Analysis of mercury, selenium, and tin concentrations in canned fish marketed in Iran

The presence of heavy metals in the environment could constitute a hazard to food security and public health. These can be accumulated in aquatic animals such as fish. In the present paper, three heavy metals (mercury, selenium, and tin) in canned products produced and sold in Iran were studied: longtail tuna, Kawakawa, Kilka, and yellowfin tuna were determined using inductively coupled plasma–optical emission spectrometer and a direct mercury analyzer. Analytical results were validated by spiking the samples with various concentrations of these metals to test recovery. The metal contents, expressed in micrograms per gram, wet weight, varied depending upon the species studied. The levels of Hg ranged from 0.0003 to 0.408 μg/g, the levels of Sn ranged from 0.036 to 0.480 μg/g, while the levels of Se ranged from 0.130 to 4.500 μg/g. Comparative evaluation of these metals in different brands of canned fish showed that the average concentrations of Hg, Sn, and Se of all species is significantly lower than adverse level for the species themselves and for human consumption when compared with FAO/WHO permissible limits. Therefore, their contribution to the total body burden of these heavy metals can be considered as negligibly small.     

Prediction of the PCDD/F and dl-PCB 2005-WHO-TEQ content based on the contribution of six congeners: Toward a new screening approach for fish samples?

Current European Union regulation regarding polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (dl-PCBs) in food and feed is based on Toxic Equivalent Quotient (TEQ) concept. For confirmatory purpose, the isotope-dilution method associated to a measurement by gas chromatography coupled with high resolution mass spectrometry is usually the method of choice for precisely measuring the 29 target congeners in three separated fractions. Time and cost related to these analyses are very significant. Various kinds of screening concepts can be considered. In the present study, we elaborated and validated a prediction model for the 2005 World Health Organization TEQ in fish, based on the measurement of 4 PCDD/F and 2 non-ortho dl-PCB congeners, potentially analyzable in a single extracted fraction by gas chromatography coupled with mass spectrometry. Large independent datasets have been used for model elaboration (n = 108) and validation (n = 363, n = 357 and n = 6).     

The metabolic fate of 14C‐parathion by some fresh water phytoplankton and its possible effects on the algal metabolism

Abstract

The growth and total carbohydrate contents of Nostoc muscorum and Tolypothrix tenuis were greatly and significantly reduced by the application of parathion. “Chlorophyll a”, carotene biosynthesis and the rate of glucose absorption were enhanced after supplementation of parathion to the culture media of both cyanobacteria. Nitrogen released to the media, total nitrogen content and total nitrogen fixed were increased in both organisms‐ Increase in protein content was accompanied by remarkable drop in amino, peptide and ammonia fractions‐ Phosphorus uptake, RNA, DNA and total phosphorus content were accelerated to reach maximum accumulation at the highest insecticide level. In metabolism study using ¹⁴C‐labelled compound, parathion was readily degraded by Nostoc and Tolypothrix. Following ten days incubation, the aqueous fractions contained 21.1% and 18.1% of the initial activity in Nostoc and Tolypothrix respectively. TLC analysis of the hydrolytic products revealed the presence of three metabolites: p‐aminophenol, p‐nitrophenol and aminoparathion.     

Starting improvement of micro-wind turbines operating in low wind speed regions

The study deals with the design and optimization of external and internal geometry of micro-wind turbines blades. A specified objective function which consists of the power coefficient and the starting time was defined and the genetic algorithm optimization technique in conjunction with the blade-element momentum theory was adopted to find the geometry of the blades including the distributions of the chord, the twist angle and also the shell thickness. Moreover, the allowable stress of the blades was considered as a constraint to the objective function. Results show that a reasonable compromise is achievable such that the starting time of the blades reduces noticeably in return for a small drop in the power coefficient. The significant improvement of the hollow blades over the solid ones indicates that the power coefficient and the starting performance could be improved through the appropriate distributions of the considered decision variables, i.e. the chord, the twist angle and also the shell thickness.     

Parameter Sensitivity of a Surface Water Quality Model of the Lower South Saskatchewan River—Comparison Between Ice-On and Ice-Off Periods

Little is known about seasonal differences (ice-on vs. ice-off periods) and the sensitivity of in-stream processes to surface water quality constituents in rivers that have a persistent ice cover in winter. The goal of this study is to investigate the sensitivity of nutrient transformation processes on surface water quality, especially rivers in cold regions where ice-covered conditions persist for a substantial part of the year. We established a sensitivity analysis framework for water quality modelling and monitoring of rivers in cold regions using the Water Quality Analysis Program WASP7. The lower South Saskatchewan River in the interior of western Canada, from the Gardiner Dam at Lake Diefenbaker to the confluence of the North and South Saskatchewan rivers, is used as a test case for this purpose. The study reveals that parameter sensitivities differ between ice-covered and ice-free periods and biological model parameters related to nutrient-phytoplankton dynamics can still be sensitive during the ice-covered season. For example, sediment oxygen demand is an important parameter during the ice-on period, whereas parameters related to nitrification are more sensitive in the ice-off period. These results provide insight into important water quality monitoring aspects in cold regions during different seasons.     

Immobilization of copper ions laden kaolin waste: influence of thermal treatment on its immobilization in cement paste

This work aims to study the influence of thermal treatment of Cu²⁺ laden kaolin wastes on its immobilization efficiency in cement paste. Compressive strength and toxicity characteristic leaching procedure (TCLP) of 5–20 % kaolin waste blended cement pastes were tested. X-ray diffraction (XRD) results illustrate that adsorption of Cu²⁺ ions modify the crystal structure of kaolinite mineral. Fourier transform infrared (FTIR) results indicate that the adsorption sites on the kaolin surface that were occupied with free water molecules have been replaced with Cu²⁺ ions adsorbed from aqueous solutions. The thermal treatment of kaolin waste improves fixation ratio of Cu²⁺ in cement pastes containing up to 20 % of thermally treated waste. This is due to: pozzolanic activity of calcined kaolin, conversion of leachable adsorbed Cu²⁺ ions into encapsulated unleachable phase that does not retard the hydration of cement as well as adsorption of much of leachable Cu²⁺ ions on surfaces of hydration products and occlusion in its lattice structure as illustrated from XRD, FTIR, thermogravimetric, scanning electron microscopy and TCLP results. The fixation ratio of Cu²⁺ in cement paste blended with 20 % of thermally treated kaolin waste, reaches maximum value of about 97 % compared to 82 % for cement paste blended with 20 % of untreated kaolin waste.     

Effect of low-density polyethylene on smoke emissions from burning of simulated debris piles

Low-density polyethylene (LDPE) plastic is used to keep piled debris from silvicultural activities—activities associated with development and care of forests—dry to enable efficient disposal by burning. The effects of inclusion of LDPE in this manner on smoke emissions are not well known. In a combustion laboratory experiment, 2-kg mixtures of LDPE and manzanita (Arctostaphylos sp.) wood containing 0, 0.25, and 2.5% LDPE by mass were burned. Gaseous and particulate emissions were sampled in real time during the entire flaming, mixed combustion phase—when the flaming and smoldering phases are present at the same time—and during a portion of the smoldering phase. Analysis of variance was used to test significance of modified combustion efficiency (MCE)—the ratio of concentrations of fire-integrated excess CO₂ to CO₂ plus CO—and LDPE content on measured individual compounds. MCE ranged between 0.983 and 0.993, indicating that combustion was primarily flaming; MCE was seldom significant as a covariate. Of the 195 compounds identified in the smoke emissions, only the emission factor (EF) of 3M-octane showed an increase with increasing LDPE content. Inclusion of LDPE had an effect on EFs of pyrene and fluoranthene, but no statistical evidence of a linear trend was found. Particulate emission factors showed a marginally significant linear relationship with MCE (0.05 < P-value < 0.10). Based on the results of the current and previous studies and literature reviews, the inclusion of small mass proportions of LDPE in piled silvicultural debris does not appear to change the emissions produced when low-moisture-content wood is burned. In general, combustion of wet piles results in lower MCEs and consequently higher levels of emissions.

Implications:Current air quality regulations permit the use of burning to dispose of silvicultural piles; however, inclusion of low-density polyethyelene (LDPE) plastic in silvicultural piles can result in a designation of the pile as waste. Waste burning is not permitted in many areas, and there is also concern that inclusion of LDPE leads to toxic air emissions.     

Contamination by organochlorine compounds in the edible tissue of four sturgeon species from the Caspian Sea (Iran)

This study focused on accumulation of organochlorine compounds (OCs), including dichloro-diphenyl-trichloroethanes (DDTs), hexachlorobenzene (HCB), hexachlorocyclohexanes (HCHs), and polychlorinated biphenyls (PCBs) accumulation in the muscle of four sturgeon (Persian sturgeon, Acipenser persicus; Stellate sturgeon, Acipenser stellatus; Ship sturgeon, Acipenser nudiventris and Beluga sturgeon, Huso huso) from the southern Caspian Sea. The DDT group was prominent in all of the sturgeon muscle tested constituting almost half or more of the total organochlorine content. Contaminant concentration generally followed this order: DDTs>PCBs>HCHs>HCB. The OCs concentrations in Beluga sturgeon (H. huso) were the highest and over four times higher than in the next highest species (A. nudiventris). From an ecotoxicological point of view, the concentrations of OCs in experimental fishes do not reflect a comparatively clean and pollution-free environment; however, results from this study shown that the inflow of organic pollutants into the Caspian Sea has been reduced when compared with prior studies. Levels of measured OCs in sturgeon were relatively low, but the level of some OCs in some of the specimens tested exceeded the guidelines for food; therefore, the maximum allowable daily consumption rate for sturgeon from this watershed may be limited by DDTs and PCBs content for high risk populations.     

Anaerobic co-digestion of wine/fruit-juice production waste with landfill leachate diluted municipal sludge cake under semi-continuous flow operation

Anaerobic co-digestion of four organic waste streams; a thickened waste activated sludge (TWAS) and screen cake (SC) from a fruit-juice/winery wastewater treatment plant along with municipal sludge cake (MC) and landfill leachate (LL) was evaluated. A total of eight semi-continuously-fed single and co-digesters were operated side-by-side at sludge retention times (SRT) of 20 and 10 days. Co-digestion of industrial waste streams (TWAS and SC) with MC and LL resulted in increased operational stability compared to the single digestion of industrial TWAS at the higher organic loading (10 d SRT). Although digester operational temperature had no statistically significant effect on organics removal and biogas production, mesophilic digesters had consistently higher total coliform densities (8838–37,959 most probable number or MPN/g-dry weight) compared to the thermophilic digesters (41–6723 MPN/g-dry weight) at both SRTs. Coliform analysis results also proved that most of the thermophilic digestates could be classified as Class A biosolids according to regulations. Furthermore, addition of industrial TWAS to co-digesters enhanced the dewaterability of the digested streams. A cost-benefit analysis confirmed the benefits and indicated that a full-scale co-digester utilizing all four waste streams can decrease the total capital and operational cost by 22% ($10.52 million).     

Chemical and biological release of 14C‐bound residues from soil treated with 14C‐p,p'‐DDT

Abstract

¹⁴C‐p,p'‐DDT‐bound residues in soil can be released by treatment with concentrated sulphuric acid at ambient temperatures. Within 6 days, about 70% of the bound residues was released. Bound residues released after 9 months incubation with ¹⁴C‐DDT showed the presence of DDT and DDE only while bound residues released after 18 months, contained in addition 13% DDD.

Release of bound ¹⁴C‐residues also occurs readily following inoculation of the soil‐bound residues with fresh soil or with individual microorganisms. Almost complete release of bound residues was observed after incubation for 45 days. The rate of release was rapid during the first two weeks and decreased thereafter. TLC and HPLC analysis showed that the released residues contained DDE (about 80%) and a smaller amount of DDD. The disappearance of DDT from the released residues may be attributed to its microbiological degradation to DDE and DDD, shortly after its release.