象山港南沙岛不同养殖类型沉积物酸可挥发性硫化物的时空分布

Seasonal and spatial distribution of acid volatile sulfide in sediment under different mariculture types in Nansha Bay,China

2007年分4个航次测定了象山港南沙岛不同养殖类型(贝类养殖、藻类养殖和网箱养殖)沉积物酸可挥发性硫化物(AVS)含量的时空变化规律。研究结果表明,南沙岛养殖区沉积物AVS变化范围为0.01—30.03μmol/g,平均3.75μmol/g,其中贝类养殖区、藻类养殖区、网箱养殖区和对照区AVS年平均含量分别为1.03、0.64、5.06和0.70μmol/g。网箱养殖中心区(S10)AVS的含量分别是贝类养殖区、藻类养殖区和对照区的8.5倍、13.6倍和12.6倍。ANOVA分析表明,表层沉积物(0—3cm)AVS含量的季节变化差异不显著,但柱状样(0—15 cm)平均含量差异显著,夏秋季明显高于冬春季。AVS含量总体上随着沉积物深度的增加而增加,6—9 cm达到最大值,夏秋季尤为明显。聚类分析表明,南沙岛养殖区调查站位分为3类,网箱养殖中心区(S10)和距离较近的S13和S12为一个类群,贝类养殖区、藻类养殖区和对照区为一个类群,其余站位为一个类群。总体上,养殖中心区AVS含量最高,随着与养殖中心区距离的增加含量逐渐降低,网箱养殖对底质AVS的影响主要集中在200 m以内,500 m以外则影响较小。

Xiangshan Bay, located on the east coast of China, is a semi-enclosed bay with slow rate of water exchange Nansha Bay, lies in the middle of Xiangshan Bay, is an important fish cage farming area. This paper presented the results of the seasonal and spatial distribution of acid volatile sulfide （AVS） in sediments from three different mariculture areas including seaweed culture area, shellfish culture area and fish cage culture area in Nansha Bay in 2007. The results revealed that AVS content in the whole investigation region ranged from 0.01 to 30.03 μmol/g, the average value was 3.75 μmol/g. The mean value of AVS in shellfish culture area, seaweed culture area, fish cage culture area and the control area were 1.03, 0.64, 5.06, and 0.70 μmol/g, respectively. Ahhough there was no significant change of AVS in surface sediment, significant difference of AVS in columnar sample （0--15cm） was found among winter, summer, spring and autumn, with the average value 3.48, 3.05, 8.31 and 6.57 μmol/g in, respectively. The value of AVS increased with the sediment depth, and reached the maximum in 6 to 9 centimeter, especially in summer and autumn. Cluster analysis showed the AVS distribution in the sediment of Nansha Bay could be divided into 3 categories： central cage area （S10） and surrounding cage area （S12 and S13）; cage culture area （S6, S7 and S14） far away from central cage area; shellfish culture area （ S1 ）, algae culture area （S2） and control area （ S5 ）. The average values of AVS in different categories were 7.34, 2.62 and 0.75 μmol/g, respectively. Overall, the AVS content was highest in central cage area and gradually reduced with the distance along the central cage area. The impact of fish cage farming on AVS mainly concentrated in the area within 200 m from fish cages and influence slightly far away from 500m.