Levels-and-chemistry-of-atmospheric-particulates-induced-by-a-spill-of-heavy-metal-mining-wastes-in-the-Donana-area,-Southwest-Spain.pdf

corresponding author e mail address xavier querol ija csic es x querol atmospheric environment 34 2000 239 253 levels and chemistry of atmospheric particulates induced by a spill of heavy metal mining wastes in the don 8 ana area southwest spain xavier querol andre h s alastuey angel lopez soler felicia plana instituto de ciencias de la tierra jaume almera csic c lluis sole received in revised form 17 march 1999 accepted 19 april 1999 abstract as a result of the collapse of the storage lakedam propertyof the boliden company pyrite richmud layer covered the guadiamar valley north of the don 8 ana natural park sw spain the present work focuses on the physico chemical characterisation of suspended particles during high atmospheric particulate events caused by soil reclamation activities intensive sampling of atmospheric particulates during the period 20 may 27 december was carried out at two moni toring stations located at aznalca h zar and in the guadiamar valley at aznalca h zar mean daily levels of 191 2 lgtsp m 3 were recorded for the soil reclamation period july august 1998 with maximum daily levels of 490 lgtsp m 3 after the reclamation activities tsp progressively decreased down to levels of 90 lgtsp m 3 in september october and 40 lgtsp m 3 in november december very high levels of major and trace elements were recorded at the two sampling sites as for tsp ambient air levels of major and trace elements increased sharply two orders of magnitude in july and august compare with the levels recorded in may and june and gradually decreased during the autumn and winter seasons mean daily levels for july and august at aznalca h zar attained values close to 2 ng m 3 for ag cd sn and tl 10 ng m 3 for ni 100 ng m 3 for mn 200 ng m 3 for as and cu and 450 ng m 3 for pb and zn in the guadiamar valley where the major soil reclamation activities were carried out the levels achieved were higher than those of aznalca h zar by a factor of 3 in september the levels recorded at both monitoring stations decreased but were still higher than the initial values by a factor of 5 showing lower standard deviations than those in july august finally the levels recorded in december were very similar to those of may as regards the grain size distribution of minor and trace elements cu mn and zn exhibit from 17 to 36 and 59 to 70 of their bulk levels in tsp in the pm2 5 and pm10 fractions respectively however as cd co pb sb se and tl showed proportions from 20 to 48 and from 80 to 90 tsp in the pm2 5 and pm10 fractions respectively the water extractablefraction of major minor and trace elements in tsp was di erent for the elements studied thus cd co tl mn and se showed a water extractable proportion from 27 to 92 of their bulk content in tsp ni as zn and cu showed an intermediate soluble fraction which ranged from 8 to 10 and pb sb and cr were mobile in a proportion 4 1999 elsevier science ltd all rights reserved keywords atmospheric particulates pm10 pm2 5 heavy metals arsenic don 8 ana spill 1 introduction in the last decades much research has been focused on atmospheric aerosols since epidemiological studies have shown that aerosols could be responsible for various pathologies of the respiratory tract berico et al 1997 high pollution events characterised by high particulate levels have been related to respiratory diseases and in creased cardiopulmonary mortality by dockery et al 1993 and schwartz 1994 the grain size distribution of aerosols plays an important role in their potential envir onmental impact since only the atmospheric particulate range 10 lm pm10 is inhaled into the deeper respir atory tract regions resulting in pathologies associated 1352 2310 99 see front matter 1999 elsevier science ltd all rights reserved pii s1 3 5 2 2 31 0 9 9 00 2 28 9 fig 1 location of sampling sites for pyrite mud p and pol luted river sediment rs and tsp sampling stations a for aznalca h zar and gr for the guardiamar valley stations with aerosol pollution for this reason the us environ mental protection agency promulgated in 1984 an air quality standard for environmental particulate matter based on the measurements of pm10 instead of on total suspended particles tsp the eu has also developed a new directive for the monitoring of pm10 instead of tsp which will be applied in 2005 eu 9272 1998 in addition to bulk tsp levels high heavy metal levels in the atmosphere could also have a major impact on the environment and on human health usepa 1984 who 1987 some elements such as as cr and ni have a special relevance due to their potential carcinogenic impact blot and fraumeni 1975 usepa 1987 atmo spheric levels of other elements such as cd hg mn pb are also regulated by who 1987 owing to their high potential toxicity mining waste entered the guadiamarriver a tributary river of the guadalquivir river on the morning of 25 april 1998 after the storage lake dam containing high heavy metals pyrite wastes and waste water collapsed thisspill occurrednearthe village of aznalco h llar sevilla south spain where the boliden apirsa mining com pany is engaged in mining sulphide ore deposits an area of 40 km long and 0 4 km wide following the agrio and guadiamar valleys was covered by a layer of pyrite slurry which varied from 3 to 30 cm thick the volume of pyrite mud sedimented in this area was estimated to be 2 0 million m3 this area is located in the north of the don 8 ana natural park near seville immediately after the ooding the ministry of the environment of spain and the autonomus council of andalucia began the soil reclamation activities in order to reduce the potential impact of the leaching of the quickly weathered high heavy metal sulphides this rec lamation work which was carried out mainly in the dry season was aimed at extracting the layer of pyrite slurry using a large number of mechanical diggers lorries and trucks giving rise to high re suspension of pyrite partic ulates the present study focuses on the monitoring of levels of heavy metals and other inorganic pollutants in sus pended particulates and on the physico chemical charac terisation of atmospheric pyrite particles around the vill age of aznalca h zar 2 methodology 2 1 the study area aznalca h zar around 3000 inhabitants is located 1 2 km from the guadiamar valley on the eastern side of an old uviatile terrace this village is situated in the central part of the ooded area of the valley 28 5 km from the storage lake dam to the south in order to monitor the levels of tsp and the poten tially toxic elements and organic compounds sampling stations were installed at aznalca h zar as well as in the guadiamar valley where workers handling the mining wastes underwent continuous exposure to high parti culate levels aznalca h zar was chosen because of its prox imity to the ooded valley the two stations selected were fig 1 1 a domestic garden in the residential area located in the southern part of aznalca h zar casa aurora 6314 50an 37318 34aw 61 m a s l c a the ooded areas of the guadiamar river were located at a distance of 500 m to the south 240x querol et al atmospheric environment 34 2000 239 253 table 1 description of pyrite mud p and polluted river sediment rs samples sample number sample typelocationdistance from the spill km p1pyrite mudagrio river0 3 p3pyrite muddoblas bridge10 0 p4pyrite mudaznalca h zar bridge 28 5 rs5river sedimentdehesa de abajo 37 5 p6pyrite mudd simo h m bridge 42 0 rs7river sedimentlos vaqueros bridge 50 5 rs8ariver sedimentcangrejo grande marsh north 67 3 rs8briver sedimentcangrejo grande marsh south 67 5 2 a sun ower eld completely covered with a layer of 3 5 cm of pyrite mud located 500 m from aznal ca h zar to the northwest from july to september high particulate levels were induced by the manip ulation of the mining wastes during the soil recla mation activities given the low mean altitude of the whole valley the atmospheric dynamics are controlled by the breeze circu lation of the guadalquivir estuary 2 2 sampling eight samples of pyrite mud and polluted river sedi ments were collected 8 d after the accident at di erent distances from the emission point along the guadiamar valley see fig 1 and table 1 for the location of the sampling sites to characterise the potential atmospheric particulate emission source the complete pro le of the layer of pyrite mud from 30 to 3 cm thick was sampled manually at sites p1 3 4 and 6 and the upper 10 cm of riversedimentsatsites rs5 rs7 rs8a andrs8b ahun dred kilogramsof samplewere collectedat each sampling site and subsequently stored in pvc containers after homogenisation individual samples were sent to di erent laboratories for physico chemical characterisation sam ples were received 12 h after sampling and sample treat ment prior analysis included sample homogenisation ri ing and drying at 503c sieving of pyrite mud and river sediments was not performed given the homogen eity and the ne grain size of the samples comparison of the results of the chemical analyses undertaken by four laboratories csic 1998 showed di erences 10 for all the elements considered in this study which demon strates an appropriate sampling representativity the tsp sampling was performed simultaneously at aznalca h zar and in the guadiamar valley in 66 and 55 daily periods respectively from 20 may until 27 decem ber 1998 samplingof bulk tsp was carriedout on a 24 h basis by means of standard mcv high volume captors 60 m3 h 1 using cellulose membrane lters of 0 45 lm pore size millipore haw p00010 20 5 25 4 cm samp ling was performed four days per week during the soil reclamation activities subsequently the frequency of the sampling decreased progressively to twice per week in septemberand october and once per week in november and december sampling of tsp grain size fractions was carried out for 7 10 d for each sampling period by means of a cas cade impactor retsch pi 1 which allows the separation of tsp into 7 grain size fractions between 0 3 and 20 lm soluble and insoluble fractions of each grain size stage were analysed to determine the water extract able fractions of major minor and trace elements in the di erent grain size ranges total particulate levels were also monitored by means of standard mcv high volume captors using quartz bre lters 2 3 analytical procedures for geochemical analyses of pyrite mud and polluted riversediments a two stepbulk sampledigestionmethod devised by querol et al 1996 in 60 ml pfa bombs was employed a digestion of volatile elements in a closed system 2 5 ml of concentrated nitric acid merc supra pure were added to 0 1 g of sample and heated at 903c in a closed bomb for 2 h after water addition milliq 18 2 m cm the mixture was centrifuged 3000 rpm for 15 min and the solution obtained was transferred to a volumetric ask the residue was washed with water and centrifuged twice before adding the washing solution to the graduated ask b digestion of non volatile elements the residue was transferred to the pfa bomb with the addition of 7 ml of supra pure hydro uoric acid and heated at 903c in a closed bomb for 3 h the mixture was dried after the addition of 2 5 ml of supra pure perchloric acid and 2 5 ml of nitric acid once total dryness was achieved 2 5 ml of supra pure nitric acid were added and the solution transferred to the graduated ask with the solutions obtained from the rst stage to make a volume of 100 ml the nal nitric acid concentration was 5 mineralogical analyses of the bulk pyrite mud samples were performed by means of x ray di raction xrd using a siemens d500 di ractometer with cu k a x querol et al atmospheric environment 34 2000 239 253241 table 2 a median percentiles 10 and 95 obtained from the grain size analysis of pyrite mud p and river sediments rs from the guadiamar valley b mineral composition of pyrite mud and polluted river sediments wt as deduced from xrd analysis amedianperc 10 perc 95 lm lm lm p112 52 047 0 p39 01 923 4 p46 41 620 6 rs57 91 8194 8 p64 61 512 8 rs78 01 627 7 rs8a5 21 422 7 rs8b6 01 525 6 bsamples mineral phasesp1p3p4p6rs7rs5rs8ars8b pyrite767873686 0 5 0 5 0 5 clay1011 515201962735 quartz867731812728 calcite 0 5 0 5 0 5 0 536645 537 gypsum64 5558 0 50 5 0 5 plagioclase 0 5 0 5 0 5 0 5 0 57 0 5 0 5 radiation the internalreferencemethodbased on chung 1974 was employed for semi quantitative xrd analysis of mud and sediment samples fluorite was used as the internal reference material grain size distribution ana lyses were obtained by means of a grain size laser ana lyser malvern sizer sbod for chemical characterisation of tsp a fraction measuring 100 cm2 from each lter was digested follow ing the previous sampling digestion procedure digestion of blank lters and standard reference materials were prepared in accordance with the same procedure the soluble fraction of tsp from the di erent grain size stages obtained with the cascade impactor was extracted with distilled water at 803c the mineral composition of the non soluble residue was determined by means of x ray di raction xrd after deposition under vacuum on silver lters millipore0 45 lm given the low sample volumes xrd intensities of selected hkl re ections for each mineral directly proportional to the mineral con centration in the sample were used instead of the semi quantitative procedures to estimate the grain size distri bution of the insoluble mineral phases the solutions obtained from the digestion of pyrite mud river sediments and lters and cascade impactor stages and leachates were analysed by a inductively coupled plasma atomic emission spectrometry icp aes for major and minor elements and some trace elements ca al p s fe mg k na mn ti as ba cr cu ni pb sr v and zn b inductively coupled plasma mass spectrometry icp ms for some of the trace elements ag as bi cd co cr cu ga ge ni mo pb sb se sn te th tl u c capillary elec trophoresis cef for anions in the particulate leachates d colorimetry flow injection analysis fia for nh 4 in particulate leachates digestions of the blank lters with 2 3 mg of the nbs 1633a reference material were used to ensure the analysis quality for the same levels of concentrations of the sample digestions the repeated analyses of the reference material con rmed relative ana lytical errors between 3 and 10 for the elements studied 3 results and discussion 3 1 pyrite mud and polluted river sediment theresultsof the mineralogicaland grain sizeanalyses of the pyrite mud and river sediment samples are sum marised in table 2 and the concentrations of major and minor elements in the pyrite mud and the polluted river sediments are shown in table 3 as deduced from the mineralogical analyses the pyrite mud samples p1 3 4 and 6 were mainly made up of pyrite 68 78 wt with minor proportions of clay min erals mainly chlinochlore quartz calcite and gypsum major heavy metal bearing phases are probably pyrite and traces of sphalerite zns chalcopyrite cufes2 242x querol et al atmospheric environment 34 2000 239 253 table 3 major minor and trace element concentrations in pyrite mud p and polluted river sediment rs samples from the guadiamar valley concentrations in wt or lg g as indicated bold numbers highlight the elements enriched in the pyrite muds with respect the natural river sediments p1p3p4p6rs5rs7rs8ars8b al 1 491 361 992 825 246 958 087 83 ca 0 390 280 450 532 057 186 026 72 p 0 020 020 020 030 050 090 080 08 ti 0 050 040 050 060 230 300 340 34 mg 0 500 560 701 100 701 383 383 24 k 0 230 190 310 401 751 712 572 50 na 0 040 040 060 060 380 370 340 47 mn 0 070 070 080 100 040 120 150 13 fe 36 4437 1736 0334 102 527 524 354 26 s 39 7541 8038 5734 410 143 680 180 15 culg g1968192420012189303183843 colg g9896898716403527 crlg g5224436543759086 aslg g5223539755505484164891718 pblg g714167109449119403711914249 znlg g944885948187801435967542578747 vlg g1 16216298121117 balg g320272441578276357320322 srlg g1714263476164220235 aglg g292033351 72 20 90 7 nilg g2122243123565347 hglg g15 916 615 014 40 031 8 0 010 08 bilg g474457680 660 30 3 cdlg g312925260 7224 81 2 galg g87111512182020 gelg g2 92 52 94 01 51 81 81 7 molg g6 26 07 38 40 61 51 01 2 sblg g4744775676442 0631 21 5 selg g1112912 0 720 40 3 snlg g132123232 463 82 8 telg g0 40 20 10 4 0 10 1 0 1 0 1 thlg g1122991210 tllg g535354550 7111 20 6 ulg g1 41 51 92 41 01 91 91 9 galena pbs and arsenopyrite feass this pyrite slurry is characterised by a ne grain size distribution 50 of particles 4 5 or 12 lm depending on the samp ling site owing to this ne grain size 95 of particles in sample p6 were 12 8 lm the csic drew attention to the potential impact on air quality during the reclama tion of the polluted soils 3rd report on the monitoring of the toxic spill by csic 1998 the polluted river sediment samples rs5 8a and 8b were made up of clay minerals mainly illite and chli nochlore quartz and calcite with minor proportions of gypsum and pyrite from 1 wt up to 6 wt in sample rs7 these samples were also characterised by a ne grain size chemically the pyrite slurry was characterised by high contents of several elements such as zn 0 8 pb 0 8 as 0 5 cu 0 2 sb 0 05 co 62 lg g tl 50 lg g bi 50 lg g cd 25 lg g ag 25 lg g hg 15 lg g and se 10 lg g the variation of these concentra tions in the pyrite mud along the guadiamar river was very low with the exception of pb which showed a grad ual increase in concentration downstream probably as a consequence of the presence of very ne galena pbs grains which were transported selectively during the ooding ge and mo were also enriched in the pyrite mud but not in high concentrations factor analysis demonstrated that some elements such as ca al mg k na p ti mn cr v sr ni ga and th x querol et al atmospheric environment 34 2000 239 253243 table 4 mean maximum and minimum levels of major and trace elements in ambient air measured at aznalca h zar and in the guadiamar valley in the period 20 may to 27 september 1998 20 may to 27 december 1998 aznalcazar n 66 guadiamar valley n 55 mea