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An Overview of the Regional Experiments for Land-Atmosphere Exchanges 2012 (Reflex 2012) Campaign

Timmermans W. J., Tol Ch. van der, Timmermans J., Ucer M., Chen X., Alonso L., Moreno J., Carrara A., Lopez R., Cruz Tercero F. de la, Corcoles H. L., Miguel E. de, Sanchez J. A. G., Pérez I., Franch B., Munoz J.-C. J., Skokovic D., Sobrino J., Soria G., MacArthur A., Vescovo L., Reusen I., Andreu A., Burkart A., Cilia Ch., Contreras S., Corbari Ch., Calleja J. F., Guzinski R., Hellmann Ch., Herrmann I., Kerr G., Lazar A.-L., Leutner B., Mendiguren G., Nasilowska S., Nieto H., Pachego-Labrador J., Pulanekar S., Raj R., Schikling A., Siegmann B., Bueren S. von, Su Z.

Acta Geophysica

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2015

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Vol. 63, no. 6

1465--1484

EN

The REFLEX 2012 campaign was initiated as part of a training course on the organization of an airborne campaign to support advancement of the understanding of land-atmosphere interaction processes. This article describes the campaign, its objectives and observations, remote as well as in situ. The observations took place at the experimental Las Tiesas farm in an agricultural area in the south of Spain. During the period of ten days, measurements were made to capture the main processes controlling the local and regional land-atmosphere exchanges. Apart from multi-temporal, multi-directional and multi-spatial space-borne and airborne observations, measurements of the local meteorology, energy fluxes, soil temperature profiles, soil moisture profiles, surface temperature, canopy structure as well as leaf-level measurements were carried out. Additional thermo-dynamical monitoring took place at selected sites.

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An Analysis of Turbulent Heat Fluxes and the Energy Balance During the REFLEX Campaign

Tol Ch. van der, Timmermans W., Corbari Ch., Carrara A., Timmermans J., Su Z.

Acta Geophysica

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2015

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Vol. 63, no. 6

1516--1539

EN

Three eddy covariance stations were installed at the Barrax experimental farm during the Land-Atmosphere Exchanges (REFLEX) airborne training and measurement campaign to provide ground truth data of energy balance fluxes and vertical temperature and wind profiles. The energy balance closure ratio (EBR) was 105% for a homogeneous camelina site, 86% at a sparse reforestation site, and 73% for a vineyard. We hypothesize that the lower closure in the last site was related to the limited fetch. Incorporating a vertical gradient of soil thermal properties decreased the RMSE of the energy balance at the camelina site by 16 W m-2. At the camelina site, eddy covariance estimates of sensible and latent heat fluxes could be reproduced well using mean vertical profiles of wind and temperature, provided that the Monin-Obukhov length is known. Measured surface temperature and sensible heat fluxes suggested high excess resistance for heat (kB-1 = 17).

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Responses to UV-B exposure by saplings of the relict species Davidia involucrata Bill are modified by soil nitrogen availability

Li Y., Gao J., Zhang L., Su Z.

Polish Journal of Ecology

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2014

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Vol. 62, nr 1

101--110

EN

Climate change scenarios suggest that plants will be exposed to increasing levels of ultraviolet radiation in the future. The dove tree, Davidia involucrata Bill (Davidiaceae) is a rare and endangered tree species in China. Its distribution is predicted to become more montane as the climate warms, exposing it to higher levels of UV-B and different soil conditions. We compared the effects of glasshouse ambient (7.08 uW cm-2) and increased (13.93 uW cm-2) UV-B on survivorship, secondary metabolites indicative of radiation damage, and putative defensive responses of Davidia involucrata saplings growing under current and increased nitrogen conditions (5 and 25 g m-2 a-1 N). Mortalities were higher among plants exposed to increased UV-B, but only in soils with high supplementary nitrogen. Increases in compounds associated with defense against radiation were more frequently recorded under high supplementary nitrogen conditions. This rare and localised plant is highly sensitive to elevated UV-B when growing in high nitrogen soils, a combination that is likely to increase in the summer.

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Vascular ground flora in relation to topography, canopy structure and gap light regimes in a subtropical broadleaved forest (South China)

Ou Y., Su Z., Ke X., Li Z.

Polish Journal of Ecology

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2012

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Vol. 60, nr 3

463-478

EN

We examined the influence of topography, canopy structure and gap light environmental variables on the patterns of vascular ground flora (vascular plants less than 1 m in height excluding tree seedlings) in a subtropical broadleaved forest in S China, using field data obtained from a 4-ha permanent plot. Both topographic and canopy environmental conditions had a significant effect on community composition, species diversity and distribution of the vascular ground flora. However, topographic factors, especially slope position and aspect, had a greater influence as compared with canopy and understory light conditions. Both number of individuals and number of individuals per species of the ground flora varied significantly with different slope position, aspect, slope steepness and transmitted direct radiation, while species richness varied significantly under different slope position and canopy leaf area index (LAI) The effects of topographic and canopy environmental conditions on ground-flora composition and structure was further confirmed by Canonical Correspondence Analysis (CCA). Multi-response Permutation Procedures (MRPP) showed significant differences in the ground-flora species composition based on all the topographic, canopy structure and gap light variables. Species indicative of topographic, canopy structure and gap light regimes were identified with a significant indicator value (IV - 35%) by Indicator Species Analysis (ISA), which indicated that certain species have their ecological preference for a particular environmental gradient.

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Determination of Bi in high-purity lead and cadmium metals by flame atomic absorption spectrometry after on-line matrix separation

Wu X., Liu P., Pu Q., Su Z.

Chemia Analityczna

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2002

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Vol. 47, No. 5

713-723

EN

Trace amounts of Bi in high-purity Pb and Cd metals were determined by flame atomic absorption spectrometry in combination with flow injection on-line matrix separation. Matrix separation and Bi(III) preconcentration was accomplished by retention of Bi(III) on a microcolumn packed with 2-mercaptobenzothiazole modified silica gel at pH 3.0 with a sample flow-rate of 5.6 mL min"'. Then adsorbed Bi(III) was eluted with a mixed eluent containing 3.0 mol L(-1) HClO(4), 0.5 mol L(-1) NaClO(4) and 0.2 mol L(-1) NaNO(3) at a flow-rate of 2.2 mL min(-1) and introduced into the atomizer of the AAS directly. Most of the common coexisting ions did not interfere with the preconcentration and determination. The limit of detection (LOD) of 0.010 ug mL'1 (which refers to the sample solution), was achieved when 0.3000 ug mL(-1) Bi(III) was preconcentrated for 60 s. The relative standard deviation (RSD) was <2.0% (n = 7) for the proposed method. The linear regression coefficient of the calibration curve was 0.9998 in a working concentration range of 0.10 ~ 2.00 ug mL(-1). The proposed method was successfully applied to the determination of trace Bi in chemically pure Pb grain and Cd band samples.

PL

Śladowe ilości Bi w czystych metalach Pb i Cd oznaczono za pomocąpłomieniowej atomowej spektroskopii atomowej w kombinacji z oddzieleniem matrycy „on linę" metodą wstrzykową. Oddzielenie matrycy oraz zatężenie Bi(III) uzyskano zatrzymując Bi(III) na mikrokolumnie z 2-merkaptobenzotiazolem osadzonym na żelu krzmionkowym przy pH 3.0 i szybkości przepływu próbki 5.5 mL min"1. Następnie zatrzymany Bi(in) eluowano mieszanym eluentern o składzie 3.0 mol L'1 HC1O4, 0.5 mol L-' NaClO4 and 0.2 mol L'1 NaNO3 przy szybkości przepływu 2.2 mL min"' i wprowadzano bezpośrednio do atomizera AAS. Większość pospolitych jonów towarzyszących nie przeszkadzała w zatężaniu i oznaczaniu Bi. Granicę detekcji 0.010 ng mL(-1) (w odniesieniu do roztworu próbki) uzyskano gdy roztwór 0.3000 ug mL(-1) zależano przez 60 s. Względne odchylenie standardowe (RSD) metody wynosiło <2.0% (n = 7). Współczynnik liniowej regresji krzywej kalibracyjnej wynosił 0.9998 w roboczym zakresie stężeń 0.10-2.00 ug mL(-1). Opracowano metodę wykorzystano do oznaczania Bi w chemicznie czystych ziarnach ołowiu i taśmach kadmowych.