The dilution and dispersion of ballast water discharged into Goderich Harbor

Observations are presented on dilution and dispersion rates of ballast water discharged under normal operational conditions at the semi-enclosed port of Goderich, Ontario. The ballast water was tagged with Rhodamine-WT dye and microscopic magnetically-attractive tracer particles. Maximum concentrations of dye immediately after discharge were diluted to 1-5% of initial ballast tank concentrations, and within 3 days had decreased to less than 0.1% of initial concentrations. Inside the harbor, there was 10-20% of the ballast water still present after 2 days, consistent with a flushing rate of 0.8-1.15 day⁻¹. Magnetic particles were collected up to 7.5 km outside the harbor after one day, consistent with a dilution factor of order 10⁵ outside the harbor. The results of this study are discussed in the context of ballast water discharge standards proposed by the International Maritime Organization to minimize the introduction of aquatic nonindigenous species through ships’ ballast water and sediments.     

国外煤层气资源与开发概况

介绍了国外主要是美国煤层气的资源、开发状况、勘探开采方法、影响煤层生产能力的地质因素,开发成本、科研机构、会议以及利用概况。     

Detecting genotoxicity using the Comet assay following chronic exposure of Manila clam Tapes semidecussatus to polluted estuarine sediments

Sediments frequently cause damage to biota due to the accumulation of toxic compounds and the bioavailability of sediment-bound contaminants. Damage can be assessed using biomarkers, such as the degree of genotoxic impact following in vivo exposure to pollutants. Genotoxic damage, expressed as single-strand DNA breaks, was measured in cells isolated from haemolymph, gill and digestive gland from the clam Tapes semidecussatus, using the single cell gel electrophoresis (Comet assay). Clams were exposed for three weeks to sediment samples collected from a polluted site and a ‘clean’ reference site.

The level of DNA damage was assessed using an image analysis package and expressed as Tail Moment. Throughout the study, significant differences in DNA damage were recorded for each tissue type between clams exposed to the two sediment samples. We conclude that the Comet assay is a useful tool for the detection of DNA damage in clams chronically exposed to polluted sediments.     

Industrial pollution at Bagnoli (Naples, Italy): benthic foraminifera as a tool in integrated programs of environmental characterisation

In the 20th century an important industrial plant operated on the coastal area of Bagnoli. After its closing, an integrated study of environmental characterisation aimed at restoration started. The survey conducted was based on chemical and sedimentological analyses integrated with benthic foraminifera analyses. Statistical analysis of the data shows sectors with a distinct type and degree of pollution. Particularly, pollution linked to the silty sediment fraction, mainly due to Pb and Zn, was recognised in front of the southern sector of the plant. The study of benthic foraminifera provides evidence for a pollution-tolerant character in some species like Haynesina germanica and Quinqueloculina parvula. In addition, two species among the 113 recognised show high percentages of abnormal specimens. These percentages show a statistical correlation with some pollutants (PAHs, Mn, Pb and Zn). In addition, Energy Dispersive Spectrometry shows small amounts of Fe ions included in deformed tests of Miliolinella subrotunda. Because the number of these deformations is positively correlated to the concentration of PAHs, Mn and Zn, the inability of some specimens to exclude the foreign elements from the crystalline reticulum of the test could be attributed to the potential toxic effect of these pollutants.