Bioavailability of copper,cadmium, zinc,and lead in tropical savanna soils assessed by diffusive gradient in thin films (DGT) and ion exchange resin membranes

The technique of diffusion gradient in thin films (DGT) for assessing bioavailable metals has not been tested under field conditions. We assessed the relationships of DGT- and cation exchange resin-membrane-measured concentrations of Cd, Cu, Pb, and Zn with plant uptake of the metals under greenhouse and field conditions. In the greenhouse, the effective concentrations of Cu, Pb, and Zn by DGT correlated significantly with uptake by sorghum (Sorghum bicolor), but cation exchange resin-membrane-measured concentrations of Cd, Pb, and Zn did not correlate with sorghum uptake. In the field, the DGT-measured concentrations of Cd, Pb, and Zn were not linearly related to uptake Cd, Pb, and Zn by lettuce (Lactuca sativa) except for Cu uptake (r = 0.87, p < 0.05). Similarly, it was only the resin-membrane-extractable Pb that correlated with Pb uptake by lettuce (r = 0.77; p < 0.05). However, fitting non-linear regression models improved the plant metal uptake predictions by DGT-measured bioavailable Cd, Cu, Pb, and Zn under field conditions. In conclusion, the DGT technique was fairly predictive of bioavailability in the greenhouse, but not in the field.     

Fuzzy logic modeling of bioaccumulation pattern of metals in coastal biota of Ondo State,Nigeria

The accumulation patterns of ten metals in tissues of plant, Eichornia crassipes, and fishes, Hydrocynus forskahlii and Oreochromis mossambicus, were modeled with simple fuzzy classification (SFC) to assess toxic effects of anthropogenic activities on the coastal biota. The plant sample was separated into root, stem, and leaves and the fishes into bones, internal tissues, and muscles. They were analyzed for As, Cd, Cr, Cu, Ni, Pb, V, Fe, Mn, and Zn after wet oxidation of their dried samples. The results were converted into membership functions of five accumulation classes and aggregated with SFC. The classification results showed that there was no metal accumulation in the plant parts while the fishes were classified into low accumulation category. The internal tissues of the fishes had higher metal accumulation than the other parts. Generally, Fe and Mn had highest concentrations in the biota but are natural to the area and may not constitute significant risk. Cr had the highest transfer and accumulation from the coastal water into the aquatic lives and may be indicative of risk prone system being a toxic metal. Metal contaminations in the zone had not significantly accumulated in the biota making them less prone to risk associated with metal accumulation.     

Multivariate analysis of potentially toxic metals in sediments of a tropical coastal lagoon

Surface sediments collected from the Lagos Lagoon, Nigeria, and three adjoining rivers were analysed for their physicochemical properties and pseudo-total concentration of the potentially toxic metals (PTM) Cd, Cr, Cu, Pb and Zn. The concentration of the PTM varied seasonally and spatially. Odo-Iyaalaro was observed to be the most polluted river, with highest concentrations of 42.1 mg kg^?1, 102 mg kg^?1, 185 mg kg^?1, 154 mg kg^?1 and 1040 mg kg^?1 of Cd, Cr, Cu, Pb and Zn, respectively, while Ibeshe River was the least contaminated, apart from a site affected by Cu from the textile industry. Some of the sediments were found to be above the consensus-based probable effect concentrations and Dutch sediment guideline for metals. Overall metal concentrations were similar to those reported for other tropical lagoon and estuarine systems affected by anthropogenic inputs as a result of rapid urbanisation. Due to the large number of samples, principal component analysis was used to examine relationships within the data set. Generally, sediments collected during the dry season were observed to have higher concentration of PTM than those collected during the rainy season. This means that PTM could accumulate over a prolonged period and then be released relatively rapidly, on an annual basis, into tropical lagoon systems.     

Effects of aqueous suspensions of titanium dioxide nanoparticles on Artemia salina: assessment of nanoparticle aggregation, accumulation, and toxicity

Aquatic stability and impact of titanium dioxide nanoparticles (TiO₂ NPs, 10–30 nm) were investigated using Artemia salina. Acute exposure was conducted on nauplii (larvae) and adults in seawater in a concentration range from 10 to 100 mg/L TiO₂ NPs for 24 and 96 h. Rapid aggregation occurred in all suspensions of TiO₂ NPs to form micrometer size particles. Yet, both nauplii and adults accumulated the aggregates significantly. Average TiO₂ content in nauplii ranged from 0.47 to 3.19 and from 1.29 to 4.43 mg/g in 24 and 96 h, respectively. Accumulation in adults was higher ranging from 2.30 to 4.19 and from 4.38 to 6.20 mg/g in 24 and 96 h, respectively. Phase contrast microscopy images revealed that Artemia were unable to excrete the particles. Thus, the TiO₂ aggregates filled inside the guts. No significant mortality or toxicity occurred within 24 h at any dose. Lipid peroxidation levels characterized with malondialdehyde concentrations were not statistically different from those of the controls (p?>?0.05). These results suggested that suspensions of the TiO₂ NPs were nontoxic to Artemia, most likely due to the formation of benign TiO₂ aggregates in water. In contrast, both mortality and lipid peroxidation increased in extended exposure to 96 h. Highest mortality occurred in 100 mg/L TiO₂ NP suspensions; 18 % for nauplii and 14 % for adults (LC₅₀?>?100 mg/L). These effects were attributed to the particle loading inside the guts leading to oxidative stress as a result of impaired food uptake for a long period of time.     

Thermally Stable Pyrolytic Biocarbon as an Effective and Sustainable Reinforcing Filler for Polyamide Bio-composites Fabrication

Natural fibers are limited in their use as reinforcement to commodity polymers. They cannot be used to reinforce engineering polymers due to their low thermal stability at high processing temperatures. This study presents an approach to successfully reinforce polyamides using a derivative of natural fibers as reinforcement without the effects of thermal degradation during melt processing. Biocarbon from miscanthus fibers was used to reinforce polyamide 6 up to 40 wt%. At 40 wt% filler content, the tensile and flexural strengths increased by 19.6 and 47% respectively in comparison to the neat polyamide. The moduli were also increased by 31.5 and 63.7% respectively. A maximum increase in impact strength of 43.7% was achieved at 20 wt% biocarbon loading. The morphology of the tensile fractured samples showed stretched polyamide ligaments attached to the biocarbon particles, indicating the presence of interaction between filler and matrix. Interestingly, more bonded interfaces were observed between the polyamide and biocarbon particles with increasing biocarbon content possibly stemming from increased biocarbon surfaces with functional groups. These composites show great potential to substitute in part or whole, some particulate filled polyamides currently used in the automotive industry.     

The search for an alternative to piped water and sewer systems in the Alaskan Arctic

Forty-two communities in rural Alaska are considered unserved or underserved with water and sewer infrastructure. Many challenges exist to provide centralized piped water and sewer infrastructure to the homes, and they are exacerbated by decreasing capital funding. Unserved communities in rural Alaska experience higher rates of disease, supporting the recommendation that sanitation infrastructure should be provided. Organizations are pursuing alternative solutions to conventional piped water and sewer in order to maximize water use and reuse for public health. This paper reviews initiatives led by the State of Alaska, the Alaska Native Tribal Health Consortium, and the Yukon Kuskokwim Health Corporation to identify and develop potential long-term solutions appropriate and acceptable to rural communities. Future developments will likely evolve based on the lessons learned from the initiatives. Recommendations include Alaska-specific research needs, increased end-user participation in the design process, and integrated monitoring, evaluation, and information dissemination in future efforts.     

Carbon and nitrogen mineralization in Vertisol as mediated by type and placement method of residue

Selection of appropriate residue application method is essential for better use of biomass for soil and environmental health improvement. A laboratory incubation experiment was conducted for 75 days to investigate C and N mineralization of residues of soybean (Glycine max L.), chickpea (Cicer arietinum L.), maize (Zea mays L.), and wheat (Triticum aestivum L.) placed on the soil surface and incorporated into the soil. The residue of soybean and chickpea had a greater decomposition rate than that of maize and wheat, despite of their placements. Higher rate of decomposition of the residue of soybean and chickpea was recorded when it was kept on the soil surface while soil incorporation of residue of wheat and maize resulted in faster decomposition. Therefore, these findings could be used as guidelines for management of crop residue application in farmland to improve soil and environmental quality.     

Investigating toxic metal levels in popular edible fishes from the South Durban basin: implications for public health and food security

Contamination of the ocean by heavy metals may have ecosystem-wide implications because they are toxic even if present in trace levels, and the relative ease of their bioaccumulation by marine organisms may affect human health, primarily through consumption of contaminated fish. We evaluated metal concentrations in six different popular edible fish species and estimated the potential health risks from consumption of contaminated fish. There was no correlation between fish length and average metal accumulation although the fish species tended to accumulate significantly more Al and Zn (P?<?0.05) than any of the other metals. Significantly higher Mn concentrations were found in fish gills compared to other body parts in all fish species. Bronze seabream, Catface rockcod, and Slinger seabream had significantly higher mean Cr concentration in the liver than in either the tissues or gills. The highest concentration of Zn in fleshy tissue was in Horse mackerel (56.71 μg g^?1) followed by Bronze seabream (31.07 μg g^?1). Al levels ranged from 5.6 μg g^?1 in Atlantic mackerel to 35.04 μg g^?1 in Horse mackerel tissue while Cu and Cr concentrations were highest in the tissues of Horse mackerel (6.83 and 1.81 μg g^?1, respectively) followed by Santer seabream (3.15; 1.09 μg g^?1) and Bronze seabream (3.09; 1.30 μg g^?1), respectively. The highest tissue concentration of Mn was detected in Bronze seabream (8.23 μg g^?1) followed by Catface rockcod (6.05 μg g^?1) and Slinger seabream (5.21 μg g^?1) while Pb concentrations ranged from a high of 8.44 μg g^?1 in Horse mackerel to 1.09 μg g^?1 in Catface rockcod. However, the estimated potential health risks from fish consumption as determined by the target hazard quotient (THQ) and hazard index (HI) were significantly lower than 1, implying that metals were not present in sufficiently high quantities to be of any health and/or food and security concern in the studied fishes.     

A review of regulations and guidelines related to winter manure application

Winter manure application elevates nutrient losses and impairment of water quality as compared to manure applications in other seasons. In conjunction with reviewing global distribution of animal densities, we reviewed worldwide mandatory regulations and voluntary guidelines on efforts to reduce off-site nutrient losses associated with winter manure applications. Most of the developed countries implement regulations or guidelines to restrict winter manure application, which range from a regulative ban to guidelines based upon weather and field management conditions. In contrast, developing countries lack such official directives, despite an increasing animal production industry and concern over water quality. An analysis of five case studies reveals that directives are derived from a common rationale to reduce off-site manure nutrient losses, but they are also affected by local socio-economic and biophysical considerations. Successful programs combine site-specific management strategies along with expansion of manure storage to offer farmers greater flexibility in winter manure management.     

Environmental pollution in Africa

Mining and minerals industries are fast-growing, but at the same time, they have gained more attention due to their impacts over the environment and society. This research aims to provide new insights into the topic of perception and awareness toward sustainability in industrial mining in Brazil. The work included in-depth interviews with a set of companies’ managers/directors focusing in particular on aspects related to the social and environmental dimensions, including communication and relationship with the community, impact assessment and mitigation strategies. The knowledge and use of for formal indicators was also evaluated and analyzed through the proposed Model for Sustainability Assessment of Mining (SAoM model), which was applied to all participating companies. The results put in evidence the existing gap between large and small companies, with these last ones showing lower awareness for the impacts of their activities. The lack of community engagement and of local stakeholders’ involvement, as well as the disregard for actions to mitigate their environmental and social impacts, is the main challenges to be overcome by this sector. The sector has then a long path to go toward sustainability and an active involvement of public institutions is required to allow for its development without compromising locals welfare.