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Goal and Scope
The Stockholm convention bans 12 prominent persistent organic pollutants (POPs), and the pertinent global monitoring programme recommends birds’ eggs as bio-indicators for the terrestrial food web. As top predators, Peregrine falcons are uniquely suited indicators because of their accumulating power for persistent and lipophilic compounds. On the other hand, the Peregrine falcon as a sentinel species was closer to extinction than other birds of prey. Only unremitting efforts of private omithologists throughout the past four decades in conjunction with the timely banning of organochlorine pesticides like DDT succeeded in saving the Peregrine population of Baden-Wueriternberg from extinction, in contrast to the Peregrine falcons of other German states or other European countries.Methods
See vd Trenck et al. (2006).Results and Conclusions
New results confirm the findings of the past long-term bio-monitoring. The main pollutants are PCBs (ca. 20 μg/g) and pp′-DDE (ca. 11 μg/g), the latter contributing >96% of all organochlorine pesticide residues (all concentrations on a dry matter basis). Both substances have followed a slightly increasing trend since 2004. The sum of the polychlorinated diphenyl ethers (PBDE) has fluctuated strongly in the past four years, and in 2006 amounted to 0.6 μg/g (mean without outliers), just as the mercury contamination of the eggs. PCB-156 as the main dioxin-like PCB followed with an average concentration of 0.35 μg/g. Only 10 out of 23 eggs analysed contained hexabromocyclododecane (HBCD) in measurable concentrations; the mean concentration of these eggs was 0.024 μg/g. Tetrabromobisphenol A (TBBA) was detected in all egg samples with a mean of 0.004 μg/g. Due to the many and diverse effects exerted by PCBs; the assessment of this group of compounds, with the aid of European and German regulations for food, proves to be a complex matter, which is currently in a state of flux. There is no doubt, however, that the mean pollution of the Peregrine eggs with toxic dioxin equivalents (WHO TEQ) has reached the no observed adverse effect level (NOAEL) known for chickens and osprey chicks, and the most polluted eggs exceed this threshold considerably. The toxic profile of PBDEs is similar to that of PCBs. They are known to promote tumour growth, to interfere with the thyroid hormone system resulting in toxicity for the neuronal development, to suppress the immune system, and to trigger stress reactions. Tests with highly purified BDE-47 have ruled out dioxin-like effects via Ah-receptor binding for this congener and such effects are therefore very unlikely for the whole class of compounds. At the present time, quantitative criteria for the assessment of the risk posed by PBDEs are not sufficiently reliable, and less so for HBCD and TBBA.Recommendations and Perspectives
It is necessary to continue the bio-monitoring of POPs and similar pollutants in the terrestrial food web and to establish NOAELs as quantitative criteria for their assessment. Possible sources of dioxin-like PCBs and PCDD/Fs are to be pinpointed, and abatement measures are to be considered where background concentrations are significantly exceeded. 相似文献Background, aim, and scope
Concentration monitoring as a basis for risk assessment is a valid approach only if there is an unambiguous relation between concentration and effect. In many cases, no such unambiguous relation exists, since various substances can exert the same effect with differing potencies. If some or all of these substances contributing to a biological effect are unknown, effect-related monitoring becomes indispensable. Endocrine-disrupting substances in water bodies, including the groundwater, are a prominent example of such a case. The aim of the investigations described here was to detect hormonally active substances in the groundwater downstream of obsolete landfills by using the E-screen assay and to possibly assign the biological effect to individual chemical compounds by means of instrumental analyses carried out in parallel. 相似文献After the discovery of chloroform in drinking water, an extensive amount of work has been dedicated to the factors influencing the formation of halogenated disinfections by-products (DBPs). The disinfection practice can vary significantly from one country to another. Whereas no disinfectant is added to many water supplies in Switzerland or no disinfectant residual is maintained in the distribution system, high disinfectant doses are applied together with high residual concentrations in the distribution system in other countries such as the USA or some southern European countries and Romania. In the present study, several treatment plants in the Somes river basin in Romania were investigated with regard to chlorine practice and DBP formation (trihalomethanes (THMs)). Laboratory kinetic studies were also performed to investigate whether there is a relationship between raw water dissolved organic matter, residual chlorine, water temperature and THM formation.
Materials and methodsDrinking water samples were collected from different sampling points in the water treatment plant (WTP) from Gilau and the corresponding distribution system in Cluj-Napoca and also from Beclean, Dej and Jibou WTPs. The water samples were collected once a month from July 2006 to November 2007 and stored in 40-mL vials closed with Teflon lined screw caps. Water samples were preserved at 4°C until analysis after sodium thiosulfate (Na2S2O3) had been added to quench residual chlorine. All samples were analysed for THMs using headspace GC-ECD between 1 and 7 days after sampling. The sample (10 mL) was filled into 20-mL headspace vials and closed with a Teflon-lined screw cap. Thereafter, the samples were equilibrated in an oven at 60°C for 45 min. The headspace (1 mL) was then injected into the GC (Cyanopropylphenyl Polysiloxane column, 30 m × 53 mm, 3 μm film thickness, Thermo Finnigan, USA). The MDLs for THMs were determined from the standard deviation of eight standards at 1 μg/L. The MDLs for CHCl3, CHBrCl2, CHBr2Cl and CHBr3 were 0.3, 0.2, 0.3 and 0.6 μg/L, respectively. All kinetic laboratory studies were carried out only with water from the WTP Gilau. The experiments were conducted under two conditions: baseline conditions (pH 7, 21°C, 2.5 mg/L Cl2) to gain information about the change of the organic matter in the raw water and seasonally variable conditions to simulate the actual process at the treatment plant and the distribution system.
Results and discussionThis study shows that the current chlorination practice in the investigated plants complies with the THM drinking water standards of the EU. The THM concentrations in all samples taken in the four treatment plants and distributions systems were below the EU drinking water standard for TTHMs of 100 μg/L. Due to the low bromide levels in the raw waters, the main THM formed in the investigated plants is chloroform. It could also be seen that the THM levels were typically lower in water supplies with groundwater as their water resource. In one plant (Dej) with a pre-ozonation step, a significantly lower (50%) THM formation during post-chlorination was observed. Laboratory chlorination experiments revealed a good correlation between chloroform formation and the consumed chlorine dose. Also, these experiments allowed a semi-quantative prediction of the chloroform formation in the distribution system of Cluj-Napoca.
ConclusionsCHCl3 was the most important trihalomethane species observed after the chlorination of water in all of the sampled months. However, TTHM concentrations did not exceed the maximum permissible value of 100 μg/L (EU). The THM formation rates in the distribution system of Cluj-Napoca have a high seasonal variability. Kinetic laboratory experiments could be used to predict chloroform formation in the Cluj-Napoca distribution system. Furthermore, an empirical model allowed an estimation of the chloroform formation in the Gilau water treatment plant.
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