage aquaculture industry has developed rapidly,but the impact of cage aquaculture on the regional environment,especially the scope of influence,is rarely reported.Large-scale fish production in cages has been carried out in Maniao Bay,Chengmai County,Hainan Province.Field surveys and sampling were conducted in March(Spring),July(Summer),October(Autumn),and December(Winter),2019.The total nitrogen(TN),total phosphorus(TP)and total organic car-bon(TOC)and other indicators in the sediments were detected and their temporal and spatial changes were analyzed as well as the fitting equations of TN,TP and TOC with the distance from the cage cul-ture area were established.The results showed that the contents of TN,TP and TOC in the surface sediments of the Maniao Bay vary between 113.48 and 1265.10mg/kg,287.90 and 760.05mg/kg and 0.03 and 1.14％,respectively.During the study period,the overall sedimentary environment was good.TN is significantly affected by seasonal changes,it is lower in summer,and tends to increase in autumn and winter.TP and TOC fluctuate up and down as a whole.TN is enriched at different degrees in spring,autumn and winter.TP is enriched in autumn,but TOC is not enriched.The content of TN in the surface sediments of Maniao Bay is high in S and A while the content in the control area(B,C)is low.The overall spatial distribution of TP and TOC content is similar to that of TN.Geographical-ly,the content is high at the mouth of the northern gulf and low at the bottom of the southern bay.Possibly affected by the northeast and southwest reciprocating flow,the aquaculture waste generated from cage aquaculture was brout out of Maniao Bay.The overall trends of TN,TP,and TOC of the surface sediments in Maniao Bay are relatively consistent.The content in the space range of 0～1 km a-way from the cage culture area shows a certain increasing trend.A decreasing trend within the space range of 1 km～3 km from the cage culture area was shown.Based on this preliminary judgment,the impact range of cage culture in Maniao Bay on surface sediment TN,TP,TOC was estimated to be a-bout 1 km.
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