Speciation of phytate ion in aqueous solution. Sequestering ability toward mercury(II) cation in NaClaq at different ionic strengths

As a contribution to understanding the speciation of mercury in the environment and to the study of the sequestering ability of phytate (Phy) toward heavy metal and organometal cations, this paper describes the results of an investigation (at t = 25 degrees C by potentiometry, ISE-H+ glass electrode) of its interactions with mercury(II) cation in NaCl aqueous solutions at different ionic strengths (I = 0.15 and 1.0 mol L(-1)), in the pH range 2.5 < or = pH < or = 9.5 and considering metal-to-ligand ratios of 1:1 < or = Hg/Phy < or = 4:1. The formation of 11 HgiHjPhy(12-2i-j)(- species with i = 1 and 0 < or = j < or = 7 and i = 2 and 0 < or = j < or = 2 was observed. Their complex formation constant values proved to be fairly dependent on ionic strength. The speciation of phytic acid and mercury(II) is also dependent on the metal-to-ligand ratio; the dependence of the stability of phytate-mercury(II) species on the phytate protonation step was modeled, and an empirical predictive relationship was proposed. From the results obtained, phytate has very good sequestering ability toward Hg2+, even in the presence of considerable excesses of chloride ion, that is, another ligand strongly interacting with mercury; this supports future studies both on the use of plants that naturally synthesize it for phytoremediation purposes and on its direct application in remediation techniques.     

Extractable iron and organic matter in the suspended insoluble material of fog droplets

In this work the formation and composition of aggregates between metals and organic material is studied in real fog samples. In a preliminary experiment it has been found that concentrated cloud samples form a yellow-brown precipitate in the presence of Fe(III). Standards of humic acids and fulvic acids co-precipitate with Fe(III), forming similar aggregates i.e. iron-humates (Fe-HA) and iron-fulvates (Fe-FA). By comparing the solubility properties of aggregates by extracting organic carbon (OC) in different pH conditions, it has been observed that fog droplet particulate samples are characterised by solubility properties more similar to those of Fe-HA than Fe-FA. Dilute alkaline solutions can also easily extract organic refractory substances that form aggregates with metals. The recoveries of the total extractable organic matter (accounting for 12% of total insoluble carbon and 15% of particulate mass) are similar to those of humic-like substances (HULIS) from particulate samples. The chromatographic behaviour and functional group characteristics measured in the alkali-extract fraction of precipitated aggregates with iron and in the insoluble particulate of fog samples, are those of humic-like material. Thus, soluble HULIS are able to interact with iron to form particulate, but the composition of a large fraction of insoluble organic carbon is still unknown. These findings have implications on the solubility and surface tension properties of fog droplets and can therefore potentially influence droplet formation, as well as cloud chemical and photochemical processes.     

Controls on microbial mercury transformations in contaminated sediments downstream of the Idrija mercury mine (West Slovenia) to the Gulf of Trieste (northern Adriatic)

Purpose

Concentrations and transformations of mercury were measured in river, estuarine, and marine sediments to determine factors affecting the fate of mercury entering the northern Adriatic Sea.

Materials and methods

Radiotracer methodology was used to compare rates of mercury methylation (²⁰³Hg), MeHg demethylation (¹⁴C), and sulfate reduction (³⁵S) in sediment depth profiles to concentrations of total and dissolved mercury species in the lower freshwater region of the Isonzo River, the coastal lagoons, and in the Gulf of Trieste, northern Adriatic Sea.

Results and discussion

Mercury was readily methylated and demethylated in all sediments, but the relative activity of these processes varied greatly with location. Methylation activity increased greatly from freshwater to the marine regions; however, demethylation was extremely high in the estuarine and lagoon sites. Ratios of methylation to demethylation were low in these coastal sites but increased further offshore in the gulf, which agreed with increased ratios of MeHg to total Hg (%MeHg) in gulf sediments. Comparisons of microbial activities indicated that sulfate reduction strongly controlled both methylation and demethylation. However, Hg methylation in coastal lagoon sediments was controlled by rapid demethylation and the bioavailability of Hg that was affected by Hg adsorption and precipitation. Methylation in offshore marine sites correlated with sulfate reduction but not the partitioning of Hg between pore water and solid phases. The decrease in sulfide production offshore exacerbated Hg methylation.

Conclusions

The freshwater to marine gradient in the Idrija/So?a/Isonzo/Adriatic region is dynamic, exhibiting horizontally variable rates of microbial activities and Hg transformations that create “hot spots” of MeHg accumulation that are controlled differently in each region.

     

Estimating the impacts of water pricing on smallholder irrigators in North West Province, South Africa

Worldwide growing water scarcity has increased the call for economic instruments to stimulate rational water use in agriculture. Furthermore, cost-recovery is now widely accepted as a cornerstone of sustainable water management. In many developing countries, where agricultural water use is often still subsidised, water pricing policies are developed for allocating water efficiently and achieving sustainability of water systems. However, the impacts of water pricing policies on irrigation water use and on farm production systems is mostly unknown. We introduce an innovative two-stage methodology that allows estimating these effects at farm level. Applying the method to small-scale irrigators in South Africa, we show that water demand is quite responsive even to small changes in water price. In addition, the introduction of a water price significantly decreases farm profit. This appears to be a problem primarily for the poorer farmers.     

Map- vs. homology-based cloning for the recessive gene ol-2 conferring resistance to tomato powdery mildew

The recessive gene ol-2 confers papilla-associated and race-non-specific resistance to tomato powdery mildew caused by Oidium neolycopersici. In order to facilitate marker assisted selection (MAS) in practical breeding programmes, we identified two simple sequence repeat (SSR) markers and one cleaved amplified polymorphic sequence (CAPS) marker which are linked to the resistance locus and co-dominantly inherited. Aiming to provide a base for ol-2 positional cloning, we used a large segregating F₂ population to merge these markers with all the ol-2 linked amplified fragment length polymorphism (AFLP^®) markers previously identified in an integrated genetic map. By screening a tomato bacterial artificial chromosome (BAC) library, we detected two BAC clones containing two expressed sequence tags (ESTs) homologous to the gene mlo, responsible for powdery mildew resistance in barley, as well as an ol-2-linked marker. Chromosomal mapping by Fluorescence in situ Hybridization (FISH) revealed major signals of the two BAC DNAs in the pericentromeric heterochromatin of the short arm of chromosome 4, in the same region where the ol-2 gene was previously mapped. The genetic and cytogenetic co-localisation between ol-2 and tomato mlo-homologue(s), in addition to the similarity of ol-2 and mlo resistances for both genetic and phytopathological characteristics, suggests that ol-2 is likely a mlo-homologue. Thus, a homology-based cloning approach could be more suitable than positional cloning for ol-2 isolation.     

Occurrence and present status of coastal dolphins (Delphinus delphis and Tursiops truncatus) in the eastern Ionian Sea

• 1. Boat surveys aimed at studying short‐beaked common dolphins and common bottlenose dolphins in eastern Ionian Sea coastal waters were conducted between 1993 and 2003. During 835 survey days, 24 771 km of total effort was distributed within an area of 480 km², resulting in 428 common dolphin and 235 bottlenose dolphin sightings.
• 2. Individual photo‐identification was performed extensively throughout this study, making it possible to monitor the number of animals seen in the study area each year and their long‐term residency patterns.
• 3. Common dolphins declined across the study period, from 2.18 encounters/100 km in 1997 to 0.40 encounters/100 km in 2003. In contrast, there was a relatively stable presence of bottlenose dolphins, some individuals showing high levels of site fidelity and others using the area only occasionally.
• 4. The local decline of common dolphins and the low density of bottlenose dolphins appeared to reflect the general status of these cetacean species in the wider Mediterranean region, where common dolphins were classified as endangered in the IUCN Red List in 2003.
• 5. Based on the available evidence, we infer that the present unfavourable status of common dolphins in eastern Ionian Sea coastal waters is largely a consequence of prey depletion.

Copyright © 2005 John Wiley & Sons, Ltd.     

IMAGING DIAGNOSIS—ULTRASONOGRAPHIC APPEARANCE OF SKELETAL MUSCLE METASTASES IN A DOG WITH HEMANGIOSARCOMA

A 13‐year‐old spayed female German shepherd dog was presented for acute onset of lethargy, anorexia, and disseminated erythematous skin lesions. Thoracic radiographs and abdominal ultrasonographic findings were consistent with metastatic hemangiosarcoma. Multiple, ill‐defined, irregularly shaped hypoechoic nodules were also detected within the thoracic and abdominal wall. Hemangiosarcoma metastases to the skeletal muscle were confirmed based on histopathological examination. Multivisceral involvement was also confirmed by necropsy. Metastatic neoplasia should be considered as a differential diagnosis for dogs with ill‐defined, irregular, hypoechoic, intramuscular nodules.     

Multidisciplinary study of a Lateglacial-Holocene sedimentary sequence near Bologna (Italy): insights on natural and anthropogenic impacts on the landscape dynamics

Journal of Soils and Sediments - This study investigated a Lateglacial to Holocene sedimentary sequence derived from a small catchment located at San Lazzaro di Savena in the surroundings of...     

Genetic diversity of Syrian pistachio (<Emphasis Type="Italic">Pistacia vera</Emphasis> L.) varieties evaluated by AFLP markers

Pistachio (Pistacia vera L.) is a strategic nut tree species in the Middle East which holds comparative advantage over other fruit trees in view of its hardiness, income generation opportunities and benefits for the ecosystem. Yet pistachio cultivation depends on a very narrow genetic base, in spite of the existence of many varieties still marginally exploited. Syria is an important center of diversity for pistachio. A country wide ecogeographic survey in this country was carried out to determine the extent of pistachio genetic diversity and its use. As a whole, 114 accessions were collected from 37 farms to assess diversity at morphological and molecular level. Molecular evaluation was carried out using Amplified Fragment Length Polymorphism (AFLP) technique and performed using seven primer pair combinations. Results from the studies allowed the identification of 25 pistachio female varieties in Syria, some of which unique and described for the first time. Three groups of pistachio diversity were identified by cluster analysis which provides useful information about the distribution of genetic diversity in Syria for enhanced use and sustainable conservation.