► We evaluate the Zn tolerance and accumulation potential of Limoniastrum monopetalum. ► L. monopetalum can survive external Zn concentrations of up to 130mmoll−1. ► L. monopetalum is almost ...unaffected by leaf concentrations up to 1400mgZnkg−1. ► L. monopetalum may be useful in the phytoremediation of Zn-polluted soils.
The coastal shrub Limoniastrum monopetalum is capable of growth in soil containing extremely high concentrations of heavy metals. A greenhouse experiment was conducted in order to investigate the effects of a range of Zn concentrations (0–130mmoll−1) on growth and photosynthetic performance, by measuring relative growth rate, total leaf area, plant height, gas exchange, chlorophyll fluorescence parameters and photosynthetic pigment concentrations. We also determined the total zinc, nitrogen, phosphorus, sulphur, calcium, magnesium, sodium, potassium, iron and copper concentrations in the plant tissues. The study species demonstrated hypertolerance to Zn stress, since survival was recorded with leaf concentrations of up to 1700mgZnkg−1 dry mass when treated with 130mmolZnl−1. L. monopetalum exhibited little overall effects on photosynthetic function at Zn levels of up to 90mmoll−1. At greater external Zn concentration, plant growth was negatively affected, due in all probability to the recorded decline in net photosynthetic rate, which may be linked to the adverse effect of the metal on photosynthetic electron transport. Growth parameters were virtually unaffected by leaf tissue concentrations as high as 1400mgZnkg−1 dry mass thus indicating that this species could play an important role in the phytoremediation of Zn-polluted areas.
Summary
Endozoochory has been recognised as the most important dispersal mechanism in invasive Prosopis species, because their sugary, tasty pods attract animals and because some of their seeds ...remain intact after passing through some animals' digestive systems. In this study, we evaluated the role of the camel (Camelus dromedarius) as a potential disperser of the seeds of invasive tree Prosopis juliflora. Four camels of similar weight (ca. 400 kg) and age (ca. 2 years) were each fed with 70 fruits (1000 seeds approximately) of P. juliflora, which were retrieved from the camels' dung at 24‐h intervals for 4 days. The seeds retrieved were tested for germination and viability, along with seeds not eaten by the camels, with and without pericarp. Less than 3% of the seeds eaten were retrieved from the camels' dung. Most of the seeds (74%) were retrieved between 24 and 72 h after ingestion. The passage through the camel gut significantly accelerated and increased seed germination of P. juliflora in comparison with uneaten seeds covered with pericarp (48–75% and 15% respectively). While gut passage liberated P. juliflora seeds from the pericarp, increasing and accelerating their germination, the viability of seeds which had not germinated after germination trials were decreased (ca. ~20%) relative to uneaten seeds that had also not germinated. Our results show that, despite the low recorded seed recovery, camels can potentially disperse seeds of P. juliflora, which is in line with field observation showing P. juliflora expansion along the camels' routes in Gebel Elba National Park, south‐east Egypt.
► We evaluate the Zn tolerance and accumulation potential of Halimione portulacoides. ► H. portulacoides can survive external Zn concentrations of up to 130mmolL−1. ► H. portulacoides is almost ...unaffected by leaf concentrations up to 1500mgZnKg−1. ► H. portulacoides may be useful in the restoration of Zn-polluted areas.
The halophytic shrub Halimione portulacoides is known to be capable of growth in soils containing extremely high concentrations of Zn. This study evaluated in detail the tolerance and accumulation potential of H. portulacoides under moderate and high external Zn levels. A greenhouse experiment was conducted in order to investigate the effects of a range of Zn concentrations (0–130mmolL−1) on growth and photosynthetic performance by measuring relative growth rate, total leaf area, specific leaf area, gas exchange, chlorophyll fluorescence parameters and photosynthetic pigment concentrations. We also determined the total zinc, nitrogen, phosphorus, calcium, magnesium, sodium, potassium, iron and copper concentrations in the plant tissues. H. portulacoides demonstrated hypertolerance to Zn stress, since it survived with leaf concentrations of up to 2300mgZnkg−1dry mass, when treated with 130mmolZnL−1. Zinc concentrations greater than 70mmolL−1 in the nutrient solution negatively affected plant growth, in all probability due to the recorded decline in net photosynthesis rate. Our results indicate that the Zn-induced decline in the photosynthetic function of H. portulacoides may be attributed to the adverse effect of the high concentration of the metal on photosynthetic electron transport. Growth parameters were virtually unaffected by leaf tissue concentrations as high as 1500mgZnkg−1dry mass, demonstrating the strong capability of H. portulacoides to protect itself against toxic Zn concentrations. The results of our study indicate that this salt-marsh shrub may represent a valuable tool in the restoration of Zn-polluted areas.
The jet energy scale (JES) and its systematic uncertainty are determined for jets measured with the ATLAS detector using proton–proton collision data with a centre-of-mass energy of
s
=
7
TeV ...corresponding to an integrated luminosity of
4.7
fb
-
1
. Jets are reconstructed from energy deposits forming topological clusters of calorimeter cells using the anti-
k
t
algorithm with distance parameters
R
=
0.4
or
R
=
0.6
, and are calibrated using MC simulations. A residual JES correction is applied to account for differences between data and MC simulations. This correction and its systematic uncertainty are estimated using a combination of in situ techniques exploiting the transverse momentum balance between a jet and a reference object such as a photon or a
Z
boson, for
20
≤
p
T
jet
<
1000
GeV
and pseudorapidities
|
η
|
<
4.5
. The effect of multiple proton–proton interactions is corrected for, and an uncertainty is evaluated using in situ techniques. The smallest JES uncertainty of less than 1 % is found in the central calorimeter region (
|
η
|
<
1.2
) for jets with
55
≤
p
T
jet
<
500
GeV
. For central jets at lower
p
T
, the uncertainty is about 3 %. A consistent JES estimate is found using measurements of the calorimeter response of single hadrons in proton–proton collisions and test-beam data, which also provide the estimate for
p
T
jet
>
1
TeV. The calibration of forward jets is derived from dijet
p
T
balance measurements. The resulting uncertainty reaches its largest value of 6 % for low-
p
T
jets at
|
η
|
=
4.5
. Additional JES uncertainties due to specific event topologies, such as close-by jets or selections of event samples with an enhanced content of jets originating from light quarks or gluons, are also discussed. The magnitude of these uncertainties depends on the event sample used in a given physics analysis, but typically amounts to 0.5–3 %.
The aim of this study was to assess how the physical (needle fragmentation by trampling) and chemical (nutritional enrichment from faeces) changes brought about by grazing influence the consumption ...of needles of Pinus pinea L. by Ommatoiulus sabulosus L. Adult individuals of O. sabulosus were introduced into trays with pine needles subjected to four treatments: (i) intact needles, (ii) trampled needles, (iii) intact needles fertilized with liquid manure, and (iv) trampled needles fertilized with liquid manure. After 30 days, litter decomposition was determined as a function of mass loss over time. Biometrie and chemical characteristics of the needles were also measured. The pine needle decomposition rate was significantly higher in the presence of O. sabulosus (20–40%) than in its absence, presenting in addition a significantly higher rate in the treatments enriched with nitrogen. Average needle length was significantly shorter in the trampled treatments (6.89 ± 0.50 cm) than in those with intact needles (11.95 ± 0.69 cm). With regard to leaf mass per area and resistance to breakage, no significant differences were found. The fertilized treatments presented significantly higher N content (50% higher) than those in the non-fertilized ones with a significantly lower C:N ratio. The results of the present study indicate that goat grazing (which produces both trampling and fertilization) favoured the consumption of pine needles by O. sabulosus, which thus influences, along with the microbial community, the decomposition rate of these needles and thereby promotes incorporation of N into the system.
(ProQuest: ... denotes formulae and/or non-USASCII text omitted; see image) The luminosity calibration for the ATLAS detector at the LHC during pp collisions at ... in 2010 and 2011 is presented. ...Evaluation of the luminosity scale is performed using several luminosity-sensitive detectors, and comparisons are made of the long-term stability and accuracy of this calibration applied to the pp collisions at ... A luminosity uncertainty of ... is obtained for the 47 pb^sup -1^ of data delivered to ATLAS in 2010, and an uncertainty of ... is obtained for the 5.5 fb^sup -1^ delivered in 2011.
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