• Journal of applied mathematics & informatics
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• 제28권5_6호
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• pp.1185-1202
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• 2010

In this paper, we have studied the dynamical behaviour such as boundedness, local and global stabilities, bifurcation of a single species population affected by environmental toxicant and population toxicant. We have also studied the effect of discrete delay of the environmental toxicant on the instantaneous growth rates of the population biomass and population toxicant due to incubation period. The length of delay preserving the stability is also estimated. Computer simulations are carried out to illustrate our analytical findings.

• 대한환경공학회지
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• 제31권10호
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• pp.855-864
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• 2009

본 연구에서는 질산화 반응이 활발히 진행되고 있는 기존 하수처리장 슬러지를 이용하여 3개월 이상 농축 배양한 후에 부착 및 부유성장 상태로 적응시킨 질화균을 이용하여 독성물질에 대한 영향을 조사하였다. 본 실험의 목적은 부유 및 부착성장 질화균을 이용하여 이들의 비표면적에 따른 독성물질의 영향을 상호비교하기 위한 것이다. 이를 위하여 부유 및 부착상태의 농축 질화균의 비표면적을 다르게 하여 각각에 대한 독성물질의 영향을 조사하였다. 연구 결과 부착성장 질화균 및 부유성장 질화균의 경우 비표면적이 클수록 독성에 대한 영향을 더 많이 받는 것으로 나타났다. 부착상태와 탈착상태의 질화균을 사용한 실험에서, 독성물질에 대한 영향은 탈착상태보다 부착상태에서 독성의 영향을 적게 받았으며, Nitrosomonas의 경우에는 1.12배, Nitrobacter의 경우에는 1.09배 독성의 영향을 적게 받았다. 부유성장 질화균을 사용한 경우에는 분쇄 전보다 분쇄 후에 독성의 영향을 더 크게 받았으며, Nitrosomonas의 경우에 1.46배, Nitrobacter의 경우에 1.35배 독성의 영향을 적게 받았다. 또한, 기질에 아질산염을 주입하지 않고 실험한 결과에서도 유사한 결과를 얻었다. 부착상태와 탈착상태의 질화균을 사용한 실험에서, 독성물질에 대한 영향은 탈착상태보다 부착상태에서 독성의 영향을 적게 받았으며, Nitrosomonas의 경우에는 1.83배, Nitrobacter의 경우에는 1.78배 독성의 영향을 적게 받았다. 부유성장 질화균을 사용한 경우에는 분쇄 전보다 분쇄 후에 독성의 영향을 더 크게 받았으며, Nitrosomonas의 경우에 1.27배, Nitrobacter의 경우에 1.32배 독성의 영향을 적게 받았다.

• Toxicological Research
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• 제17권
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• pp.37-39
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• 2001

As the preliminary data collection for further chemical risk assessment. toxicants rating works is now rather extensively implemented in China. It consists of two parts, ie., rating of the hazard level of the exposed toxicant and that of the toxicant's profession. In the first part, the rating are based on six criteria, ie., acute toxicity, incidence of acute poisoning, prevalence of chronic poisoning, consequence of chronic poisoning, carcinogenecity and MAC level. Four hazardous levels are to be classified as extreme, high, medium, mild. In the second part. three determinants as weighted coefficients are taken into account, ie., toxicant's hazard level. exposure time and folds of MAC surpassing. Eventually, the index of classification C by which the work with toxic hazard can be classified is able to be calculated and assessed. Several comments were discussed and new recommendations were demonstrated.

• Fisheries and Aquatic Sciences
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• 제22권7호
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• pp.15.1-15.8
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• 2019

Corexit 9500 is a dispersant commercially available in Nigeria that is used to change the inherent chemical and physical properties of oil, thereby changing the oil's transport and fate with potential effects on the environment. The aim of this study was to assess the biochemical (enzymes and electrolyte) toxicity of Corexit 9500 dispersant on the gills, liver and kidney of juveniles of Clarias gariepinus after exposure for 21 days. One hundred sixty fish were used without gender consideration. Range-finding tests were conducted over a 96-h period after acclimatisation of the test organisms in the laboratory. The test organisms (10/treatment) were exposed to Corexit 9500 in the following concentrations-0.00, 0.0125, 0.025 and 0.05 ml/l in triplicate. Twenty-one days later, fish was dissected. 0.5 g from each of the following organs-gills, liver and kidney tissues-was removed, homogenised and tested for enzymes [superoxide dismutase (SOD), catalase (CAT), alanine aminotransferase (ALT), aspartate transaminase (AST), alkaline phosphatase (ALP)], urea, creatinine and electrolytes (sodium ($Na^+$), potassium ($K^+$), chloride ($Cl^-$), bicarbonate ($HCO_3{^-}$)) following standard methods. In the gills, SOD and ALT to AST ratio were significantly lower than in control while the creatinine was significantly higher in the toxicant. In the kidney, creatinine was significantly higher in fish exposed to the toxicant. In the liver, ALP increased in the toxicant while urea was decreased. The mean electrolyte concentrations ($Na^+$, $K^+$, $Cl^-$ and $HCO_3{^-}$) increased significantly in the concentration of the toxicant (P < 0.05). The alterations observed in the activities of these electrolytes and enzymes indicated that Corexit 9500 interfered with transamination and metabolic functions of the fish.

• 대한약학회:학술대회논문집
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• 대한약학회 2002년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.2
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• pp.294.2-295
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• 2002

Methylmercury (MeHg: CH3HgCl) is a ubiquitous environmental toxicant that readily bioaccumulates in aquatic foodchains. This toxicant is most highly exposed to humans through the ingestion of contaminated food. and thus is an ongoing health concern. Thus far. MeHg has been suggested to exert its toxicity through its high reactivity to thiols of bioactive proteins. elevation in intracellular Ca2＋ concentration. and generation of reactive oxygen species. but its mechanism remains poorly understood. (omitted)

• 한국환경독성학회:학술대회논문집
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• 한국환경독성학회 2000년도 추계심포지움 및 학술발표회:바이오모니터링 기법을 이용한 환경위해성 평가
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• pp.47-47
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• 2000

• 한국환경교육학회지:환경교육
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• 제2권1호
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• pp.92-99
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• 1991

According to our secondary school curriculum for natural science and technical circles, there be used 353 of chemical reagents including 24 kinds of harmful and toxicant components. At present, most school are discharging their school laboratory waste water without any chemical and physical treatments. So as to solve the environmental problem for water pollution, this study tried to research a kind of adsorbant utilizing saw dust, wasted wood sources and designed the simple processing system using the adsorbent. This adsorbent was made by extracting lignin substances from raw saw dust under the solution of 0.5N-NaOH at the temperature of $100^{\circ}C$. Their metal removed rates was measured not only by processing of column and vessel. but also by comparing the standard solution and real waste water. The results were proved as more than 90(%) of the adsorptive efficiency on the average from Pb, Cd, Cu except Cr(VI)in case of the school experimental waste water soaked in vessels a long with 4g of the adsorbent for 24 hours. The new processing system enables to remove most harmful and toxicant metals by filtering, sedimenting and adsorbing at the low cost.

• 한국독성학회:학술대회논문집
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• 한국독성학회 2003년도 춘계학술대회 논문집
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• pp.29-30
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• 2003

The heavy metal cadmium is a xenobiotic toxicant of environmental and occupational concern and it has been classified as a human carcinogen. Inhalation of cadmiumhas been implicated in the development of emphysema and pulmonary fibrosis, but, the detailed mechanism by which cadmium induces adverse biological effects is not yet known.(omitted)

• 한국독성학회:학술대회논문집
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• 한국독성학회 2002년도 Molecular and Cellular Response to Toxic Substances
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• pp.116-116
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• 2002

It is believed that cell and/or tissue toxicity is resulted from alterations in expression of many genes in response to environmental stresses or toxicants. New technology, such as DNA microarray analysis, can measure the expression of thousands of genes at a time providing the potential to accelerate discovery of toxicant pathways and specific gene targets.(omitted)

• 한국물환경학회지
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• 제24권5호
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• pp.533-536
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• 2008

Korean water quality guidelines for agricultural were derived to protect agricultural water uses according to the Canadian methodology. The adverse effect of heavy metals in agricultural water was of concern due to its persistence, bioaccumulation and ecotoxicity to crop plants. The ecotoxicity data of cadmium, copper, lead, and zinc were collected for the crops grown in Korea, and used to estimate the species maximum acceptable toxicant concentration (SMATC), which corresponds to the water quality guideline. Values of irrigation per year and soil bulk density were revised to reflect the Korean situation. The estimated guideline values for cadmium, copper, lead, and zinc were 0.01, 0.5, 0.1, and 1.0 mg/L, respectively. These values are in agreement with the agricultural water quality guidelines of foreign countries and current Korean water quality standard for the protection of public health. Current water quality standards in agricultural uses were for management of public water resource, and was not prepared to protect crop plants from contaminants. The results of this study will be a basis for the designation of Korean water quality guidelines for the protection of agricultural water uses in the future.