Traffic congestion and ozone precursor emissions in Bilbao (Spain)

GOAL. SCOPE. BACKGROUND: In urban environments, the measured levels of ozone are the result of the interaction between emissions of precursors (mainly VOCs and NOx) and meteorological effects. In this work, time series of daily values of ozone, measured at three locations in Bilbao (Spain), have been built. Then, after removing meteorological effects from them, ozone and traffic data have been analyzed jointly. The goal was to identify traffic situations and link them to ozone levels in the area of Bilbao. METHODS: To remove meteorological effects from the selected ozone time series, the technique developed by Rao and Zurbenko was used. This is a widely used technique and, after its application, the fraction obtained from a given ozone time series represents an ozone forming capability attributable to emissions of precursors. This fraction is devoid of any meteorological influence and includes only the apportion of periodicities above 1.7 years. In the case of Bilbao, the ozone fractions obtained at three locations have been compared on that time scale with traffic data from the area. RESULTS AND DISCUSSION: For the 1993-1996 period, a regression analysis of the ozone and traffic fractions due to periodicities above 1.7 years (long-term fractions), shows that traffic is the main explanatory factor for ozone with R2 ranging from 0.916 to 0.996 at the three locations studied. Analysis of these longterm fractions has made it possible to identify two traffic regimes for the whole area, associated to different profiles of ozone forming capability. The first one favors low ozone forming capability, and is associated with a situation of fluent traffic. The second one shows high ozone forming capability and represents congestion. Joint analysis of raw data of ozone and traffic do not show any clear pattern due to the strong masking effects that seasonal-meteorological effects (mainly radiation) have on the measured ozone signal. If only immission data of ozone are available, as in this case, a comparison between ozone and traffic can only be made on the long-term time scale, since that is the only fraction embedded in the ozone time series that can exclusively be attributed to emissions of precursors. This fact stresses the need to study the different fractions embedded in the time series of ozone measured levels separately. CONCLUSION: Though the coefficients obtained in the regression are only valid for the 1993-1996 period, these traffic regimes represent long-term targets (congestion or fluent traffic) that can inspire policies for a joint management of the traffic and pollution by ozone in the area of Bilbao beyond that period. RECOMMENDATIONS AND OUTLOOK: The results of this work show the need of a joint management of ozone and traffic in Bilbao. Since an accurate knowledge of traffic was not available, the use of emission factors to relate traffic and actual ozone levels has not been possible. For this reason, this study has focused on the long-term fractions of traffic and ozone. In the future, if a more accurate knowledge of traffic is available, it will be possible to find relationships between traffic and ozone on all time scales.     

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Growth of Plants on TBT-contaminated Harbour Sludge and Effect on TBT Removal (10 pp)

Background Worldwide, large amounts of sediments have to be dredged annually from waterways and harbours. These sediments are sometimes polluted with a variety of toxic compounds. In some countries, including Belgium, the load with the biocide tributyltin (TBT) from ship coatings prohibits the dumping of harbour sludge into the sea. Land-based dumping is a commonly used alternative. Objective This research investigated the feasibility to use land-deposited harbour sludge for plant production. In a field trial, the growth of 38 more or less salt-tolerant plant species on low and high TBT-contaminated sediments was studied. The elimination of TBT from sludge with and without vegetation was compared. The uptake of TBT and its degradation products di- and monobutyltin (DBT and MBT) into harvest products under field conditions was determined. - Experimental Set-up. Sediments dredged in May 2003 from the brackish waters of the port of Antwerp were analysed in the laboratory for soil texture, pH, electroconductivity, sodium, magnesium, potassium, calcium, ammonium, nitrate, total nitrogen, chloride, sulphur and the organotins TBT, DBT and MBT. The sediments were lagooned for one year to dewater, desalinate and improve their structure. Salt-tolerant domestic and wild plants were selected and sown in May 2004. In August 2004, plants were harvested and the produced biomass was determined. Samples were taken from vegetated and non-vegetated top and bottom sediments and from plants growing above soil and analysed for TBT, DBT and MBT. Results The fresh sediments showed a good supply with nutrients and a neutral pH, but were rather saline (EC 14 mS cm-1 of the saturated paste extract). The salinity decreased to 3.7 mS cm-1 during lagoonation. The high and the low contaminated sediment had initially 43 and 1.6 mg TBT kg-1 dry weight, respectively. Besides TBT, several other contaminants were present in the sediments at critical levels. The biomass production of the plant species from the field trial ranged from 0.2 to 13 tons dry mass per hectare. Plants performing excellently were barley, sorghum, rape seed, a clover/grass mix and reed. If at all, a positive influence of TBT on plant growth was seen. TBT was degraded significantly faster (>40%) below barley. The uptake of TBT, DBT and MBT into stem and leaves of reed, grass and clover was very low, but measurable and not related to concentrations in soil. No uptake of TBT or its metabolites into corn of barley was found. Discussion This study confirmed former results: the toxicity of TBT to higher plants is low, and even high levels in soils would not be a hindrance for crop production. The removal of TBT seemed to be increased by both lagooning and plant growth, although the target values for sea dumping in use in certain European countries were not reached. A plausible explanation for the faster degradation of TBT under vegetation is that oxygen is a limiting factor, and plants dewater the soil, thus aerating it. The uptake of the organotins TBT, DBT and MBT into harvest products is probably due to attached soil particles. Conclusions To summarize, barley was the optimal species: it grew very well despite the salinity of the dredged sediments, it had a significantly positive effect on TBT removal; it showed no measurable uptake of TBT or the other butyltins into the harvested product; and it is a cash crop well established in European agriculture. Outlook The amounts of dredged sediments are high, and good soils are becoming increasingly rare. The feasibility of using dredged sediments for non-food production, such as energy crops, should be investigated by a critical risk assessment.     

Seasonal Fluctuation in Heavy Metal Pollution in Iran´s Siahroud River - A Preliminary Study (7 pp)

Background The management of its available water resources has become a key issue for Iran. During the last few decades, the water quality of Siahroud River in the coastal plain of the Caspian Sea in Gilan Province in Northern Iran has significantly degraded. The scarcity of water has been compounded by rapid population growth and increasing pollution from fertilizers, pesticides, and municipal and industrial wastes. One of the sources of this degradation is the movement of heavy metals from the river's watershed into the various water systems supported by the river, including the water system for Rasht City. Methods To study the magnitude of heavy metal pollution in the Siahroud River, seven heavy metals including Zn, Cu, Pb, Cd, Mn, Fe, and Ni were measured in duplicate from replicated water samples collected over five consecutive seasons and analyzed by Atomic Absorption Spectrometry. In situ measurements of pH were taken with the samples and total organic carbon (TOC) was analyzed by IR gas measurement. Results The results demonstrated that four of the seven heavy metals including Pb, Fe, Cd, and Mn exceeded permissible safe levels as established by the United States Environmental Protection Agency. Multivariate factor analysis suggested that industrial land-use was the main contributing factor for the high levels of Fe and Mn in the Siahroud River, whereas, Cd was principly from agricultural activities in the watershed. The data also suggested that pH and TOC had an important role in the behaviour of Pb and Mn, and that the elevated levels of these two heavy metals in Siahroud River was the consequence of other anthropogenic sources. Only negligible levels of Zn, Cu and Ni were detected. Finally, all the sampling stations were subjected to cluster analysis. The results indicated that three different zones could be distinguished according to the levels of pollution. In addition, it was shown that the urban areas did not have a significant impact on the heavy metal pollution in the river. This observation stems from the fact that the data from the sampling stations before and after Rasht City were not significantly different. Recommendation . Preventive measures need to be undertaken in the land-use systems and watersheds of the Siahroud River to reduce the pollution levels of Pb, Cd, Mn and Fe.     

湿热法处理实现厨余垃圾饲料化的研究

探索了湿热法工艺处理厨余垃圾并将其饲料化的可行性.实验表明,湿热法处理可以在满足消毒杀菌的同时,降低厨余原料中的高油脂含量和高含盐量,调节营养成分,实现物化性状的均一.经湿热法处理后的厨余垃圾的饲用价值得到明显改善,可作为良好的饲料原料,同时可回收利用油脂.总之,湿热法工艺可实现厨余垃圾的无害化、减量化和资源化处理,对于消除环境污染、缓解我国饲料原料紧张及资源回收利用等方面有着显著的环境效益、社会效益和经济效益,具有重要的现实意义.     

"老龄期"填埋场渗滤液COD蒸发规律研究

"老龄期"填埋场渗滤液由于可生化性差而难于处理.采用常规蒸发、减压蒸发和载气蒸发处理不同pH值的"老龄期"渗滤液.实验结果表明,3种蒸发方式下,冷凝液COD下降过程中均存在明显的浓度转折点,转折点之后COD维持较低水平,为"老龄期"渗滤液的"三分处理法"提供理论依据.与常规蒸发相比,减压蒸发和载气蒸发的前期冷凝液COD较高,且浓度转折点偏后.     

Pilot-plant study of wastewater sludge decontamination using a ferrous sulfate bioleaching process.

The objective of this research was to investigate the performance of the ferrous sulfate bioleaching (FSBL) process in a pilot plant for decontamination and stabilization of wastewater sludge. Batch and continuous experiments, conducted with two 4-m3 bioreactors using indigenous iron-oxidizing bacteria (20% v/v of inoculum) with addition of 4.0 g ferrous sulfate heptahydrate per liter of sludge initially acidified to pH 4.0, were sufficient for effective heavy metal (cadmium, copper, manganese, zinc, and lead) removal yields. The average metal removal yields during the FSBL process were as follows: cadmium (69 to 75%), copper (68 to 70%), manganese (72 to 73%), zinc (65 to 66%), and lead (16%). The FSBL process was also found to be effective in removing both fecal and total coliforms (abatement > 5 to 6 log units). The nutrients content (nitrogen, phosphorus, and magnesium) were also preserved in decontaminated sludge.     

Clearance of PCDD/Fs via the gastrointestinal tract in occupationally exposed persons.

A digestive tract mass balance was performed on six men with high body burdens of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). Intake via food was measured by analyzing duplicate portions of the food consumed by the volunteers and excretion via feces was determined by quantitative collection and analysis of the feces. Blood samples were taken to determine the current body burden. The results showed that the quantity of non-metabolized chemical excreted in the feces clearly exceeded the uptake via food for all of the 2,3,7,8-substituted PCDDs and some of the PCDFs, indicating a significant clearance across the gastrointestinal tract. The concentrations of these PCDD/F congeners in blood and feces were highly correlated (r > 0.8), demonstrating that the fecal PCDD/F content was determined by the body burden. The half lives in the test persons due to fecal clearance of non-metabolized chemical were estimated from the excretion rate and the current body burden and ranged between 10 years (Cl8DD) and 33 years (2,3,4,7,8-Cl5DF). These were compared with the overall contaminant half-lives due to all clearance processes which were calculated from the body burden and the decrease in blood concentrations measured over several years. The fecal clearance of non-metabolized PCDD/F contributed on average between 37% (2,3,7,8-Cl4DD) and 90% (Cl8DD) to the total elimination. This indicates that the gastrointestinal pathway plays a decisive role in the clearance of most 2,3,7,8-subsituted PCDD/F congeners.