| 1. |
- Karlsson, Per Erik, 1957, et al.
(författare)
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Evidence for Impacts of Near-ambient Ozone Concentrations on Vegetation in Southern Sweden
- 2009
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Ingår i: Ambio. - : Royal Swedish Academy of Sciences. ; 38:8, s. 425-431
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Tidskriftsartikel (refereegranskat)abstract
- Substantial impacts of near-ambient ozone concentrations on agricultural crops, trees, and seminatural vegetation are demonstrated for southern Sweden. Impacts of ambient ozone levels (2–15 μL L-¹ hr annual accumulated ozone exposure over a threshold of 40 nL L-¹ [AOT40]) range from a 2%–10% reduction for trees (e.g., leaf chlorophyll, tree growth) up to a 15% reduction for crops (e.g., yield, wheat/potato). Visible leaf injury on bioindicator plants caused by ambient ozone levels has been clearly demonstrated. The humid climatic conditions in Sweden promote high rates of leaf ozone uptake at a certain ozone concentration. This likely explains the comparatively large ozone impacts found for vegetation in southern Sweden at relatively low ozone concentrations in the air. It is important that the future methods used for the representation of ozone impacts on vegetation across Europe are based on the leaf ozone uptake concept and not on concentration-based exposure indices, such as AOT40.
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| 5. |
- Piikki, Kristin, 1975, et al.
(författare)
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Impact of elevated O3 and CO2 exposure on potato (Solanum tuberosum L. cv. Bintje) tuber macronutrients (N, P, K, Mg, Ca)
- 2007
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Ingår i: Agriculture, Ecosystems & Environment. - : Elsevier BV. - 0167-8809. ; 118:1-4, s. 55-64
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Tidskriftsartikel (refereegranskat)abstract
- It was investigated whether exposure of elevated ozone (O3) and carbon dioxide (CO2) concentrations affected the macronutrient (N, P, K, Mg, Ca) concentrations in potato (Solanum tuberosum L.) tubers in three open-top chamber experiments from Sweden and Finland. The tuber concentrations of N, P, K and Mg correlated positively with O3 exposure (although not significantly in the case of N and P) but the O3 exposure had no effect on the tuber concentration of Ca. A likely mechanism behind the observed O3 effects was suggested to be that the more progressed senescence of O3 exposed plants was associated with a larger extent of reallocation of mobile nutrients from the haulm to the tubers. In addition, the uptake of macronutrients may have been less negatively affected by O3 exposure than the assimilation of carbon. O3 tended to reduce the total tuber contents of all investigated nutrients, which imply a reduced fertilizer need per unit field area. This was not associated with a decreased fertilizer need per tonnage of yield, as the tuber nutrient concentrations were increased by O3 exposure. The increased CO2 concentration did not significantly affect any of the investigated macronutrients in the present dataset but did generally prevent the O3 induced increases in nutrient concentrations to be expressed (only significant in the case of N and Mg). The O3 induced increase in tuber K concentration, may mediate earlier observed O3 effects on potato tuber concentrations of citric and malic acids. To conclude, anticipated future (and even presently occurring) O3 exposure has a negative impact on the total tuber contents of K and Ca and probably also on the total tuber contents of N, P and Mg. O3 exposure causes increased tuber concentrations of N, P, K and Mg at an early harvest. The O3 induced increase in tuber concentration tended to diminish by a CO2 elevation.
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| 6. |
- Piikki, Kristin, 1975, et al.
(författare)
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Mätningar av marknära ozon och meteorologi vid kustnära och urbana miljöer i Halland, Skåne och Västra Götalands län
- 2008
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Under sommaren 2007 mättes ozon- (O3) halter samt meteorologi kontinuerligt under ca en månads tid vardera, på en ö i havet (Nidingen, N län), vid en kustnära plats med förväntat höga ozonhalter (Backåkra, M län) samt i en urban parkmiljö (Göteborg, O län). På dessa platser samt på ytterligare fyra olika platser i Göteborg mättes även O3- och kväveoxid- (NOx = NO2 + NO) halter med diffusionsprovtagare på vecko-basis. Mätningarna vid Nidingen, Backåkra samt parkmiljön i Göteborg gjordes inte samtidigt utan under olika perioder under olika delar av sommarhalvåret. Jämförelser med andra kustnära platser (Råö, som ligger strax söder om Göteborg, och Malmö), där ozonhalten mättes under hela sommaren, visade att den kustnära ozondynamiken med hög medelhalt och liten dygnsvariation fanns vid båda mätplatserna, men var mer utpräglad på Nidingen än i Backåkra. Värdena för några olika ozonindex, bland annat 8-timmars-medelvärde, som används i miljömålet Frisk Luft samt inom Miljökvalitetsnormerna, var högre på Nidingen, trots att landets högsta ozonbelastning, enligt vissa modellberäkningar, kan förväntas i Skåne. En slutsats blir att små öar i havet kan vara mycket utsatta för ozon. Mätningarna i Göteborg visade att ozonförekomsten kan skilja sig väsentligt mellan olika urbana platser beroende på vindförhållanden och närhet till NOx-utsläpp, och att det bara är på platser med mycket hög trafiktäthet som titrering med NO har stor betydelse för den lokala ozonhalten. Ozonförekomsten i urban parkmiljö (Slottsskogen) kan vara relativt hög. Diffusionsprovtagarna fungerade bra för ozon och NO2.. I rapporten utvärderas olika enkla matematiska modeller för att uppskatta olika ozonindex utifrån mätningar med diffusionsprovtagare i kombination med temperaturmätningar eller genom att ta hänsyn till lokalens topografiska läge. Flera olika metoder fungerade väl och rekommendationer ges för hur de bör tillämpas i olika situationer.
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| 7. |
- Piikki, Kristin, 1975, et al.
(författare)
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The grain quality of spring wheat (Triticum aestivum L.) in relation to elevated ozone uptake and carbon dioxide exposure
- 2008
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Ingår i: European Journal of Agronomy. - : Elsevier BV. - 1161-0301. ; 28:3, s. 245-254
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Tidskriftsartikel (refereegranskat)abstract
- Ozone (O-3) and carbon dioxide (CO2) effects on the quality of spring wheat (Triticum aestivum L.) were evaluated. The dataset originated from 13 European open-top chamber experiments, including three countries, 10 years and four cultivars. The O-3 exposure significantly reduced the protein yield, even though the grain protein concentration (GPC) was increased and tended to increase the Zeleny value and the Hagberg falling number. These variables reached values representing enhanced grain maturity after elevated 03 exposure, possibly explained by O-3 induced early senescence. The CO2 elevation was demonstrated to increase the protein yield but reduce the GPC and the Zeleny value. Both O-3 and CO2 were demonstrated to affect wheat grain yield (GY) but by different means; O-3 reduced GY (P<0.001) mainly by limiting the 1000-grain weight, while CO2 enhanced GY (P < 0.01) mainly by increasing the number of grains produced per unit ground area. Two earlier used O-3 indices, the accumulated stomatal uptake of O-3 above a flux threshold of 6 nmol m(-2), s(-1) (AF(st)6), and the accumulated O-3 dose above a concentration threshold of 40 nmol mol(-1) (AOT40), were employed in parallel in the derivation of dose-response relationships with all investigated variables (GY, number of grains per unit area, 1000-grain weight, protein yield, GPC, Zeleny value, wet gluten, dry gluten, starch concentration, Hagberg falling number, specific weight and water quotient). The uptake-based index (AF(st)6) tended to better explain variation in the response variables and yielded dose-response regressions of a higher statistical quality than did the external-dose index (AOT40). Based on an independent subset of the present data, the validities of (1) a negative linear relationship between GPC and GY and (2) a positive but decelerating relationship between protein yield and GY including both O-3 and CO2 treatments were tested and confirmed. (c) 2007 Elsevier B.V. All rights reserved.
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| 8. |
- Piikki, Kristin, 1975, et al.
(författare)
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The impact of tropospheric O3 on leaf number duration and tuber yield of the potato (Solanum tuberosum L.) cultivars Bintje and Kardal
- 2004
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Ingår i: Agriculture, Ecosystems & Environment. - : Elsevier BV. - 0167-8809. ; 104:3, s. 483-492
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Tidskriftsartikel (refereegranskat)abstract
- Ozone (O3) is a major phytotoxic air pollutant with the potential to cause severe yield losses in potato (Solanum tubersosum L.) and in other crops. The present study was aimed (i) to investigate the O3 sensitivity of two potato cultivars (Bintje and Kardal) in relation to their earliness in maturation, and (ii) to analyse possible O3 effects on potato tuber dry mass (DM) production in relation to leaf duration. The experiment was performed in the southwest of Sweden using open-top chamber (OTC) technique. The crops were exposed to three levels of O3: charcoal-filtered air (CF), non-filtered air (NF) and non-filtered air + 26 nmol mol−1 O3 (NF+). In addition, ambient air plots were used to monitor the impact of the OTC enclosure. Leaf number duration (LND) was calculated as the number of leaves integrated over the temperature sum accumulation during the season. In the present study, the O3 effects on potato were characterised by visible injury of the leaves and earlier leaf senescence. The haulm/plant DM ratio was significantly lower in NF+ compared to CF and NF. The conclusions were (i) that the early to intermediate maturing cultivar Bintje tended to suffer more from O3 injury than the late maturing cultivar Kardal, (ii) that this was due to a difference in the ability to compensate for haulm damage by the development of new leaves rather than to a difference in leaf O3 sensitivity, and (iii) that a rather low O3 exposure can induce a significant reduction in LND in potato. The O3 effects on tuber DM (−2% in NF+ and +31% increase in CF, both compared to NF) could not be statistically demonstrated, although there was a strong correlation between LND and tuber DM.
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| 9. |
- Piikki, Kristin, 1975, et al.
(författare)
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The open-top chamber impact on vapour pressure deficit and its consequences for stomatal ozone uptake
- 2008
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Ingår i: Atmospheric Environment. - : Elsevier BV. - 1352-2310 .- 1873-2844. ; 42:26, s. 6513-6522
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Tidskriftsartikel (refereegranskat)abstract
- The vapour pressure deficit (VPD) in open-top chambers (OTCs) was analysed in relation to time of day and ambient meteorology. Effects of observed VPD differences (ΔVPD) between OTCs and the ambient air (AA) on stomatal conductance (gs) were simulated using 10 model functions from the literature. The dataset originated from 17 OTC crop experiments performed in Belgium, Germany and Sweden. ΔVPD is the resulting difference between the OTC effect on es(T), which is the temperature-dependent saturation pressure of water vapour and the OTC effect on ea, which is the prevailing partial pressure of water vapour in the air (ΔVPD = Δes(T) − Δea). Both Δes(T) and Δea were positive during daylight hours. ΔVPD was small in comparison and sensitive to changes in Δes(T) or Δea. ΔVPD was negative between 07:30 and 10:30 and positive thereafter with a maximum at 20:30 (local time). The positive afternoon ΔVPD was due to an early decrease in Δea, probably caused by ceased transpiration, while the positive Δes(T) persisted throughout the evening, most likely because of restrained cooling in the OTCs. Both the negative morning ΔVPD and the positive evening ΔVPD were more pronounced during clear, warm and dry weather. Circumstances when VPD had a stronger limiting effect on gs inside the OTCs compared to in the ambient air coincided with high ambient ozone concentrations ([O3]). Calculated wheat O3 uptake over an [O3] threshold of 40 nmol mol−1 was reduced by 8.7% in OTCs, assuming that VPD was the only factor limiting gs and that gs was the only resistance for O3 uptake. VPD is one factor of considerable importance for gs and the OTC impact on VPD may contribute to an underestimation of O3 effects expressed in relation to the external O3 exposure.
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| 10. |
- Söderström, Mats, et al.
(författare)
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Sensor mapping of Amazonian Dark Earths in deforested croplands
- 2016
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Ingår i: Geoderma. - : Elsevier BV. - 0016-7061 .- 1872-6259. ; 281, s. 58-68
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Tidskriftsartikel (refereegranskat)abstract
- Amazonian Dark Earths (ADEs) are fertile soils for agricultural production as well as important archaeological resources for understanding the pre-Columbian past of the Neotropical lowland rainforest. ADEs are threatened by expanding land exploitation and there is a need to develop efficient approaches to soil mapping and analysis for documenting these soils. In this paper we assess the potential of satellite remote sensing and proximal soil sensing to map, predict and monitor ADEs in land affected by agro-industrial development. We use instruments based on portable x-ray fluorescence (PXRF) and electromagnetic induction (EMI) as well as high-resolution satellite data (Spot 6) for detailed soil surveys at a 10-ha ADE site now mainly used for soybean production on the Belterra Plateau, Pará, Brazil. We predict the regional occurrence of ADE in a c. 250 km2 test area centred on the known ADE site São Francisco using satellite data. Multivariate adaptive regression splines models were parameterised for predictions of soil organic carbon (SOC), cation exchange capacity (CEC), phosphorus (P) and depth of the A horizon in ADEs from sensor data – both from individual sensors and in sensor combinations. Combining sensors gave the best validation results: the highest modelling efficiencies (E) were 0.70 (SOC), 0.88 (CEC) and 0.74 (for both P and A depth). The most powerful single proximal sensor outputs in the predictions were Sr from the PXRF data and magnetic susceptibility (MSa) as measured by the EMI instrument. In the regional satellite based model we located 17 previously unrecorded ADE sites > 2 ha. Ground control checks showed that 10 out of 11 sites were correctly classified. We conclude that these sensors are useful in studies of ADE in deforested cropland and provide new opportunities for detailed studies of the archaeological record.
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