Namin Koo

Evaluation of the effectiveness of various amendments on trace metals stabilization by chemical and biological methods

We evaluated the effects of five different kinds of amendments on heavy metals stabilization. The five amendments were: zero valent iron, limestone, acid mine drainage treatment sludge, bone mill, and bottom ash. To determine bioavailability of the heavy metals, different chemical extraction procedures were used such as, extraction with (Ca(NO(3))(2), DTPA; toxic characteristic leaching procedure (TCLP), physiologically based extraction test (PBET) that simulates gastric juice, and sequential extraction test. Bioavailability was also determined by measuring uptake of the heavy metals by lettuce (Lactuca sativa L.) and earthworms (Eisenia fetida). In addition, dehydrogenase activity was measured to determine microbial activity in the soil with the different amendments. The addition of amendments, especially limestone and bottom ash, resulted in a significant reduction in extractable metal contents. Biological assays using lettuce, earthworm, and enzyme activity were found as appropriate indicators of available metal fraction after in situ stabilization of heavy metals. In conclusion, TCLP and sequential extraction test appear to be promising surrogate measure of metal bioavailability in soils for several environment endpoints.

Using response surface methodology to assess the effects of iron and spent mushroom substrate on arsenic phytotoxicity in lettuce (Lactuca sativa L.).

The effects of iron (Fe) and spent mushroom substrate (SMS) arsenic (As) phytotoxicity towards lettuce in artificial soils were investigated to separate the adverse soil parameters relating to As toxicity using a response surface methodology. SMS induced the root elongation of lettuce in both control and As-treated soils. However, in phytotoxicity test using a median effective concentration (EC(50)) of As, Fe and the interaction between both parameters (Fe*SMS) significantly affected EC(50), which explained 71% and 23% of the response, respectively. The refined model was as follows: EC(50) of As (mgkg(-1))=10.99+60.03 × Fe-10.50 × Fe*SMS. The results confirmed that the soil parameters relating to the As mobility in soils were important factors affecting its toxicity. In conclusion, Fe significantly reduced the As phytotoxicity. However, although SMS enhanced the root elongation, SMS in As-treated soils decreased EC(50) of As on the root growth via its interaction with Fe. Despite the limitations of the artificial soils and range of parameters studied, the application of this statistical tool can be considered a powerful and efficient technique for interpretation and prediction of the complicated results caused by the interactions between many factors within the soil environments.

Effects of Soil Amendments on the Early Growth and Heavy Metal Accumulation of Brassica campestris ssp. Chinensis Jusl. in Heavy Metal-contaminated Soil

There have been many studies about efficiency of amendments for heavy metal stabilization through chemical assessment. The objective of this study was to evaluate the efficiency of several soil amendments (lime, agric-lime, dolomite, steel slag, fly ash and acid mine drainage sludge) on heavy metals stabilization through not only chemical but also biological assessments (phytotoxicity test) in abandoned mining area soil. In order to achieve the goal, we conducted preliminary screening experiment targeting 12 types of crop plants such as radish, young radish, chinese cabbage, winter grown cabbage, cabbage, bok choy, chicory, crown daisy, carrot, chives, spinach, and spring onion. The results of inhibition rates of early plant growth in metal-contaminated soil against non-contaminated soil and the correlations between inhibitions items showed that the bok choy was appropriate specie with respect to confirm the effect of several amendments. Several amendment treatments on contaminated soil brought about the changes in the root and shoot elongation of bok choy after 1 week. Agric-lime, dolomite and steel slag treatments showed the great efficiency of reducing on mobility of heavy metals using chemical assessment. But in contrary, these treatments resulted in the reduction of root and shoot elongation and only AMD sludge increased that of elongation, significantly. When considering both chemical and biological assessments, AMD sludge could be recommended the compatible amendment for target contaminated soil. In conclusion, biological assessment was also important aspect of decision of successful soil remediation.

Arsenate tolerance mechanism of Oenothera odorata from a mine population involves the induction of phytochelatins in roots

We investigated the arsenate tolerance mechanisms of Oenothera odorata by comparing two populations [i.e., one population from the mine site (MP) and the other population from an uncontaminated site (UP)] via the exposure of hydroponic solution containing arsenate (i.e., 0-50 microM). The MP plants were significantly more tolerant to arsenate than UP plants. The UP plants accumulated more As in their shoots and roots than did the MP plants. The UP plants translocated up to 21 microg g(-1) of As into shoots, whereas MP plants translocated less As (up to 4.5 microg g(-1)) to shoots over all treatments. The results of lipid peroxidation indicated that MP plants were less damaged by oxidative stress than were UP plants. Phytochelatin (PC) content correlated linearly with root As concentration in the MP (i.e., [PCs](root)=1.69x[As](root), r(2)=0.945) and UP (i.e., [PCs](root)=0.89x[As](root), r(2)=0.979) plants. This relationship means that increased PC to As ratio may be associated with increased tolerance. Our results suggest that PC induction in roots plays a critical role in As tolerance of O. odorata.

The Applicability of the Acid Mine Drainage Sludge in the Heavy Metal Stabilization in Soils

The Applicability of the Acid Mine Drainage Sludge in the Heavy Metal Stabilization in Soils Min-Suk Kim, Hyungi Min, Byeongjoo Lee, Sein Chang, Jeong-Gyu Kim, Namin Koo, Jeong-Sik Park and Gwan-In Bak (Division of Environmental Science and Ecological Engineering, Korea University, Korea, Division of Forest Soil & Water Conservation, Korea Forest Research Institute, Envrionmental Safety Team, Korea Testing & Research Institute, Technology Research Center, Mine Reclamation Corporation)

Effects of Various Amendments on Heavy Metal Stabilization in Acid and Alkali Soils

BACKGROUND: Recent studies using many amendments for heavy metal stabilization in soil were conducted in order to find out new materials. But, the studies accounting for the use of appropriate amendments considering soil pH remain incomplete. The aim of this study was to investigate the effects of initial soil pH on the efficiency of various amendments. METHODS AND RESULTS: Acid soil and alkali soil contaminated with heavy metals were collected from the agricultural soils affected by the abandoned mine sites nearby. Three different types of amendments were selected with hypothesis being different in stabilization mechanisms; organic matter, lime stone and iron, and added with different combination. For determining the changes in the extractable heavy metals, water soluble, Mehlich-3, Toxicity Characteristic Leaching Procedure, Simple Bioavailability Extraction Test method were applied as chemical assessments for metal stabilization. For biological assessments, soil respiration and root elongation of bok choy (Brassica campestris ssp. Chinensis Jusl.) were determined. CONCLUSION: It was revealed that lime stone reduced heavy metal mobility in acid soil by increasing soil pH and iron was good at stabilizing heavy metals by supplying adsorption sites in alkali soil. Organic matter was a good source in terms of supplying nutrients, but it was concerning when accounting for increasing metal availability.

Effects of the Incorporation of Phosphorus and Iron into Arsenic-Spiked Artificial Soils on Root Growth of Lettuce using Response Surface Methodology

We investigated effects of phosphorus (P) and iron (Fe) on root elongation (RE) of lettuce in arsenic (As)–spiked soils using response surface methodology (RSM). To stabilize interactions between As and Fe in a soil preparation, the sequential incorporation method using Fe and P (SIMFe-P) was applied. From a phytotoxicity assay, As in roots (Asroot) was negatively associated with RE, Fe in soils, and P in roots and soils. The P in roots was also positively related to RE. In a model study, As and interaction factor between P and Fe showed negative coefficients but others showed positive ones. From a confirmation study, RE on exposure to As was verified to be much greater in soils treated by SIMFe-P than in soils separately treated with both elements. These results indicated that application of SIMFe-P to As-contaminated soils might be expected to have an advantage during the early stage of plant root growth.

Growth Response and Arsenic Uptake of White Clover (Trifolium repens) and Evening Primrose(Oenothera odorata) Colonized with Arbuscular Mycorrhizal Fungi in Arsenic-Contaminated Soil

A greenhouse experiment was conducted to investigate the role of the arbuscular mycorrhizal (AM) fungus, Glomus mosseae (BEG 107) in enhancing growth and arsenic (As) and phosphorus (P) uptake of white clover (Trifolium repens) and evening primrose (Oenothera odorata) in soil collected from a gold mine having concentrations of 381.6 mg total As kg -1 and 20.5 mg available As kg -1 . Trifolium repens and O. odorata are widely distributed on abandoned metalliferous mines in Korea. The percent root colonization by the AM fungus was 55.9 % and 62.3 % in T. repens and O. odorata, respectively, whereas no root colonization was detected in control plants grown in a sterile medium. The shoot dry weight of T. repens and O. odorata was increased by 323 and 117 % in the AM plants compared to non-mycorrhizal (NAM) plants, respectively. The root dry weight increased up to 24 % in T. repens and 70% in O. odorata following AM colonization compared to control plants. Mycorrhizal colonization increased the accumulation of As in the root tissues of T. repens and O. odorata by 99.7 and 91.7 % compared to the NAM plants, respectively. The total uptake of P following AM colonization increased by 50% in T. repens and 70 % in O. odorata, whereas the P concentration was higher in NAM plants than in the AM plants. Colonization with AM fungi increased the As resistance of the host plants to As toxicity by augmenting the yield of dry matter and increasing the total P uptake. Hence, the application of an AM fungus can effectively improve the phytoremediation capability of T. repens and O. odorata in As-contaminated soil.

Pine Forest Soil Characteristics and Major Soil Impact Factors for Natural Regeneration

Received: March 27, 2017 Revised: June 15, 2017 Accepted: June 22, 2017 This study was conducted to identify characteristics of domestic pine forest soils and to elucidate major soil influencing factors for natural regeneration. We analyzed the physico-chemical characteristics of the soil samples collected from 23 pine forests and confirmed the similar results with the forest soil characteristics. Soil pH, organic matter content, total nitrogen, exchangeable Ca, silt content, and exchangeable Al were selected as the major soil factors among the exposed soils through 10 days of pine seedlings exposure and cultivation experiments and statistical analysis. Multiple regression analysis showed that soil pH had a positive effect on specific root length (SRL) of red pine seedlings and exchangeable Al was a significant factor affecting negative change in SRL. Taken together, the reduction of exchangeable Al by soil pH adjustment would be helpful for natural regeneration by restoring the forest and improving the fine root and root integrity of pine seedlings. Therefore, soil pH and exchangeable Al could be recommended as a major soil factor to be carefully considered in the monitoring and management of soil in pine forests that need to be renewed in the future.