Waters

The determination of extractable trace metals in sediments using sequential extraction procedures has been performed in many laboratories within the last ten years in order to study environmental pathways (e.g. mobility of metals, bounding states). However, the results obtained by different laboratories could hardly be compared due to lack of harmonized schemes. Owing to the need for standardization and subsequent validation of extraction schemes for sediment analysis, the Measurements and Testing Programme (formerly BCR Programme) of the European Commission has organized a project to adopt a sequential extraction procedure that could be used as a mean of comparison of data of extractable trace metals in sediments. A scheme was designed after a series of investigations on existing schemes and tested in interlaboratory studies. This paper presents the results of two round-robin exercises on extractable trace metals using this sequential extraction protocol and describes the final version of the extraction procedure amended according to the most recent improvements.

In the Mediterranean Sea, crustose coralline algae form endemic algal reefs known as Coralligenous (C) build-ups. The high degree of complexity that C can reach through time creates notable environmental heterogeneity making C a major hotspot of biodiversity for the Mediterranean basin. C build-up can variably modify the submarine environment by affecting the evolution of submerged landforms, although its role is still far from being systematically defined. Our work proposes a new, ad-hoc semi-automated, GIS-based methodology to map the distribution of C build-ups in shallow coastal waters using high-resolution bathymetric data, collected on a sector of the southern Apulian continental shelf (Southern Adriatic Sea, Italy). Our results quantitatively define the 3D distribution of C in terms of area and volume, estimating more than 103,000 build-ups, covering an area of roughly 305,200 m2, for a total volume of 315,700 m3. Our work firstly combines acoustic survey techniques and geomo...

Abstract: Strontium isotopes are a powerful tool for investigating the geographical origins of people and animals but assignment of provenance requires reference maps and databases. This paper presents a map of strontium isotope variations across Britain for use in archaeological and other studies, and is produced by direct measurement of strontium isotope compositions of biosphere components, predominantly plants. The map characterizes the biosphere signature of specific lithologies: a technique that is applicable ...

A sequential injection (SI) method was developed for the spectrophotometric determination of chlorine based on the reaction between tetramethylbenzidine (TMB) and free chlorine. The advantages resulting from the use of TMB are considerable: TMB is highly selective for chlorine, it enables a fairly low quantification limit and represents a less toxic alternative to reagents such as tolidine. The use of this reaction in SI adds other advantages as it enhances the degree of automation, minimisation of reagent consumption (6.8mug TMB/assay) and low effluent production (2.5mL/determination). The developed method allowed a quantification limit of 90mug/L with a working range of 0.09-1.30mgOCl(-)/L and a determination rate of 60det./h. Based on these features, the system was applied to tap-water and surface water samples with no previous treatment required. The results obtained with the developed system were compared to the reference method, diethyl-p-phenylelediamine (DPD) colorimetric me...

High background noise is an important obstacle in successful signal detection and perception of an intended acoustic signal. To overcome this problem, many animals modify their acoustic signal by increasing the repetition rate, duration, amplitude or frequency range of the signal. An alternative method to ensure successful signal reception, yet to be tested in animals, involves the use of two different types of signal, where one signal type may enhance the other in periods of high background noise. Humpback whale communication signals comprise two different types: vocal signals, and surface-generated signals such as ‘breaching’ or ‘pectoral slapping’. We found that humpback whales gradually switched from primarily vocal to primarily surface-generated communication in increasing wind speeds and background noise levels, though kept both signal types in their repertoire. Vocal signals have the advantage of having higher information content but may have the disadvantage of loosing this ...

— Kariat Bamohamed is an agricultural region located to the west of the city of Taounate and north of the city of Fez. The surface waters in the region are mainly composed by the Sebou river and many natural springs. The study concerns the analysis of hydrochemical parameters (T°, pH, CE, MES, O 2 , BOD 5 , COD, Cl-, PO 4 3 , NH 4 + and NO 3-) along the middle Sebou river region of Kariat Bamohamed in order to establish a diagnosis of the state of pollution of the surface waters of this part of the river. Wa ter sampling was carried out at four study stations during flood period and during low water period. In the light of the results obtained on the surface waters of the Sebou river, it is concluded to a degradation of water quality in both the winter and summer periods. In particular, an increase in the values of ammonium, COD and BOD 5 in addition to an acidic pH due to margine discharges and leaching of fertilizers and other discharges of wastewaters from the cities of Fez and Kariat Bamohamed.

Abstract Anionic surfactants in water samples were determined by a spectrophotometric and a spectrofluorimetric method involving flow injection coupled with liquid-liquid extraction. On-tube detection without any phase separators was adopted by using a glass capillary flow cell (inner diameter 0.8 mm). Two kinds of dyes were examined: cationic dyes, such as Methylene Blue and Ethyl Violet, and neutral dyes, such as Rhodamine B and 4-(4-dimethylaminophenylazo)-2-methylquinoline. The latter dyes were found to be advantageous and were dissolved in an organic phase as an electrically neutral species. They combined with anionic surfactants in the presence of protons, and changed their colour and/or fluorescence intensity. By using the second group of reagents, anionic surfactants could be determined with low background noise.

Schwertmannite precipitated from acid mine drainage at the Kristineberg Zn–Cu mine in northern Sweden has been characterised regarding elemental composition, phase transformation as a function of pH and time, SO42-release and speciation of SO42-...

Arsenic is a naturally occurring toxic and carcinogenic element. The degree of the toxicity depends on its chemical form and the concentration. Application of a sensitive, selective, simple and rapid method for detection and monitoring of different oxidation states of arsenic in waters is of great importance because main route of population exposure is through drinking water. In this work chronopotentiometric stripping analysis (CSA) was used for the determination of As(III) and As(V) in tap, well, river and rain waters from Vojvodina (Serbia). Gold film electrode on the glassy carbon support was used as the working electrode. The experimental parameters of the technique were investigated and optimized. Detection limit of the method for the electrolysis time of 600 s was 2 ?g/dm3 of As(III).