Studies of corrosion tendency of drinking water in the distribution system at the University of Benin

Ensemble of corrosion indices was combined to study the corrosion tendency of the drinking water supply at the University of Benin, Nigeria. The experimental results were analysed in terms of three corrosion indices-Langelier Index, Ryznar Index and Larson–Skold Index. According to the evaluation, the Langelier Index ranged from −5.569 to −3.684, Ryznar Index was between 13.340 and 16.418 while the Larson–Skold Index was between 1.191 and 31.750. Results indicated that the water may be corrosive. A regression of these indices on iron concentration (ppm) showed that Langelier Index, Ryznar Index and Larson–Skold Index have R ² of 0.5868, 0.6577 and 0.7063, respectively. The positive correlation between iron levels and the corrosion indices suggested that iron levels were directly related to increase in corrosion tendency.     

Hyperaccumulation of Pb, Zn and Cd in herbaceous grown on lead-zinc mining area in Yunnan, China

A field survey of herbaceous growing on lead-zinc mining area in Yunnan, China were conducted to identify species accumulating exceptionally large concentrations of Pb, Zn and Cd in shoots. In total, 220 plant samples of 129 species of 50 families and 220 soil samples in which the plants were growing were collected. According to accumulation concentration in plant shoots and the concentration time levels compared to plants from non-polluted environments, 21 plant samples of 16 species were chosen as best-performing specimens, 11 plant samples of 10 species for Pb, 5 plant samples of 4 species for Zn and 5 plant samples of 5 species for Cd. Sonchus asper (L.) Hill in Qilinkeng had hyperaccumulation capacity to Pb and Zn. Corydalis pterygopetala Franch in Paomaping had hyperaccumulation capacity to Zn and Cd. All 5 Cd hyperaccumulators came from Lanping lead-zinc mining area. Out of 11 Pb hyperaccumulators, 7 came from Minbingying of Huice lead-zinc mining area. The average of the concentration time levels compared to plants from non-polluted environments were higher than 10 times in all plant samples, the concentration time levels changed from 203 times to 620 times for Pb, from 50 times to 70 times for Zn and from 145 times to 330 times for Cd. Out of 21 plant samples, translocation factor changed from 0.35 to 1.90, only translocation factor of 7 plant samples were higher than 1. Enrichment coefficients of all samples were lower than 1. These plant species were primarily heavy metal hyperaccumulator, and will be used in phytoremediation of the metallic pollutants in soils after further research in accumulation mechanism.     

Stabilization of As, Cr, Cu, Pb and Zn in soil using amendments--a review

The spread of contaminants in soil can be hindered by the soil stabilization technique. Contaminant immobilizing amendments decrease trace element leaching and their bioavailability by inducing various sorption processes: adsorption to mineral surfaces, formation of stable complexes with organic ligands, surface precipitation and ion exchange. Precipitation as salts and co-precipitation can also contribute to reducing contaminant mobility. The technique can be used in in situ and ex situ applications to reclaim and re-vegetate industrially devastated areas and mine-spoils, improve soil quality and reduce contaminant mobility by stabilizing agents and a beneficial use of industrial by-products. This study is an overview of data published during the last five years on the immobilization of one metalloid, As, and four heavy metals, Cr, Cu, Pb and Zn, in soils. The most extensively studied amendments for As immobilization are Fe containing materials. The immobilization of As occurs through adsorption on Fe oxides by replacing the surface hydroxyl groups with the As ions, as well as by the formation of amorphous Fe(III) arsenates and/or insoluble secondary oxidation minerals. Cr stabilization mainly deals with Cr reduction from its toxic and mobile hexavalent form Cr(VI) to stable in natural environments Cr(III). The reduction is accelerated in soil by the presence of organic matter and divalent iron. Clays, carbonates, phosphates and Fe oxides were the common amendments tested for Cu immobilization. The suggested mechanisms of Cu retention were precipitation of Cu carbonates and oxy-hydroxides, ion exchange and formation of ternary cation-anion complexes on the surface of Fe and Al oxy-hydroxides. Most of the studies on Pb stabilization were performed using various phosphorus-containing amendments, which reduce the Pb mobility by ionic exchange and precipitation of pyromorphite-type minerals. Zn can be successfully immobilized in soil by phosphorus amendments and clays.     

A synthesis of progress and uncertainties in attributing the sources of mercury in deposition

A panel of international experts was convened in Madison, Wisconsin, in 2005, as part of the 8th International Conference on Mercury as a Global Pollutant. Our charge was to address the state of science pertinent to source attribution, specifically our key question was: "For a given location, can we ascertain with confidence the relative contributions of local, regional, and global sources, and of natural versus anthropogenic emissions to mercury deposition?" The panel synthesized new research pertinent to this question published over the past decade, with emphasis on four major research topics: long-term anthropogenic change, current emission and deposition trends, chemical transformations and cycling, and modeling and uncertainty. Within each topic, the panel drew a series of conclusions, which are presented in this paper. These conclusions led us to concur that the answer to our question is a "qualified yes," with the qualification being dependent upon the level of uncertainty one is willing to accept. We agreed that the uncertainty is strongly dependent upon scale and that our question as stated is answerable with greater confidence both very near and very far from major point sources, assuming that the "global pool" is a recognizable "source." Many regions of interest from an ecosystem-exposure standpoint lie in between, where source attribution carries the greatest degree of uncertainty.     

Preliminary screening of perfluorooctane sulfonate (PFOS) and other fluorochemicals in fish, birds and marine mammals from Greenland and the Faroe Islands

Extensive screening analyses of perfluorooctane sulfonate (PFOS) and related perfluorinated compounds in biota samples from all over the world have identified PFOS as a global pollutant and have shown its bioaccumulation into higher trophic levels in the food chain. Perfluorinated compounds have been found in remote areas as the Arctic. In this study a preliminary screening of PFOS and related compounds has been performed in liver samples of fish, birds and marine mammals from Greenland and the Faroe Islands. PFOS was the predominant fluorochemical in the biota analyzed, followed by perfluorooctane sulfonamide (PFOSA). PFOS was found at concentrations above LOQ (10 ng/g wet weight) in 13 out of 16 samples from Greenland and in all samples from the Faroe Islands. The results from Greenland showed a biomagnification of PFOS along the marine food chain (shorthorn sculpin < ringed seal < polar bear). The greatest concentration of PFOS was found in liver of polar bear from east Greenland (mean: 1285 ng/g wet weight, n = 2). The geographical distribution of perfluorinated compounds in Greenland was similar to that of persistent organohalogenated compounds (OHCs), with the highest concentrations in east Greenland, indicating a similar geographical distribution to that of OHCs, with higher concentrations in east Greenland than in west Greenland.     

Regulatory failure and the polluter pays principle: why regulatory impact assessment dominates the polluter pays principle

Environmental Economics and Policy Studies - This paper shows possible inconsistencies in environmental law, in which regulatory impact assessment (RIA) and the polluter pays principle (PPP)...     

Crystalline phase analysis and phosphorus availability after thermochemical treatment of sewage sludge ash with sodium and potassium sulfates for fertilizer production

Phosphorus rich sewage sludge ash is a promising source to produce phosphorus recycling fertilizer. However, the low plant availability of phosphorus in these ashes makes a treatment necessary. A thermochemical treatment (800–1000 °C) with alkali additives transforms poorly plant available phosphorus phases to highly plant available calcium alkali phosphates (Ca,Mg)(Na,K)PO₄. In this study, we investigate the use of K₂SO₄ as additive to produce a phosphorus potassium fertilizer in laboratory-scale experiments (crucible). Pure K₂SO₄ is not suitable as high reaction temperatures are required due to the high melting point of K₂SO₄. To overcome this barrier, we carried out series of experiments with mixtures of K₂SO₄ and Na₂SO₄ resulting in a lower economically feasible reaction temperature (900–1000 °C). In this way, the produced phosphorus potassium fertilizers (8.4 wt.% K, 7.6 wt.% P) was highly plant available for phosphorus indicated by complete extractable phosphorus in neutral ammonium citrate solution. The added potassium is, in contrast to sodium, preferably incorporated into silicates instead of phosphorus phases. Thus, the highly extractable phase (Ca,Mg)(Na,K)PO₄ in the thermochemical products contain less potassium than expected. This preferred incorporation is confirmed by a pilot-scale trial (rotary kiln) and thermodynamic calculation.

     

Radionuclides in marine macroalgae from Amchitka and Kiska Islands in the Aleutians: establishing a baseline for future biomonitoring

Levels of radionuclides in seven species of marine brown algae and Ulva were determined to establish a baseline for the Northern Pacific Ocean/Bering Sea (Aleutian Islands). There were differences in levels among algal species and locations (Amchitka Island vs Kiska Island). No values were above the minimum detectable activity (MDA) level for (137)Cs, (129)I, (60)Co, (152)Eu, (90)Sr, and (99)Tc. There were interspecific differences in some radionuclides: Ulva lactuca (=Ulva fenestrata) had the highest levels of (241)Am, Alaria fistulosa had the highest levels of (239,240)Pu, and Fucus distichus (=Fucus gardneri) had the highest levels of (234)U, (235)U, and (238)U. However, levels of all radionuclides were generally low and near the MDA for all isotopes. Although Amchitka Island had higher levels of (239,240)Pu than Kiska, the differences were very small and not significant biologically. The data indicate that algae can be useful bioindicators of actinides because they accumulate them at very low environmental levels, allowing them to provide early warning of any potential seepage of radionuclides into the marine environment. Further, the data indicate that some species (the intertidal Fucus) are better accumulators than others, and these should be used as bioindicators in future monitoring schemes.     

Estimating High Latitude Carbon Fluxes With Inversions Of Atmospheric CO2

Atmospheric inversions have proven to be useful tools, showing for example the likely existence of a large terrestrial carbon sink in the northern mid-latitudes. However, as we go to smaller spatial scales the uncertainties in the inversions increase rapidly, and the task of finding the distribution of the sink between North America, Europe and Asia has been shown to be very difficult. The uncertainty in the fluxes due to network selection, transport model error and inversion set up tends to be too high for studying either net annual fluxes or interannual variability on spatial scales such as the North American Boreal or Eurasian Boreal regions. We discuss the path forward; to couple together the atmospheric inversions with process based terrestrial carbon models, creating carbon data assimilation systems. Such systems are being developed now and could prove to be very powerful. The multi-disciplinary nature of the data assimilation system requires information from flux towers, soil and above ground biomass inventories, remote sensed fields, atmospheric CO₂ concentrations and climate data as well as model development and will need a massive community effort if it will succeed.     

Assessment of zerovalent iron for stabilization of chromium, copper, and arsenic in soil

Stabilization of soil contaminated with trace elements is a remediation practice that does not reduce the total content of contaminants, but lowers the amounts of mobile and bioavailable fractions. This study evaluated the efficiency of Fe(0) to reduce the mobility and bioavailability of Cr, Cu, As and Zn in a chromated copper arsenate (CCA)-contaminated soil using chemical, biochemical and biotoxicity tests. Contaminated soil was stabilized with 1% iron grit. This treatment decreased As and Cr concentrations in leachates (by 98% and 45%, respectively), in soil pore water (by 99% and 94%, respectively) and in plant shoots (by 84% and 95%, respectively). The stabilization technique also restored most of analyzed soil enzyme activities and reduced microbial toxicity, as evaluated by the BioTox test. After stabilization, exchangeable and bioaccessible fractions of Cu remained high, causing some residual toxicity in the treated soil.