Natural attenuation of diesel aliphatic hydrocarbons in contaminated agricultural soil

A diesel fuel spill at a concentration of 1 L m(-2) soil was simulated on a 12 m(2) plot of agricultural land, and natural attenuation of aliphatic hydrocarbons was monitored over a period of 400 days following the spill after which the aliphatic hydrocarbon concentrations were found to be below the legal contamination threshold for soil. The main fraction of these compounds (95%) remained at the surface layer (0-10 cm). Shortly after the spill (viz. between days 0 and 18), evaporation was the main origin of the dramatic decrease in pollutant concentrations in the soil. Thereafter, soil microorganisms used aliphatic hydrocarbons as sources of carbon and energy, as confirmed by the degradation ratios found. Soil quality indicators, soil microbial biomass and dehydrogenase activity, regained their original levels about 200 days after the spill.     

Evaluation of stream ecological integrity using litter decomposition and benthic invertebrates

Biomonitoring programs to access the ecological integrity of freshwaters tend to rely exclusively on structural parameters. Here we evaluated stream ecological integrity using (a) benthic macroinvertebrate derived metrics and a biotic index as measures of structural integrity and (b) oak litter decomposition and associated fungal sporulation rates as measures of functional integrity. The study was done at four sites (S1, S2, S3 and S4) along a downstream increasing phosphorus and habitat degradation gradient in a small stream. The biotic index, invertebrate metrics, invertebrate and fungal communities' structure and sporulation rates discriminated upstream and downstream sites. Decomposition rates classified sites S4 and S2 as having a compromised ecosystem functioning. Although both functional and structural approaches gave the same results for the most impacted site (S4), they were complementary for moderately impacted sites (S2 and S3), and we therefore support the need for incorporating functional measures in evaluations of stream ecological integrity.     

Sample preparation and biomass determination of SRF model mixture using cryogenic milling and the adapted balance method

The biogenic fraction of a simple solid recovered fuel (SRF) mixture (80 wt% printer paper/20 wt% high density polyethylene) is analyzed with the in-house developed adapted balance method (aBM). This fairly new approach is a combination of combustion elemental analysis (CHNS) and a data reconciliation algorithm based on successive linearisation for evaluation of the analysis results. This method shows a great potential as an alternative way to determine the biomass content in SRF. However, the employed analytical technique (CHNS elemental analysis) restricts the probed sample mass to low amounts in the range of a few hundred milligrams. This requires sample comminution to small grain sizes (<200 μm) to generate representative SRF specimen. This is not easily accomplished for certain material mixtures (e.g. SRF with rubber content) by conventional means of sample size reduction.This paper presents a proof of principle investigation of the sample preparation and analysis of an SRF model mixture with the use of cryogenic impact milling (final sample comminution) and the adapted balance method (determination of biomass content). The so derived sample preparation methodology (cutting mills and cryogenic impact milling) shows a better performance in accuracy and precision for the determination of the biomass content than one solely based on cutting mills. The results for the determination of the biogenic fraction are within 1–5% of the data obtained by the reference methods, selective dissolution method (SDM) and ¹⁴C-method (¹⁴C-M).     

Predicting species dominance shifts across elevation gradients in mountain forests in Greece under a warmer and drier climate

Regional Environmental Change - The Mediterranean Basin is expected to face warmer and drier conditions in the future, following projected increases in temperature and declines in precipitation....     

Results from a reference laboratory for prenatal diagnosis of sickle cell disorders in Cuba

A nationwide programme for the prevention of sickle cell (SS and SC) disorders was initiated in Cuba in 1983. Couples at risk were identified by screening pregnant women and the partners of those who carry an abnormal haemoglobin, followed by genetic counselling and the offer of prenatal diagnosis. Prenatal diagnosis was performed in one laboratory, which had carried out 1068 prenatal tests for Hb SS and SC disorders by the end of 1992. The centralization of the service has permitted rapid identification and resolution of problems.     

Walker-Warburg syndrome: Prenatal ultrasound findings

The prenatal sonographic findings in a case of Walker-Warburg syndrome are described. The patient was not at risk for this condition. Ultrasound examination at 34 weeks' gestation revealed hydrocephaly, Dandy-Walker anomaly, and striking ocular abnormalities. From a review of the literature it appears that while intracranial abnormalities can lead to the diagnosis in cases at risk for this syndrome, ocular abnormalities are rather characteristic for this syndrome and they should be searched for in every case of hydrocephaly or encephalocele.     

秘鲁亚马孙地区与毁林相联系的国家农业政策:Tambopata的案例研究,1986～1997

亚马孙流域的毁林速度随地区不同而异,其涨落由宏观经济政策和当地的社会因素而定.我们运用遥感和野外调查,研究了1986～1991年(当时有农村信贷和担保市场)和1991～1997年(其间施加了结构调整措施)秘鲁一边疆地区的毁林格局和原因.1986～1991年间,最高的毁林速度(总的比率1.5%)出现于道路两旁,1991～1997年,路旁的毁林速度下降(总的比率0.7%),同时,大面积的再生使森林覆被得以净增长(0.5%).河旁毁林速度相对稳定.直至今日,河旁农场还保留着更多的农田和森林,而路旁的农场则以牧场和演替生长为主.老住户要比新来者在农场保留更多的森林,但是对城市市场的邻近度是森林覆被最强的预测因子.未来的信贷计划必须反映出经济发展的空间格局和生态脆弱性,同时要有利于休耕地和次生林的恢复.     

气候波动与土地利用变化对西班牙比利牛斯山脉中部径流影响的评价

在地中海国家扩大灌溉土地的面积,应当考虑气候与土地利用变化对水资源的影响.本文利用降水和温度资料,分析了20世纪中叶以来西班牙比利牛斯山脉中部流域径流的变化趋势.降水与径流之间关系的年变化表明,径流在所研究期间的后半时段相对较低,这一趋势与土地利用变化一致.在月水平上,降水量在10月、4月和7月明显增加,而在3月则有下降;温度在1月和2月有所增加,而在4月则趋于下降.但过去50年间径流在大部分月份中呈显著下降趋势,土地利用和植被覆盖的变化是解释年平均径流下降大约30%的惟一非气候因素.