Heavy metals and organic carbon in sediments from the Tuy River basin,Venezuela

The Tuy River basin, located in north-central Venezuela with an annual average temperature of 27°C and precipitation of 140 cm, was selected to conduct a geochemical study of bottom sediments, with the object of establishing the natural and human influences in the abundance and distribution of Fe, Mn, Cr, Co, Cu, Ni, Pb, Zn and organic carbon. The basin is lithologically divided into two sub-basins, north and south. The north sub-basin drains a iow-grade metasedimentary terrain with a population density of 800 persons km^–2 and approximateiy 600 industrial sites, while the south sub-basin in underlain by metavolcanic and ultramafic rocks, with a population density of less than 10 persons km^–2.Stream bottom sediment samples (150) were collected during the years of 1979–1986 in 16 unpolluted sites and 13 polluted sites. The sediments were air dried at room temperature and sieved through a 120 stainless steel mesh (125 m). Samples of grain size smaller than 125 m were analysed, the heavy metals being determined by atomic absorption spectrometry and the organic carbon (Corg) by dry combustion.The higher concentrations of heavy metals and organic carbon found in the pristine areas were in the south sub-basin, especially in those areas with higher annual precipitation and tropical forest. This indicated that the metavolcanic and ultramafic rocks yield higher concentrations of heavy metals than the metasedimentary rocks. It was also noted that the higher concentrations of Cr and Ni are associated with the ultramafic rocks. The results obtained from the sediment samples collected in the polluted sites showed that the elements Pb, Zn and Corg are enriched up to 4 times as a result of ail the human activities taking place in the basin. Organic carbon is an excellent indicator of domestic wastewater, Pb and Zn are good indicators of the automotive traffic and industrial effluents. The concentrations of each heavy metal did not show any significant correlation with grain size fractions; however, the concentration of organic carbon did show a negative correlation with grain size. The lithological, climatic and vegetation influence in the abundance of heavy metals and organic carbon in stream sediments clearly indicates the necessity of establishing background levels for the area under study when carrying out studies in environmental geochemistry.     

Fly ash content and distribution in lake sediments around a large power station: inferences from magnetic susceptibility analysis

The bulk magnetic susceptibility of sediments from artificial and natural lakes around a large coal-fired power station in NE Spain has been measured. Higher magnetic susceptibility values are found in lake sediments located SE of the power station. This distribution of susceptibility values is compatible with environmental and meterological studies of emissions from the power station, which indicate a dominant SE plume direction. Mineralogical studies, by means of X-ray diffraction and scanning electron microscopy, show that the highest susceptibility values found in the sediments are caused by magnetic iron spinels in the fly ash that is transferred to the environment by the power station particulate emissions. After the quantitative mineralogical studies of fly ash, two different methods of fly ash content determination in the sediments have been devised, showing very similar results. The low background magnetic susceptibility of the sediments in the study area and the high susceptibility resulting from the input of magnetic fly ash particles allows both delimitation of the polluted area around the power station, and quantification of the fly ash input into the natural sediments.     

Sequestration of pyrrolizidine alkaloids by larvae ofTellervo zoilus (Lepidoptera: Ithomiinae) and their role in the chemical protection of adults against the spiderNephila maculata (Araneidae)

Summary Life stages of the primitive Australian ithomiine butterflyTellervo zoilus and its larval hostplant, the apocynaceous vineParsonsia straminea, were quantitatively assayed for pyrrolizidine alkaloids (PAs). PAs were found in all stages, mainly as N-oxides, being most concentrated in larvae and freshly-emerged adults. Although adults feed at various confirmed PA sources this probably does not compensate for losses, as wild-caught adults had considerably lower concentrations of PAs. The main alkaloid present in both freshly-emerged adults and in leaves of the host-plant was lycopsamine (1b), stored by butterflies in the N-oxide form. Its presence in higher proportion, in relation to intermedine (1a), in larvae, pupae and adults ofTellervo in relation to the host-plants suggests the inversion of intermedine to lycopsamine by the insects. No 14-member ring macrocyclic PAs were detected in either food-plant or butterflies. Several other PAs were found in wild-caught adults reflecting visits to other PA sources. PAs were also found in high concentrations in freshly-emerged individuals of the danaineEuploea core bred onParsonsia straminea. Wild-caughtDanaus affinis had high PA levels acquired from adult feeding. Freshly emergedEuploea raised onIschnocarpus frutescens andDanaus raised onIschnostemma carnosum (both PA-free) were preyed on by the orb weaving spiderNephila maculata, and showed no PAs. In all cases where PAs were present, most butterflies were liberated, usually cut out of the web unharmed, byNephila. The spider's response was not closely linked to PA concentration, however, and may also depend on hunger levels and previous experience with PA-containing butterflies. All control and other non-PA containing butterflies were consumed although rejection of some body parts of freshly-emergedDanaus affinis suggests that compounds other than PAs may be involved.     

Imposex in the commercial snail Bolinus brandaris in the northwestern Mediterranean

A survey of the degree of imposex in populations of the commercial muricid Bolinus brandaris (L.) was carried out at six locations along the Catalan Coast (NW Mediterranean). Imposex was found to be a widespread phenomenon; the occurrence of a penis was observed in all females studied with the exception of those from St. Carles (South of Catalunya) where only 37% were affected. Other indices such as Relative Penis Length (RPL) and Vas Deferens Sequence (VDS) were applied; RPL varied from 4.5% in St. Carles--the least affected area--to 29.8% in the vicinity of Barcelona; similar results were obtained for VDS. Tissue organotin residues ranged from 6 to 140 ng g(-1) w.w. as Sn. Despite legislation restricting the use of tributyltin (TBT) in antifouling paints, this paper evidences the occurrence of organotin pollution far from the source, with levels of both TBT and triphenyltin (TPhT) high enough to cause environmental concern.     

环境应急监测工作现状存在的问题及对策研究

近年来,各类突发性环境污染事故时有发生,造成生命、财产的巨大损失和生态系统的严重破坏,这一问题引起了世界各国的高度重视.由于突发性污染事故具有爆发的突然性.危害的严重性以及影响的广泛性和长期性等特点,采取切实有效的措施来预防这类事故的发生以及提高对事故处理处置应变能力,已经成为环境保护一项非常重要的工作,因此建立健全有效的环境应急监测系统,加强各级环境监测站应急监测能力建设,提高其应急监测能力,意义十分重大.环境应急监测对于防范突发性环境污染事故,在事前预防、事中监测、事后恢复的各个过程中起着极其重要的作用,环境应急监测已成为环境监测的重要组成部分.本文系统地分析了我国环境应急监测工作现状,针对实际工作中存在的问题,提出了解决对策.     

Evidence of coprostanol estrogenicity to the freshwater mussel Elliptio complanata

Coprostanol (5 beta (H)-cholestan-3 beta ol) is a reduced metabolite of cholesterol produced by micro-organisms found in the intestinal tract of mammals. This substance abounds in urban effluents and is accumulated by organisms living in the vicinity of municipal effluent outfalls. In an earlier study, freshwater mussels exposed to contaminated river water for 62 days accumulated large quantities of coprostanol (Cop) in their soft tissues (16 micrograms/g dry wt.). Moreover, these mussels were found to have elevated levels of vitellin in their hemolymphs, suggesting estrogenic effects. Although municipal wastewaters are known to contain other estrogenic compounds capable of inducing Vn synthesis in mussels, the estrogenic potential of coprostanol was singled out for examination. To this end, mussels were first injected with concentrations of coprostanol via the abductor muscle route, and allowed to stand in aerated water for 72 h at 15 degrees C. The levels of Vn in mussel hemolymph were assayed using the organic alkali-labile phosphate method. A competitive estradiol-binding assay was then devised to measure the ability of coprostanol to compete in the binding of fluorescein-labeled estradiol-albumin to cytosolic proteins. Coprostanol partially reversed the binding of labeled estradiol-albumin to cytosolic proteins with an EC50 of 1 mM. In addition, injections of coprostanol and estradiol-17 beta led to increased levels of vitellins in the hemolymph of treated mussels. Moreover, incubation of cop in gonad homogenate extracts in the presence of NADPH led to the formation of two compounds, as determined by high-performance thin-layer chromatography. One of these compounds appears to be the C17 oxidation product of coprostanol, whose polarity is similar to that of estradiol. The results present evidence that coprostanol is estrogenic to freshwater mussels.     

Applicability of Fenton and H2O2/UV reactions in the treatment of tannery wastewaters

In this paper we evaluated the H2O2/UV and the Fenton's oxidation processes for the treatment of tannery wastewater under different experimental conditions. Efficiencies were judged by the amounts of organic substances degraded or eliminated under these treatment techniques. Daphnia magna and Vibrio fischeri were used to monitor toxicity. Organic compounds contained in the untreated and treated tannery wastewater were determined and identified using substance specific techniques. Gas chromatography-mass spectrometry (GC-MS) in positive electron impact (EI(+)) mode was applied to determine volatile organics. Atmospheric pressure ionization (API) mass (MS) and tandem mass spectrometry (MS-MS) coupled with flow injection analysis (FIA) or liquid chromatography (LC) were used to detect or identify polar organic pollutants. The experimental results indicated that both oxidation processes--H2O2/UV at pH 3 and Fenton at pH 3.5--are able to reduce TOC content by mineralisation of the organic compounds.     

Evaluation of relative photonic efficiency in heterogeneous photocatalytic reactors

The evaluation of photonic efficiency in heterogeneous photocatalysis remains elusive because the number of absorbed photons is difficult to assess experimentally. The photonic efficiency of heterogeneous photocatalytic reactors depends on the reactor geometry, irradiation source, and photocatalyst properties. In this work, the relative photonic efficiency of heterogeneous photocatalytic reactors to degrade an azo dye was evaluated using phenol as the standard system. The experimental tests were carried out in a batch reactor under different conditions of pH, catalyst dosage, initial concentration, and ultraviolet (UV) lamps. The kinetics of disappearance of both phenol and azo dye were studied using the initial rate method and were described according to the Langmuir-Hinshelwood (L-H) kinetic model. It was observed that the relative photonic efficiency depends on the adsorption/desorption properties of the photocatalyst.