期刊
ENVIRONMENTAL POLLUTION
卷 238, 期 -, 页码 812-822出版社
ELSEVIER SCI LTD
DOI: 10.1016/j.envpol.2018.03.102
关键词
Nitrogen; Surface ozone; Phosphorus; Stomatal ozone uptake; Poplar; Risk assessment
资金
- National Natural Science Foundation of China [31401895]
- China Scholarship Council [201606615002]
- Fondazione Cassa di Risparmio di Firenze [2013/7956]
- project MOTTLES [LIFE15 ENV/IT/000183]
Assessing ozone (03) risk to vegetation is crucial for informing policy making. Soil nitrogen (N) and phosphorus (P) availability could change stomatal conductance which is the main driver of O-3 uptake into a leaf. In addition, the availability of N and P could influence photosynthesis and growth. We thus postulated that the sensitivity of plants to O-3 may be changed by the levels of N and P in the soil. In this study, a sensitive poplar clone (Oxford) was subject to two N levels (NO, 0 kg N ha(-1); N80, 80 kg N ha(-1)), three P levels (PO, 0 kg P ha(-1); P40, 40 kg P ha(-1); P80, 80 kg P ha(-1)) and three levels of O-3 exposure (ambient concentration, AA; 1.5 x AA; 2.0 x AA) for a whole growing season in an O-3 free air controlled exposure (FACE) facility. Flux-based (POD0 to 6) and exposure-based (W126 and AOT40) dose-response relationships were fitted and critical levels (CLs) were estimated for a 5% decrease of total annual biomass. It was found that N and P availability modified the dose-response relationships of biomass responses to O-3. Overall, the N supply decreased the O-3 CLs i.e. increased the sensitivity of poplar to O-3. Phosphorus alleviated the O-3-caused biomass loss and increased the CL. However, such mitigation effects of P were found only in low N and not in high N conditions. In each nutritional treatment, similar performance was found between flux-based and exposure-based indices. However, the flux-based approach was superior, as compared to exposure indices, to explain the biomass reduction when all nutritional treatments were pooled together. The best O-3 metric for risk assessments was POD4, with 4.6 mmol m(-2) POD4 as a suitable CL for Oxford poplars grown under various soil N and P conditions. (C) 2018 Elsevier Ltd. All rights reserved.
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