• 한국물환경학회지
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• 제23권1호
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• pp.81-86
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• 2007

This paper describes a study on the role of limestone which might affect the dissolution of phosphates when phosphate containing sediments are put under anaerobic conditions. A small quantity of calcium hydroxy-apatite, alone or mixed with limestone powder, was put in contact with aqueous solution of acetic acid or carbonic acid, and variations of phosphate concentration were determined time dependantly. The results showed that the concentration was remarkably low in the presence of limestone, signifying that the coexistence of limestone suppresses the dissolution of phosphate by organic acid and/or carbonic acid. Separate experiments conducted by developing an anaerobic condition, after mixing lake sediments with dried leaves and limestone, showed that the existence of limestone suppressed the dissolution of phosphate. These results show that the application of limestone might be a useful measure to prevent deterioration of water quality originated from eutrophication by inhibiting the internal loading of P in eutrophic water-bodies.

• 한국물환경학회지
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• 제24권3호
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• pp.285-290
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• 2008

This study was done to explain the role of limestone which might intervene in the phosphorus cycle in a lake. The effects of limestone on the dissolution of phosphate were estimated by simulations with the computer model Visual MINTEQ, which is designed for the chemical equilibrium calculations. According to the calculations limestone shows remarkable effects for the suppression of phosphate dissolution. The limestone can suppress the dissolution of phosphates by sacrificing themselves to acids, and as a consequence can increase the hardness and alkalinity of the lake. Both hardness and alkalinity play an important role in reducing soluble P and thus alleviate the eutrophication potential.

• 한국토양비료학회지
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• 제29권2호
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• pp.113-123
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• 1996

국내산(國內産)과 수입(輸入) 중국산(中國産) 입상(粒狀) 용성인비(熔成燐肥)의 물리화학적 특성을 비교하기 위해 pH의 경시적 변화, 입도분포(粒度分布), 수중 및 토양중 붕괴도(崩壞度), 토양중 경도(硬度), 제품의 화학성분(化學成分) 함량(含量) 분석(分析), 수중 및 토양중 구용성(枸溶性) 인산(燐酸) 용출율(溶出率) 등(等)을 검토한 결과를 요약(要約)하면 다음과 같다. 1. pH의 경시적(傾時的) 변화(變化)는 중문통(中文統)(농암갈색(濃暗褐色) 토양(土壤))이 평대통(坪垈統)(흑색(黑色) 토양(土壤))보다, 수입(輸入) 중국산(中國産) 제품(製品)이 풍농비료 제품 보다, 중문통(中文統)에 용성인비(熔成燐肥)를 다량(多量) 시용(施用)한 것이 소량 시용한 것 보다 pH의 변화(變化)가 컸었다. 2. 국내산(國內産) 용성인비(熔成燐肥)는 수입 중국산 용성인비에 비하여 pH, 석회(石灰), 알카리분 및 가용성(可溶性) 규산함량(珪酸含量)이 낮았으나 인산(燐酸) 전량(全量), 구용성(枸溶性) 인산(燐酸), 고토(苦土)(가용성(可溶性) 구용성(枸溶性)) 및 구용성(枸溶性) 망간은 약간 높거나 서로 비슷하였다. 3. 입도(粒度)의 크기는 수입(輸入) 중국산(中國産) 제품(製品)이 가장 크고 그 다음이 경기화학(京畿化學) 제품(製品)이며 풍농비료(豊農肥料)의 제품(製品)은 비교적 입자가 작았다. 4. 수중(水中) 및 토양중(土壤中) 붕괴도(崩壞度)는 초기(初期)에는 풍농비료 제품과 경기화학 제품이 낮았으나 후기(後期)에는 경기화학 제품>수입 중국산 제품>풍농비료 제품의 순으로 붕괴도가 낮았다. 5. 토양중(土壤中) 경도(硬度)는 경기화학(京畿化學) 제품(製品)이 가장 단단하였고 그 다음이 풍농비료(豊農肥料) 제품(製品)이며 수입(輸入) 중국산(中國産) 제품(製品)은 경도계로 측정할 수 없을 정도로 약하였다. 6. 구용성(枸溶性) 인산(燐酸) 용출율(溶出率)은 초기에는 경기화학(京畿化學) 제품(製品)이 가장 높았고 풍농비료(豊農肥料) 제품(製品)은 가장 낮았으며, 용출 50일에는 3제품(製品) 모두 90% 이상 용출되었고 용출 70일 이후는 제품간(製品間) 차이가 거의 없었다. 7. 토양중(土壤中) 구용성(枸溶性) 인산(燐酸) 용출율(溶出率)은 풍농비료(豊農肥料) 제품(製品)이 가장 높았고 수입(輸入) 중국산(中國産) 제품(製品)이 가장 낮았으며 용출일 100일에도 60%를 넘지 못하였다.

• Journal of Periodontal and Implant Science
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• 제38권sup2호
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• pp.273-298
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• 2008

Purpose: The aim of this review is to introduce a novel bone-graft material for hard-tissue regeneration based on the calcium phosphate glass(CPG). Materials and Methods: CPG was synthesized by melting and subsequent quenching process in the system of CaO-$CaF_2-P_2O_5$-MgO-ZnO having a much lower Ca/P ratio than that of conventional calcium phosphates such as HA or TCP. The biodegradability and bioactivity were performed. Effects on the proliferation, calcification and mineralization of osteoblast-like cells were examined in vitro. Influence in new bone and cementum formations was investigated in vivo using calvarial defects of Sprague-Dawley rats as well as 1-wall intrabony defect of beagle dogs. The application to the tissue-engineered macroporous scaffold and in vitro and in vivo tests was explored. Results: The extent of dissolution decreased with increasing Ca/P ratio. Exposure to either simulated body fluid or fetal bovine serum caused precipitation on the surface. The calcification and mineralization of osteoblast-like cells were enhanced by CPG. CPG promoted new bone and cementum formation in the calvarial defect of Sprague-Dawley rats after 8 weeks. The macroporous scaffolds can be fabricated with $500{\sim}800{\mu}m$ of pore size and a three-dimensionally interconnected open pore system. The stem cells were seeded continuously proliferated in CPG scaffold. Extracellular matrix and the osteocalcin were observed at the $2^{nd}$ days and $4^{th}$ week. A significant difference in new bone and cementum formations was observed in vivo (p<0.05). Conclusion: The novel calcium phosphate glass may play an integral role as potential biomaterial for regeneration of new bone and cementum.