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Recent estimates show that land degradation is rapidly progressing worldwide. Therefore, efforts are being made in Korea toward Land Degradation Neutrality (LDN) to extend the development of green areas. As part of this effort, artificial ecosystems created through land-use changes are restored to forests. We examined grassland created through land-use change, an afforested site planted for forest restoration, and a nearby primary forest according to the LDN indicators. The grassland created about 40 years ago showed higher bulk density and available phosphorus compared to the forest and showed relatively low carbon and nitrogen contents. According to the assessment of LDN indicators, the soil organic carbon stock and productivity calculated from the normalized difference vegetation index of the afforested site for restoring the grassland to forest did not change. The assessment of the restoration effect was not made in the short-term, but in near future, the planted trees are expected to grow, restoring the land to forest. This study shows that the LDN program of Korea should follow carefully established restoration policies and strategies to achieve positive results.

The Jeongseon Alpine Center, a degraded forestland, has a very unique soil feature as it was filled with soil cut from the nearby area and has not yet been rehabilitated since the end of the 2018 Winter Olympics. Therefore, this study attempted to identify a way to establish a stable and efficient planting groundwork to successfully restore this distinctive region. Six different planting groundworks, control, biochar, leaf-mold, mulching, tillage, and polyacrylamide treatments were constructed in September 2020. Soil-related indices have been tracked while the growth and physiological responses of planted Pinus densiflora (Pd) and Larix kaempferi (Lk) seedlings were monitored until May 2022. Mulching had 2–4 times the average SWC when compared to the control. Simultaneously, there was the least variation in soil temperature change, and total soil loss was only 0.05 ton/ha. Similarly, the leaf-mold had a relatively high SWC, and soil fertility increased, while total soil loss was 6.37 tons/ha, indicating a high trend in line with biochar. The Pd leaf-mold had the highest in Amax, E, gs, and Jmax. Furthermore, following the leaf-mold, mulching showed the second-highest photosynthetic indices in general, and the height and DRC also demonstrated favorable results in the above two treatments. Mulching had 1.6 to 2.2 times higher than the control group in PIabs and PItotal, which represent photosynthetic vitality, so the impact on environmental stress was thought to be less than that of leaf-mold. The mulching of Lk showed the greatest growth and physiological responses, Nonetheless, the photosynthetic indices were rather low when compared to Pd, with no discernible differences across treatments. As a result, the considerable effect of the planting groundwork method could not be demonstrated. Therefore, in the case of Pd, the leaf-mold showed the best growth and physiological response. Nevertheless, in terms of soil temperature maintenance and soil loss for slope stability, mulching is assessed to be the most ideal planting groundwork method.

Green buffer (GB) zones are designed to prevent the spread of air pollutants and odors from industrial complexes (ICs) to residential areas (RAs). We analyzed changes in the concentration of particulate matter (PM) and the number of high PM pollution days for 10 years after the GB was implemented, using the National Atmospheric Environmental Research Stations 2001–2018 dataset. We also performed field measurements of PM10 and PM2.5 from February 2018 to January 2019 to analyze the PM concentrations at human breathing height throughout the GB. Before GB implementation (2001–2006), PM10 in the RA was 9% higher than that in the IC. After GB zone implementation (2013–2018), PM10 in the RA was 11% lower than that of the IC. Furthermore, the PM concentration in the RA (slope = ∆Concentration/∆Time, −2.09) rapidly decreased compared to that in the IC (slope = −1.02) and the western coastal area (WCA) (slope = −1.55) over the 10-year period. At PM concentrations at human breathing height, PM10 and PM2.5 in the RA were lower than those in the IC by 27% and 26%, respectively. After GB implementation, the wind speed was positively correlated but SOx was negatively correlated with the PM reduction rate at a local scale. These results show that there was a reduction of PM during and after GB implementation, implying the need for proper management of GBs and continuous measure of pollutant sources at the green buffers of industrial complexes.

Ammonia (NH3) is an important precursor for particulate secondary aerosol formation. This study was conducted to evaluate the applicability of a passive sampler (PAS) for estimating the NH3 emission from chemical fertilizer application (85 kg-N&middot, ha&minus, 1) at field scale and to compare the results with a chamber system for the calculation of NH3 emission flux at lab scale. The application of chemical fertilizer increased the ambient NH3 concentration from 7.11 to 16.87 &mu, g&middot, m&minus, 3. Also, the ambient NH3 concentration measured by the PAS was found to be highly influenced by not only the chemical fertilizer application but also the weather (temperature and rainfall). Wind rose diagram data can be useful for understanding the distribution of ambient NH3 concentration. In the case of a chamber with few environmental variables, NH3 was emitted very quickly in the early stages and gradually decreased, whereas it was delayed at intervals of about one week at the site. It was found that daily temperature range, atmospheric disturbance by wind and rainfall, changes in soil moisture, and the presence of a flooded water table were the main influencing factors. The PAS data and the chamber system data were observed to have significant differences in spatial-temporal scale. In order to reduce the gap, it seems to be necessary to further develop a chamber system, in order to improve the precision of field analysis and to strengthen the connection between experimental results.

Using a fumigation sterilizer (Dazomet) for nematode control, this study determined the effect of soil sterilization on the quantity and quality of the growth of Pinus densiflora Siebold &amp, Zucc. and Larix kaempferi (Lamb.) Carri&egrave, re seedlings in an open-field nursery at Jeongseon-gun, Kangwon-do, Republic of Korea. Most soil nematodes disappeared after fumigant sterilization. The organic matter content, cation exchange capacity, and Mg2+ content of the soil increased significantly, but the electrical conductivity (EC) decreased. The quantity of pine and larch seedlings was highly correlated with the soil nematode density. The soil properties changed due to soil fumigation, which affected the growth of both species. Pine seedling growth was affected by the soil chemical properties, such as available phosphorus (AP), Ca2+, Mg2+, and EC, and the growth of larch seedlings was affected by the EC and nematode density. The quality of the pine seedlings improved, whereas that of larch did not. This was a result of the difference in their tolerance to soil salinity. The seedling quality index (SQI) of the two species was related to the EC, but the pine seedlings were more affected by the EC, indicating that the control of soil nematodes by fumigant treatment significantly increased the quantity of seedlings produced and partly improved their quality. Soil management using a fumigant treatment was more efficient for producing pine seedlings than larch. Our results can be used to improve agricultural and forestry economics.

For the ammonia generated in Korea, the contribution rate of livestock manure is high, and a large amount of ammonia (NH3) is emitted into the atmosphere during the soil application process. Volatilization of NH3 is affected by soil characteristics as well as manure characteristics, but the current inventory does not sufficiently reflect this. This study was conducted to confirm the change of the NH3 emitted from liquid fertilizer (LF) due to soil pH and to evaluate the impacts of biochar (BC) on the suppression of NH3 volatilization. Estimating the NH3 emission flux using the chamber for 24 soils after LF treatment, it showed a tendency to increase exponentially as the pH in soil increased from 4 to 7. In addition, the parallel treatment of BC and LF increased the soil pH, thereby increasing the NH3 emission flux. The rise of soil pH due to LF treatment is a temporary phenomenon that appears in the early stage, but since NH3 volatilization is also highest at the beginning of LF application, the effect of soil characteristics on emission factor and its inventory should be considered when calculating the amount of NH3 emissions. Therefore, follow-up studies such as subdividing and enhancing the NH3 emission factor by soil characteristics and developing a reduction coefficient to certify the amount of emission reduction are needed.

Soil acidification caused by anthropogenic activities adversely affects forest ecosystems by altering soil pH, which is an important factor in soil quality and function. Liming is one suggested way to solve this problem. This study was performed to evaluate the effects of liming in acidic forest soils by determining soil microbial biomass, microbial community structure, and extracellular enzyme activities associated with carbon, nitrogen, and phosphorus cycling. Lime treatment increased soil pH by up to 40%, significantly increased organic matter (OM) content at some sites, and altered the enzyme activity of the soil. With liming, the microbial biomass appeared to be affected by the chemical properties of the soil, such as pH, Ca2+, Mg2+, K+, and exchangeable aluminum (Ale) levels, although there were no significant differences at the site level. Enzymatic activity was found to be affected by pH, Ca2+, Mg2+, electrical conductivity (EC), and Ale, and acid phosphatase (AP) and phenol oxidase (POX) activity were significantly affected by lime treatment. AP activity decreased from 0.62 to 0.66, and POX activity increased from 1.75 to 3.00 in part of the sites. The bacterial community richness was influenced by pH as a direct effect of lime treatment. The fungal community richness was associated with changes in K+ that were not due to lime treatment. The bacterial community structure was affected by soil OM, total nitrogen (TN), pH, and Ca2+, and the fungal community structure was affected by pH, Mg2+, and K+. In conclusion, changes in soil environmental conditions by liming can affect soil microbial communities and functions through direct or indirect processes, further changing ecosystem processes.

Spent coffee grounds (SCG) and charred spent coffee grounds (SCG-char) have been widely used to adsorb or to amend heavy metals that contaminate water or soil and their success is usually assessed by chemical analysis. In this work, the effects of SCG and SCG-char on metal-contaminated water and soil were evaluated using chemical and biological assessments; a phytotoxicity test using bok choy (Brassica campestris L. ssp. chinensis Jusl.) was conducted for the biological assessment. When SCG and SCG-char were applied to acid mine drainage, the heavy metal concentrations were decreased and the pH was increased. However, for SCG, the phytotoxicity increased because a massive amount of dissolved organic carbon was released from SCG. In contrast, SCG-char did not exhibit this phenomenon because any easily released organic matter was removed during pyrolysis. While the bioavailable heavy metal content decreased in soils treated with SCG or SCG-char, the phytotoxicity only rose after SCG treatment. According to our statistical methodology, bioavailable Pb, Cu and As, as well as the electrical conductivity representing an increase in organic content, affected the phytotoxicity of soil. Therefore, applying SCG during environment remediation requires careful biological assessments and evaluations of the efficiency of this remediation technology.

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)

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.

This study was conducted to determine the changes in soil chemical properties and the growth of seedling according to the different dredged soil improving methods at slope of Saemangeum sea dike. Undersea dredged soil was improved by five different methods. Seedlings of Ulmus davidiana var. japonica, Chionanthus retusa, Celtis sinensis, and Pinus thunbergii were planted after 9 month of experience site installation, then soil pH, NaCl concentration in soil, soil organic matter (SOM), and survival rate and height of seedling was measured. Initial soil pH was highest in the control plot but it decreased to the similar level with other soil improving plots after 35 months. There were no differences in NaCl concentration between the control and soil improving plots, and it showed decreasing tendency during the study period. In the control plot, initial SOM was lowest among that of other plots during the study period. The survival rate of 36 months after planting of P. thunbergii was highest among the species. The gap of the tree growth of P. thunbergii between the control plot and the soil improving plots was small, however, other species showed relatively higher tree height in the soil improving plots than the control plots. Creation forest with P. thunbergii might be a cost effective afforestation in coastal reclaimed land since it rarely needs additional improvement of dredged soil.

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.

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.

One potential plant species suggested for phytoremediation of heavy metal contaminated soils in Korea is evening primrose (Oenothera odorata). In this study, the tolerance mechanism of O. odorata to Cd exposure was investigated using tissue concentration of malondialdehyde (MDA) and growth decline (fresh weight and root elongation) as indicators of Cd induced stress when grown under hydroponic conditions. Compounds containing thiol functional groups including phytochelatins (PCs) were also determined in both root and shoot. In response to elevated Cd concentrations, the growth of O. odorata decreased, and shoot synthesis of MDA increased as the concentration of Cd accumulated in the tissue also increased. Simultaneously, MDA synthesis in the root was suppressed despite much more Cd being accumulated in the roots compared to the shoots. The suppression of MDA synthesis in the roots was related to PCs synthesis since much higher PC concentrations were observed in roots than in shoots. The synthesized PCs resulted in mitigation of Cd activity through complexation and compartmentalization in tissue and consequently Cd induced MDA production was reduced. Therefore, this study clearly demonstrated that PC synthesis has a significant role in the Cd tolerance of O. odorata. Refereed/Peer-reviewed

To determine the appropriate allocation of resources for the future restoration of the abandoned mining district of Kangwon in Korea, identification of the main pollutants and the main sources discharging these pollutants is crucial. Therefore, a 2-year study was undertaken to quantify the amount of pollutants in the Uchen stream (a potential sink for contamination), which runs through the district, and to determine the potential sources of these pollutants, including mine drainage and soil. Arsenic (As) was the main pollutant in mine drainage and soils showing concentrations above the Korean regulated standard levels of 50 μg L⁻¹ and 50 mg kg⁻¹ for water and soil, respectively. In addition, the pollution index (PI) showed that mine drainages were polluted by As to a moderate (2 ≤ PI < 3) or strong (4 ≤ PI < 5) degree. Consequently, As load in mine drainage and soil contributed to increased amounts of As in the stream. The As loads in mine drainages (11 and 587 g month⁻¹ for mine adit 1 and 2, respectively) accounted for only 9% of the total As load to the stream (6,378 g month⁻¹); and the influence of mine drainages on As contents in the stream was more reliant on the total volume of mine drainage generated rather than the As concentration in the mine drainage. Approximately 91% of the As in the stream was derived from the soils within the study area. Refereed/Peer-reviewed

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.

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.

A greenhouse experiment was conducted to evaluate the effect of four different amendments, bone mill, bottom ash, furnace slag, and red mud, as immobilizing agents and the plant species Miscanthus sinensis and Pteridium aquilinum in aided phytostabilization of Pb/Zn mine tailings. The effects of amendments and plants on the availability and mobility of heavy metals were evaluated using single extraction, sequential extraction, pore-water analysis, and determination of heavy metal concentrations in plants. The application of Fe-rich amendments significantly reduced the amount of soluble and extractable heavy metals in the tailings ( p M. sinensis reduced CaCl 2 -extractable heavy metals by 56–91%, red mud and P. aquilinum treatment was the most effective at decreasing bioaccessible Pb, reducing it to 34% of the total Pb. Compared to control, water soluble Cd, Cu, Pb, and Zn were reduced by 99, 99, 98, and 99%, respectively, in the red mud and P. aquilinum tailings. M. sinensis accumulated heavy metals mainly in the root, and had lower translocation factors compared with P. aquilinum . The results of this study suggest that M. sinensis can be used in aided phytostabilization for these types of mine tailings and Fe-rich amendments are effective for the in situ immobilization of metals.

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.

The objectives of this study were to elucidate the effects of soil amendments [Ferrous sulfate (Fe(II)), red mud, Fe(II) with calcium carbonate (Fe(II)/L) or red mud (RM/F), zero-valent iron (ZVI), furnace slag, spent mushroom waste and by-product fertilizer] on arsenic (As) stabilization and to establish relationships between soil properties, As fractions and soil enzyme activities in amended As-rich gold mine tailings (Kangwon and Keumkey). Following the application of amendments, a sequential extraction test and evaluation of the soil enzyme activities (dehydrogenase and β-glucosidase) were conducted. Weak and negative relationships were observed between water-soluble As fractions (As(WS)) and oxalate extractable iron, while As(WS) was mainly affected by dissolved organic carbon in alkaline tailings sample (Kangwon) and by soil pH in acidic tailings sample (Keumkey). The soil enzyme activities in both tailings were mainly associated with As(WS). Principal component and multiple regression analyses confirmed that As(WS) was the most important factor to soil enzyme activities. However, with some of the treatments in Keumkey, contrary results were observed due to increased water-soluble heavy metals and carbon sources. In conclusion, our results suggest that to simultaneously achieve decreased As(WS) and increased soil enzyme activities, Kangwon tailings should be amended with Fe(II), Fe(II)/L or ZVI, while only ZVI or RM/F would be suitable for Keumkey tailings. Despite the limitations of specific soil samples, this result can be expected to provide useful information on developing a successful remediation strategy of As-contaminated soils.

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(NO3)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.