Measurement of the biodegradation of starch-based materials by enzymatic methods and composting

The aim of this study was to evaluate the suitability of in vitro enzymatic methods for assaying the biodegradability of new starch-based biopolymers. The materials studied included commercial starch-based materials and thermoplastic starch films prepared by extrusion from glycerol and native potato starch, native barley starch, or crosslinked amylomaize starch. Enzymatic hydrolysis was performed using excessBacillus licheniformis -amylase andAspergillus niger glucoamylase at 37°C and 80°C. The degree of degradation was determined by measuring the dissolved carbohydrates and the weight loss of the samples. Biodegradation was also determined by incubating the samples in a compost environment and measuring the weight loss after composting. The results indicated that the enzymatic method is a rapid means of obtaining preliminary information about the biodegradability of starch-based materials. Other methods are needed to investigate more accurately the extent of biodegradability, especially in the case of complex materials in which starch is blended with other polymers.     

Determination of some aliphatic and polycyclic aromatic hydrocarbons in marine sediments of the Baltic Sea

Two representative samples of surficial marine sediments have been studied, one from the northern Baltic Proper and the other from the Gulf of Finland. Aliphatic hydrocarbons were determined by gas chromatography on a fused silica capillary column, and six polyaromatic hydrocarbons were determined by gas chromatography-mass fragmentography. Hydrocarbons were extracted with a benzene-methanol mixture and ultrasonic agitation. The aliphatic hydrocarbons were tentatively identified by their retention times. The polyaromatic hydrocarbons (PAHs) were identified on the basis of their retention times and mass fragmentograms by direct comparison with those of standard compounds. The aliphatic hydrocarbon contents ranged from 0,1 to 2,6 μg/g dry matter. In both samples there was a clear maximum at n-C₁₇ and also a clear odd-carbon predominance. The PAH contents ranged from 4 to 120 ng/g dry matter. The PAH concentration was about 58 per cent higher in the sample from the Gulf of Finland than in the sample from the Baltic Proper.     

利用新一旧冰川沉积物中的类胡萝卜素色素作为波罗的海蓝藻赤潮的标志物

1999年5月从哥特兰海盆、波罗的海本体北部和芬兰湾东部采集到的新-旧冰川沉积物中类胡萝卜素色素的分布情况进行了研究.其目的在于对最近几个世纪以来发生在波罗的海的蓝藻赤潮的发生时间及强度做出+个全面的、系统的、历史性的回顾.色素的存在是利用高压液相色谱(LLC)来检测的,检测的主要重点是把色素作为蓝藻赤潮标志物.从三个采样点采集到的沉积物中的色素的含量有明显差异.总的来说,来自于哥特兰海盆的沉积样中色素的含量最高,而芬兰湾东部样品中的含量最低.在三组沉积样中的最上层(0～lcm)是以β-胡萝卜素为主的胡萝卜素.在岩心样品的深层以蓝藻叶黄素与玉米黄素为主.据我们所知,蓝藻叶黄素和玉米黄素是第一次在波罗的海滨海螺期(Litorina stage)早期的沉积物中被发现.这与沉积物深度相关的色素含量的减少与碳含量的减少是一致的,也和波罗的海蓝藻赤潮发生的强度和时间的历史记录相一致.这一切都表明,第二次世界大战之前在这里很少有蓝藻赤潮发生的记录.