Distribution and sources of bioaccumulative air pollutants at Mezquital Valley, Mexico, as reflected by the atmospheric plant <i>Tillandsia recurvata</i> L.

Abstract

Abstract. Mezquital Valley (MV), a Mexican wastewater-based agricultural and industrial region, is a "hot spot" of regulated air pollutants emissions, but the concurrent unregulated ones, like hazardous metals and polycyclic aromatic hydrocarbons (PAH), remain undocumented. A biomonitoring survey with the epiphytic Tillandsia recurvata was conducted there to detect spatial patterns and potential sources of 20 airborne elements and 15 PAH. The natural δ13C and δ15N ratios of this plant helped in source identification. The regional mean concentration of most elements was two (Cr) to over 40 times (Ni, Pb, V) higher than reported for Tillandsia in other countries. Eleven elements, pyrene and chrysene had 18–214% higher mean concentration at the industrial south than at the agricultural north of MV. The total quantified PAH (mean, 572 ng g−1; range, 143–2568) were composed by medium (65%, phenanthrene to chrysene), low (28%, naphthalene to fluorene) and high molecular weight compounds (7%, Benzo(b)fluoranthene to indeno(1,2,3-cd)pyrene). The δ13C (mean, −14.6‰; range, −15.7‰ to −13.7‰) was consistently lower than −15‰ near the major petroleum combustion sources. The δ15N (mean, −3.0‰; range, −9.9‰ to 3.3‰) varied from positive at agriculture/industrial areas to negative at rural sites. Factor analysis provided a five-factor solution for 74% of the data variance: 1) crustal rocks, 39.5% (Al, Ba, Cu, Fe, Sr, Ti); 2) soils, 11.3%, contrasting contributions from natural (Mg, Mn, Zn) and saline agriculture soils (Na); 3) cement production and fossil fuel combustion, 9.8% (Ca, Ni, V, chrysene, pyrene); 4) probable agricultural biomass burning, 8.1% (K and benzo(g,h,i)perylene), and 5) agriculture with wastewater, 5.2% (δ15N and P). These results indicated high deposition of bioaccumulative air pollutants at MV, especially at the industrial area. Since T. recurvata reflected the regional differences in exposition, it is recommended as a biomonitor for comparisons within and among countries where it is distributed: southern USA to Argentina.

Soot and SO<sub>2</sub> contribution to the supersites in the MILAGRO campaign from elevated flares in the Tula Refinery

“…It considers total TIC soot emissions and MHR SO 2 emissions. The spatial distribution is similar to that reported by Zambrano García et al (2009), with a tendency of transport towards the northeast. For these primary pollutants the distribution is similar, but it can change for secondary pollutants.…”

An overview of the MILAGRO 2006 Campaign: Mexico City emissions and their transport and transformation

“…Particulate matter (PM) impacts human health (Pope and Dockery, 2006) visibility , climate (Forster et al, 2007), and ecosystems (Zambrano et al, 2009). Negative impacts of PM on human health have been documented in the MCMA (e.g., Romieu et al, 1996;Osornio-Vargas et al, 2003;Evans et al, 2002) as discussed in more detail in Section 10 below.…”

Air Pollutant Characterization in Tula Industrial Corridor, Central Mexico, during the MILAGRO Study

“…In this paper, stable carbon isotopes in T. recurvata were used as a tracer of long-term signature of the plume trajectory. Metals, stable isotopes, and PAHs in T. recurvata are described by Zambrano García et al [22] to show the signature source of the principal emitters in Mezquital Valley.…”