Quality characteristics of Satsuma mandarin (Citrus unshiu Marc.var.miyagawa) harvest on early December according to production areas and sea level altitude of Cheju were investigated. Soluble solids and flesh ratio were distributed 9.32∼12.50, 75.95%-81.3 in citrus fruits harvested in orchards located below 10m sea level altitude (lower area), and was 10.23-12.17 , 77.35%-80.29% on those over 150m sea level altitude )higher area), respectively. Acid content of citrus juice was 0.95%-1.26% in fruits harvested inlower area, and was 1.02%-1.39% in higher area. In proportion to late harvesting , Brix/acid ratio and fruits quality was improved. Soluble solids of fruits harvested in higher area were higher than those of fruits from higher area, but acid contents were on the contrary . In sensory evaluation on fruit appearance, the differences between two altitudes were not clear.

Physicochemical properties and sensory evaluation of Satsuma mandarin produced in Cheju were investigated . Fruit index(width/Length), soluble solids and acid content of Citrus unshiu marc. var. miyagawa(miyagawa) and C. unshiu marc. var.(okitsu) harvested at 1st December were 1.16 and 1.23, 12.12 and 12.01, 0.97 and 1.09, respectively. and the fruit of miyagawa was showed somewhat round in shape, compared to ikitsu. the taste of miyagawa seemed to be better than okitsu. However, compared to miyagawa, peel thickness was thinner, flesh ratio was higher, and firmness was higher as 0.502kg-force in kitsu. Nevertheless there were some differences among panelist groups in sensory evaluation , middle size of citrus fruits were favorable to most panelists, but except very small or very large size of fruits, there were not so much differences in okitsu. The panelists referred to somewhat flat-shaped fruits from that sensory evaluation score was increased to 1.3 in fruit index. nevertheless there were not so much differences in full-colored fruits, the citrus peel color of reddish yellow was more favorable than greenish or pale yellow color. the score was increased more linearly according to citrusfruit produced in optimum ciltivation area, and was prefered to thinner in peel thickness , Correlation between soluble solids, acid content , Brix/acid ratio and flesh ratio with sensory evaluation score were not showed significantly, it was different to with citrus juice. This data obtained in this experiments are supposed to be applied to the quality evaluation of Satsuma mandarin produced in Cheju .

The purpose of this paper is to present the environment change of Cheju Island as land development process using GSIS(Geo-Spatial Information System) technique. We implemented the process based on the maps of soil color, underground water pollution points, land use, land development planning and land sight seeing supported by Cheju Province Office. To use the maps for GSIS data, first we transformed the picture data of the office into raster structured picture data using scanner. Second, the coordinate system was added to raster data using 1/50000 geographic map. Third, we estimated land planning process using GSIS technique(overlay and reclass technique). The results showed that land development effected the natural environment(forest, green field, farm land). However, the chemical pollution and land sight seeing was not so much effected by the land development that was found.

To study the residue of organophosphorus pesticides in the ocean environment on the Cheju island, EPN[O-ethyl-O-4-nitrophenyl phenylphosphonothioate] and monocrotophos [Dimethyl-1-methyl-2-methy] carbamoylvinylphosphate] of organophosphorus pesticides are surveyed on coastal environment of Cheju city and Wimi in May and October 1996. The qualified limit detection of EPN and monocrotophos are 0.005ng/mL and 0.006ng/mL., in the water by GC-FPD, respectively. The qualified limit detection of EPN and monocrotophos are 0.010ng/g and 0.012ng/g in the solid such as sediment and sea organism by GC-FPD, respectively. EPN and monocrotophos are not detected in seawater and sediment. Moreover EPN and monocrotophos are neither detected in seaweed cava (Ecklonia cava), Agar (Gelidium amansii), turban sell(Batillus cornutus) and sea urchin(Anthocidaris Crassispina). EPN, monocrotophos used in the farm on the Cheju island are not residued in the coastal environment in the Cheju island.

The adsorption and leaching of organophosphorus pesticides (phenthoate, diazinon, methidathion) were investigated in Namwon soil(black volcanic soil), Aewol soil(very dark brown volcanic soil) and Mureung soil(dark brown nonvolcanic soil) sampled in Cheju Island. The Freundlich constant, K value, was 52.4, 31.3 and 27.7 for phenthoate, diazinon and methidathion in Namwon soil, respectively and decreased in the order of phenthoate, diazinon and methidathion among the pesticides. The K value of phenthoate was 52.4, 15.9 and 5.9 for Namwon, Aewol and Mureung soil, respectively and was the highest for Namwon soil with very high organic matter content and cation exchange capacity(CEC). The Freundlich constant, 1/n, showed a high correlation with organic matter content, i.e., its value was less than unity for organic matter rich soil(Namwon soil) and greater than unity for organic matter poor soil(Mureung soil). Total recoveries of pesticides in soil and leachate with leaching in soil column, were in the range of about 74∼86%. The leaching of pesticides was less for phenthate with high K values, and more for methidathion with low K values among the pesticides. It was slower for Namwon soil with high K values, and faster for Mureung soil with low K values among the soils.

Physicochemical properties of Satsuma mandarin(Citrus unshiu Marc. var. miyagawa) harvested in middle of November according to production areas of Cheju were investigated. Peel thickness of citrus fruits was ranged from 2.54mm to 3.13mm, and it was lower on fruits harvested in western areas than those of other areas in Cheju. Soluble solids were ranged from 10.1 to 12.0Brix, and it was lower on fruits harvested in southern areas. Acid contents of citrus juice were ranged from 1.28% to 1.42%, it was higher on fruits harvested in eastern areas, specific gravity of citrus fruits was ranged between 0.86 and 0.88. Flesh ratio was ranged from 75.1% to 77.6%, it was lower on fruits harvested in southern areas. Soluble solids, acid content and specific gravity harvested in southern areas of below 100m and over 150m sea level altitude were 11.8 and 11.2, 1.43% and 1.40%, 0.87 and 0.9, respectively. Fruits quality harvested in southern areas was better, compared to other harvest areas of Cheju.

In order to manage the water quality from the flowing streams in Cheju Island, the characteristics of water quality was investigated from August, 1996 to May, 1997 and the pollutant loadings for future were estimated from the watershed at each stream. Comparing the mean concentrations of each water quality with the criterion of water quality in river, it was under I class except for Changgo Stream, for DO, under I class at the whole station for SS and under Ⅱ class for BOD. As the pollutant loadings at each stream in 2020 is compared with those in 1996, the estimated results are as follows : 1) for BOD, 59% at Donghong Stream, 24% at Yeonoe Stream, 44% at Ohngpo Stream and 57% at Changgo Stream. 2) for T-N, 91% at Donghong Stream, 76% at Yeonoe Stream, 63% at Ohngpo Stream and 89% at Changgo Stream. 3) for T-P, 69% at Donghong Stream, 42% at Yeonoe Stream, 45% at Ohngpo Stream and 73% at Changgo Stream The point source loadings discharged through combined sewer could be treated at sewage treatment plant. However, the expected slow decreasing rate of BOD, T-N, and T-P loadings is due to the part of untreated nonpoint source loadings. Nonpoint source loading overflow typically occurs when the flow of stormwater combined with sewage exceeds the capacity of the interceptor sewers. Since most of the sewers used in Cheju Island are the combined sewers, the combined overflow sewage is bypassed into the receiving water area after a rainstorm. Therefore, a means to control nonpoint source loadings should be considered for the river and marine water quality management.

Soybean [Glycine max (L.) Merr.), mungbean [Vigna radiata (L.) Wilcz.], cowpea [V. unguiculata (L.) Walp.], adzuki bean [V. angularis (Willd.) Ohwi & Ohashi], maize [Zea mays L.], sorghum [Sorghum bicolor (L.) Moench], sorghum ~times sudangrass [So bicolor intraspecific hybrid], and Japanese millet [Echinochloa crusgalli var. frumentacea (Link) W.F. Wight] were grown at two planting dates (18 June and 15 July) at Cheju in 1997 to select the best forage legumes adapted to Cheju Island for grass-legume forage rotation. Averaged across planting dates and cultivars, dry matter (DM), crude protein (CP), and total digestible nutrient (TDN) yields were 5,646, 1,056, and 3,637 kg/ha for soybean, 4,458, 676, and 2,661 kg/ha for mungbean, 3,289, 553, and 2,055 kg/ha for cowpea, 3,931, 674, and 2,489 kg/ha for adzuki bean, 12,695, 969, and 7,642 kg/ha for maize, 17,071, 1,260, and 8,857 kg/ha for sorghum, 16,355, 1,163, and 8,543 kg/ha for sorghum ~times sudangrass hybrid, and 8,288, 929, and 4,091 kg/ha for Japanese millet. Soybean was higher in CP, ether extract (EE), and TON content but was lower in nitrogen free extract content compared with the three other legumes. The legumes had much higher CP (13.7 to 21.9%), EE (2.42 to 6.23%), and TDN (58.7 to 69.9%) content but lower in crude fiber (CF) content (17.3 to 25.3%) than did the grasses tested except maize which had relatively lower CF content but higher TDN content. These results suggest that soybean could be the best forage legume for grass-legume forage rotation in the Cheju region.

Two determinate soybean cultivars, 'Baegunkong' and 'Namhaekong', were planted on 8 Jone, 23 June, and 8 July 1996 at Cheju at planting densities of 33, 43, 53, 63 plants per m2 to determine the optimum planting density of double crop soybean for recently recommended cultivars in Cheju area at various planting dates. The plant height, and the diameter and node number of main stems decreased as planting was delayed. The plant height increased but the stem diameter and node number decreased with increasing planting density. Pod number per plant was greater for Namhaekong than for Baegunkong and was not affected by planting date. Pod number per plant decreased but pod numbers per ~textrmm2 increased with increasing planting density. The number of seeds per pod was greater at the two later plantings and fewer at the highest planting density. 100-seed weight decreased with delaying planting. The seed weight was lighter at the highest planting density for Baegunkong but there was no difference for Namhaekong among the planting densities. The seed yield of Baegunkong was greater for 23 June and 8 July plantings (2,280 and 2,420 kg/ha) than for 8 June planting (1,450 kg/ha) while that of Namhaekong was greatest at 23 June planting (2,690 kg/ha) compared with 8 June and 8 July plantings (1,890 and 2,080 kg/ha). Across the planting dates and cultivars, seed yield increased from 1,860 to 2,290kg/ha as the planting density increased from 33 to 53 plants/~textrmm2 and then leveled off with a further increase in planting density.

Based on the X-ray powder diffraction (XRD) and M ssbauer spectroscopy, the thermal behavior and phase transformations of two clays are investigated for raw and fired conditions, which are collected from Kwangryeongli and Ildo district in Cheju Island. M ssbauer spectra at room temperature and 20for two clays show that paramagnetic Fe3- is the structural iron of the layer silicate and ferrihydrite, and superparamagnetic goethite has about 50% of total iron contents. The XRD peaks of hematite for the fired clays appear from 800℃ in Kwangryeongli clay and from 600℃ in Ildo district clay, respectively. The structural Fe2+ was completely oxidized into Fe3- at 400℃ for Kwangryeongli clay and 500℃~600℃ for Ildo district clay, respectively. The structural Fe2+ was completely oxidized into Fe3- at 400℃. For the temperature ranging from 400℃ to 700℃~800℃, two fired clays exhibit the dehydroxylation of the clay mineral. A disintegration of the clay mineral structure is observed from 700℃~800℃ to 1100℃, followed by the onset and spread of vitrification process. It is also shown that well-crystallized hematite phase is formed at the temperature higher than 1100℃ and the relative absorption area decreases, which might be related to the recrystallization of alluminosilicate matrix.

The characteristics of spring machanism in the Cheju Island were analyzed by statistical techniques. Basic characteristics, areal and altitudinal variations, and correlations of spring data were ivestigated. In this study, however, the subjects of the study are the 451 springs, the whole basin of Cheju Island devided into four groups. In this study, analyzed the spring phenomena on the basis of both the geologic elements and the topographic elements. Also, the spring zone in Cheju Island are classified into three types that the mountain area, the middle area, the coastal area in spring distribution by altitude. The quentity of spring and variability show subvariety on the average according to Meinzer`s classification and the whole basin of spring shows various distributions from Third to Sixth. The results of this study can be utilized to evaluate the condition of groundwater development in Cheju Island.

Effect of storage on the tree and quality of early cultivar of Citrus unshiu Marc. produced in Cheju according to harvest time were investigated. Soluble solids, acid content, flesh ratio, firmness and specific cavity of the fruits harvested at 27th of November were 12.0, 1.03%, 79.98%, 0.774kg-force, 0.912, respectively. Soluble solids, total sugar and reducing sugar were increased gradually, but acid content was decreased slightly as delayed in harvest time. Otherwise specific gravity and firmness were not shown in great during harvest time, color index(a/b) was increased sharply till late November and then remained in stationary phase. On these result, we recommend that the harvest time of early cultivar of Citrus unshiu Marc. would be during December because of wilting partly. Fully ripened-fruits harvested late, compared to ordinary harvest time, with cold storage would be kept more quality and freshness of fruits for fresh consumption than the fruits harvested early and stored at room temperature.

In order to investigate the adsorption characteristics of organochlorine pesticides chlorothalonil and dicofol with soil colors and regions for soils of an orange orchard, the soils were sampled at 3 regions, respectively, among black volcanic, dark brown volcanic, and brown nonvolcanic soils. Every soil has a higher clay proportion (49-75%) in soil texture and the organic carbon content and cation exchange capacity with soil decreased in the following sequence: Black volcanic > Dark brown volcanic > Brown nonvolcanic soils. Especially those in black volcanic soils were much higher than others. The retention time, quantitative detection limit, and extractian, efficiencies of chlorothalonil and dicofol were 2.82min, 1.5ng/mL, 93.6% and 3.64min, 4.5ng/mL, 94.2%, repectively. The Freundlich constant, Kd, was higher in dicofol compared to chlorothalonil and in the black volcanic soils that have higher organic carbon content and cation exchange capacity. The Freundlich constant, 1/n, was in the range of 0.76-0.89 in the black volcanic soils that have a higher organic matter(16.4-19.8%), whereas it was in the range of 1.02-1.13 in the brown nonvolcanic soils that have a lower organic matter(2.4-3.4%), and so it was considered that 1/n was dependent on the organic matter.

Physicochemical properties affecting on the quality of Citrus unshiu Marc. var miyagawa and C. unshiu Marc. var, okitsu according to cultivation area in Cheju were investigated. Linear correlations (r>0.9) were showed between fruit size and peel thickness. There were much difference between cultivation areas in soluble solids of C. unshiu Marc. var. okitsu. The difference were not so much in soluble solids and acid contents of citrus fruits produced at same area below 65mm of fruit diameter, but the quality of large size fruits were inferior. Brix/Acid ratio could not be index for quality evaluation, because of individual deviation. Soluble solid content of citrus fruits produced in south Cheju was higher than that produced in north Cheju. Acid content and Brix/Acid ratio of citrus fruits produced in south Cheju was lower than that produced in north Cheju. The quality of C. unshiu Marc. var. miyagawa clad not so much difference between cultivation area, but the difference of quality were recognized significantly in C. unshiu Marc. var. okitsu.

This study was carried out to investigate the chemical characteristics of rainwater sampled in Cheju City from July 1994 to June 1996. Concentrations of major Ions (Cl^-, SO_4^2-,NO_3^-, Na^+, K^+, Ca^2+, Mg^2+ and NH_4^+) were determined. The pH of rainwater, calculated from the volume weighted H^+ concentration, was found to be 5.61, indicating extensive neutralization of the acidity in the rain. The relative magnitude of average ionic concentrations followed the relation Cl^-> SO_4^2-> Na^+> Ca^2+> NH_4^+> NO_3^-> Mg^2+> K^+. The ions associated with sea salt, namely Na^+ and Cl^-, dominated the total concentration of ions in the rainwater and the SO_4^2- ion accounts for 20% of total concentration. [H^+]/[nss-SO_4^2-+NO_3] ratio and a multiple regression for SO_4^2- and NO_3^- ions against H^+, Ca^2+ and NH_4^suggested that all of SO_4^2+ and NO_3^- in rainwater was not necessarily associated with H_2SO_4, anf HNO_3, but might also occur in combination with NH_4^+ or Ca^2+. The monthly mean concentrations of SO_4^2-, Ca^2+ and NH_4^+ in spring time was higher than those in other seasons. These results may be attributed to the fertilizer application as the local sources and the yellow sand phenomina as a regional-scale sources.

The conditions of cold stroage of Citrus unshiu Marc. var. okitsu produced in Cheju were investigated. The changes of peel moisture contents soluble solids, total sugar, vitamin C and density were slightly occured, and decay ratio was below 20% on keeping freshness relatively till late of March during cold storage. After thats decayed citrus fruits were increased gradually mainly from cold injury with lower temperature and high humidity. The loss of fruit weight, decrease of fruit hardness, and decrease of acid content were occured gradually during cold stroage. Because of the difficulty of long term storage for Citrus unshiu, the conditions and periods of cold storage would be determined after considering the physicochemical properties of fruits every year.

Total carotenoid contents, color values and spectrum characterization in the range of UV of fruit juice and organic acid and free sugar contents determined by HPLC were investigated on 10 varieties of Cheju citrus fruits. Carotenoid contents of juice were 0.47-9.20/ml which showed higher with Dangyooja while showed lowest content with Meiwa Kumquat. Lightness (L) of juice was highest in Meiwa Kumquat, and in the order of Sankyool, Navel orange and Hungjin. Redness(a) and yellowness(b) were in the order of Dangyooja, Natsudaidai, Sambokam and Kinkoji. The maximum absorption wavelengths if citrus Juices were variable at 269.5-285.5nm according to varieties and it was observed that were changed by mixing with Juices of other varieties. Major organic acids of citrus juice were citric and malic acid, and citric acid was 64.4-95.1% of total organic acids. Ascorbic acid was high in Navel orange, Sudachi and Dangyooja, and low in Meiwa Kumquat and Hungjin. Major free sugars were sucrose, glucose and fructose. Sucrose was 49.2-75.2% of total free sugars, and high in Sankyool and Meiwa Kumquat. Glucose and fructose were high in Meiwa Kumquat and Navel Orange.

Physicochemical properties and the conditions of cold storage of kiyomi clangor(Citrus unshiu x sinensis) produced in Cheju were investigated. Firmness, edible part ratio, soluble solids, and acid content were decreased gradually with incurasing fruit size. Carbohydrates in juice were consisted of 65.12% sucrose, 19.65% fructose, and 15.23% glucose The main organic acrid In juice was 57.4% of citric acid, and others were lactic acid, malic acid, oxalic acid and fumaric acid, respectively. Weight loss were occured very. slowly to about 6% till late of May, but decayed fruits were occurred very slowly to about 6% till late of May, but decayed fruits were arisen to about 8% at 3, and about 13% at 5 of storage temperature. The changes of peel moisture content, soluble solids, total sugar, vitaamin C, and density of fruits were slightly occured during cold storage. Cold storage at 3 and 87% relative humidity kept freshness of citrus fruits for a long-term without damage of cold injury.

This study was conducted for the efficient utilization of a scoria, which is abundantly found in Cheju island, as adsorbent and the scoria was examined for its performance in clarification of adsorption of heavy metal ions. The order in heavy metal ions adsorbed on scoria was; Pb^+>Cd^2+>Cu^2+>Ag^+>Co^2+>Zn^2+>Cr^3+>Cr^6+. This tendency was relatively consistent with the decreasing order of radius of hydrated metal ion. Also, the smaller scoria size and the larger amounts of scoria showed higher removal efficiency for heavy metal ions. The same scoria size showed more effective removal efficiency for heavy metal ions at lower initial concentration than at higher initial concentration. The adsorption abilities of original scoria and chemically treated scoria were compared. Adsorption isotherm of scoria was generally obeyed to Freundlich formula than Langmuir formula and Freundlich constant, 1/n was obtained in the range of 0.2∼0.4.

In order to determine the quality of Citrus unshiu(medium cultivar of satsuma mandarin) produced in Cheju, citrus fruits sampled at sorting places and harvested directly on citrus tree in south and north area of Cheju were analyzed. The fruits were grown in size till early of November, and soluble solids were increased continuously after that. Compared with the quality of citrus fruits as a factor of soluble solids, firmness, total sugar, pH, and color index, the optimum harvest periods were supposed to be reasonable from early of December for C. unshiu Marc. var. yonezawa and C. unshiu Marc. var. hayashi, Fruit weights and peel thickness had a linear correlation with increasing fruit size, but soluble solids and acid contents had not a correlation. The selection of C. unshiu variety was needed to determine by the properties of storage.