Fatty-acids and their C-13 signatures in seep carbonates from hydrocarbon seeps on the upper (GC 185) and lower (AC 645) continental slope of the Gulf of Mexico

Here we reported the fatty-acids and their δ 13C values in seep carbonates collected from Green Canyon lease block 185 (GC 185; Sample GC-F) at upper continental slope (water depth: ∼540 m), and Alaminos Canyon lease block 645 (GC 645; Sample AC-E) at lower continental slope (water depth: ∼2200 m) of the Gulf of Mexico. More than thirty kinds of fatty acids were detected in both samples. These fatty acids are maximized at C16. There is a clear even-over-odd carbon number predominance in carbon number range. The fatty acids are mainly composed of n-fatty acids, iso-/anteiso-fatty acids and terminally branched odd-numbered fatty acids (iso/anteiso). The low δ 13C values (−39.99‰ to.32.36‰) of n-C12:0, n-C13:0, i-C14:0and n-C14:0 suggest that they may relate to the chemosynthetic communities at seep sites. The unsaturated fatty acids n-C18:2 and C18:1Δ9 have the same δ 13C values, they may originate from theBeggiatoa/Thioploca. Unlike other fatty acids, the terminally branched fatty acids (iso/anteiso) show lowerδ 13C values (as low as −63.95‰) suggesting a possible relationship to sulfate reducing bacteria, which is common during anaerobic oxidation of methane at seep sites.

GC-MS测定土壤中阿特拉津、六氯苯等十种农药残留

建立了气相色谱-质谱-选择离子监测(GC-MS-SIM)同时测定土壤中10种农药(三嗪类除草剂、酰胺类除草剂和有机氯农药)的多残留分析方法.样品采用正己烷/丙酮(1:1,V/V)超声提取、氟罗里硅土柱层析净化、GC-MS-SIM测定.10种农药在0.01(0.02)—1.0(2.0)mg.l-1范围内线性良好,相关系数介于0.9963—0.9998之间;在10,50和250ng.g-1添加水平下,平均回收率介于81%—117%之间,相对标准偏差均小于14.4%;方法检出限达到ppb至sub-ppb级(0.1—1.3ng.g-1).将此方法应用于辽宁省不同性质土壤中70个实际土壤样品的分析,阿特拉津、乙草胺、六氯苯、丁草胺、狄氏剂和艾氏剂有检出,该法对不同性质土壤具有广泛适用性.

超声波法提取土壤样品中1,2,4-三氯苯和GC测定

本方法采用超声波振荡提取，用10％的丙酮正已烷混合溶液作为提取剂，对易挥发的1，2，4－三氯苯的分析具有简单、快速、灵敏、可靠、节省试剂的特点，也适用于土壤环境样品氯苯类化合物的测定。