【作者】 杨华；

【导师】 邹立；

【作者基本信息】 中国海洋大学 ， 环境科学， 2009， 硕士

【摘要】 本论文于2007年9月、2008年4月和2008年7月,在黄河三角洲潮间带采集42个表层沉积物样品(表层0～1 cm),于2008年7月采集1个长度为34 cm的柱状样品(从表层到底层依次以1、2、3和5 cm为单位,共切割样品14个)。研究黄河三角洲潮间带表层及柱状沉积物中直链烷基苯的分布及降解特征,探讨LABs在潮间带区域的迁移转化规律,以及其与人文活动等因素的关系。以一取代烷基苯混标作为外标物,利用GC-MS分析测定样品中直链烷基苯(linear alkyl benzenes, LABs)的含量,用加标实验分析方法的精密度,以回收率实验来评价定量分析结果的准确度。主要结果和结论如下:1 LABs的水平分布特征以每种同系物所占总量的百分含量来看,春季以C10-LAB、C11-LAB和C13-LAB为主,所占总量的百分含量分别为13 %～45 %、17 %～36 %和9 %～37 %;夏季以C12-LAB和C13-LAB为主,所占总量的百分含量分别为22 %～64 %和12 %～39 %;秋季以C13-LAB、C11-LAB和C10-LAB为主,所占总量的百分含量分别为14 %～50 %、22 %～35 %和13 %～55 %。春、夏和秋季LABs浓度范围分别为2.67 ng/g～11.67 ng/g(平均4.74 ng/g),4.00 ng/g～37.33 ng/g (平均16.75 ng/g)和0.33 ng/g～11.00 ng/g(平均5.67 ng/g),春季和秋季接近,并且远低于夏季。调查区域由南向北表层沉积物LABs平均浓度分别为12.24 ng/g、10.31 ng/g和6.87 ng/g,呈现由南向北逐渐降低的趋势,南部平均浓度约为北部平均浓度的2倍。结果显示,LABs呈现近河口高远河口低的分布规律,显示其陆源输入特征。与世界不同地区河口海岸沉积物中LABs的浓度比较可知,本文所得结果较低,其原因可能有两个:一该区域的人口数量和工业化程度与其他区域相比均处于较低水平;二黄河三角洲潮间带区域沉积速率快,河口和近岸区可达9 cm/年,该区域高的沉积量相当于LABs被稀释,这也可能是其浓度较低的原因。2 LABs的垂直分布特征沉积物柱状样中LABs的种类以C13-LAB和C12-LAB为主,所占总量的百分含量分别为:18 %～30 %和11 %～51 %,与表层沉积物中LABs的种类大体相同。LABs的含量为5.67 ng/g～79.67 ng/g,并随深度波动变化,具体规律为:中下层浓度最高为79.67 ng/g,表层浓度仅低于中下层为53.33 ng/g,中层浓度在5.67 ng/g～30.00 ng/g之间波动变化,底层浓度最低为5.67 ng/g。以每年9 cm的沉积速率为依据,本研究中柱状沉积物不同层次对应的时间为:1 cm～7 cm、7 cm～16 cm、16 cm～25 cm和25 cm～34 cm分别对应2008年初至2008年7月、2007年、2006年和2005年。相应的LABs的总量分别为123.00 ng/g、107.00 ng/g、109.00 ng/g和11.33 ng/g。上述结果表征出该区域中心城市洗涤剂用量的年度变化特点。由LABs浓度变化可以推知:研究区域中心城市2008年洗涤剂用量大于2007年和2006年,2006、2007两年用量相当,2005年用量远小于2006、2007、2008这三年。由2006年LABs的总量约为2005年总量的9.6倍可以推知2005年至2006年,洗涤剂的用量显著增加。3 LABs的降解行为潮间带区域南部,春季和秋季表层沉积物样品中LABs的浓度有从近岸到离岸逐渐减小的趋势,分别从近岸的11.67 ng/g和7.33 ng/g逐渐减小到离岸的6.67 ng/g和0.67 ng/g,夏季样品中LABs的含量变化趋势不明显;中部浓度分布也呈现出从近岸到离岸逐渐减小的趋势,春、夏、秋三个季节的浓度分别从近岸的5.00 ng/g、37.33 ng/g和11.00 ng/g逐渐减小到离岸的4.22 ng/g、16.89 ng/g和0.33 ng/g;北部浓度分布较均匀,无明显变化。结果表明,LABs呈现出从近岸到离岸逐步降解的行为规律。各站位LABs同分异构体的种类存在差别,多以2、3取代为主,5、6取代含量较低。本文用十二烷基苯内取代异构体与外取代异构体浓度的比值即I/E值来表示LABs的降解程度。得到LABs的降解率为15.00 %～53.65 %,平均值为37.58 %。该结果与我国珠江三角洲地区以及维多利亚港、波士顿海港等沉积物中的降解率相近。低的污水处理率和处理效果是造成该区域降解率较低的一个主要因素,未经处理的生活污水的排放是造成水质污染的一个重要来源。4影响沉积物中LABs分布的主要因素黄河三角洲潮间带沉积物中LABs与POC和粒度均无相关性,表明粒度不是LABs在该区域沉积的决定性因素;该区域沉积速率较快,LABs进入环境之后被迅速埋藏,高的沉积量相当于LABs被稀释,导致表层沉积物中LABs含量较低并且主要分布在河口附近,所以沉积速率大小及离陆源输入距离的远近成为影响LABs含量及分布的主要因素。更多还原

【Abstract】 42 surface sediments (0～1 cm) were collected in September 2007, April 2008 and July 2008 and a length of 34 cm column sediments (cutting samples using 1, 2, 3 and 5 cm as unit from surface to bottom , a total of 14 samples) were collected in July 2008 in the intertidal areas of the Yellow River Delta. The distribution and degradation of linear alkyl benzenes (LABs) in surface and column sediments were studied, as well as the transportation and transformation in the intertidal areas and the impact of anthropogenic activities. A mixture of LABs (containing 1- Cn-LAB) was used as external standard and GC-MS was used for quantification and identification. Precision and accuracy were monitored by standard addition experiment and recovery experiments, respectively. The main results and conclusions were demonstrated as followed.1 The distributions of LABs in surface sedimentsC10-LAB, C11-LAB and C13-LAB dominated and ranged at 13 %～45 %,17 %～36 % and 9 %～37 % in spring, respectively. C12-LAB and C13-LAB dominated and ranged at 22 %～64 % and 12 %～39 % in summer, respectively. C13-LAB, C11-LAB and C10-LAB dominated and ranged at 14 %～50 %,22 %～35 % and 13 %～55 % in autumn, respectively. The total LABs in surface sediments ranged at 2.67 ng/g～11.67 ng/g (average 4.74 ng/g),4.00 ng/g～37.33 ng/g (average 16.75 ng/g) and 0.33 ng/g～11.00 ng/g (average 5.67 ng/g) in spring, summer and autumn. The concentrations in spring and autumn followed a similar pattern and were much lower than those in summer. The average LABs in surface sediments decreased from the south (12.24 ng/g) to the middle (10.31 ng/g) and to the north (6.87 ng/g), in which the average LABs in the south was two times as much as that in the north. Meanwhile, the LABs in surface sediments decreased as well from close estuary to far estuary, indicating a terrestrial input of LABs to the intertidal area. The result of LABs in the intertidal area of the Yellow River Delta was lower than those of most coastal waters in the world. The relative low population and industrialization, as well as the high deposition rate (up to 9 cm/a) in this study area might be responsible for the low LABs.2 Vertical distribution of LABs in column sediments C13-LAB and C12-LAB dominated and ranged at 18 %～30 % and 11 %～51 %, respectively. The species of LABs detected in column sediments were similar to that in the surface sediments. The LABs in column sediments were located at 5.67～79.67 ng/g, waving by depth. The highest concentration of 79.67 ng/g was located at the middle and lower and a higher concentration of 53.33 ng/g at the surface; the concentration of LABs in the middle were located at 5.67 ng/g～30.00 ng/g waving by depth and the lowest concentration were 5.67 ng/g appeared at the bottom. According to the deposition rate, the depths of 1～7, 7～16, 16～25 and 25～34 cm were corresponding with the periods from to January 2008 to July 2008, 2007, 2006, and 2005, with the total LABs of 123.00 ng/g, 107.00 ng/g, 109.00 ng/g and 11.33 ng/g, respectively. It was suggested that the amount of detergent in 2008 were higher than those in 2007 and 2006, that in 2007 was similar to that in 2006, and that in 2005 was the lowest. The total LABs in 2006 was 9.6 times as big as that in 2005. Meanwhile, the results showed that detergent amount significantly increased from 2005 to 2006.3 The degradation of LABsThe LABs in surface sediments in the south ranged from 11.67 ng/g to 6.67 ng/g in spring and from 7.33 ng/g to 0.67 ng/g in autumn, with a decreasing tendency from near shore to off shore areas. The LABs in surface sediments in the middle section ranged from 5.00 ng/g to4.22 ng/g in spring, from 37.33 ng/g to 16.89 ng/g in summer and from 11.00 ng/g to 0.33 ng/g in autumn, respectively, with a decreasing tendency from near shore to off shore areas either. The distributions of LABs in north areas were symmetrical. The LABs distribution tendency indicated a degradation gradually from near shore to off shore areas. The LABs isomers were different among sites. 2- Cn-LAB, 3- Cn-LAB dominated, while 5- Cn-LAB and 6- Cn-LAB were lower. The ratio of internal and external isomers of n- C12-LAB was designated as I/E, and the I/E value represented the degree of LAB degradation. It was estimated that the 15.00 %～53.65 % (averaged at 37.58 %) LABs were degraded when reaching the intertidal sediments. This is agreed with those in the Pearl River Delta, Victoria Harbor and Boston Harbor. The degradation ratio of LABs suggested that the domestic sewage discharged in this region was basically without treating or poorly treated, and thus the discharge of urban sewage was one of the important sources of water pollution.4 Factors on the distribution of LABs LABs, POC and grain size were irrelevant by linear relationship analysis in the intertidal areas of the Yellow River Delta. It was suggested that the grain size was not the primary factor impacting on the distribution of LABs, but the high deposition rate (up to 9 cm/a) in this study area was responsible for the low LABs in surface sediments and the high LABs in close estuary. The deposition rate and terrestrial input were the most potential factors on the distribution of LABs.更多还原