J.P. Lacaux

Emission factor estimates of cereal waste burning in Spain

Abstract Every year more than 5 million ha of cereal fields are affected by fires in order to eliminate cereal waste in Spain. The characteristics of this type of fire with intense flames are similar to those of the African dry savanna heading fires. This paper surveys the atmospheric emission caused by this process by combining results of field and combustion chamber experiments. Combustion chamber experiments show that during the flaming phase 88% of the fire exposed carbon is converted into CO2 and during the smoldering phase this percentage changes to 74%. These combustion chamber experiments also show that the soluble part of the aerosols emitted during the course of fires only represent 3% of the total particulate matter (TPM) produced, being the ions K+ and CI− the predominant ones. The cereal waste fire process can be represented by an arithmetic combination that takes into account the amounts of mass burned during the two phases of the fire: 0.90 flaming +0.10 smoldering. Emission factor estimates from field burning experiment are 13±7xa0g TPMxa0kg−1(dm) and 2.8±0.2xa0g NOxxa0kg−1 (dm). Finally, we obtain average emissions of 80–130xa0Gg TPM, 17–28xa0Gg NOx, 210–350xa0Gg CO and 8–14xa0Tg CO2 in Spain. These emissions represent nearly 25% of the total NOx and 50% of the total CO2 emissions by other pollution sources during the burning period in Spain.

Precipitation chemistry in intertropical Africa

Abstract Rainwater samples from Kollo (Niger) and Lamto (Ivory Coast) were collected during the year 1994. Two phases were analyzed, the dissolved was obtained with a 0.2 μm filtration and the total was obtained after evaporation and an HF : HNO 3 digestion. Mg, V, Cr, Mn, Co, Zn, Rb, Sr, Ba, Pb, U, Al, Fe, Cs, REEs and Th were analyzed in both phases and Na, K, Ca and Cl in the dissolved phase. Except for Zn in Lam to with a value of 53, enrichment factors EF, calculated with respect to Al normalization in the total phase, do not show any significant enriched values (EF > 10). However, event by event, at low Al amounts, some elements V, Cr, Mn, Co, Zn, Pb and Mg, Rb, Sr and Ba are obviously enriched. Anthropogenic activities for metals and Ba or natural emissions for Mg, Rb, Sr can explain these enriched values. The REE patterns of precipitation particles are almost flat with La/Yb values (16.5–21.5) higher than the upper-crust values (13.6). These values are comparable with those measured in suspended sediments from Congo rivers. Dissolved-total distributions are: Zn > Sr > Mn > Co > Mg > Ba > Cr > Rb > V > Ph > U > Th > Cs > La > Ce > Al > Fe for Lamto samples and Zn > Sr > Mg > Mn > Rb > Co > Ba > Cr > Pb > V > Cs > Th > U > Al > La > Ce > Fe for Kollo samples. The percentage of the dissolved fraction is conversely proportional to the amount of Al in precipitations. Precipitation particles in Lamto and Kollo are strongly depleted in Mg, Mn, Rb, Sr and Ba compared to the upper-crust composition. The Rb/La mean ratios of 1.62 in Lamto and 1.70 in Kollo differ from the upper-crust value (3.73) and indicate that these particles have already been involved in weathering processes. All the information obtained in this study shows that terrigeneous particle emission is the main source of trace elements, in this region. Nevertheless, the contribution from other sources (ocean, vegetation, human activities) become evident when the amount of crustal dust particles in the atmosphere is very low.

Experimental study of the scavenging process by means of a sequential precipitation collector, preliminary results

Abstract From January 1986 to July 1989, 103 rain events were sampled with a sequential collector in Vitoria, a moderately industrialized city (Spanish Basque country). Each sample was analysed in terms of pH, conductivity and the ionic concentration of Cl−, NO−3, SO2−4, NH+4, Na+, K+, Ca2+ and Mg2+. On average, the rainwater samples were acid, with a mean pH value of 4.9 the major ions being SO2−4 and Ca2+. Events with highly acid characteristics (pH ⩽ 4.5) represent 14% of the total collected. Analysis of meteorological conditions in relation with the average ionic concentrations points out the influence of anthropogenic sources from southwestern France and from the northern Basque country. The decrease in the wet deposition (in percentage of the total deposition per rainfall event) throughout precipitation is particularly apparent for NH+4 and Ca2+ ions. In precipitation related to the meteorological Local-class, the atmospheric removal appears to be more efficient, especially for Ca2+, and we can also note a precipitation-neutralizing effect. Precipitation scavenging is mainly controlled by the total amount of water precipitated. However, the intensity of the rain modified the deposition rate.

Cereal waste burning pollution observed in the town of Vitoria (northern Spain)

Abstract Agricultural waste burning is a widespread practice throughout the world but there is little information about its pollutant impact. This paper deals with a preliminary study of the pollution observed in Vitoria (Northern Spain) caused by cereal waste burning. The mean hourly flux of pollutants produced by cereal waste burning fires can reach values of 1.4xa0kt of CO 2 , 13xa0t of TPM and 3xa0t of NO x in the area around Vitoria. Measurements obtained in the area of emission and inside fire plumes show high ratios (NO 2 /NO x ) indicating that nitrogen oxides emitted by the source undergo a rapid transformation in the same area of emission. Results relating to aerosol composition collected in Vitoria during burning periods show an increase in the concentration of K + , NO 3 − and Cl − ions, that are inter-correlated. The modification of the ionic composition of aerosols also affects the chemistry of the rain collected in Vitoria. During the burning period, it is particularly noticeable that anthropogenic pollution (usually identifiable by the correlation between SO 4 2− and NO 3 − concentrations) disappears, indicating the existence of an independent source of NO 3 − not linked to the SO 4 2− source. Similar results were deduced studying BAPMON data collected in Spain during cereal waste burning. Finally, we note that ozone concentration measured at Vitoria is not affected by the pollution generated by the burning fires.

Organic acids in precipitation in the Basque country (North of Spain)

Abstract This paper discusses the results of the measurement of organic anions in precipitation collected since July 1989 in Olaeta, a rural village in the Basque Country (North of Spain). In order to gain a deeper knowledge of the characteristics and acids responsible for the free acidity observed in precipitation, a study was started within the EPOCA programme (Estudios en el Pirineo Occidental de la Contaminacion Acida), for measuring organic anions: formiate, acetate and propionate. These results show that it was possible to observe organic anions in nearly every event, with a 5% contribution to the anionic total, and with an appreciable seasonal variation in concentration. The maximum contribution of organic acids to free acidity (H + ) is 6% in rain events with pH≤5.0. There is significant correlation between acetic acid and inorganic ions of marine origin Cl − , Na + and Mg 2+ which might indicate the importance which the air masses of marine origin are going to have in the concentration of this acid. There is also significant correlation between formic acid and SO 4 2− and H + ions which might indicate the relatively importance contribution of formic acid to free acidity.

Relationship between the atmospheric particulate fraction and the ionic content of precipitation in an area under influence of a waste incinerator located in the Basque country (Spain)

Abstract During the period between April 1988 and April 1991, the relationship between the ionic content of the atmospheric particulate fraction and the rainwater collected at Olaeta, a cattle raising and forested area in the Basque Country, has been studied. The site is affected by the emissions from a waste incinerator located 11 kin away in a north-easterly direction. SO42− and NH4+ ions are the most important species in the particulate fraction with 4.6 μg m−3 for each of them. The precipitation is characterized by very high concentrations of Cl− ion with 173.4 μeq l ( Cl − Na + ratio = 3), the next important ions are NH4+, Ca2+ and SO42− with 95.9, 91 and 69.2 μeq l −1 respectively. The average H+ concentration is 47.9 μeq l −1 (pH = 4.3). The contributions of both soluble particulate fraction and gases to the ionic concentrations recorded in the precipitation differ widely from one type of ion to another, the contribution of HCl gas being the most important one. Approximately, 95% of Cl− ion present in the rainwater come from the gaseous phase. The contribution of the particulate fraction to the rainwater concentrations varies between 100% (for SO42− and NH4+ ions) and 22% (for Ca2+ ion). The scavenging ratio for Cl− ion (W = 40,000) is very high as it is mainly in the gaseous phase in the atmosphere. The scavenging ratios of NH4 and SO4− ions are the lowest (W = 600 and 1000 respectively), probably because these species are in the fine particle range of the aerosol.

Chemical composition of acid rain in the North of Spain: the EPOCA program

Abstract The EPOCA program (Estudios en el Pirineo Occidental sobre Contaminacion Acida), whose main goal is to show the possible effects of an “acid rain” type pollution on the forests of the Spanish Basque country, is presented in this paper. A measurement network comprising two automatic precipitation collectors located at Vitoria and at Llodio has been operating since December 1985. 30% of the events of rainfall were acidic with a pH ⩽5. However, rain with an alkaline character (pH>6) is found in 25% (Vitoria) and 40% (Lldio) of the cases. The statistical analysis of the chemical components confirms that the chemical contents of the acid rain have an anthropogenic character and those of the alkaline rain a soil origin. Both sources play an important part in the temporal trend of pH values and precipitation chemistry.

Evaluation of origin and distribution of wet deposition recorded in the Spanish Basque country

Abstract Within the framework of the EPOCA programme (Estudios en el Pirineo Occidental de la Contaminacion Acida), wet deposition of inorganic pollutants was measured at five rural sites in the Spanish Basque Country between Dec 85 and Apr 91. Na+, Ca2+, SO4 2‐ exc, and NH4 + ions were the main species found in the rainwater samples. The average pH value ranged between 4.9 and 5.6 depending on the site. Relationship between the ionic concentrations and the back‐trajectories showed that trajectories coming from Europe resulted in the highest NO3 ‐, SO4 2‐ exc and H+ concentrations. NO3 ‐ and H+ incursion in the study area by a long‐range‐transport phenomenon was estimated in 20 μeq 1‐1 for each ion. By means of both the one‐way analysis of variance and the range tests for the wet deposition, two of the sites resulted to be able to represent both qualitatively and quantitatively the wet deposition collected at all sites.

Concentration and size distribution of atmospheric particulate matter on a forested area in the basque country (Spain).

Abstract Throughout the period going from October 1989 to September 1990, we measured the air concentrations of both SO2 gas and of the atmospheric particulate fraction, both in total and split into in size ranges, by means of a Denuder‐filter system and of a cascade impactor, respectively, all of it for a forested area located in the centre of the Basque Country in northern Spain. The results thrown when the Denuder‐filter system was used, show the SO4 2‐and NH4 + ions, with 4.6 μg m‐3 of each, as being the most important species in the particulate fraction, whereas the NO3 ‐ ion would come second in the scale, with 0.9 μg m‐3. The average concentration of SO2 gas was 3.2 μg m‐3. The levels of SO2 gas and those of the SO4 2‐ ion, both calculated for Summer and Winter, are related in such a way that their correlation shows the considerable effect of local emissions on the actual air concentrations for both species during the Winter season. Likewise, after an assessment of the above correlation, according ...

Formation of Cloud Particles from Large Hot Plume in Controlled Experiments

For electrical production from nuclear energy, the existing cooling systems release their heat into the atmosphere as a combination of latent and sensible heat, such devices need a very important water flow. And the increasing consumption of electrical power implies new elaborating of plants more powerful but not heavy in water because it becomes more and more difficult to find appropriate sites near river or sea. For this reason, the forthcoming cooling tower will have to emit only waste dry heat. Such released heat over a small area can be intense. Thus there is legitimate concern about the effects of such heat source on natural atmospheric processes and the possible initiation of atmospheric processes which otherwise would not occur.