• Economic and Environmental Geology
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• v.40 no.3 s.184
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• pp.277-293
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• 2007

Seasonal and spatial variations in the concentrations of trace elements, pH and Eh were found in a creek watershed affected by mine drainage and leachate from several waste rock dumps within the As-Pb-rich Indae mine site. Because of mining activity dating back to about 40 years ago and rupture of the waste rock dumps, this creek was heavily contaminated. Due to the influx of leachate and mine drainage, the water quality of upstream reach in this creek was characterized by largest seasonal and spatial variations in concentrations of Zn(up to $5.830 mg/{\ell}$), Cu(up to $1.333 mg/{\ell}$), Cd(up to $0.031 mg/{\ell}$) and $SO_4^{2-}$(up to $173 mg/{\ell}$), relatively acidic pH values (3.8-5.1) and highly oxidized condition. The most abundant metals in the leachate samples were in order of Zn($0.045-13.909 mg/{\ell}$), Fe($0.017-8.730mg/{\ell}$), Cu($0.010-4.154mg/{\ell}$) and Cd($n.d.-0.077mg/{\ell}$), with low pH(3.1-6.1), and high $SO_4^{2-}$(up to $310 mg/{\ell}$). The mine drainage also contained high concentrations of Zn, Cu, Cd and $SO_4^{2-}$ and remained constantly near-neutral pH values(6.5-7.0) in all the year. While the leachate and mine drainage might not affect short-term fluctuations in flow, it may significantly influence the concentrations of chemicals in the stream. The abundance and chemistry of Fe-(oxy)hydroxide within this creek indicated that the Fe-(oxy)hydroxide formation could be responsible for some removal of trace elements from the creek waters. Spatial and seasonal variations along down-stream reach of this creek were caused largely by the influx of water from uncontaminated tributaries. In addition, the trace metal concentrations in this creek have been decreased nearly down to the background level at a short distance from the discharge points without any artificial treatments after hydrologic mixing in a tributary. The nonconservative(i.e. precipitation, adsorption, oxidation, dissolution etc.) and conservative(hydrologic mixing) reactions constituted an efficient mechanism of natural attenuation which reduces considerably the transference of trace elements to rivers.

• Journal of Food Hygiene and Safety
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• v.34 no.3
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• pp.219-226
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• 2019

This study was conducted to understand the overall status of the monitoring program for pesticide residues in foods of South Korea. Further propositions for its improvement were made, and from this study, the status on this program can be summarized as follows. In South Korea, the Ministry of Food and Drug Safety (MFDS) is responsible for overall control of pesticide residue monitoring. Depending on the time of monitoring (sampling at distribution or production step), the government agency responsible for monitoring is different: MFDS, Regional Offices of Food and Drug Safety and local governments are responsible for monitoring of foods at the distribution step, while the National Agricultural Products Quality Management Service (NAQS) and local governments are responsible for monitoring of foods in the production step (partially at sale and distribution steps). According to purpose of monitoring, domestic monitoring programs could be divided into two types: MFDS's "Residue Survey" and NAQS's "National Residue Survey" are conducted mainly for risk assessment purposes and various monitoring programs by the Regional Offices of Food and Drug Safety and local governments are conducted mainly for regulation purposes. For imported foods, monitoring should be conducted at both steps of customs clearance and distribution: the MFDS and the Regional Offices of Food and Drug Safety are responsible for the former, and for the latter, local governments are also responsible. However, it appeared that systematic and consistent monitoring programs are not being conducted for imported foods at the distribution step. Based on the information described above and more detailed information included in this paper, the following proposals for improving the monitoring program were forwarded: i) further clarification of monitoring program purpose, ii) strengthening of the monitoring program for imported foods, iii) providing the public with monitoring results by publication of an annual report and database. It is thought that exhaustive review on the pesticide residue monitoring program and efforts for its improvement are needed in order to assure both food safety and the success of the recently begun positive list system (PLS).