| 1. |
- Broberg, Malin, 1989, et al.
(författare)
-
CO2-induced changes in wheat grain composition: Meta-analysis and response functions
- 2017
-
Ingår i: Agronomy. - : MDPI AG. - 2073-4395. ; 7:2
-
Tidskriftsartikel (refereegranskat)abstract
- Elevated carbon dioxide (eCO2) stimulates wheat grain yield, but simultaneously reduces protein/nitrogen (N) concentration. Also, other essential nutrients are subject to change. This study is a synthesis of wheat experiments with eCO2, estimating the effects on N, minerals (B, Ca, Cd, Fe, K, Mg, Mn, Na, P, S, Zn), and starch. The analysis was performed by (i) deriving response functions to assess the gradual change in element concentration with increasing CO2 concentration, (ii) meta-analysis to test the average magnitude and significance of observed effects, and (iii) relating CO2 effects on minerals to effects on N and grain yield. Responses ranged from zero to strong negative effects of eCO2 on mineral concentration, with the largest reductions for the nutritionally important elements of N, Fe, S, Zn, and Mg. Together with the positive but small and non-significant effect on starch concentration, the large variation in effects suggests that CO2-induced responses cannot be explained only by a simple dilution model. To explain the observed pattern, uptake and transport mechanisms may have to be considered, along with the link of different elements to N uptake. Our study shows that eCO2 has a significant effect on wheat grain stoichiometry, with implications for human nutrition in a world of rising CO2.
|
|
| 2. |
- Broberg, Malin, 1989, et al.
(författare)
-
Fertilizer efficiency in wheat is reduced by ozone pollution
- 2017
-
Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 607-608, s. 876-880
-
Tidskriftsartikel (refereegranskat)abstract
- Inefficient use of fertilizers by crops increases the risk of nutrient leaching from agro-ecosystems, resulting in economic loss and environmental contamination. We investigated how ground-level ozone affects the efficiency by which wheat used applied nitrogen (N) fertilizer to produce grain protein (NE P , N efficiency with respect to protein yield) and grain yield (NE Y , N efficiency with respect to grain yield) across a large number of open-top chamber field experiments. Our results show significant negative ozone effects on NE P and NE Y , both for a larger data set obtained from data mining (21 experiments, 70 treatments), and a subset of data for which stomatal ozone flux estimates were available (7 experiments, 22 treatments). For one experiment, we report new data on N content of different above-ground plant fractions as well as grain K and P content. Our analysis of the combined dataset demonstrates that the grain yield return for a certain investment in N fertilizer is reduced by ozone. Results from the experiment with more detailed data further show that translocation of accumulated N from straw and leaves to grains is significantly and negatively affected by ozone, and that ozone decreases fertilizer efficiency also for K and P. As a result of lower N fertilization efficiency, ozone causes a risk of increased N losses from agroecosystems, e.g. through nitrate leaching and nitrous oxide emissions, a hitherto neglected negative effect of ozone. This impact of ozone on the N cycle implies that society is facing a dilemma where it either (i) accepts increased N pollution and counteracts ozone-induced yield reductions by increasing fertilization or (ii) counteracts N pollution under elevated ozone by reducing fertilization, accepting further yield loss adding to the direct effect of ozone on yield.
|
|
| 3. |
- Klingberg, Jenny, 1978, et al.
(författare)
-
Influence of urban vegetation on air pollution and noise exposure – A case study in Gothenburg, Sweden
- 2017
-
Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 599-600, s. 1728-1739
-
Tidskriftsartikel (refereegranskat)abstract
- Air pollution levels (NO2, PAHs, O3) were investigated, before (BLE) and after (ALE) leaf emergence, in the urban landscape of Gothenburg, Sweden. The aims were to study the 1) spatial and temporal variation in pollution levels between urban green areas, 2) effect of urban vegetation on air pollution levels at the same distance from a major emission source (traffic route), 3) improvement of urban air quality in urban parks compared to adjacent sites near traffic, 4) correlation between air pollution and noise in a park. O3 varied little over the urban landscape. NO2 varied strongly and was higher in situations strongly influenced by traffic. Four PAH variables were included: total PAH, total particle-bound PAH, the quantitatively important gaseous phenanthrene and the highly toxic particle-bound benzo(a)pyrene. The variation of PAHs was similar to NO2, but for certain PAHs the difference between highly and less polluted sites was larger than for NO2. At a vegetated site, NO2 and particulate PAH levels were lower than at a non-vegetated site at a certain distance from a busy traffic route. This effect was significantly larger ALE compared to BLE for NO2, indicating green leaf area to be highly significant factor for air quality improvement. For particulate PAHs, the effect was similar BLE and ALE, indicating that tree bark and branches also could be an important factor in reducing air pollution. Parks represented considerably cleaner local environments (park effect), which is likely to be a consequence of both a dilution (distance effect) and deposition. Noise and air pollution (NO2 and PAH) levels were strongly correlated. Comparison of noise levels BLE and ALE also showed that the presence of leaves significantly reduced noise levels. Our results are evidence that urban green spaces are beneficial for urban environmental quality, which is important to consider in urban planning.
|
|
