No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Radionuclide ((226)Ra, (232)Th, (40)K) accumulation among plant species in mangrove ecosystems of Pattani Bay, Thailand
Abstract
Little is known regarding phytoremediation of radionuclides from soil; even less is known about radionuclide contamination and removal in tropical ecosystems such as mangrove forests. In mangrove forests in Pattani Bay, Thailand, 18 plant species from 17 genera were evaluated for radionuclide concentrations within selected plant parts. Two shrub species, Avicennia marina and Pluchea indica, accumulated the highest (232)Th (24.6Bqkg(-1)) and (40)K (220.7Bqkg(-1)) activity concentrations in roots, respectively. Furthermore, the aquatic species Typha angustifolia accumulated highest (232)Th, (40)K and (226)Ra activity concentrations (85.2, 363.5, 16.6Bqkg(-1), respectively) with the highest transfer factors (TFs) (3.0, 2.0, 5.9, respectively) in leaves. Leaves of T. angustifolia had an absorbed dose rate in air (D) over the recommended value (74.8nGyh(-1)) that was considered sufficiently high to be of concern for human consumption.
... Metal concentrations in plant tissue differ among species, indicating their differing capacities for metal uptake and accumulation (Schück and Greger 2020). This implies the important role of an appropriate plant species for phyto-management strategy concerning metal removal (Kaewtubtim et al. 2017). ...
... Furthermore, constructed wetlands (CWs) are an established ecological wastewater treatment method (Stefanakis 2016) and is a known effective and sustainable technology (Kadlec and Wallace 2009;. CWs are simple to manage and do not require chemical additions compared to conventional treatment technologies (Kadlec and Wallace 2009;Stefanakis et al. 2014). ...
... Furthermore, constructed wetlands (CWs) are an established ecological wastewater treatment method (Stefanakis 2016) and is a known effective and sustainable technology (Kadlec and Wallace 2009;. CWs are simple to manage and do not require chemical additions compared to conventional treatment technologies (Kadlec and Wallace 2009;Stefanakis et al. 2014). The aerobic conditions that can be established in the system prevent odor development, oxidize the biological oxygen demand (BOD), and promote the nitrification process (Stefanakis et al. 2014;Gaballah et al. 2017). ...
Though having an economic and ecological impact on Marriott Lake management in Egypt, water hyacinth (Eichhornia crassipes) is an aquatic floating macrophyte with a known phytoremediation potential. In order to assess its remediation potential, pilot floating treatment wetlands (FTWs) with E. crassipes were built in duplicates to evaluate the removal of nutrients and heavy metals from the polluted lake water. The experimental design included units with different water depths (15, 25, and 35 cm; D15, D25, and D35, respectively) and plant coverage (90, 70, 50, and 0%; P90, P70, P50, and P0, respectively). The pilot FTWs were monitored over a 7-day operation cycle to identify the optimum combination of design (plant coverage, water depth) and operation (hydraulic retention time; HRT) parameters needed for maximum BOD5, TN, NH4-N, and TP removal. NH4-N removal reached 97.4% in the D25P50 unit after 3 days, BOD5 75% in the D15P90 after 3 days, TN 82% in the D25P70 after 4 days, and TP 84.2% in the D35P70 after 4 days. The open-water evaporation rate was higher than the evapotranspiration rate in the planted units, probably due to the warm climate of the study area. Metals were also sufficiently removed through bioaccumulation in plant tissues in the order of Fe > Pb > Cu > Ni (62.5%, 88.9%, 81.7%, and 80.4% for D25P50, D25P70, D25P50, and D25P90, respectively), while most of the assimilated metal mass was translocated to the plant roots. The biochemical composition of the plant tissue was significantly different between the shoot and root parts. Overall, the FTW with 70% E. crassipes coverage, 25-cm water depth, and an HRT of 3–5 days was identified as the optimum design for effective remediation of the polluted Marriott Lake in Egypt.
... Both of plants are reported to have the potential for metal accumulation, especially at the top of the soil. According to Kaewtubtim et al. 2017 [8], many species of plants are able to lose metals, especially at the roots. S. portulacastrum is considered a halophyte species that can tolerate and accumulate large amounts of heavy metals and is feasible as phytoremediation for heavy metal contaminants [2]. ...
... Both of plants are reported to have the potential for metal accumulation, especially at the top of the soil. According to Kaewtubtim et al. 2017 [8], many species of plants are able to lose metals, especially at the roots. S. portulacastrum is considered a halophyte species that can tolerate and accumulate large amounts of heavy metals and is feasible as phytoremediation for heavy metal contaminants [2]. ...
... If there are change in the redox potential into oxidation, Cu are easily released from the sediment so that it will be available for biota [13]. Pluchea indica are able to accumulate heavy metals, especially in root and stem [8]. Pluchea indica is suitable for phytoremediation [8]. ...
Mangrove-associated plants can be used as bioindicators of heavy metals pollution in the aquatic environment such as brackish water ponds. The purpose of this research was to know the heavy metals content in roots, stems and leaves of dominant (Pluchea indica and Sesuvium portulacastrum). This research was conducted from January to Juli 2018 in Blanakan Ponds, Subang. Sampling was done using stratified random sampling method. Heavy metals content were analyzed using the Shimadzu 6300 Atomic Absorption Spectrophotometer. Result showed that Pluchea indica and Sesuvium portulacastrum were able to absorb heavy metals. In Pluchea indica, concentration of Zn ranged 9–28 mg/kg. The highest concentration of Zn were found in roots, concentration of Pb ranged 0.24–16 mg/kg. Concentration of Zn in Sesuvium portulacastrum ranged from 6–19 mg/kg, with highest concentration were found in roots, concentration of Pb ranged 0.55–15 mg/kg. Meanwhile, sediments of Zn content (101.27 mg/kg) > Pb (31.27 mg/kg) > Cu (10.88 mg/kg). The bioconcentration factor of Cu in Pluchea indica was > 1 in all of the plant parts (roots, stems and leaves), while Sesuvium portulacastrum was only high in roots. Translocation factors higher than 1 were mostly found in Pluchea indica than Sesuvium portulacastrum. It is important to study the possibility of Pluchea indica as bioindicator and accumulator of heavy metals.
... To some extent, constructed wetlands are considered a practical method for pollution control and waste management (Horne 2000). Eichhornia crassipes and T. angustifolia are known to have phytoremediation potential for various contaminants such as heavy metals and radionuclides (Kaewtubtim et al. 2016(Kaewtubtim et al. , 2017Mishra and Maiti 2017). Generally, a single plant species is screened for its phytoremediation potential; however, synergetic effects from two or more plant species in the same mesocosm should better mimic field conditions as these species grow together naturally and may work synergistically for optimal remediation. ...
... The plants accumulated low quantities of heavy metals. For those species that are grown in contaminated media but take up only low quantities of contaminants, beneficial uses may include alternative energy sources, construction of buildings or furniture, and natural handicrafts (Kaewtubtim et al. 2017). However, high priority must be given to plant species for contaminant phytoremediation, i.e., as hyperaccumulators for phytoextraction or excluders for phytostabilization. ...
... Selection of an effective plant species for metal accumulation must be addressed when using a phytomanagement strategy (Kaewtubtim et al. 2017). Metal concentrations in plant tissue differ among species at the same site, indicating their differing capacities for metal uptake (Deng et al. 2004). ...
The ability of a mixture of Typha angustifolia and Eichhornia crassipes to remove organics, nutrients, and heavy metals from wastewater from a Thailand fresh market was studied. Changes in physicochemical properties of the wastewater including pH, temperature, chemical oxygen demand, dissolved oxygen, biochemical oxygen demand (BOD), total P, TOC, conductivity, total Kjeldahl nitrogen, NO3−-N, NH3-N, and metal (Pb, Cd, and Zn) concentrations were monitored. In the aquatic plant (AP) treatment, 100% survival of both species was observed. Dry biomass production and growth rate of T. angustifolia were approximately 3.3× and 2.7× of those for E. crassipes, respectively. The extensive root system of the plants improved water quality as determined by a marked decrease in turbidity in the AP treatment after 7 days. BOD content served as a useful indicator of water quality; BOD declined by 91% over 21 days. Both T. angustifolia and E. crassipes accumulated similar quantities of metals in both roots and shoots. Accumulation of metals was as follows: Zn > Cd > Pb. A study of calorific value and biomass composition revealed that T. angustifolia and E. crassipes possessed similar carbon content (~ 35%), hydrogen content (~ 6%), and gross calorific value. E. crassipes contained up to 16.9% ash and 65.4% moisture. Both species are considered invasive in Thailand; however, they may nonetheless provide practical benefits: In addition to their combined abilities to treat wastewater, T. angustifolia holds potential as an alternative energy source due to its high biomass production.
... Metal concentrations in plant tissue differ among species, indicating their differing capacities for metal uptake and accumulation (Schück and Greger 2020). This implies the important role of an appropriate plant species for phyto-management strategy concerning metal removal (Kaewtubtim et al. 2017). ...
... Furthermore, constructed wetlands (CWs) are an established ecological wastewater treatment method (Stefanakis 2016) and is a known effective and sustainable technology (Kadlec and Wallace 2009;. CWs are simple to manage and do not require chemical additions compared to conventional treatment technologies (Kadlec and Wallace 2009;Stefanakis et al. 2014). ...
... Furthermore, constructed wetlands (CWs) are an established ecological wastewater treatment method (Stefanakis 2016) and is a known effective and sustainable technology (Kadlec and Wallace 2009;. CWs are simple to manage and do not require chemical additions compared to conventional treatment technologies (Kadlec and Wallace 2009;Stefanakis et al. 2014). The aerobic conditions that can be established in the system prevent odor development, oxidize the biological oxygen demand (BOD), and promote the nitrification process (Stefanakis et al. 2014;Gaballah et al. 2017). ...
... The experiments with caesium showed high accumulation in S. portulacastrum (Nikalje et al. 2022) which corresponds well with findings of a high transfer factor for 40 K for S. portulacastrum: 1.5-1.6 (Kaewtubtim et al. 2017). In the case of radioactive contamination, it would be a vulnerable species. ...
... Trees and shrubs in mangrove forests are salt-tolerant with the ability to accumulate heavy metals and natural radionuclides like 40 K (Table 2). Kaewtubtim et al. (2017) recorded a transfer factor of 40 K as high as 1.8 to stems of Avicennia marina. A high transfer factor of 40 K was characteristic of most of the plants growing in the south-Asia mangrove forest. ...
The development of the nuclear industry in the countries of the Arabian Gulf demands an investigation of its potential impact on the environment and human activities. It should involve routine monitoring of radionuclide from existing nuclear facilities as well as modelling of accidental release of radioactivity. Agriculture is usually considered the human activity which is the most endangered with radioactive pollution. Although the traditional concept of low-developed agriculture in the United Arab Emirates has been already described from a radioecological point of view, herein, the recent trends of agriculture are recorded. Due to climatic changes and population increase, the use of saline lands will be more pressing. Apart from it, the risk assessment for nuclear events, which was formed mainly for temperate zones, neglected another aspect of arid zones which is underground water reservoirs refilled with episodic heavy rains. The sandy or saline soils are not an effective barrier for the migration of radionuclide deposited in topsoil. A hypersaline environment could prevent the adsorption of radionuclide on soil particles and allow their high bioavailability for halophyte plants. The new principal challenges in radioecological research in arid zones are impacts on (i) saline agriculture, (ii) underground water reservoirs, and (iii) proposal for countermeasures in order to minimise the impact of radioactive contamination.
... hence, it's essential to estimate the radionuclide concentration in various ecosystems [4]. [1,[3][4][5]9,10,12,[14][15][16][17]19]. ...
... It can be also assumed that the Peruvammba, which joins Arabian sea at Payyanur town may carry the weathered radioactive elements directly into the open sea or the rate of weathering by the river action may be inadequate to transport adequate quantity of radionuclides downstream in a detectable amount. As mangroves have the ability to store and redistribute radionuclides from sediments through root uptake, there is a higher possibility that the sediments were largely absorbed by the plants resulting in lower levels of activity concentration in the collected sediment samples [12]. ...
dionuclides
in the sediments samples collected from the mangrove environs of Payyanur, Kerala by employing 5″× 5″ flat type NaI (Tl) detector. Determination of radiological risk parameters was done and compared with their average values for India and the world. It was found that the mean activity concentrations of 40K, 226Ra, and
232Th were, respectively, 7.2 ± 2.5 Bq kg-1, 2.6 ± 0.9 Bq kg-1, and 13.6 ± 2.8 Bq kg-1. The findings show that the mean activity concentration of 40K, 226Ra, and 232Th and all the radiological parameters are well within the global average values.
... It reflects the plant's ability to transfer the metal element from the roots to the above-ground parts. 45 The BCF and TF were expressed as follows: ...
BACKGROUND
Soil in uranium mining areas is contaminated by uranium and associated heavy metals, posing a significant threat to human health and ecological security. Chelating agent assisted phytoremediation is a cost‐effective and ecologically friendly remediation approach for uranium and associated heavy metals contaminated soil. In this work, a novel slow‐release composite chelating agent (SRCMC‐g‐CMCD‐EDTA/AC) was fabricated using carboxymethyl chitosan‐graft‐carboxymethyl‐β‐cyclodextrin (CMC‐g‐CMCD) as a slow‐release carrier and EDTA/ammonium citrate (AC) as a composite chelating agent through the spray drying method, which was used for phytoremediation of soil co‐contaminated with uranium and chromium.
RESULTS
CMC‐g‐CMCD exhibited superior slow‐release performance for both EDTA and AC in comparison with CMC and CMCD. When applied to soil contaminated with uranium (U) and chromium (Cr), SRCMC‐g‐CMCD‐EDTA/AC effectively regulated the release of U and Cr. Sunflowers (Helianthus annuus L.) grown in treated soil showed a significant increase in U and Cr uptake by 70.55% and 35.55%, respectively, and reduced leaching losses by 34.88% and 37.42%.
CONCLUSION
SRCMC‐g‐CMCD‐EDTA/AC not only assists in the phytoremediation of soil co‐contaminated with U and Cr but also reduces the risk of leaching into groundwater during the soil phytoremediation process. SRCMC‐g‐CMCD‐EDTA/AC‐assisted phytoremediation technology was an effective and environmentally friendly remediation means for the removal of U and heavy metals from contaminated soils in uranium mining areas. © 2024 Society of Chemical Industry (SCI).
... The annual incidence of exposure to these elements in the global population is well known (UNSCEAR 2000). Also well reported worldwide, is the influence of radionuclide activity concentrations in natural ecosystems, the transfer between compartments, and accumulation and biomagnification in certain species (Davies et al. 2018;Dragović and Mandić 2010;IAEA 2010;Kaewtubtim et al. 2017;Narayana and Rajashekara 2010). ...
The 238 U, 226 Ra, 210 Pb, 232 Th, 40 K, and 137 Cs activity concentrations in sand, soil, sediments, and Baccharis trimera were determined by gamma spectrometry. Gross alpha-beta activity and 226 Ra, 228 Ra, and 210 Pb activity concentrations in water were also evaluated. The radionuclide mobility between compartments was assessed, and the transfer factor between soil and vegetation was calculated. In general, 238 U series were not in secular equilibrium with 226 Ra loss and 210 Pb enrichment. The 226 Ra, 228 Ra, and 210 Pb activity concentrations in water were below the detection limit in all analyzed samples. The 210 Pb, 40 K, and 137 Cs activity concentrations in Baccharis trimera and the transfer factor from soil were quantified in different seasons. The 210 Pb transfer factor ranged from 0.41 to 2.33, as affected by precipitation. Finally, 137 Cs could only be identified in samples collected in winter. This work provides a radiological condition baseline of the region of Barra de Valizas-Aguas Dulces, and it will be useful for assessing future effects due to human impact.
... Understanding the behaviour of radionuclides [7][8][9][10][11][12], including concentrations and distribution, can provide useful data for appraising human health risk [13]. As a result of the high population density in Istanbul, it is selected as the study area, considering that there can be a great number of individuals affected by natural radiation. ...
The Cumulative Hazard Index method has been proposed for the first time to determine the low and high-risk levels of radionuclides. The significant radiological parameters and risk analyses for 226Ra, 232Th and 40K pollution levels control in the soil are determined through the probability distribution functions. The activity concentration of 226Ra, 232Th and 40K in samples were found to vary from of 16 ± 0.6 to 62 ± 3.2 Bq kg−1 with an average 30 ± 1.1 Bq kg−1, 24 ± 0.9 to 63 ± 1.3 Bq kg−1 with an average 37 ± 1.0 Bq kg−1 and 316 ± 5.8 to 878 ± 6.9 Bq kg−1 with an average 525 ± 6.2 Bq kg−1, respectively.
... 137 Cs and 40 K are similar in chemical properties, and their geochemistry could be similar because they both have the same valence state, +1, in the last orbit (Marčiulionienė et al., 2015). Some researchers reported 40 K translocation from the soil to the plant (Galhardi et al., 2017;James et al., 2011;Kaewtubtim et al., 2017;Kritsananuwat et al., 2017). ...
This research attempted to investigate the plant/soil concentration ratios (CRs) of 137Cs and 40K in plants that grow on the Anzali Lagoon of the Caspian coast, Iran. The activity concentrations of 137Cs and 40K were measured in soil samples, annual plants (Echinochloa crus-galli, Digitaria sanguinalis, and Trifolium repens), and perennial plants (Phragmites australis, and Cynodon dactylon). The relationship of activity concentration with soil particle density, and pH of soil samples, CR, and 137Cs/40K discrimination factor (DF) were determined. The activity concentration of 137Cs in the soil, annual plants, and perennial plants ranged between 12- and 124 (Bq/kg dry weight), 2- and 17 (Bq/kg dw), and 2 - and 14 (Bq/kg dw), respectively. The geometric mean (GM) values of DF in annual and perennial plants were 0.57 and 0.55, respectively. The CR for 137Cs and 40K varied as a non-linear relation in annual plants and perennial plants. This study showed that the CRs for 137Cs in annual plants were higher than the CRs for perennial plants.
... In fact, the selection of the appropriate species demonstrated to be one of the most 832 challenging tasks, as plants need to be hypertolerant to toxic elements and frequently 833 to poor and degraded soils, hyperaccumulators and, depending on site specific 834 situations and management targets, they also need to have a fast growth rate, high 835 biomass production and resistance to diseases and pests (Watanabe 1997 Wang et al. 2017a). Several promising results were obtained, but a 840 compilation of available data demonstrates, that it will be difficult to find a species 841 with similar accumulation abilities, for different radionuclides and metals (Gouthu et al. 1997;Kaewtubtim et al. 2017; X. Wang et al. 2017a, b), thus an in situ 843 phytoextraction strategy, for many contaminated soils, will always require a multi- 844 species approach. The selection of different species, with different niches, even if 845 they are poor accumulators or excluders (with low roots to shoots translocation), but 846 hypertolerant to contamination, will also contribute to establish of hyperaccumulator 847 plants and also to reestablish soil functions ( Pinheiro et al. 2013;Kaewtubtim et al. 848 2017) (Fig. 3). ...
The release of radionuclides in the environment is of major concern. Radionuclides arise mainly from nuclear power production, nuclear accidents, nuclear weapons testing, uranium mining and processing and nuclear waste disposal. Remediation of the affected areas is urgently needed, since the presence of these contaminants represents a major human and environmental health concern. Bioremediation and phytoremediation have been considered the eco-friendly alternative to the environmentally problematic remediation of contaminated soils, recovering functions that make some future uses possible. Available studies demonstrate that both methodologies, combined or not with other chemical or physically-based strategies (to mitigate the availability of radionuclides), have the potential to be used inexpensively and effectively in the restoration of contaminated environments. In addition, bioremediation and phytoremediation are environment friendly procedures, and are therefore more accepted by regulatory bodies. In this chapter, the main problems associated to each type of radioactively contaminated site will be identified and the most relevant bioremediation and phytoremediation techniques to deal with this type of contamination, will be reviewed. Furthermore, the advantages and disadvantages of using such techniques will also be discussed with a perspective of identifying knowledge gaps and highlighting new approaches to deal with this challenging issue. The reasons for the existence of few applications in real scenarios of contamination will also be analyzed.
Radioactive pollution has become a cause of concern these days, especially with the growing industrial revolution. After traditional fossil fuels, nuclear power is important for fulfilling the growing needs of the world that leads to the release of radionuclides like uranium (235,238U), cesium (137Cs), neptunium (237Np), plutonium (239Pu), americium (241,243Am), curium (245Cm), strontium (90Sr), barium (133,140Ba), etc. that have long-term radiological and chemical toxicities, which make them hazardous even in small concentrations. They can also pollute the environment to varying degrees. They have long-term negative impacts on human health, including neurological abnormalities, birth deformities, infertility, and numerous types of cancer in different organs. Thus, there is an utmost need for the management and isolation of radioactive waste for the safety of the people and the future of the world. Phytoremediation is the process of removing contaminants from the contaminated site or making sure that the contaminants are less harmful after the process. Some of the phytoremediation approaches known to have mitigated radioactive pollutants include Phytoextraction, Phytodegradation, Phytostabilization, Phytovolatilization, Rhizofilteration, and/or a combination of these methods. A few of the plant species that have been reported for radionuclide phytoremediation include Triticum, Calotropis, Brassica, Helianthus, Catharanthus, Eichhornia, etc. Compared to existing remediation technologies, phytoremediation is more economical and environmentally beneficial. However, there are still some challenges that need to be addressed for more commercial applications of these methods such as the selection of suitable plant species, slower and long-term low performance, seasonal factors, applicability for contaminants deep in the soil, proper disposal, and management of plant due to potential chance of spread of more invasive plant species. Along with that, these approaches may face regulatory hurdles and public skepticism due to concerns about potential exposure to contaminants, negative effects on local communities and individuals near the contaminated sites, and long- term effects on the ecosystem and local biodiversity due to the risks associated with these remediation methods. Addressing these challenges will require ongoing study, technological developments, and a case-by-case assessment of phytoremediation’s feasibility for specific radioactive contaminants and environmental conditions. With ongoing research being continuously explored in this field, phytoremediation is projected to assume a growing function in the wider picture of environmental remediation, providing a sustainable and natural solution to the challenges faced by radioactive contaminants. The present study aims to present a comprehensive review exploring the pivotal role of plants in mitigating the threat of radioactive pollutants through phytoremediation elucidating its fundamental principles, mechanisms, hyperaccumulating plant species, addressing present challenges, and future research directions for phytoremediation to tackle this critical environmental concern.
Radioactive radium (Ra) mainly comes from the mining and milling of uranium and other metal or non-metal mines, phosphate production and fertilizer use, production of oil and gas, coal combustion, wastewater treatment, and various wastes from the above activities, which is ubiquitous in the environment. Phytoremediation is a green and cheap remediation technology for metal/radionuclide-contaminated sites. Radium is often of particular interest and there are many literatures on parameters of Ra concentration in plants and transfer factors from soil to plant from a radiological impact assessment point of view. However, review articles on phytoremediation of Ra-polluted soil are relatively few. This review focused on radium-polluted soil phytoremediation, involving two main strategies of phytoextraction and phytostabilization, which covered the potential (hyper)accumulators for Ra, characteristics of Ra uptake from soil by plants, influencing factors, and phytostabilization application. In future research works, more attention should be paid to the deep insights and mechanism researches of Ra uptake/immobilization by plants. This review will deepen the understanding of the relationship of radium-soil-plants, and to enhance the potential application of phytoremediation as an alternative treatment technology for remediation of Ra-polluted soil site.
High contamination of soils with heavy metals, mainly due to increasing anthropogenic activity, significantly contributed to the reduction of soil fertility worldwide and has an adverse impact on crop production and non-target organisms. In addition, toxic metals accumulating in the consumable parts of plants in quantities exceeding permissible levels pose a serious risk to human and animal health. Phytoremediation presents an environment-friendly green approach to clean areas contaminated with toxic metals. Metal-tolerant medicinal and aromatic plants have been found to be suitable candidates for this purpose because they can grow on metal-contaminated soils without significant adverse effects on plants, whereas the metal-induced stress has a positive effect on the quantity and possibly also on the quality of the essential oil without translocation of metals into essential oil, which ensures an economic profit of such a solution. In this chapter, attention is focused on the impact of heavy metals on the growth and physiological and biochemical characteristics of plants, classification of plants in terms of metal accumulation capacity, phytoremediation techniques and the impact of soil metal contamination on the yield of essential oils of medicinal and aromatic plants. The potential of individual medicinal and aromatic plants (herbs, succulents, shrubs and trees) for decontamination of soils polluted with heavy metals by phytoextraction or phytostabilization and the impact of microorganisms and chelating agents on the phytoremediation efficiency is discussed. The pharmacological activities of some medicinal shrubs and trees are briefly mentioned as well.
Lead (Pb) is a major toxicological concern of the present day that demands immediate attention. The use of aquatic macrophytes with high Pb tolerance and accumulation may be a very convenient and economically viable solution for remediating Pb. We examined the ability of Salvinia cucullata, Alternanthera sessilis, Lemna minor, and Pistia stratiotes to remove 0.12 mM, 0.24 mM, 0.36 mM, and 0.48 mM Pb for 96-h under hydroponic cultivation system. The plants accumulated variable amounts of Pb: S. cucullata > A. sessilis > P. stratiotes > L. minor, with low mobility of Pb from root to shoot. Lead uptake kinetics were monitored up to 96-h. After 96-h, the uptake efficiency for S. cucullata (98–99%), A. sessilis (79–96%), L. minor (45–79%), and P. stratiotes (40–76%) was noted. For S. cucullata and A. sessilis, an extremely high uptake rate was seen within the initial 24-h of trials, followed by slower uptake till 96-h. P. stratiotes and L. minor worked best at 0.12 mM Pb. Pb-Phytotoxicity became prominent at 0.48 mM exposure with biomass loss and morphological changes. The plants had a quick growth rate, extensive root system, high biomass yield, and the ability to tolerate and accumulate Pb that made them suitable for phytoremediation purposes.
NOVELTY STATEMENT: Lead phytoremediation potential of four aquatic macrophytes found in Indian waters was evaluated. These macrophytes, often considered as weeds, could be used for phytoremediation purposes that would turn out to be a sustainable means of the utilization of natural resources in developing countries like India. In this study, not only metal accumulation by plants but also the lead uptake kinetics at several time intervals and valuable growth attributes were estimated to establish the suitability of these plants as probable lead phytoremediators. Two of the plant species, Salvinia cucullata, and Alternanthera sessilis, showed excellent Pb accumulation capacities that had not been reported earlier, to the best of our knowledge. The work is all the more significant as there have been needs for identifying Pb-phytoremediators well suited to native climate and growth conditions that could take up large amounts of metal from the substratum.
Certain plants have demonstrated the capability to take up and accumulate metals, thus offering the potential to remediate metal-contaminated water and sediment. Several aquatic species have further been identified which can take up metal and metal oxide engineered nanoparticles (ENPs). It is important to evaluate if aquatic plants exhibiting potential for metal phytoremediation can be applied to remediation of metallic ENPs. Understanding the interactions between ENPs and aquatic plants, and evaluating possible influences on metal uptake and phytoremediation processes is therefore essential. This review article will address the feasibility of green plants for treatment of ENP-affected aquatic ecosystems. Discussion will include common types of ENPs in current use; transformations of ENPs in aquatic systems; the importance of microorganisms in supporting plant growth; ENP entry into the plant; the influence of microorganisms in promoting plant uptake; and recent findings in phytoremediation of ENP-affected water, including applications to constructed wetlands.
This study determines uptake and accumulation of radionuclides and heavy metals by Pluchea indica and Avicennia marina and evaluates phytoremediation potential via greenhouse and field experiments. P. indica and A. marina are considered excluders for40K and262Ra, and Pb since roots accumulated them in higher quantities compared to other plant parts, and the bioconcentration factor (BCF) and transfer factor (TF) values for Pb, and40K and262Ra were >1, respectively. Absorbed dose rate in air (D) showed significant values in sediments, which were generally over the maximum recommended value of 55nGyh-1. Phytostabilization of radionuclides and heavy metals may serve as an appropriate strategy for mangrove-polluted areas. D values in sediments were considered sufficiently high to recommend long-term monitoring. Radionuclide activities may increase in the food chain via uptake and accumulation of edible plants, ultimately resulting in harm to human health.
A study of natural radioactivity of Rock, Sediment, and Building samples collected from different areas of Sikiti settlement, in southwestern Nigeria was carried out via gamma-ray spectrometry, using NaI (Tl) detector. The mean Activity concentration of 40 K, 226 Ra and 232 Th in Rock samples was 935.05 ± 702.08 BqKg-1 , 3.04 ± 5.44 BqKg-1 and 271.69±301.04 BqKg-1 respectively. Mean Activity concentration of 40 K, 226 Ra and 232 Th in Building samples was 426.95±129.19 BqKg-1 , 28.15 ± 16.93 BqKg-1 and 107.30±23.83 BqKg-1 respectively, while Sediments samples had 426.03±137.50 BqKg-1 , 28.52±10.03 BqKg-1 and 30.32±15.35 BqKg-1 concentrations respectively. The external and internal hazard indices for rock samples were above permissible limit (i.e. >1). Also the external and internal hazard indices for sediment and building material samples were below permissible limit (i.e. <1). Therefore, rocks, sediments, and building materials found in Sikiti settlement may be used by farmers, miners and residents of the area with a lot of caution, to prevent radiation exposure which may result from long term cumulative effect.
Expansion of land use in coastal areas results in natural resources being degraded, particularly by soil and water pollution. The objectives of this study were to assess land-use patterns and determine the influence of land-use types on soil heavy-metal contamination in Pattani Bay, Thailand. In studying land use, high-resolution SPOT satellite images were used and analyzed using ArcView GIS 3.2a and ENVI 3.5 software. Collections from 16 soil-sampling sites with topsoil and subsoil layers (0–20 and 21–50 cm in depth) from nine land-use types were carried out during March and April 2006. The heavy metals mercury, lead (Pb), cadmium, arsenic (As), and zinc were analyzed using a Perkin Elmer Optima 2100 DV. Results found that land uses in 2006 were mainly dominated by agricultural, residential, and mangrove-forest areas. In agricultural areas, paddy field were the main land use, followed by shrimp farms. In residential areas, most land was used for living, infrastructure, and industry. Land-use types affected soil pollution in different ways. Municipality areas, industrial zones, and dockyard areas had the highest potential for soil contamination by heavy metals, particularly Pb and As, while shrimp farming and traditional land uses such as salt flats, paddy fields, orchards, and mangrove forests showed low levels of metals. At the dockyard and Pattani River–mouth sampling sites, Pb was recorded in high concentrations of 385.77 and 557.15 mg/kg, respectively; the latter exceeds the soil quality standards of the United States Environmental Protection Agency soil screening levels for residential areas (400 mg/kg). A high concentration of As was found at the dockyard, Pattani River mouth, and industrial zone (4.46, 4.75, and 3.48 mg/kg, respectively), while the EPA standard is not to exceed 4.0 mg/kg. The results indicate that using coastal lands without planning and good management negatively influences soil resources degradation, especially in the area of soil pollution.
The study deals with the accumulation of Pb, Zn and Cd in an important mangrove species, Avicennia marina (Forssk.) Vierh., in the Vamleshwar mangrove ecosystem, near Narmada estuary, West coast of Gujarat, India with height differences of 0.5, 1.5, 2.5 meters and carried out under field conditions during October, 2009. The site was located on 21�30�11.55�� N latitude and 72�43�53.68�� E longitude. Mangrove receives heavy metal pollution from upstream areas of Narmada estuary and highly populated settlements. However, little is known about the capacity of mangrove plants to take up and store heavy metals in them. Water, sediment and plant parts such as roots, stems and leaves were analyzed for finding the trace metal accumulation of different height groups by Inductive Coupled Plasma Analyser (ICPA). Amount of the content of metals found in the water, sediment and plant parts were in the order of Pb>Zn>Cd. The average contents of heavy metals in the waters were 57.83 mg l-1 for Pb, 3.89 83 mg l-1 for Zn and 0.42 mg l-1 for Cd. It was observed that the average contents of Pb (73.6 mg l-1), Zn (8.1 mg l-1) and Cd (0.73 mg l-1) in the sediments were below the critical soil concentrations. The concentrations of heavy metals in different parts of Avicennia marina were in the order Roots>stem>leaf except for Cd, but Cd found higher in leaf. The ranges of the content of heavy metals in plants were 18.5-102.2 mg l-1 for Pb, 3.5-19.5 mg l-1 for Zn and 0.2-4.1 mg l-1 for Cd. The concentrations of all heavy metals in Avicennia marina except Pb were falling within the normal range and were much more in the plants have the highest height. The present study has shown the potential of Avicennia marina as a phytoremediation species for selected heavy metals in many mangrove ecosystems.
Soil contamination by cadmium (Cd) poses a serious environmental and public health concern. Phytoremediation, i.e., the use of plants to remove contaminants from soil, has been proposed for treatment of Cd-contaminated ecosystems. In this study, we demonstrated the potential of Vetiveria zizanioides, commonly known as vetiver, to serve as an effective phytoremediation agent. Two ecotypes, i.e., India and Sri Lanka, were grown in greenhouse pots and in the field. Soils were amended with cow manure, pig manure, bat manure, and an organic fertilizer. Among all amendments, pig manure performed best in both greenhouse and field studies in terms of increasing total V. zizanioides biomass production in both ecotypes. In both greenhouse and in the field, tissue of the Sri Lanka ecotype had higher Cd concentrations than did the India ecotype. In the greenhouse, the presence of Cd did not affect total biomass production or root dry weight. The Sri Lanka ecotype had 2.7 times greater adventitious root numbers and 3.6 times greater Cd accumulation in roots than did the India ecotype. In the field study, the Sri Lanka ecotype offers potential as an excluder species, as it accumulated Cd primarily in roots, with translocation factor values <1 and a bioconcentration coefficient for roots >1 for all experiments except for the pig manure amendment. In addition, the highest Cd concentration in the Sri Lanka ecotype root (71.3 mg kg(-1)) was consistent with highest Cd uptake (10.4 mg plant(-1)) in the cow manure treatment. The India ecotype contained lower root Cd concentrations, and Cd accumulation was slightly higher in shoots compared to roots, with translocation factor (TF) values >1. The India ecotype was therefore not considered as an excluder in the Cd-contaminated soil. With the use of excluder species combined with application of organic amendments, soil contamination by Cd may be treated by alternative remediation methods such as phytostabilization.
Greenhouse and field experiments were conducted to evaluate the influence of three different organic amendments (cow manure, pig manure, and organic fertilizer) on the Cd phytostabilization potential of Eucalyptus camaldulensis grown on Cd-contaminated soil. The application of all amendments, particularly organic fertilizer, improved plant growth (i.e., height and biomass production) when compared to the control (Cd-contaminated soil alone), in both greenhouse and field experiments. E. camaldulensis treated with organic fertilizer experienced the greatest height (39 cm and 3.8 m) and biomass production (2.0 g and 3.3 kg) in greenhouse and field experiments, respectively. Plants grown on amended soils had lower Cd accumulation than those grown on the Cd soil alone. Among the treatments, organic fertilizer resulted in a translocation factor < 1 and a bioconcentration factor for the root (BCFR) > 1, indicating the potential of this species to stabilize Cd in the roots. The results showed that E. camaldulensis is a promising species for phytostabilization of Cd-contaminated soil. The wood of the mature tree is used in the manufacture of commercial products; given the low Cd uptake by E. camaldulensis, it is feasible to harvest the wood grown on Cd-affected soils for making paper and furniture.
Natural 226Ra, 232Th and 40K radionuclides concentration in beach Sediments along Safaga coast of Red sea, Egypt has been carried out using a NaI (Tl) gamma ray spectrometric technique. The total average concentrations of radionuclides ± uncertainty of 226Ra, 232Th and 40K were 22.2 ± 1.7, 19.2 ± 2.5, and 477.6 ± 27.6 Bq.kg-1, respectively. The total average absorbed dose rate is found to be 41.4 nGyh-1, whereas the annual effective dose rate has an average value of 54 µSvy-1. The total organic matter (TOC), carbonates (CaCo3) and Heavy metals distribution have been measured at some locations, the concentration for the investigated heavy metals overtake the allowable limits recommended by the Canadian Environmental Quality Guidelines, this assigned to the ratio of metals pollution is caused by anthropogenic activities (phosphate shipment as in Abu Tartour harbor and navigation as in Touristic harbor) and or by natural impacts such in mangrove interment. Statistical analyses were carried out between the parameters obtained from the radioactivity to know the existing relations and to study the spatial distribution of radionuclide.
In a mangrove forest in Pattani Bay, Thailand, rhizosphere soil and leaf, stem and root tissue from various plant species were tested for concentrations of Cd, Cr, Cu, Mn, Ni, Pb and Zn. Of these metals, Pb concentrations in the mangrove sediment were somewhat elevated. Mn occurred in highest concentrations in tissue of all mangrove species whereas Cd contents were lowest. Both sediment physicochemical properties (e.g., pH, EC, redox potential) and plant species characteristics have likely influenced metal concentrations in plant tissue. Several mangrove species fit the criteria for excluder plants as they accumulated metals mainly in roots, with a resultant translocation factor (TF) < 1 and a bioconcentration factor (BCF) > 1. These include Cyperus involucratus for Cu, Ipomoea pes-caprae for Zn, Typha angustifolia for Mn, and Phragmites karka for Pb. Furthermore, some species have accumulator potential, as metals accumulated in aboveground biomass (leaves and stem), and have TF > 1 and BCF > 1; however, these species (e.g., Thespesia populnea for Ni and C. involucratus for Cr) did not accumulate metals to the extent that they fit the criteria for hyperaccumulators. Continued investigation of metals in sediment and plant organs must be carried out to determine additional species suitable for phytoremediation, and to ensure healthy food chains in coastal ecosystems.
Two toxic heavy metals, cadmium (Cd(II)) and lead (Pb(II)), in samples of local vegetables were analyzed by graphite furnace atomic absorption spectroscopy (GFAAS). Pak-Leang (Gnetum gnemon Linn.), Pak-Waen (Marsilea crenata Presl.), Mun-Poo (Glochidion littorale Blume Baill.), and Chamuang (Garcinia cowa Roxb.) were from fresh markets in 4 districts namely Muang, Phunphin, Kanchanadit and Ban Na Doem, Surat Thani province. The preparation of samples was carried out by mixed acid digestion procedure in order to extract the heavy metals. From the GFAAS analysis of sample solutions, the average lead contents were as follows: 0.10 ± 0.11 mg kg-1 in Pak-Leang, 0.04 ± 0.07 mg kg-1 in Pak-Waen, 0.14 ± 0.17 mg kg-1 in Mun-Poo and 0.02 ± 0.05 mg kg-1 in Chamuang. The results indicated that the concentrations of lead within these local vegetables were under the maximum allowable level according to the standard of the Ministry of Public Health, Thailand. On the other hand, analysis of cadmium found that 3 certain vegetables including Pak-Waen (0.48 ± 0.27 mg kg-1), Mun-Poo (0.78 ± 0.72 mg kg-1) and Chamuang (0.34 ± 0.27 mg kg-1), were contaminated with cadmium higher than the maximum allowable levels in the average for the standards of Australia-New Zealand, Codex, China and the European Union. The assessment of heavy metal indicated that these accumulation quantities in edible plants could be valuably evident for public concerns and research-based food safety.
Measurements of natural radioactivity levels and heavy metals in sediment and soil samples of the Anzali international wetland were carried out by two HPGe-gamma ray spectrometry and atomic absorption spectroscopy techniques. The concentrations of (235)U, (226)Ra, (232)Th, (40)K, and (137)Cs in sediment samples ranged between 1.05 ± 0.51-5.81 ± 0.61, 18.06 ± 0.63-33.36 ± .0.34, 17.57 ± 0.38-45.84 ± 6.23, 371.88 ± 6.36-652.28 ± 11.60, and 0.43 ± 0.06-63.35 ± 0.94 Bq/kg, while in the soil samples they vary between 2.36-5.97, 22.71-38.37, 29.27-42.89, 472.66-533, and 1.05-9.60 Bq/kg for (235)U, (226)Ra, (232)Th, (40)K, and (137)Cs, respectively. Present results are compared with the available literature data and also with the world average values. The radium equivalent activity was well below the defined limit of 370 Bq/kg. The external hazard indices were found to be less than 1, indicating a low dose. Heavy metal concentrations were found to decrease in order as Fe > Mn > Sr > Zn > Cu > Cr > Ni > Pb > Co > Cd. These measurements will serve as background reference levels for the Anzali wetland.
Mangroves are essential for protecting coastal environments and biodiversity; however few studies encompass the distribution of radionuclides in soils from these ecosystems. By applying high resolution gamma-ray spectrometry, natural radionuclides were quantified in soils from the Chico Science Mangrove and Rio Formoso Mangrove (RFM), areas subjected to different human impacts. The activity concentrations of 226Ra and 228Ra were quite similar for the mangroves despite the differences found for 40K. Moreover, no correlation with the environmental impacts on the mangroves was observed, although RFM soil was 40K-enriched compared to deep sediments from other estuaries in the world.
The importance of biodiversity (below and above ground) is increasingly considered for the cleanup of the metal contaminated and polluted ecosystems. This subject is emerging as a cutting edge area of research gaining commercial significance in the contemporary field of environmental biotechnology. Several microbes, including mycorrhizal and non-mycorrhizal fungi, agricultural and vegetable crops, ornamentals, and wild metal hyperaccumulating plants are being tested both in lab and field conditions for decontaminating the metalliferous substrates in the environment. As on todate about 400 plants that hyperaccumulate metals are reported. The families dominating these members are Asteraceae, Brassicaceae, Caryophyllaceae, Cyperaceae, Cunouniaceae, Fabaceae, Flacourtiaceae, Lamiaceae, Poaceae, Violaceae, and Euphobiaceae. Brassicaceae had the largest number of taxa viz. 11 genera and 87 species. Different genera of Brassicaceae are known to accumulate metals. Ni hyperaccumulation is reported in 7 genera and 72 species and Zn in 3 genera and 20 species. Thlaspi species are known to hyperaccumulate more than one metal i.e. T. caerulescence = Cd, Ni. Pb, and Zn; T. goesingense = Ni and Zn and T. ochroleucum = Ni and Zn and T. rotundifolium = Ni, Pb and Zn. Plants that hyperaccumulate metals have tremendous potential for application in remediation of metals in the environment. Significant progress in phytoremediation has been made with metals and radionuclides. This process involves rising of plants hydroponically and transplanting them into metal-polluted waters where plants absorb and concentrate the metals in their roots and shoots. As they become saturated with the metal contaminants, roots or whole plants are harvested for disposal. Most researchers believe that plants for phytoremediation should accumulate metals only in the roots. Several aquatic species have the ability to remove heavy metals from water, viz., water hyacinth (Eichhornia crassipes (Mart.) Solms); pennywort (Hydrocotyle umbellata L.) and duckweed (Lemna minor L.). The roots of Indian mustard are effective in the removal of Cd, Cr, Cu, Ni, Pb, and Zn and sunflower removes Pb, U, 137Cs, and 90Sr from hydroponic solutions. Aquatic plants in freshwater, marine and estuarine systems act as receptacle for several metals. Hyperaccumulators accumulate appreciable quantities of metal in their tissue regardless of the concentration of metal in the soil, as long as the metal in question is present. The phytoextraction process involves the use of plants to facilitate the removal of metal contaminants from a soil matrix. In practice, metal-accumulating plants are seeded or transplanted into metal-polluted soil and are cultivated using established agricultural practices. If metal availability in the soil is not adequate for sufficient plant uptake, chelates or acidifying agents would be applied to liberate them into the soil solution. Use of soil amendments such as synthetics (ammonium thiocyanate) and natural zeolites have yielded promising results. Synthetic cross-linked polyacrylates, hydrogels have protected plant roots from heavy metals toxicity and prevented the entry of toxic metals into roots. After sufficient plant growth and metal accumulation, the above-ground portions of the plant are harvested and removed, resulting the permanent removal of metals from the site. Soil metals should also be bioavailable, or subject to absorption by plant roots. Chemicals that are suggested for this purpose include various acidifying agents, fertilizer salts and chelating materials. The retention of metals to soil organic matter is also weaker at low pH, resulting in more available metal in the soil solution for root absorption. It is suggested that the phytoextraction process is enhanced when metal availability to plant roots is facilitated through the addition of acidifying agents to the soil. Chelates are used to enhance the phytoextraction of a number of metal contaminants including Cd, Cu, Ni, Pb, and Zn Researchers initially applied hyperaccumulators to clean metal polluted soils. Several researchers have screened fast-growing, high-biomass-accumulating plants, including agronomic crops, for their ability to tolerate and accumulate metals in their shoots. Genes responsible for metal hyperaccumulation in plant tissues have been identified and cloned. Glutathione and organic acids metabolism plays a key role in metal tolerance in plants. Glutathione is ubiquitous component cells from bacteria to plants and animals. In phytoremediation of metals in the environment, organic acids play a major role in metal tolerance. Organic acids acids form complexes with metals, a process of metal detoxification. Genetic strategies and transgenic plant and microbe production and field trials will fetch phytoremediaition field applications. The importance of biodiversity and biotechnology to remediate potentially toxic metals are discussed in this paper. Brassicaceae amenable to biotechnological improvement and phytoremediation hype are highlighted.
Radioactivity concentrations and heavy metal content were measured in soil samples collected from the area of Kragujevac, one of the largest cities in Serbia. The specific activities of (226)Ra, (232)Th, (40)K and (137)Cs in 30 samples were measured by gamma spectrometry using an HPGe semiconductor detector. The average values ± standard deviations were 33.5 ± 8.2, 50.3 ± 10.6, 425.8 ± 75.7 and 40.2 ± 26.3 Bq kg(-1), respectively. The activity concentrations of (226)Ra, (232)Th and (137)Cs have shown normal distribution. The annual effective doses, radium equivalent activities, external hazard indexes and excess lifetime cancer risk were also estimated. A RAD7 device was used for measuring radon exhalation rates from several samples with highest content of (226)Ra. The concentrations of As, Co, Cr, Cu, Mn, Ni, Pb and Zn were measured, as well as their EDTA extractable concentrations. Wide ranges of values were obtained, especially for Cr, Mn, Ni, Pb and Zn. The absence of normal distribution indicates anthropogenic origin of Cr, Ni, Pb and Zn. Correlations between radionuclide activities, heavy metal contents and physicochemical properties of analysed soil were determined by Spearman correlation coefficient. Strong positive correlation between (226)Ra and (232)Th was found.
Land, surface waters, and ground water worldwide, are increasingly affected by contaminations from industrial, research experiments, military, and agricultural activities either due to ignorance, lack of vision, carelessness, or high cost of waste disposal and treatment. The rapid build-up of toxic pollutants (metals, radionuclide, and organic contaminants in soil, surface water, and ground water) not only affects natural resources, but also causes major strains on ecosystems. Interest in phytoremediation as a method to solve environmental contamination has been growing rapidly in recent years. This green technology that involved “tolerant plants” has been utilized to clean up soil and ground water from heavy metals and other toxic organic compounds. Phytoremediation involves growing plants in a contaminated matrix to remove environmental contaminants by facilitating sequestration and/or degradation (detoxification) of the pollutants. Plants are unique organisms equipped with remarkable metabolic and absorption capabilities, as well as transport systems that can take up nutrients or contaminants selectively from the growth matrix, soil or water. As extensive as these benefits are, the costs of using plants along with other concerns like climatic restrictions that may limit growing of plants and slow speed in comparison with conventional methods (i.e., physical and chemical treatment) for bioremediation must be considered carefully. While the benefits of using phytoremediation to restore balance to a stressed environment seem to far outweigh the cost, the largest barrier to the advancement of phytoremediation could be the public opposition. The long-term implication of green plant technology in removing or sequestering environmental contaminations must be addressed thoroughly. As with all new technology, it is important to proceed with caution.
Due to the Fukushima Daiichi nuclear disaster in 2011 and the development of nuclear power plant in neighboring countries such as Vietnam in the near future, radionuclide assessment in marine sediment during 2010 - 2011 may be useful as background levels for radiation protection in Thailand. Marine sediments (10 samples) were collected approximately 1 km away from the coastline along Chonburi to Pattaya, Chonburi Province. The sediments were ground and sieved through 2-mm test sieve after air drying. Radionuclides were measured with a gamma spectrometer equipped with a well-calibrated HPGe detector. The samples were prepared in the same geometry as the reference material. The optimal counting time was 60,000 - 80,000 s for statistical evaluation and uncertainties. No contamination of 137Cs as an artificial radionuclide was found. Naturally-occurring radionuclides including 238U, 232Th and 40K were found. The mean specific activities of 238U, 232Th and 40K were 44 ± 10, 59 ± 17 and 463 ± 94 Bq/kg in the rainy season (2010); 41 ± 6, 50 ± 9 and 484 ± 83 Bq/kg in the winter (2010), and 39 ± 6, 41 ± 7 and 472 ± 81 Bq/kg in the summer (2011), respectively. The mean specific activities were higher than the values in the UNSCEAR report of 35, 30 and 400 Bq/kg for 238U, 232Th and 40K, respectively. From the measured specific activities, the absorbed dose rate, radium equivalent activity, external hazard index and annual external effective dose rate were calculated in order to assess the health risk. No radiation hazards related to the radioactivity in the sediment were expected. The accumulation of radionuclides varied with the particle size and the organic matter content in the sediment. The accumulation of heavy metals showed similar results to that of the radionuclides in the sediment.
Radiation exposure, including the ingestion of radium, has been causally associated with leukemia in man. Groundwater samples from 27 counties on or near Florida phosphate lands were found to exceed 5 pCi/L total radium in 12.4% of measurements. The incidence of leukemia was greater in those counties with high levels of radium contamination (>10% of the samples contaminated) than in those with low levels of contamination. Rank correlation coefficients of 56 and 45 were observed between the radium contamination level and the incidence of total leukemia and acute myeloid leukemia, respectively. The standardized incidence density ratio for those in high-contamination counties was 1.5 for total leukemia and 2.0 for acute myeloid leukemia. Further investigation is necessary, however, before a causal relationship between groundwater radium content and human leukemia can be established.
(JAMA 1985;254:621-626)
Mangrove crabs (Sesarma mederi) can be used as bioindicators of the environment. This study aimed to estimate the heavy metal content in S. mederi in various Thai mangroves and compare them with other studies for international regulations for human consumption. S. mederi were obtained from the mangroves of the Chao Phraya, Tha Chin, and Mae Klong rivers. The concentrations of Cd, Cu, and Pb in the rivers were low compared to the marine standards of Thailand and estuarine water elsewhere. The concentrations of Cd and Cu in sediments were rather similar to those in other rivers. The results showed that crabs accumulated metals in the order: Cd > Cu > Pb > Zn. The bioconcentration factor of Cd and Cu was highest in Mae Klong, while Pb and Zn were highest in Chao Phraya. Although metal concentrations in crabs were within the ranges found in other studies, they exceeded the maximum ranges according to standards. Hence as mangrove crabs are highly consumed as traditional and international Thai food, they may be a potential health hazard for human consumers. Consequently, the use of mangrove crab could be an interesting tool for monitoring estuary pollution.
Papua New Guinea (PNG) is currently experiencing environmental problems relating to mining activities. Despite valuable earnings received from the mining projects in PNG, environment in the mining vicinity is being degraded causing lots of instability on surrounding environment and ecosystems. Phytoremediation is seen to be a cost effective bioremedial solution where plants are used to remove metal contaminants that are being released into the environment by mining operations. The case study alludes to Phragmite karka as an effective plant for absorbing heavy metals (Cd, Cu, Fe, Hg, Pb, and Hg) from mine soil environment. In addition, heavy metals are known to be toxic and causes harm to surrounding environment and ecosystems through bioaccumulation and food chain process. This paper focuses mainly on heavy metals (Cd, Cu, Fe, Hg, Pb, and Hg) that are being absorbed by native Phragmite karka plant species after rehabilitation program of Wau Namie Mine Sites (WNMS) through random sampling and analysis of samples using standard ICP and ASS technique. The results from soil analyses of WNMS have shown significantly high concentrations of heavy metals when compared to European Standard Average Concentrations of heavy metals in soils. However, Phragmite karka have shown positive results of absorbing heavy metals as indicated by the results. This indicates phytoextractive ability and efficiency of plants to absorb and stabilise contaminants within its systems. Furthermore, heavy metal has made the site unfit for introduced plant species in rehabilitated sites to survive. Overall, this case study has revealed that Phragmite karka as the potential phytoremediation plant in soil environment of mine site.
Pot and field experiments were conducted to elucidate the phytostabilization potential of two grass species (Thysanolaena maxima and Vetiveria zizanioides) with respect to lead (Pb) tailing soil. Three fertilizers (Osmocote® fertilizer, cow manure, and organic fertilizer) were used to improve the physicochemical properties of tailing soil. V. zizanioides treated with organic fertilizer and cow manure showed the highest biomass (14.0 ± 2.6 and 10.5 ± 2.6 g per plant, respectively) and the highest Pb uptake in the organic fertilizer treatment (T. maxima, 413.3 μg per plant; V. zizanioides, 519.5 μg per plant) in the pot study, whereas in field trials, T. maxima attained the best performances of dry biomass production (217.0 ± 57.9 g per plant) and Pb uptake (32.1 mg per plant) in the Osmocote® treatment. In addition, both grasses showed low translocation factor (1). During a 1-year field trial, T. maxima also produced the longest shoot (103.9 ± 29.7 cm), followed by V. zizanioides (70.6 ± 16.8 cm), in Osmocote® treatment. Both grass species showed potential as excluder plants suitable for phytostabilization applications in Pb-contaminated areas.
Legumes are important for nitrogen cycling in the environment and agriculture due to the ability of nitrogen fixation by rhizobia. In this review, we introduce an important and potential role of legume-rhizobia symbiosis in aiding phytoremediation of some metal contaminated soils as various legumes have been found to be the dominant plant species in metal contaminated areas. Resistant rhizobia used for phytoremediation could act on metals directly by chelation, precipitation, transformation, biosorption and accumulation. Moreover, the plant growth promoting (PGP) traits of rhizobia including nitrogen fixation, phosphorus solubilization, phytohormone synthesis, siderophore release, and production of ACC deaminase and the volatile compounds of acetoin and 2, 3-butanediol may facilitate legume growth while lessening metal toxicity. The benefits of using legumes inoculated with naturally resistant rhizobia or recombinant rhizobia with enhanced resistance, as well as co-inoculation with other plant growth promoting bacteria (PGPB) are discussed. However, the legume-rhizobia symbiosis appears to be sensitive to metals, and the effect of metal toxicity on the interaction between legumes and rhizobia is not clear. Therefore, to obtain the maximum benefits from legumes assisted by rhizobia for phytoremediation of metals, it is critical to have a good understanding of interactions between PGP traits, the symbiotic plant-rhizobia relationship and metals.
Expansion of land use in coastal areas results in natural resources being degraded, particularly by soil and water pollution. The objectives of this study were to assess land-use patterns and determine the influence of land-use types on soil heavy-metal contamination in Pattani Bay, Thailand. In studying land use, high-resolution SPOT satellite images were used and analyzed using ArcView GIS 3.2a and ENVI 3.5 software. Collections from 16 soil-sampling sites with topsoil and subsoil layers (0-20 and 21-50 cm in depth) from nine land-use types were carried out during March and April 2006. The heavy metals mercury, lead (Pb), cadmium, arsenic (As), and zinc were analyzed using a Perkin Elmer Optima 2100 DV. Results found that land uses in 2006 were mainly dominated by agricultural, residential, and mangrove-forest areas. In agricultural areas, paddy field were the main land use, followed by shrimp farms. In residential areas, most land was used for living, infrastructure, and industry. Land-use types affected soil pollution in different ways. Municipality areas, industrial zones, and dockyard areas had the highest potential for soil contamination by heavy metals, particularly Pb and As, while shrimp farming and traditional land uses such as salt flats, paddy fields, orchards, and mangrove forests showed low levels of metals. At the dockyard and Pattani River-mouth sampling sites, Pb was recorded in high concentrations of 385.77 and 557.15 mg/kg, respectively; the latter exceeds the soil quality standards of the United States Environmental Protection Agency soil screening levels for residential areas (400 mg/kg). A high concentration of As was found at the dockyard, Pattani River mouth, and industrial zone (4.46, 4.75, and 3.48 mg/kg, respectively), while the EPA standard is not to exceed 4.0 mg/kg. The results indicate that using coastal lands without planning and good management negatively influences soil resources degradation, especially in the area of soil pollution.
Abstract. Assemblages of shrimp in association with habitat, season, and environmental parameters were examined.
The tested hypotheses was that habitat, season, and water parameters affect species diversity, density, and community
structure of shrimps in the shallow semi-enclosed tropical bay, Thailand. Samples were collected monthly at fi ve
different habitats with different bottom characteristics and vegetation between February 2011 and January 2012 by
an encircling seine net. Altogether, 32,523 shrimps from 14 species were collected. Acetes sp., Metapenaeus moyebi,
and Metapenaeus lysianassa dominated the catch with 50.6%, 22.0%, and 17.6%%, respectively. Most of them were
juveniles or adults of small sized-species. Both habitat and month had highly signifi cant impacts on density of shrimps
(P<0.005), but only monthly factor affected species richness (P<0.05). Cluster dendogram indicated further that
the difference in community structure of shrimps was based mainly on seasonal impact. Canonical correspondence
analysis (CCA) recorded different responses of shrimp assemblages to specifi c water quality parameters. Water
temperature was the major factor structuring shrimp assemblage in the bay.
Key words. Gulf of Thailand, shrimp ecology, shrimp and environment, decapod crustacean
The focus of this article was to explore the translocation of (109)Cd, (57)Co, (65)Zn, (63)Ni, and (134)Cs via xylem and phloem in the newly found hyperaccumulator Solanum nigrum L. Two experiments with the uptake via the roots and transport of (109)Cd, (57)Co, and (65)Zn labeled by roots, and the redistribution of (109)Cd, (65)Zn, (57)Co, (63)Ni, and (134)Cs using flap label in S. nigrum in a hydroponic culture with a standard nutrient solution were conducted. The results showed that (109)Cd added for 24 h to the nutrient medium of young plants was rapidly taken up, transferred to the shoot, and accumulated in the cotyledons and the oldest leaves but was not efficiently redistributed within the shoot afterward leading to a rather low content in the fruits. In contrast, (57)Co was more slowly taken up and released to the shoot, but afterward, this element was redistributed from older leaves to younger leaves and maturing fruits. (65)Zn was rapidly taken up and transferred to the shoot (mainly to the youngest leaves and not to the cotyledons). Afterward, this radionuclide was redistributed within the shoot to the youngest organs and finally accumulated in the maturing fruits. After flap labeling, all five heavy metals tested ((109)Cd, (57)Co, (65)Zn, (63)Ni, (134)Cs) were exported from the labeled leaf and redistributed within the plant. The accumulation in the fruits was most pronounced for (63)Ni and (65)Zn, while a relatively high percentage of (57)Co was finally found in the roots. (134)Cs was roughly in the middle of them. The transport of (109)Cd differed from that previously reported for wheat or lupin and might be important for the potential of S. nigrum to hyperaccumulate cadmium.
Fifty three samples of different types of imported and locally produced drinks consumed in the central zone of Malaysia were analyzed using gamma-ray spectrometry system equipped with a high purity germanium (HPGe) detector. The activity concentrations of the natural radionuclides 238 U, 232 Th and 40 K present in the studied samples were measured and the radium equivalent activities Ra eq were calculated. In addition, the radiation hazard index (HI) was calculated. The average concentrations of 238 U, 232 Th and 40 K were 0.69 ± 7×10¯ 4 , 1.3 ± 8×10¯ 4 and 20.52 ± 6×10¯ 4 Bq/Kg, respectively. The values of Ra eq were between 0.002 and 10.0 Bq/kg. The HI were between 0.002 and 0.03, which is below one (the higher limit of HI). The results obtained were compared to the standard accepted international values and found to be within the acceptable limits. Keywords: Activity concentration; NORM; radiation hazard index; radium equivalent; 238 U, 232 Th and 40 K ABSTRAk Lima puluh tiga sampel daripada pelbagai jenis minuman tempatan dan import yang terdapat di zon tengah Malaysia dianalisis menggunakan sistem spektroskopi sinar dengan pengesan germanium berketulenan tinggi (HPGe). Kepekatan radionuklid, tabii 238 U, 232 Th dan 40 K dalam sampel diukur dan setara radium Ra eq dikira. Selain itu, indeks bahaya sinaran (HI) juga dikira. Kepekatan aktiviti 238 U, 232 Th dan 40 K dalam sampel berada dalam julat 0.69 ±7×10¯ 4 , 1.3 ±8×10¯ 4 dan 20.52 ± 6×10¯ 4 Bq/Kg. Nilai Ra eq berada dalam julat antara 0.002 dan 10.0 Bq/kg. Indeks bahaya sinaran (HI) berada dalam julat antara 0.002 dan 0.03, kurang daripada satu (had atas HI). Keputusan yang diperoleh dibandingkan dengan piawai di peringkat antarabangsa dan didapati berada dalam julat yang boleh diterima. Kata kunci: Indeks bahaya sinaran; kepekatan aktiviti; kesetaraan radium; NORM; 238 U, 232 Th dan 40 K InTRoDuCTIon
Alexandria and Rashid being part of the Mediterranean Sea basin cities are concerned with the protection of the marine environment of their territorial waters and coasts. One of the major sources of pollution in the surface water and sediments is the radionuclides.The present study is devoted to reliable detection, identification and classification of the radionuclides using the gamma ray spectrometer to measure the density of the radionuclides (i.e. 238U, 232Th, 40K) along the Alexandria and Rashid beaches and try to know the sources of these radionuclides.Surface sediments and sea water samples were collected from Alexandria and Rashid coastal beaches. The results demonstrate that the main source of radiation along the Alexandria and Rashid beaches is the black sands, which is rich in radio-nuclides, supplied by the River Nile during the flooding period in the last 5000 years through the Rashid branch of the Nile. These black sands accumulate mostly on the Rashid beach. The sea waves carry part of these black sands to Alexandria beaches westward.The distribution of 40K along the Alexandria coast revealed that, the western area of Al-Max coast was poor in 40K. On the other hand, the eastern area of Alexandria was rich in 40K, there was a wide relationship between the presence of 40K in sediments and the biological density of fauna and flora in the coast. The behavior of 40K in sediments along the Alexandria coast has been detected as non-uniform correlations between the data at different stations reveal significant differences between their radiometric properties. The lower 40K values for seawater have been detected at stations receiving low saline water discharged from inland sources. The salinity affects the behavior of 40K in surface seawater. This was due to the solubility of 40K in seawater.The measured values for 238U and 232Th for seawater are very low.The continuous monitoring of the radio-nuclides is recommended to assure good environment of these beaches because they are bathing beaches of Alexandria, and an important resource as summer resort.
Heavy metals always pose serious ecological risks when released into the environment due to their elemental non-degradable nature, regardless of their chemical form. This calls for the development of efficient and low-cost effluent treatment and metal recuperation technologies for contaminated waste water, not only because regulatory limits need to be met but also because the waste itself can be a resource for certain precious metals. Biosorption is a general property of living and dead biomass to rapidly bind and abiotically concentrate inorganic or organic compounds from even very diluted aqueous solutions. As a specific term, biosorption is a method that utilizes materials of biological origin - biosorbents formulated from non-living biomass - for the removal of target substances from aqueous solutions. Recent research on biosorption provides a solid understanding of the mechanism underlying microbial biosorption of heavy metals and related elements. This book gathers review articles analyzing current views on the mechanism and (bio)chemistry of biosorption, the performance of bacterial, fungal and algal biomass, and the practical aspects of biosorbent preparation and engineering. It also reviews the physico-chemical evaluations of biosorbents and modelling of the process as well as the importance of biosorption during heavy metal removal using living cells. It is a reference work for scientists, environmental safety engineers and R&D specialists who wish to further promote biosorption research and use the accumulated knowledge to develop and build industrial applications of biosorption in heavy metal separation technologies.
This chapter presents the influence of radionuclides on the plant growth with particular emphasis on phytoremediation technology for radioactive decontamination. After radiological catastrophe, radionuclide fallout can contaminate soil, leading potentially to higher radiation exposure of human population. Most of the conventional remedial technologies are expensive and inhibit the soil fetility; this subsequently causes negative impacts on the ecosystem. It is shown in this review that phytoremediation is a cost-effective, environmentally friendly, aesthertically pleasing approach most suitable for radioactive decontamination waste area. This chapter reports how physical, chemical processes, and biological accumulation influence the destiny of radionuclides in plants. A case study showed that accumulation properties of common reed could be useful in phytoremediation of mine waters or for bioindication of radionuclides in such waters. High-activity concentrations of radionuclides in the U-mill tailings did not negatively impact on plants growth. This means that common reed belongs to the metal-resistant plants with a metal-tolerance mechanism against toxic elements.
The concentration and mobility spatial distribution of heavy metals (lead, zinc, cadmium and chromium) including potential ecological risk have been evaluated for the polluted surface soil from mining activities in Upper Klity village, Thailand. Soil samples were collected from the residential and agricultural areas and the area of ore dressing plant. Heavy metals content presented higher in the ore dressing plant area than those found in residential and agricultural areas. Lead was the predominant polluted metal with two hot spots surrounding the ore dressing plant and open pit mine. Mobility distribution of these metals was followed closely with their concentration. Vertical soil profiles proved that mobility factors were only high at the top soil layer and became lower at deeper soil layers for all metals, and the quantities of lead, zinc, cadmium and chromium in both soil profiles can be ordered from large to small as: Reducible, Residual, Oxidizable, Acid extraction and Exchangeable fractions. These results indicated that the contamination was caused by anthropogenic mining activities. Potential Ecological Risk (PER) exhibited a low potential ecological risk with the averages of 3.79 and 81.3 in agricultural and ore dressing plant areas, respectively. However, most individual potential ecological risk values were small and classified as low for all heavy metals. This study recommends that heavy metals were unlikely to cause additional adverse health risk effects in residential and agricultural area. On the other hand, the risk of heavy metals pollution in the ore dressing plant area should be of primary concern. © 2015, Thai Society of Higher Eduation Institutes on Environment. All rights reserved.
Fourteen Brassica species consisting of seven leafy vegetables and seven root vegetables were examined for (137)Cs uptake differences in relation to their fine-root morphological characters. A pot experiment was conducted from November 2014 to February 2015 in a Phytroton using a contaminated soil of Fukushima prefecture. Leafy vegetables showed bigger root diameters, larger root surface area and larger root volume. Consequently, leafy vegetables had higher (137)Cs uptake compared to root vegetables. Among the three fine-root parameters, only root surface area was observed as a significant contributing factor to higher (137)Cs uptake in terms of transfer factor (TF, dry weight basis). Kakina exhibited higher (137)Cs TF value (0.20) followed by Chinese cabbage (0.18) and mizuna (0.17). Lower TF values were observed in turnip (0.059), rutabaga (Kitanoshou) (0.062) and radish (Ha daikon) (0.064).
Two exotic species, Sonneratia caseolaris ( L. ) Engl. and S. apetala B. Ham., were introduced to Futian Mangrove Forest Nature Reserve, Shenzhen Bay, in 1993 for afforestation. Winter cold caused frigid harm but did not appear to be an obstacle to the introduction. The cold tolerance of the parental and filial generation increased in several years. The two Sonneratia spp. could propagate by seeds and disperse in Shenzhen Bay. While the two species grew faster than indigenous species, at the same time they promoted the growth of indigenous species, but they could not replace indigenous mangrove species. Suitable habitat was more important than the distance from the source in the natural spreading for the two species. The niche of the two species did not overlap with the niche of indigenous species. The two species did not self-regenerate, although they could disperse on localized area in Shenzhen Bay. Therefore, it was unlikely that the two species would pose ecological disaster.
The nature of sedimentary organic matter from mangroves and the continental margin of eastern Brazil (8°-24°S) has been investigated in order to obtain information on sources and diagenetic processes. The organic matter content of mangrove sediments is three to four times higher than the maximum content of continental margin sediments. Downslope distribution of organic carbon, nitrogen, amino acids and hexosamines shows an enrichment in water depths between 800 m and 1000 m. The distribution of individual amino acids and hexosamines is highly variable in sedimentary organic matter from mangroves and the continental margin, and the observed compositional differences are mainly due to diagenetic alteration. Organic matter is highly reactive in mangrove sediments and refractory in slope sediments, which suggests that recycled organic matter forms the bulk of the organic matter in upper slope sediments. From the qualitative differences between organic matter in mangrove sediments and in continental margin sediments it appears that mangrove-derived organic matter is not a significant component of the latter. It is also conceivable that organic matter is retained in mangroves or that it undergoes severe decomposition in coastal waters.
The specific activities of (238)U, (226)Ra, (40)K, and (222)Rn in chemical fertilizers were measured using gamma ray spectrometer and Cr-39 detector. In this study, 21 chemical fertilizers were collected from Eastern Saudi Arabian markets. The specific activities of (238)U ranged from 23 ± 0.5 to 3900 ± 195 Bq kg(-1); (226)Ra ranged from 5.60 ± 2.80 to 392 ± 18 Bq kg(-1); and (40)K ranged from 18.4 ± 3 to 16,476 ± 820 Bq kg(-1). The radon concentrations and the radon exhalation rates were found to vary from 3.20 ± 1.20 to 1532 ± 160 Bq m(-3) and from 1.60 to 774 mBq m(-2) h(-1), respectively. Radium equivalent activities (Raeq) were calculated for the analyzed samples to assess the radiation hazards arising due to the use of these chemical fertilizers in the agriculture soil. The Raeq for six local samples (nitrogen, phosphorous, and potassium (NPK) and single superphosphate (SSP)) and one imported sample (Sulfate of Potash (SOP)) were greater than the acceptable value 370 Bq kg(-1). The total air absorbed doses rates in air 1 m above the ground (D) were calculated for all samples. All samples, except one imported granule sample diammonium phosphate (DAP), were higher than the estimated average global terrestrial radiation of 55 nGy h(-1). The highest annual effective dose was in triple super phosphate (TSP) fertilizers (2.1 mSv y(-1)). The results show that the local TSP, imported SOP, and local NPK (sample 13) fertilizers were unacceptable for use as fertilizers in agricultural soil. Furthermore, the toxic elements and trace metals (Pb, Cd, Cr, Co, Ni, Hg, and As) were determined using atomic absorption spectrometer. The concentrations of chromium in chemical fertilizers were higher than the global values.
Abstract A survey was undertaken, in arsenic (As) contaminated area of the Nadia district, West Bengal, India, to find native As accumulator plants. As was determined both in soil and plant parts. The results showed that the mean translocation factor of Pteris vittata L, Phragmites karka (Cav.) Trin. Ex. Steud and Christella dentata Forssk were higher than 1. It thus appeared that these plants can be efficient accumulators of As. Phytoremediation ability of C. dentata and P. karka was evaluated and compared with known As-hyperaccumulators -P. vittata and Adiantum capillus veneris L. Plants were grown in the As spiked soil (25, 50, 75 and 100 mg kg(-1)). As accumulation was found to be highest in P. vittata, 117.18 mg kg(-1) in leaf at 100 mg kg(-1) As treatment, followed by A. capillus veneris, P. karka and C. dentata being 74, 83.87 and 40.36 mg kg(-1), respectively. Lipid peroxidation increased after As exposure in all plants. However, the antioxidant enzyme activity and molecules concentration also increased which helped the plants to overcome As-induced oxidative stress. The study indicates that P. karka and C. dentata could be considered as As-accumulators and find application for As-phytoextraction in field conditions.
Economic development of a nation is linked to richness of natural resources. Minerals are one of the important natural resources. Thailand is rich in minerals such as zinc (Zn), lead (Pb), tin (Sn) and gold (Au). Thailand's largest zinc deposits are located in Phatat Phadaeng sub-district, Mae Sot, Tak. Mining operations generate huge amounts of waste which is detrimental to the quality of the local environment. Thus the waste generated by mine operations is often piled up in the vicinity of the mining site. Due to strong weather conditions, the residual metals from the piled up metallic waste get eroded and transported to the local ecosystem. Decontamination of contaminated ecosystems is complex and cost-prohibitive and thus several undesirable health effects are witnessed often. Phytomanagement deals with use of a wide variety of phytodiversity to stabilize the mine waste and thus reduce the bioavailability of toxic doses of metals. Phytomanagement also deals with control of leaching of mine waste to surrounding ecosystems and feasible options for production of safe food are dealt with in this manuscript. Phytomanagement is emerging as a potential field of phytotechnology for restoration of mine waste.
Papua New Guinea (PNG) is currently experiencing environmental problems relating to mining activities. Despite valuable earnings received from the mining projects in PNG, environment in the mining vicinity is being degraded causing lots of instability on surrounding environment and ecosystems. Phytoremediation is seen to be a cost effective bioremedial solution where plants are used to remove metal contaminants that are being released into the environment by mining operations. The case study alludes to Phragmite karka as an effective plant for absorbing heavy metals (Cd, Cu, Fe, Hg, Pb, and Hg) from mine soil environment. In addition, heavy metals are known to be toxic and causes harm to surrounding environment and ecosystems through bioaccumulation and food chain process. This paper focuses mainly on heavy metals (Cd, Cu, Fe, Hg, Pb, and Hg) that are being absorbed by native Phragmite karka plant species after rehabilitation program of Wau Namie Mine Sites (WNMS) through random sampling and analysis of samples using standard ICP and ASS technique. The results from soil analyses of WNMS have shown significantly high concentrations of heavy metals when compared to European Standard Average Concentrations of heavy metals in soils. However, Phragmite karka have shown positive results of absorbing heavy metals as indicated by the results. This indicates phytoextractive ability and efficiency of plants to absorb and stabilise contaminants within its systems. Furthermore, heavy metal has made the site unfit for introduced plant species in rehabilitated sites to survive. Overall, this case study has revealed that Phragmite karka as the potential phytoremediation plant in soil environment of mine site.
Nuclear power reactors are operating in 31 countries around the world. Along with reactor operations, activities like mining, fuel fabrication, fuel reprocessing and military operations are the major contributors to the nuclear waste. The presence of a large number of fission products along with multiple oxidation state long-lived radionuclides such as neptunium ((237)Np), plutonium ((239)Pu), americium ((241/243)Am) and curium ((245)Cm) make the waste streams a potential radiological threat to the environment. Commonly high concentrations of cesium ((137)Cs) and strontium ((90)Sr) are found in a nuclear waste. These radionuclides are capable enough to produce potential health threat due to their long half-lives and effortless translocation into the human body. Besides the radionuclides, heavy metal contamination is also a serious issue. Heavy metals occur naturally in the earth crust and in low concentration, are also essential for the metabolism of living beings. Bioaccumulation of these heavy metals causes hazardous effects. These pollutants enter the human body directly via contaminated drinking water or through the food chain. This issue has drawn the attention of scientists throughout the world to device eco-friendly treatments to remediate the soil and water resources. Various physical and chemical treatments are being applied to clean the waste, but these techniques are quite expensive, complicated and comprise various side effects. One of the promising techniques, which has been pursued vigorously to overcome these demerits, is phytoremediation. The process is very effective, eco-friendly, easy and affordable. This technique utilizes the plants and its associated microbes to decontaminate the low and moderately contaminated sites efficiently. Many plant species are successfully used for remediation of contaminated soil and water systems. Remediation of these systems turns into a serious problem due to various anthropogenic activities that have significantly raised the amount of heavy metals and radionuclides in it. Also, these activities are continuously increasing the area of the contaminated sites. In this context, an attempt has been made to review different modes of the phytoremediation and various terrestrial and aquatic plants which are being used to remediate the heavy metals and radionuclide-contaminated soil and aquatic systems. Natural and synthetic enhancers, those hasten the process of metal adsorption/absorption by plants, are also discussed. The article includes 216 references.
Pot and field experiments were conducted to investigate the effects of soil amendments (cow manure, rice straw, zeolite, dicalcium phosphate) on the growth and metal uptake (Cd, Zn) of maize (Zea mays) grown in Cd/Zn contaminated soil. The addition of cow manure and rice straw significantly increased the dry biomass, shoot and root length, and grain yield of maize when compared with the control. In pot study, cow manure, rice straw, and dicalcium phosphate all proved effective in reducing Cd and Zn concentrations in shoots and roots. Cd and Zn concentrations in the grains of maize grown in field study plots with cow manure and dicalcium phosphate amendments to highly contaminated soil (Cd 36.5 mg kg(-1) and Zn 1520.8 mg kg(-1)) conformed to acceptable standards for animal feed. Additionally both cow manure and dicalcium phosphate amendments resulted in the significant decrease of Cd and Zn concentrations in shoots of maize.
The present study examined the relationships between soil characteristics, microbial community structure and function in the forests artificially planted with exotic Sonneratia apetala at stand ages of 1-, 2-, 7-, 10- and 14-years and Sonneratia caseolaris of 1-, 4-, 7-, 10- and 14-years in Futian National Nature Reserve, Shenzhen Bay, China. The 7-years old forests of both Sonneratia species reached peak growth and had the highest content of nitrogen and phosphorus, enzymatic activities, including dehydrogenase, cellulase, phosphatase, urease and ß-glucosidase, except arylsulphatase which increased continuously with stand ages. The microbial community structure reflected by phospholipid fatty acid (PLFA) profiles also reached the maximum value in the 7-years old forests and soil bacterial PLFAs in both forests were significantly higher than fungal PLFAs. The canonical correlation analysis revealed that differences in microbial structural variables were significantly correlated to the differences in their functional variables, and the highest correlation was found between the soil enzymatic activities and the content of carbon and nitrogen.
A field investigation was conducted for the vegetation composition and (226)Ra uptake by native plant species at a uranium mill tailings impoundment in South China. 80 species belonging to 67 genera in 32 families were recorded in the sampling sites. The Poaceae and Asteraceae were the dominant families colonizing the impoundment. The number of the plant species and vegetation community composition in the sampling sites seemed most closely related to the activities of (226)Ra and the pH value of the uranium tailings. The plant species in the sampling sites with relatively low activities of (226)Ra and relatively high pH value formed a relatively stable vegetation community. The plant species in the sampling sites with medium activities of (226)Ra and medium pH value formed the transitional vegetation community. The plant species in the sampling sites with relatively high activities of (226)Ra and relatively low pH value formed a simple unstable vegetation community that was similar to that on the unused grassland. The activities of (226)Ra and transfer factors (TFs) varied greatly with the plant species. The high activities of (226)Ra and TFs were found in the leaves of Pteris multifida (150.6 Bq/g of AW; 9.131), Pteridium aquilinum (122.2 Bq/g of AW; 7.409), and Dryopteris scottii (105.7 Bq/g of AW; 6.408). They satisfied the criteria for a hyperaccumulator for (226)Ra. They may be the candidates for phytoremediation of (226)Ra in the uranium mill tailings impoundment areas and the contaminated soils around.
The aim of this study was to investigate the concentrations and pollution status of heavy metals (Cu, Cd, Ni, Pb, Zn and Cr) in the mangrove surface sediments from the Farasan Island, Coast of Red Sea, Saudi Arabia. The ability of mangroves (Avicennia marina) to accumulate and translocate heavy metal within their different compartments was also investigated. Five sampling sites were chosen for collection of sediments and different compartments (leaf, branch and root) of A. marina. The results showed that the maximum and average concentrations of Cd, Cu and Pb in the studied area exceeded their world average concentration of shale. Additionally, only the maximum concentration of Zn exceeded its world average shale concentration. Based on the quality guidelines of sediment (SQGs), the collected sediment samples were in moderate to heavy rate for Cu, non-polluted to heavy rate for Pb and Zn, and non-polluted to moderate rate for Cr and Ni. The average metal concentrations of A. marina in the studied area were observed in the order Cu (256.0-356.6mgkg(-1))>Zn (29.5-36.8mgkg(-1))>Cr (8.15-14.9mgkg(-1))>Ni (1.37-4.02mgkg(-1))>Cd (not detectable-1.04mgkg(-1))>Pb (not detectable). Based on bio-concentration factors (BCF), their most obtained values were considered too high (>1), suggesting that A. marina can be considered as a high-efficient plant for bioaccumulation of heavy metals. Among all metals, Cu and Cr were highly bio-accumulated in different parts of A. marina. In terms of heavy metal contamination control via phyto-extraction, our findings suggest also that A. marina may be classified as potential accumulator for Cu in aboveground parts, as indicated by higher metal accumulation in the leaves combined with bio-concentration factor (BCF) and translocation factor (TF) values >1.