The anthropogenic contribution to the organic load of the Lippe River (Germany). Part I: Qualitative characterisation of low-molecular weight organic compounds

GC/MS-screening analyses of water samples from the Lippe River, Germany, revealed the presence of a wide spectrum of low-molecular weight organic compounds ranging from non-polar constituents like aliphatic hydrocarbons to polar constituents like n-carboxylic acids and phenols. Most of the identified compounds could be attributed to anthropogenic input and are used as plasticizers, flame retardants, pharmaceutical drugs or fragrances. Some of them had rarely been noticed as organic pollutants of aquatic environments before. These are, among others, 9-methylacridine, the plasticizer 2,2,4-trimethyl-1,3-pentandioldiisobutyrate (TXIB), the surfactant 2,4,7,9-tetramethyl-5-decyne-4,7-diol (TMDD), triphenylphosphinoxide and the flame retardant tris(chloropropyl)phosphate. On the other hand, most of the identified trialkyl phosphates, pharmaceutical drugs and synthetic fragrances have been reported in surface waters by several authors so far. Input pathways of the detected compounds were traced back by sampling various input sources of organic matter such as discharges of wastewater and Lippe River tributaries. Several contaminants were ubiquitous in Lippe River water and also occurred in sewage effluent from a municipal sewage treatment plant and in samples from the tributaries. This observation suggests that they are typical sewage derived contaminants and have the potential to be used as anthropogenic molecular markers.     

Synthesis and relative response factors for the 22 tetrachlorodibenzo-p-dioxins (TCDDs) by electron-impact ionization mass spectrometry

We report the response factors of all of the tetrachlorodibenzo-p-dioxins (TCDDs) relative to 2, 3, 7, 3-TCDD by electron-impact ionization mass spectrometry. We used CP SIL 88 capillary column interfaced a ZAB-2F high-resolution mass spectrometer operating at 10,000 resolving power     

Two-dimensional distribution of microbial activity and flow patterns within naturally fractured chalk

The two-dimensional distribution of flow patterns and their dynamic change due to microbial activity were investigated in naturally fractured chalk cores. Long-term biodegradation experiments were conducted in two cores ( approximately 20 cm diameter, 31 and 44 cm long), intersected by a natural fracture. 2,4,6-tribromophenol (TBP) was used as a model contaminant and as the sole carbon source for aerobic microbial activity. The transmissivity of the fractures was continuously reduced due to biomass accumulation in the fracture concurrent with TBP biodegradation. From multi-tracer experiments conducted prior to and following the microbial activity, it was found that biomass accumulation causes redistribution of the preferential flow channels. Zones of slow flow near the fracture inlet were clogged, thus further diverting the flow through zones of fast flow, which were also partially clogged. Quantitative evaluation of biodegradation and bacterial counts supported the results of the multi-tracer tests, indicating that most of the bacterial activity occurs close to the inlet. The changing flow patterns, which control the nutrient supply, resulted in variations in the concentrations of the chemical constituents (TBP, bromide and oxygen), used as indicators of biodegradation.     

Butanol extraction to predict bioavailability of PAHs in soil

The feasibility of a mild-solvent extraction procedure to predict the bioavailability of individual polycyclic aromatic hydrocarbons (PAHs) in soil was assessed. The quantities that were degraded during the course of biodegradation of phenanthrene and pyrene in soil with or without plants correlated with the amounts extracted by n-butanol, with R2 values of 0.971 and 0.994, respectively. Six consecutive groups of earthworms removed ca. 70% of the pyrene remaining after extensive biodegradation, a value similar to the quantity extracted by n-butanol. The amount of chrysene aged in sterilized soil that was extracted by n-butanol was not statistically different from the quantities assimilated by earth-worms (Eisenia fetida) introduced into the soil. Such a mild extraction procedure may be useful as a means of predicting PAH bioavailability.     

Evaluation of alternative oil spill cleanup techniques in a Spartina alterniflora salt marsh

Three oil spill situations which cause long-term impact were simulated in 1 m(2) salt marsh plots to evaluate the effectiveness of alternative cleanup techniques at removing oil and reducing damage to Spartina alterniflora. Cleanup techniques, implemented 18-24 h after oiling, were not effective at removing oil after sediment penetration. When oil remained on the sediment surface, flushing techniques were most effective at removal, reducing levels of added oil by 73% to 83%. The addition of dispersant to the flushing stream only slightly enhanced oil removal. Clipping of vegetation followed by sorbent pad application to sediment was moderately effective, reducing added oil by 36% to 44%. In contrast to flushing and clipping, burning increased the amount of oil in sediment by 27% to 72%. Although flushing and clipping were effective at oil removal, neither technique reduced initial damage to plants or enhanced long-term recovery. While flushed plots sustained no additional plant damage due to cleanup, clipped and burned plots sustained additional initial plant damage. Based on these results, first considerations should be given to natural tidal flushing as the means to remove oil, especially in salt marshes subject to ample tidal inundation. Although our results do not support cleanup in salt marshes with ample tidal inundation, low pressure flushing may be warranted when fuel oils or large quantities of crude oil impact salt marshes subject to reduced tidal flushing. Flushing, when warranted, should be initiated prior to oil penetration into the substrate. Clipping may be considered as a cleanup response only when heavy oil cannot be effectively removed from vegetation by flushing. Burning is not recommended because it enhances oil penetration into sediment and causes substantial initial plant damage.     

Chemical assays of availability to earthworms of polycyclic aromatic hydrocarbons in soil

The bioavailable concentration of an organic pollutant is less than the concentration determined by vigorous extraction of soil. Because bioavailability varies with the particular compound, soil, and aging time, an assay for bioavailability is needed. Three methods were tested: extraction with a 25% aqueous solution of tetrahydrofuran (THF), 95% ethanol, and C18 membranes. Evaluations were conducted with a mixture of four polycyclic aromatic hydrocarbons (PAHs) added to five dissimilar soils and with pyrene as sole PAH added to six soils, and the availability of aged and freshly added compounds was determined. Assimilation by earthworms (Eisenia fetida) was used to assess bioavailability. For extraction with THF and earthworm uptake, the correlation coefficients of determination (R2) for anthracene, chrysene, pyrene, and benzo(a)pyrene added as a mixture exceeded 0.85. The R2 values for assays with the C18 membrane were 0.77 or higher. The values for pyrene added alone were 0.710 and 0.823, respectively. R2 values for assays with ethanol often exceeded 0.87, but lower values were sometimes obtained. We suggest that such solvent or solid-phase extractions may be useful in assessing PAH bioavailability.     

A model of the emergence of infectious pancreatic necrosis virus in Scottish salmon farms 1996–2003

Infectious pancreatic necrosis virus (IPNV) is an increasingly common pathogen in farmed Scottish Atlantic salmon; over 80% of marine sites are now infected, although most do not suffer clinical disease. The increasing prevalence of this pathogen in farms over the period 1996–2003 is modelled using a simple susceptible–infected (SI) epidemic model. Because salmon production approximately doubled over this period, population-dependent and -independent transmission models are compared. The model generates mean R₀ (increase ratio) of 1.41 in fresh and 1.45 in marine water farms at the national level; higher values apply with time under population-dependent transmission (1.58, freshwater, 1.80 marine by 2003). Regional differences in R₀ are mostly moderate, indicating similar regional processes in spite of substantial difference in prevalence. Prevalence of IPNV for marine sites was further increased by the use of smolts (young salmon) from multiple freshwater sources. The model suggests that prevalence is entering dynamic equilibrium and will stabilise or only increase slowly as population increases. Cutting freshwater transmission is the most effective single strategy at reducing IPNV prevalence, but a combination of strategies (including reducing the number of sources of smolts) is better and indeed is required for eradication. Eradication would require cuts in transmission of at least 30–45% and this is unlikely to be practicable.     

Morphological evidence for vertical transmission of symbiotic bacteria in the viviparous sponge<Emphasis Type="Italic"> Halisarca dujardini</Emphasis> Johnston (Porifera,Demospongiae, Halisarcida)

All stages of vertical transmission of symbiotic bacteria, from the penetration into oocytes to the formation of rhagon, were investigated in the White Sea (Arctic) representatives of Halisarca dujardini Johnston (Demospongiae). Small populations of free-living specific symbiotic bacteria inhabit the mesohyl of H. dujardini. They are represented by a single morphotype of small spiral gram-positive bacteria. Vertical transmission of symbiotic bacteria between generations in sponges may occur in different ways. In the case of H. dujardini the bacteria penetrate into growing oocytes by endocytosis. A part of the bacteria plays a trophic role for oocytes and the other part remains undigested in membrane-bound vacuoles within the cytoplasm. In cleaving embryos bacteria are situated between the blastomeres or in the vacuoles. In the blastula all bacteria are disposed in the blastocoel. The symbionts are situated in intercellular spaces in free-swimming larvae and during metamorphosis. Symbiotic bacteria do not play any trophic role in the period of embryonic and postembryonic development of H. dujardini. No signs of destruction and digestion of bacteria were revealed at any stage of development.Communicated by O. Kinne, Oldendorf/Luhe