scholarly journals A dynamic biophysical fugacity model of the movement of a persistent organic pollutant in Antarctic marine food webs

2011 ◽  
Vol 8 (3) ◽  
pp. 263 ◽  
Author(s):  
Roger Cropp ◽  
Georgina Kerr ◽  
Susan Bengtson-Nash ◽  
Darryl Hawker
Keyword(s):  
Organic Pollutants ◽  
Organic Pollutant ◽  
Ecosystem Model ◽  
Seasonal Effects ◽  
Long Distance ◽  
Fugacity Model ◽  
Long Distance Transport ◽  
Antarctic Waters ◽  
The Antarctic ◽  
Antarctic Environment

Environmental contextPersistent organic pollutants (POPs) are potentially toxic chemicals capable of long distance transport and are often found far from their source. Little is known of their behaviour in Antarctica, where the marine plankton food web is driven by strong seasonal variations in solar radiation. Here the first dynamic coupled ecosystem–fugacity model to describe how POPs distribute through the Antarctic environment is presented. The model is used to identify the important processes that govern the presence of hexachlorobenzene in Antarctic plankton. AbstractPolar regions can be repositories for many persistent organic pollutants (POPs). However, comparatively little is known of the movement and behaviour of POPs in Antarctic ecosystems. These systems are characterised by strong seasonal effects of light on plankton dynamics. This work describes a mass-conserving, fugacity-based dynamic model to describe the movement of POPs in the Antarctic physical and plankton systems. The model includes dynamic corrections for changes in the population volumes and the temperature dependence of the fugacity capacities, and was developed by coupling a dynamic Nutrient–Phytoplankton–Zooplankton–Detritus (NPZD) ecosystem model to fugacity models of the chemistry and biology of the Southern Ocean. The model is applied to the movement of hexachlorobenzene, a POP found in the Antarctic environment. The model predicts that the burden of HCB in the plankton varies with the seasonal cycle in Antarctic waters, and induces a seasonal variation in the biomagnification factor of zooplankton. This suggests that time series of POP concentrations in Antarctic biotic and abiotic systems should be measured over complete seasonal cycles. Furthermore, detritus is shown to be a key contributor to the movement of POPs in polar environments, linking physical and biological components of the model.

The Fine Structure of Phloem Cells

1985 ◽  
Vol 43 ◽  
pp. 632-635
Author(s):  
James Cronshaw
Keyword(s):  
Structural Studies ◽  
High Concentration ◽  
Long Distance ◽  
Phloem Tissue ◽  
Sieve Elements ◽  
Long Distance Transport ◽  
P Protein ◽  
Companion Cells ◽  
Electron Microscopical ◽  
Distance Transport

Long distance transport in plants takes place in phloem tissue which has characteristic cells, the sieve elements. At maturity these cells have sieve areas in their end walls with specialized perforations. They are associated with companion cells, parenchyma cells, and in some species, with transfer cells. The protoplast of the functioning sieve element contains a high concentration of sugar, and consequently a high hydrostatic pressure, which makes it extremely difficult to fix mature sieve elements for electron microscopical observation without the formation of surge artifacts. Despite many structural studies which have attempted to prevent surge artifacts, several features of mature sieve elements, such as the distribution of P-protein and the nature of the contents of the sieve area pores, remain controversial.

Diatom Fouling of the Little Picked Whales in the Antarctic Waters

2012 ◽  
Vol 48 (1) ◽  
pp. 28-34 ◽  
Author(s):  
V. L. Zinchenko ◽  
V. P. Gerasimyuk
Keyword(s):  
Antarctic Waters ◽  
The Antarctic

Electrospun-based TiO2 nanofibers for organic pollutant photodegradation: a comprehensive review

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Khee Chung Hui ◽  
Hazwani Suhaimi ◽  
Nonni Soraya Sambudi
Keyword(s):  
Visible Light ◽  
Organic Pollutants ◽  
Organic Pollutant ◽  
Hollow Fibers ◽  
Promising Alternative ◽  
Tio2 Nanofibers ◽  
As Doping ◽  
Secondary Pollutants ◽  
Photocatalytic Reactors ◽  
Light Area

Abstract Titanium dioxide (TiO2) is commonly used as a photocatalyst in the removal of organic pollutants. However, weaknesses of TiO2 such as fast charge recombination and low visible light usage limit its industrial application. Furthermore, photocatalysts that are lost during the treatment of pollutants create the problem of secondary pollutants. Electrospun-based TiO2 fiber is a promising alternative to immobilize TiO2 and to improve its performance in photodegradation. Some strategies have been employed in fabricating the photocatalytic fibers by producing hollow fibers, porous fibers, composite TiO2 with magnetic materials, graphene oxide, as well as doping TiO2 with metal. The modification of TiO2 can improve the absorption of TiO2 to the visible light area, act as an electron acceptor, provide large surface area, and promote the phase transformation of TiO2. The improvement of TiO2 properties can enhance carrier transfer rate which reduces the recombination and promotes the generation of radicals that potentially degrade organic pollutants. The recyclability of fibers, calcination effect, photocatalytic reactors used, operation parameters involved in photodegradation as well as the commercialization potential of TiO2 fibers are also discussed in this review.

scholarly journals From tree to architecture: how functional morphology of arborescence connects plant biology, evolution and physics

2021 ◽  
Author(s):  
Anita Roth-Nebelsick ◽  
Tatiana Miranda ◽  
Martin Ebner ◽  
Wilfried Konrad ◽  
Christopher Traiser
Keyword(s):  
Land Plant ◽  
Plant Evolution ◽  
Ecological Niches ◽  
Long Distance ◽  
Ongoing Research ◽  
Long Distance Transport ◽  
Theoretical Approaches ◽  
Trade Offs ◽  
Interfacial Physics ◽  
Plant Water Transport

AbstractTrees are the fundamental element of forest ecosystems, made possible by their mechanical qualities and their highly sophisticated conductive tissues. The evolution of trees, and thereby the evolution of forests, were ecologically transformative and affected climate and biogeochemical cycles fundamentally. Trees also offer a substantial amount of ecological niches for other organisms, such as epiphytes, creating a vast amount of habitats. During land plant evolution, a variety of different tree constructions evolved and their constructional principles are a subject of ongoing research. Understanding the “natural construction” of trees benefits strongly from methods and approaches from physics and engineering. Plant water transport is a good example for the ongoing demand for interdisciplinary efforts to unravel form-function relationships on vastly differing scales. Identification of the unique mechanism of water long-distance transport requires a solid basis of interfacial physics and thermodynamics. Studying tree functions by using theoretical approaches is, however, not a one-sided affair: The complex interrelationships between traits, functionality, trade-offs and phylogeny inspire engineers, physicists and architects until today.

scholarly journals Leaf-derived ABA regulates rice seed development via a transporter-mediated and temperature-sensitive mechanism

2021 ◽  
Vol 7 (3) ◽  
pp. eabc8873
Author(s):  
Peng Qin ◽  
Guohua Zhang ◽  
Binhua Hu ◽  
Jie Wu ◽  
Weilan Chen ◽  
...  
Keyword(s):  
Seed Development ◽  
Starch Synthesis ◽  
Biological Significance ◽  
Grain Filling ◽  
Temperature Sensitive ◽  
Rice Seed ◽  
Dependent Manner ◽  
Long Distance ◽  
Long Distance Transport ◽  
Mechanistic Basis

Long-distance transport of the phytohormone abscisic acid (ABA) has been studied for ~50 years, yet its mechanistic basis and biological significance remain very poorly understood. Here, we show that leaf-derived ABA controls rice seed development in a temperature-dependent manner and is regulated by defective grain-filling 1 (DG1), a multidrug and toxic compound extrusion transporter that effluxes ABA at nodes and rachilla. Specifically, ABA is biosynthesized in both WT and dg1 leaves, but only WT caryopses accumulate leaf-derived ABA. Our demonstration that leaf-derived ABA activates starch synthesis genes explains the incompletely filled and floury seed phenotypes in dg1. Both the DG1-mediated long-distance ABA transport efficiency and grain-filling phenotypes are temperature sensitive. Moreover, we extended these mechanistic insights to other cereals by observing similar grain-filling defects in a maize DG1 ortholog mutant. Our study demonstrates that rice uses a leaf-to-caryopsis ABA transport–based mechanism to ensure normal seed development in response to variable temperatures.

scholarly journals New evidence of arsenic translocation and accumulation in Pteris vittata from real-time imaging using positron-emitting 74As tracer

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yi Huang-Takeshi Kohda ◽  
Zhaojie Qian ◽  
Mei-Fang Chien ◽  
Keisuke Miyauchi ◽  
Ginro Endo ◽  
...  
Keyword(s):  
Imaging System ◽  
Pteris Vittata ◽  
Long Distance ◽  
Long Distance Transport ◽  
Hydroponic Cultivation ◽  
Tracer Imaging ◽  
Serial Images ◽  
First Time ◽  
New Evidence ◽  
Hyperaccumulator Plant

AbstractPteris vittata is an arsenic (As) hyperaccumulator plant that accumulates a large amount of As into fronds and rhizomes (around 16,000 mg/kg in both after 16 weeks hydroponic cultivation with 30 mg/L arsenate). However, the sequence of long-distance transport of As in this hyperaccumulator plant is unclear. In this study, we used a positron-emitting tracer imaging system (PETIS) for the first time to obtain noninvasive serial images of As behavior in living plants with positron-emitting 74As-labeled tracer. We found that As kept accumulating in rhizomes as in fronds of P. vittata, whereas As was retained in roots of a non-accumulator plant Arabidopsis thaliana. Autoradiograph results of As distribution in P. vittata showed that with low As exposure, As was predominantly accumulated in young fronds and the midrib and rachis of mature fronds. Under high As exposure, As accumulation shifted from young fronds to mature fronds, especially in the margin of pinna, which resulted in necrotic symptoms, turning the marginal color to gray and then brown. Our results indicated that the function of rhizomes in P. vittata was As accumulation and the regulation of As translocation to the mature fronds to protect the young fronds under high As exposure.

Sign in / Sign up

Export Citation Format

Share Document