• Korean Journal of Soil Science and Fertilizer
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• v.41 no.1
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• pp.55-64
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• 2008

A detailed understanding and appreciation of the important mechanisms operating at the soil:root interface, commonly identified as the rhizosphere, is critical for evaluating the potential for particular plant species to be successfully used as part of a phytoremediation technique. For specific plants, mechanisms may exist to overcome the inherit limitation of the phytoremediation technique when poorly mobile soil metals are of interest. In the present study, the influence of root exudates on the rhizosphere chemistry of soil and consequential metal uptake were investigated following culture of vetiver grass (Vetiveria zizanioides), recognized as a promising plant for land stabilization, in three different long-term contaminated soils and one non-contaminated control soil. The soil solution pH increased (0.3-1.1 units) following vetiver grass culture and dissolved organic carbon (DOC) also significantly increased in all soils with the highest increase in PP02 (23 to $173mg\;L^{-1}$). Chemical changes are contributed to root exudation by vetiver grass when exposed to high concentration of heavy metals. Chemical changes, consequently, influenced metal (Cd, Cu, Pb, and Zn) solubility and speciation in the rhizosphere. The highest solubility was observed for soil Ko01 (eg. 2091 and $318{\mu}g\;L^{-1}$ for Cd and Pb, respectively). Initial heavy metal solubility in soils varied with soil and either increased or decreased following vetiver grass culture depending on the soil type. An increase in pH following plant culture generally resulted in a decrease in metal solubility, while elevated DOC due to root exudation resulted in an increase in metal solubility via the formation of metal-DOC complexes. Donnan speciation demonstrated a significant decrease in free Cd and Zn in the rhizosphere and the concentration of Cd, Pb, and Zn in vetiver grass shoot was highly correlated with soluble concentration rather than total soil metal concentration.

• Journal of People, Plants, and Environment
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• v.23 no.1
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• pp.15-21
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• 2020

In this study, we compared efficiency of different aquatic plants in removing indoor pollutants and examined their potential to purify indoor air. Two liter of water in chamber was used as the control, while the other chambers containing water lettuce (Pistia stratiotes), water hyacinth (Eichhornia crassipes), and water coin (Hydrocotyle umbellata) were used as treatment groups. Temperatures inside all the chambers were maintained between 20 ℃ and 23 ℃. Humidity in the chambers with aquatic plants increased by 30% and 50% control respectively. The removal of formaldehyde per unit leaf area was examined in each aquatic plant. It turned out that water hyacinth removed the highest amount of formaldehyde, followed by water lettuce and water coin. Both water hyacinth and water lettuce increased the amount of removal of formaldehyde until the end of the experiment. In the case of airborne dust (PM 10) and fine dust (PM 2.5), water coin, which had the highest number of leaves, removed more PM 10 and PM 2.5 than the other aquatic plants, with statistically significant difference. In addition, both water coin and water hyacinth smoothly opened and closed stomata before and after the experiment. Consequently, as the aquatic plants were effective in controlling humidity and removing pollutants, they can be used as air purifying plants.

• Journal of the Korea Organic Resources Recycling Association
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• v.23 no.4
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• pp.21-31
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• 2015

The aim of this study is to determine the removal efficiency of total nitrogen and phosphorus from treated swine wastewater by Phragmites australis and Miscanthus sacchariflorus var Geode Uksae-1, and to determine its biomass total energy value and biomethane potential. Plants were grown with a bedding mixture either soil and sand or soil, sand, and bioceramic. Treeated swine wastewater with Total nitrogen (TN) and Total phosphorus (TP) of 222.78 mg/L and 66.11 mg/L, respectively, was utilized. The TN and TP removal is higher in the bio-ceramic-soil-sand bedding media treatment. The highest TN removal of 96.14% was performed by Miscanthus sacchariflorus var Geode Uksae-1, but the elemental analysis shows that Phragmites australis contains more nitrogen than Miscanthus sacchariflorus var Geode Uksae-1, indicating higher nitrogen uptake. The highest TP removal of 98.12% was performed by Phragmites australis. The cellulose content of the plant grown with the bioceramic-soil-sand bedding was approximately 3-6% higher than that of the plant grown in the soil-sand bedding. Different growing substrates may have an effect on the fiber content of plants. The biomethane potential of the produced biomass of the plants was between 57.01 and $99.25L-CH_4/kg$ VS. The lignin content is believed to inhibit the breakdown of plant biomass, resulting in the lowest methane production in the Phragmites australis grown in the soil-sand bedding media.

• Economic and Environmental Geology
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• v.37 no.1
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• pp.99-106
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• 2004

Pollution reduction and/or control technology becomes one of the pressing post-semiconductor research field to lead an advanced industrial structure. Soil/groundwater remediation techniques may act as a core technology which will create many demands on pollution reduction areas. A plenty numbers of abandoned metal mines were left without any remediation action in Korea, and it may be potential sources of heavy metal and As contamination in the ecosystem. In order to bring this soil contamination to a settlement, the emerging soil/groundwater remediation techniques should be introduced. Main research topics in the United States and Europe move towards the clean remediation technology without any secondary impact and the feasible application of developing technique into the field scale study. With these advantages, several soil/groundwater techniques such as electrokinetic soil processing, permeable reactive barrier, stabilization/solidification, biosorption, soil flushing with biosurfactant, bioleaching and phytoremediation will be summarized in this paper.

• Environmental Engineering Research
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• v.19 no.2
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• pp.145-149
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• 2014

Arsenic (As) is one of the heavy metals which causes acute bio-toxicity even at low concentration and has disastrous effect on environment. In some countries, As contamination has become alarming and increasing day by day as consequences of unsustainable management practices. Many existing physical, chemical and biological processes for As removal from water system are not feasible due to techno-economic limitations. The present study highlights the scope of biological strategy for As removal through phytoextraction. Arsenic uptake and accumulation in the biomass of three plant species and their As tolerance abilities have been investigated to develop an efficient phytoextraction system in combination of these plant species. Three non-crop plant species, Pteris vittata; Mimosa pudica, and Eichhornia crassipus were treated with 0-200 mg/L As in liquid nutrient solution for 14 days. P. vittata accumulated total 9,082.2 mg (8,223 mg in fronds) As/kg biomass and Eichhornia total 6,969 mg (4,517 mg in fronds)/kg biomass at 200 mg/L As concentration, respectively. Bioaccumulation factor (BF) and translocation factor (TF) were estimated to differentiate between excluders, accumulators and accumulation in above ground biomass. Pteris and Eichhornia have highest BF (67 and 17) and TF (64 and 3), respectively. In contrast, Mimosa accumulated up to 174 mg As/kg plant biomass which is low in comparison with other two plants, and both BF and TF were ${\leq}1$. This study reveals that Pteris and Eichhornia are As hyperaccumulator, and potential candidates for As removal from water system.

• Journal of Korean Society of Forest Science
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• v.99 no.5
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• pp.711-719
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• 2010

We investigated physiological responses and phytoextraction ability of Pinus thunbergii in cadmium contaminated soil as part of our efforts in identifying plant materials for the restoration and revegetation of forest soil contaminated by heavy metals. Thirty seedlings (ten per treatment) were assigned to three treatments (control, 0.3 and 0.6 mM $CdSO_4$ solution) at first year experiment. At second year, ten seedlings per treatment treated with Cd during the first year experiment were divided by two groups (no Cd-treated and consecutive Cd-treated group). At first experiment, photosynthetic pigment content, and superoxide dismutase (SOD) and glutathione reductase (GR) activities have significantly reduced by Cd application, and the reduction rate was increased much higher as the rate of Cd application increased. On the other hand, thiol and malondialdehyde (MDA) content were significantly increased at the application of 0.6 mM of Cd. At the second year experiment, a general increase in chlorophyll and carotenoid content was observed with Cd treatment while SOD and GR activities showed a relative reduction compared to the control. Similar to the first year measurement, thiol and MDA contents also increased considerably due to Cd treatment. At harvest, dry matter was significantly reduced by Cd treatment especially at the rate of 0.6 mM Cd, but dry yield of P. thunbergii treated with 0.3 mM Cd was less affected and it was comparable with the control seedling. Cadmium concentration in seedling tissues increased with increasing Cd application rate while Cd uptake was higher in seedlings supplied with 0.3 mM Cd, which could be ascribed to their high dry matter. Overall, our study has demonstrated the unique physiological response of P. thunbergii to Cd-prolonged exposure by showing that the changes in photosynthetic pigment content and antioxidative enzyme activities were dependent on the concentration and duration of treatment. In addition, our results have demonstrated the potential of P. thunbergii to withstand up to 0.3 mM Cd (equivalent to cumulative Cd concentration of 134.4 to 268 mg $kg^{-1}$) without showing growth reduction, hence it might be used for phytoremediation of Cd contaminated areas.

• Journal of Microbiology and Biotechnology
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• v.25 no.8
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• pp.1205-1215
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• 2015

Arbuscular mycorrhizal fungi (AMF) have great potential for assisting heavy metal hyperaccumulators in the remediation of contaminated soils. However, little information is available about the symbiosis of AMF associated with an antimony (Sb) accumulator plant under natural conditions. Therefore, the objective of this study was to investigate the colonization and molecular diversity of AMF associated with the Sb accumulator ramie (Boehmeria nivea) growing in Sb-contaminated soils. Four Sb mine spoils and one adjacent reference area were selected from Xikuangshan in southern China. PCR-DGGE was used to analyze the AMF community composition in ramie roots. Morphological identification was also used to analyze the species in the rhizosphere soil of ramie. Results obtained showed that mycorrhizal symbiosis was established successfully even in the most heavily polluted sites. From the unpolluted site Ref to the highest polluted site T4, the spore numbers and AMF diversity increased at first and then decreased. Colonization increased consistently with the increasing Sb concentrations in the soil. A total of 14 species were identified by morphological analysis. From the total number of species, 4 (29%) belonged to Glomus, 2 (14%) belonged to Acaulospora, 2 (14%) belonged to Funneliformis, 1 (7%) belonged to Claroideoglomus, 1 (7%) belonged to Gigaspora, 1 (7%) belonged to Paraglomus, 1 (7%) belonging to Rhizophagus, 1 (7%) belonging to Sclervocystis, and 1 (7%) belonged to Scutellospora. Some AMF sequences were present even in the most polluted site. Morphological identification and phylogenetic analysis both revealed that most species were affiliated with Glomus, suggesting that Glomus was the dominant genus in this AMF community. This study demonstrated that ramie associated with AMF may have great potential for remediation of Sb-contaminated soils.

• Journal of Wetlands Research
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• v.25 no.2
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• pp.145-158
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• 2023

Constructed wetlands (CWs) are effective technologies for urban wastewater management, utilizing natural physico-chemical and biological processes to remove pollutants. This study employed a bibliometric analysis approach to investigate the progress and future research trends in the field of CWs. A comprehensive review of 100 most-recently published and open-access articles was performed to analyze the performance of CWs in treating wastewater. Spain, China, Italy, and the United States were among the most productive countries in terms of the number of published papers. The most frequently used keywords in publications include water quality (n=19), phytoremediation (n=13), stormwater (n=11), and phosphorus (n=11), suggesting that the efficiency of CWs in improving water quality and removal of nutrients were widely investigated. Among the different types of CWs reviewed, hybrid CWs exhibited the highest removal efficiencies for BOD (88.67%) and TSS (95.67%), whereas VSSF, and HSSF systems also showed high TSS removal efficiencies (83.25%, and 78.83% respectively). VSSF wetland displayed the highest COD removal efficiency (71.82%). Generally, physical processes (e.g., sedimentation, filtration, adsorption) and biological mechanisms (i.e., biodegradation) contributed to the high removal efficiency of TSS, BOD, and COD in CW systems. The hybrid CW system demonstrated highest TN removal efficiency (60.78%) by integrating multiple treatment processes, including aerobic and anaerobic conditions, various vegetation types, and different media configurations, which enhanced microbial activity and allowed for comprehensive nitrogen compound removal. The FWS system showed the highest TP removal efficiency (54.50%) due to combined process of settling sediment-bound phosphorus and plant uptake. Phragmites, Cyperus, Iris, and Typha were commonly used in CWs due to their superior phytoremediation capabilities. The study emphasized the potential of CWs as sustainable alternatives for wastewater management, particularly in urban areas.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.9
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• pp.1060-1068
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• 2007

Perchlorate contamination in aquatic system is a growing concern due to the human health and ecological risks associated with perchlorate exposure. In spite of potential risks associated with perchlorate, drinking water standard has not been established worldwide. Recently, US EPA has issued new protective guidance for cleaning up perchlorate contamination with a preliminary clean-up goal of 24.5 ppb. In Korea, the drinking water standard and discharge standard for perchlorate has not been established yet and little information is available to address perchlorate problems. Perchlorate treatment technologies include ion exchange, microbial reactor, carbon adsorption, composting, in situ bioremediation, permeable reactive barrier, phytoremediation, and membrane technology. The process description, capability, and advantage/disadvantages of each technology were described in detail in this review. One of recent trends in perchlorate treatment is the combination of available treatment options such as combined microbial reduction and permeable reactive burier. In this review, we provided a brief perspective on perchlorate treatment technology and to identify an efficient and cost-effective approach to manage perchlorate problem.

• Korean Journal of Environmental Agriculture
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• v.26 no.1
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• pp.25-35
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• 2007

Excess runoff contaminated with N and P can impact the quality of downstream water. It has been known that aquatic plants improve the water quality through their intake of organic or inorganic nutrients. This study was conducted to select aquatic plants having high purification ability for nutrient N and P, and mineral nutrients related to EC such as K, Ca, Na, Cl, and $SO_4$ in raw sewage water in greenhouse. We assessed nutrient phytoremediation potential of alien hydrophyte and hydro-crop as well as native landscape hydrophyte to select suitable aquatic plant applied to artificial wetland and buffering site of stream-side. The amount of irrigation water during whole growing period of aquatic plane ranged from 225 L $m^{-2}$ to 444 L $m^{-2}$. Oryza sativa, Typha orientalis, Zizania latifolia, Aster subulatus, Coix lachryma-jobi var. mayuen, Paspalum disdichum var. indutum which had high biomass consumed the large amount of irrigation water over 350 L $m^{-2}$. As a result of analysis of water purification effect N and P content of shoot biomass, and media soil after experiment, Oryza sativa, Zizania latifolia, Aster subulatus, Coix lachryma-jobi var. mayuen, Paspalum distichum var. indutum showed high purification ability about eutrophication elements such as T-N and T-P. It is presented that Pistia stratiotes, Eichhornia crassipes, and Paspalum distichum var. indutum had excellent purification ability about K, Ca, Na, and Cl. Moreover, Paspalum distichum var. indutum greatly removed $SO_4$ in row sewage water.