Development of a hybrid pollution index for heavy metals in marine and estuarine sediments

Heavy metal pollution of sediments is a growing concern in most parts of the world, and numerous studies focussed on identifying contaminated sediments by using a range of digestion methods and pollution indices to estimate sediment contamination have been described in the literature. The current work provides a critical review of the more commonly used sediment digestion methods and identifies that weak acid digestion is more likely to provide guidance on elements that are likely to be bioavailable than other traditional methods of digestion. This work also reviews common pollution indices and identifies the Nemerow Pollution Index as the most appropriate method for establishing overall sediment quality. Consequently, a modified Pollution Index that can lead to a more reliable understanding of whole sediment quality is proposed. This modified pollution index is then tested against a number of existing studies and demonstrated to give a reliable and rapid estimate of sediment contamination and quality.     

Manganese content of Tradescancia species exposed to automotive combustion of methylcyclopentadienyl manganese tricarbonyl in urban and rural landscapes

The purpose of this study is to assess the effect of manganese (Mn) from methylcyclopentadienyl manganese tricarbonyl (MMT) on grass (Tradescancia) species beside the major urban and rural highways in the greater Toronto area. Grass clippings were collected at distances up to 40 m from the roadside of a wooded, weakly exposed site (E+) and two unwooded, highly exposed sites (E++ and E+++) to Mn contamination. Statistical tests, including analysis of variance and correlation coefficients, were used to compare the Mn deposition on grass species with respect to distance and traffic density. A higher deposition of Mn was expected at the highly exposed sites when compared with the weakly exposed site, but a significantly higher concentration of Mn was observed at weakly exposed rural E+ site (Mn = 54.07 microg/g; dry wt) than the highly exposed urban E++ (Mn = 38.17 microg/g; dry wt) and E+++ (Mn = 35.63 microg/g; dry wt) sites. A significant correlation coefficient was found for Mn and traffic density (r2 = 0.311, p = 0.0074) at the weakly exposed site than at the highly exposed (r2 = 0.1589, p = 0.1052) urban sites. These data demonstrate that despite the continuous use of MMT in Canadian gasoline, the levels do not appear to exceed the worldwide tolerable levels (17-334 g/g; dry wt) in grass species inhabiting ecosystems next to major highways in urban regions.     

Electronic waste (e-waste): material flows and management practices in Nigeria

The growth in electrical and electronic equipment (EEE) production and consumption has been exponential in the last two decades. This has been as a result of the rapid changes in equipment features and capabilities, decrease in prices, and the growth in internet use. This creates a large volume of waste stream of obsolete electrical and electronic devices (e-waste) in developed countries. There is high level of trans-boundary movement of these devices as secondhand electronic equipment into developing countries in an attempt to bridge the 'digital divide'. The past decade has witnessed a phenomenal advancement in information and communication technology (ICT) in Nigeria, most of which rely on imported secondhand devices. This paper attempts to review the material flow of secondhand/scrap electronic devices into Nigeria, the current management practices for e-waste and the environmental and health implications of such low-end management practices. Establishment of formal recycling facilities, introduction of legislation dealing specifically with e-waste and the confirmation of the functionality of secondhand EEE prior to importation are some of the options available to the government in dealing with this difficult issue.     

Source apportionment of ultrafine and fine particle concentrations in Brisbane, Australia

Purpose

To investigate the significance of sources around measurement sites, assist the development of control strategies for the important sources and mitigate the adverse effects of air pollution due to particle size.

Methods

In this study, sampling was conducted at two sites located in urban/industrial and residential areas situated at roadsides along the Brisbane Urban Corridor. Ultrafine and fine particle measurements obtained at the two sites in June?CJuly 2002 were analysed by positive matrix factorization.

Results

Six sources were present, including local traffic, two traffic sources, biomass burning and two currently unidentified sources. Secondary particles had a significant impact at site 1, while nitrates, peak traffic hours and main roads located close to the source also affected the results for both sites.

Conclusions

This significant traffic corridor exemplifies the type of sources present in heavily trafficked locations and future attempts to control pollution in this type of environment could focus on the sources that were identified.     

Petroleum hydrocarbons and limiting nutrients in <Emphasis Type="Italic">Macura reptantia</Emphasis>, <Emphasis Type="Italic">Procambarus clarkii</Emphasis> and benthic sediment from Qua Iboe Estuary,Nigeria

The levels of total petroleum hydrocarbons in two commonly consumed benthopelagic shellfishes, Macura reptantia and Procambarus clarkii, harvested from benthic sediment of Qua Iboe Estuary were determined using a gas chromatography with flame-ionization detector. Seventy-two (72) samples each of benthic sediment and the shellfishes were collected monthly between June 2003 and February 2004 covering the peak periods of the wet and dry seasons. Concentrations of hydrocarbons were highly variable and ranged between 5.00 and 232.00 μg/g dry weight of benthic sediment, 3.05 and 11.30 μg/g dry weight of M. reptantia, 1.62 and 9.00 μg/g dry weight of P. clarkii. Pearson’s correlation analysis of total hydrocarbon concentrations in subtidal sediments with levels in the fauna species yielded positive significant (P < 0.05) correlations in M. reptantia (r = 0.737) and P. clarkii (r = 0.924). This is indicative of a long term and chronic accumulation of hydrocarbons in the estuarine ecosystem, reflecting the potential for exposure of the resident biota and the risk to human health.     

Mechanical performance and Taguchi optimization of kenaf fiber/cement-paperboard composite for interior application

Demand for particleboards keeps increasing and as such more trees are fell for its production, engendering deforestation. For the purpose of reducing falling of trees, this study, focused on recycling of waste paper in the development of paperboard as alternative to particleboards used for furniture and interior household applications. Kenaf fiber (KF) was blended at varying proportions of 0, 1, 2, 3, 4, and 5 wt.% with 20 wt.% constant cement and 20 wt.% constant coconut shell powder while the remaining was paper pulp. Board specimen developed were cured for 14, 28, and 90 days and mechanical properties were examined. Results obtained showed that fiber dosage improved bond strength and screw holding strengths as compared with the control mix. Similarly, modulus of rupture was enhanced with KF loading as compared with control mix while 1 to 3 wt.% KF spawned enhancement of modulus of elasticity. However, 4 and 5 wt.% KF led to a reduction in the modulus. Infusion of the fiber enhanced tensile strength from 1 to 3 wt.% content. 14-day and 28-day curing periods were observed to improve properties while the 90-day curing period is detrimental to all properties. Optimization via signal-to-noise ratio revealed an optimum mix of 2 wt.% obtained for fiber and an optimum curing duration of 28 days.

     

Transition to Lead-Free Products in the US Electronics Industry: A Model of Environmental,Technical, and Economic Preferences

The European Union’s Restriction on the Use of Certain Hazardous Substances (Directive 2002/95/EC) targeted at electronic products took effect in 2006. In contrast, the USA has no comparable national policy on these products. To understand corporate responses to policy differences across jurisdictions, we conducted a structured-questionnaire survey of individuals in 109 companies that are representative of the US electronics industry. The results reveal that 70% of these companies have already adopted lead-free solder for electronics with 49% of the total preferring the SnAgCu formulation, despite uncertainties associated with environmental impacts of this alternative alloy. We use a modified life cycle impact assessment method based on endpoint modeling approach to derive weighting factors that represent the respondents’ value system for tradeoffs among environmental impacts. We use a modified fuzzy Technique for Order Preference by Similarity to Ideal Solution approach to evaluate technical criteria dominance in declared preferences. A statistical model of corporate behavior is also presented. The results provide the first systematic framework that accounts for environmental impact, technological challenge, and business strategy concurrently toward formulating a comprehensive national policy for materials selection in electronic products.     

Assessment of Use,Reuse, and End‐of‐Life Disposal and X‐Ray Fluorescence Analysis Screening of Waste Mobile Phones in Nigeria

Insights into consumer behavior, hazards of inappropriate disposal, and opportunities to reclaim valuable resources     

RETRACTED ARTICLE: Biomonitoring fallout <Superscript>137</Superscript>Cs in resident and migratory fishes collected along the southern coast of India and assessment of dose

The globally distributed fallout radionuclide ¹³⁷Cs was monitored in 25 resident and 22 migratory fish species collected from some regions of west and east coast of southern India to establish a baseline data. The samples were collected during June 2008 to June 2009. Higher level of ¹³⁷Cs was noted in planktivorous fishes and lower level in herbivores. A significant variation in ¹³⁷Cs was observed between fishes with different feeding habits and different migratory pattern. Oceanodromic migratory fishes displayed higher cesium levels than other migratory types. Similarly, migratory fishes displayed higher ¹³⁷Cs concentration compared to resident fishes. The overall range of ¹³⁷Cs varied from 0.06 to 0.3 Bq/kg in fishes. The biological concentration varied from 55 to 250. The average external dose rate to fishes was calculated to be 2.7 × 10⁻⁷ μGy/h, while the internal dose rate varied from 8.50 × 10⁻⁶ to 5.27 × 10⁻⁵ μGy/h. The hazard quotient for fishes was found to be less than 1. The average intake of ¹³⁷Cs via fishes to the public was calculated to be 3.5 Bq/year and subsequently the committed effective dose was 0.05 μSv/year. The data obtained were less than global average and comparable to those of many regions.     

Sediment-associated trace and major metals in the headwaters of a tropical reservoir

Bed sediment samples of the two headwaters of a tropical reservoir in Southwestern Nigeria were analysed for some metal concentrations using ICP-OES for a period of one year. Sediment samples were collected bi-monthly from both the lower and upper reaches of the streams from May 2013 to March 2014. Sediment samples were microwave-digested and analysed using ICP-OES. Concentrations of metals were higher in the lower reach than in the upper reach, and wet season concentrations were higher than in the dry season with the exception of Fe and Mn. The annual mean metal concentrations were as follows: Fe (121.72?±?6.82?µg/g); Mn (9.34?±?2.57?µg/g); Na (6.20?±?2.29?µg/g); K (0.65?±?0.57?µg/g); Mg (8.07?±?1.36?µg/g); Ca (13.92?±?2.85?µg/g); Ba (0.17?±?0.17?µg/g); Al (106.54?±?5.55?µg/g); and Se (0.6?±?0.19?µg/g). These values were lower in comparison with the baseline concentrations of elements on the earth’s crust. Contamination assessment of all the metals investigated in this study showed that metals in the bed sediments of the two headstreams had not reached pollution status with the exception of Se.