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"Wasserverschmutzung"
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Management and mitigation of acid mine drainage in South Africa : input for mineral beneficiation in Africa
This book ascertains that there are three schools of thought regarding the acid mine drainage (AMD) challenge in South Africa and elsewhere. The first school of thought, is that which has resigned itself to fate. The second school of thought is held by those who have hope that the problem can be managed, albeit with a considerable degree of difficulty. The third school comprises those that are energised to try (on a large scale) the various AMD remediation technologies and innovations brought to the fore by various research and development bodies. This book thus presents multifaceted potential channels for dealing with AMD challenges.
Book
Does size and buoyancy affect the long-distance transport of floating debris?
Floating persistent debris, primarily made from plastic, disperses long distances from source areas and accumulates in oceanic gyres. However, biofouling can increase the density of debris items to the point where they sink. Buoyancy is related to item volume, whereas fouling is related to surface area, so small items (which have high surface area to volume ratios) should start to sink sooner than large items. Empirical observations off South Africa support this prediction: moving offshore from coastal source areas there is an increase in the size of floating debris, an increase in the proportion of highly buoyant items (e.g. sealed bottles, floats and foamed plastics), and a decrease in the proportion of thin items such as plastic bags and flexible packaging which have high surface area to volume ratios. Size-specific sedimentation rates may be one reason for the apparent paucity of small plastic items floating in the world's oceans.
Journal Article
Impact of landfill leachate contamination on surface and groundwater of Bangladesh: a systematic review and possible public health risks assessment
Dumping of solid waste in the non-engineered landfill is very common in the developing countries. Among the different disadvantages of this kind of landfilling, leachate is the major concern to public health, which is a toxic byproduct generated from the landfill; and can percolate to the ground water and consequently migrate in surface water. Using systematic review on published data, the present study endeavors to compare the leachate contamination potential of four major landfills of Bangladesh, named Amin Bazar, Matuail, Mogla Bazar and Rowfabad; which are situated in 3 of the 6 big mega cities of Bangladesh and assessed the effects of leachate leakage on surrounding water body as well as on human health. This study, for the first time calculated the leachate pollution index (LPI) for the landfill sites of Bangladesh and found that the LPI of Matuail landfill site (19.81) is much higher which is comparable to some polluted landfill sites of India and Malaysia. The concentrations of several potentially toxic metals found in the surface and ground water in the vicinity of the landfill sites were above the maximum permissible limit values of department of Environment, Bangladesh and World Health Organization (WHO). The human health risk index for toxic heavy metals in different vegetables and rice grain showed high health risk potential for Pb, Cd, Ni, and Mn. The total carcinogenic risk for Ni and Pb are found very high in the edible plants near those landfill sites, suggesting the risk of Ni and Pb induced carcinogenesis by the consumption of those plants. The present conditions of surface, ground water and agriculture products near the landfill sites of Bangladesh are much frightening to the biota and local inhabitants.
Journal Article
Cyclodextrin-based adsorbents for the removal of pollutants from wastewater: a review
Water is a vital substance that constitutes biological structures and sustains life. However, water pollution is currently among the major environmental challenges and has attracted increasing study attention. How to handle contaminated water now mainly focuses on removing or reducing the pollutants from the wastewater. Cyclodextrin derivatives, possessing external hydrophilic and internal hydrophobic properties, have been recognized as new-generation adsorbents to exert positive effects on water pollution treatment. This article outlines recent contributions of cyclodextrin-based adsorbents on wastewater treatment, highlighting different adsorption mechanisms of cyclodextrin-based adsorbents under different influencing factors. The crosslinked and immobilized cyclodextrin-based adsorbents all displayed outstanding adsorption capacities. Particularly, according to specific pollutants including metal ions, organic chemicals, pesticides, and drugs in wastewater, this article has classified and organized various cyclodextrin-based adsorbents into tables, which could pave an intuitive shortcut for designing and developing efficient cyclodextrin-based adsorbents for targeted wastewater pollutants. Besides, this article specially discusses cost-effectiveness and regeneration performance of current cyclodextrin-based adsorbents. Finally, the challenges and future directions of cyclodextrin-based adsorbents are prospected in this article, which may shed substantial light on practical industrial applications of cyclodextrin-based adsorbents.
Journal Article
Potential health risk and levels of heavy metals in water resources of lead–zinc mining communities of Abakaliki, southeast Nigeria
Heavy metals are potential health risk, especially in mining sites where they deteriorate from sulfide-rich ore bodies. Lead, cadmium, arsenic and mercury are very carcinogenic, while others are toxic. The assessment of the levels of these metals in water resources of the lead–zinc mining communities of Enyigba, Mkpuma Akpatakpa, Ameka, Amorie, Amanchara and Alibaruhu was carried out, and the potential health risk has been investigated. These areas make up the main mining communities of Abakaliki, where active and abandoned mines are located. One hundred and six water samples were analyzed in two seasons using atomic absorption spectrophotometric and ultra-violet/visible spectroscopy. Result indicates levels of Pb2+ > Hg2+ > As2+ > Cd2+ > Mn2+ > Ag2+ > Se2+ > Ni2+ > Cr2+ > Cu2+ in water sources. High levels of Mn2+(63.45 mg/L), Pb2+(11.42 mg/L), Cr3+(14.60 mg/L), Ni2+(1.260), Cd2+(15.67 mg/L), Ag+(6.06 mg/L), Hg2+(2.60 mg/L), As(4.13 mg/L), Se2+(2.68 mg/L), Zn2+(10.53 mg/L) and Co2+(0.9 mg/L) above the WHO recommended standard for drinking water were observed. Only Cu2+ recorded safe concentrations in 100% samples analyzed. Levels of associated metals including Pb2+, As, Hg2+, Se2+ and Cd2+ are higher in groundwater especially in areas close to the active mines; this is due to mineralization in the area. Seasonal analysis shows a decreased concentration of chemical constituents in the rainy season relative to the dry season. Potential health risk is associated with accumulation of toxic heavy metals in tissues including Parkinson disease, arsenicosis, acrodynia, selenoises, Alzheimer’s disease, hair loss, mental imbalance and abortion in women abound in the areas. Alternative water supply sources and sensitization on the potential health risk are highly advocated in these communities.
Journal Article
Adsorption of Acid Blue 92 Dye from Aqueous Solutions by Single-Walled Carbon Nanotubes: Isothermal, Kinetic, and Thermodynamic Studies
The aim of this study was to investigate the adsorption of Acid Blue 92 (AB92) dye onto single-walled carbon nanotubes (SWCNTs). The adsorbent was characterised by SEM, TEM, FTIR, and BET. The study comprised batch experiments conducted under varying conditions of dosage (0.01–0.2 g/L), time (10–180 min), pH (3–11), and dye initial concentration (10–200 mg/L). The optimum removal efficiency of 99.4% was achieved for AB92 at an adsorbent dosage of 0.12 g/L, dye initial concentration of 10 mg/L, pH of 3, and contact time of 75 min. The adsorption was best-fit to the pseudo-second order kinetics and Langmuir isotherm models. The monolayer adsorption capacity (
q
m
) was 86.91 mg/g at 333 K. The activation energy of the system was 16.62 kJ/mol. Thermodynamics analysis revealed that the process was spontaneous (
∆G
0
was between −12.73 and −16.08 kJ/mol) and endothermic (
∆H
0
= 2.51 kJ/mol). The positive
∆S
0
value (0.055 kJ/mol K) also suggests the affinity of the SWCNTs adsorbent for AB92. The mechanism of AB92 dye uptake by SWCNTs was majorly by hydrogen bonds, dipole-induced dipole bonds, London dispersion interactions, π-π acceptor–donor interactions, and the hydrophobic effect. The results reveal that SWCNTs is an effective adsorbent for AB92 removal from industrial effluents and wastewater.
Highlights
• Removal of Acid Blue 92 by single-walled carbon nanotubes (SWCNTs) was examined.
• The SWCNTs at dosage of 0.12 g/L removed 99.4% of the dye within 75 min at pH 3.
• The pseudo-second order kinetics and Langmuir isotherm equations explained the process.
Journal Article
Phytoremediation of heavy metals by four aquatic macrophytes and their potential use as contamination indicators: a comparative assessment
The present study estimated the ability of four aquatic macrophytes (
Eichhornia crassipes
(Mart.) Solms
, Ludwigia stolonifera
(Guill. & Perr.) P.H. Raven
, Echinochloa stagnina
(Retz.) P. Beauv. and
Phragmites australis
(Cav.) Trin. ex Steud.) to accumulate Cd, Ni and Pb and their use for indicating and phytoremediating these metals in contaminated wetlands. Three sites at five locations in the Kitchener Drain in Gharbia and Kafr El-Sheikh Governorates (Egypt) were selected for plant, water and sediment sampling. The water in the Kitchener Drain was polluted with Cd, while Pb and Ni were far below the maximum level of Pb and Ni in the irrigation water. In comparison to the other species,
P. australis
accumulated the highest concentrations of Cd and Ni, while
E. crassipes
accumulated the highest concentration of Pb in its tissues. The four species had bioaccumulation factors (BAFs) greater than one, while their translocation factors (TFs) were less than 1 for most heavy metals, except Cd in the leaf and stem of
E. stagnina
and
L. stolonifera
, respectively, and Ni in the stem and leaf of
E. stagnina
. The BAF and TF results indicated that the studied species are suitable for phytostabilizing the studied heavy metals, except Ni in
E. stagnina
and Cd in
L. stolonifera
, which are suitable for phytoextracting these metals. Significant positive correlations were found between the investigated heavy metals in the water or sediment and the plant tissues. Their high BAFs, with significant proportional correlations, supported the potential of these species to serve as bioindicators and biomonitors of heavy metals in general and in the investigated metals specifically.
Journal Article
Aquatic plants and ecotoxicological assessment in freshwater ecosystems: a review
This paper reviews the current state-of-the-art, limitations, critical issues, and new directions in freshwater plant ecotoxicology. We selected peer-reviewed studies using relevant databases and for each (1) publication year, (2) test plant species, (3) reference plant group (microalgae, macroalgae, bryophytes, pteridophytes, flowering plants), (4) toxicant tested (heavy metal, pharmaceutical product, hydrocarbon, pesticide, surfactant, plastic), (5) experiment site (laboratory, field), and (6) toxicant exposure duration. Although aquatic plant organisms play a key role in the functioning of freshwater ecosystems, mainly linked to their primary productivity, their use as biological models in ecotoxicological tests was limited if compared to animals. Also, toxicant effects on freshwater plants were scarcely investigated and limited to studies on microalgae (80%), or only to a certain number of recurrent species (
Pseudokirchneriella subcapitata
,
Chlorella vulgaris
,
Lemna minor
,
Myriophyllum spicatum
). The most widely tested toxicants on plants were heavy metals (74%), followed by pharmaceutical products and hydrocarbons (7%), while the most commonly utilized endpoints in tests were plant growth inhibition, variations in dry or fresh weight, morpho-structural alterations, chlorosis, and/or necrosis. The main critical issues emerged from plant-based ecotoxicological tests were the narrow range of species and endpoints considered, the lack of environmental relevance, the excessively short exposure times, and the culture media potentially reacting with toxicants. Proposals to overcome these issues are discussed.
Journal Article
Identification of microplastics in wastewater samples by means of polarized light optical microscopy
Many reports state the potential hazards of microplastics (MPs) and their implications to wildlife and human health. The presence of MP in the aquatic environment is related to several origins but particularly associated to their occurrence in wastewater effluents. The determination of MP in these complex samples is a challenge. Current analytical procedures for MP monitoring are based on separation and counting by visual observation or mediated with some type of microscopy with further identification by techniques such as Raman or Fourier-transform infrared (FTIR) spectroscopy. In this work, a simple alternative for the separation, counting and identification of MP in wastewater samples is reported. The presented sample preparation technique with further polarized light optical microscopy (PLOM) observation positively identified the vast majority of MP particles occurring in wastewater samples of Montevideo, Uruguay, in the 70–600 μm range. MPs with different shapes and chemical composition were identified by PLOM and confirmed by confocal Raman microscopy. Rapid identification of polyethylene (PE), polypropylene (PP) and polyethylene terephthalate (PET) were evidenced. A major limitation was found in the identification of MP from non-birefringent polymers such as PVC (polyvinylchloride). The proposed procedure for MP analysis in wastewater is easy to be implemented at any analytical laboratory. A pilot monitoring of Montevideo WWTP effluents was carried out over 3-month period identifying MP from different chemical identities in the range 5.3–8.2 × 10
3
MP items/m
3
.
Journal Article
Occurrence, composition and biological risk of organophosphate esters (OPEs) in water of the Pearl River Estuary, South China
Since the production of brominated flame retardants has been gradually phased out, organophosphate esters (OPEs) are increasingly used as the substitutes. Given their toxicity and water solubility, OPEs may jeopardize the aquatic environment and organisms. Here, we examined the concentration, composition, and biological risk of OPEs in the water collected from the eight major waterways in the Pearl River Delta, a highly industrialized region in China. We found a widespread occurrence of OPEs in this region (∑
9
OPEs: 134 to 442 ng L
−1
), dominated by TCPP, TCEP, and TnBP. Halogenated OPEs were dominant over alkyl and aromatic OPEs. The biological risk of OPEs, mainly contributed by TPhP and TnBP, was low (
RQ
< 0.1). The contamination level of OPEs in the Pearl River Delta was likely associated with the degree of industrial activities. Although OPEs posed low risk to aquatic organisms, more attention should be paid to some OPEs in the future, such as TnBP, due to the high usage and toxicity. Considering the concentrations of OPEs worldwide and their usage, OPEs may become the emerging pollutants of global concern in the next decade.
Journal Article