Evidence of Toxoplasma gondii Exposure among Horses in Korea

The present study investigated the seroprevalence of Toxoplasma gondii (T. gondii) antibodies by ELISA in horses reared in Korea. Serum samples were collected from 2009 through 2013 from 816 horses reared in Korea. Analysis was performed using a commercial toxoplasmosis ELISA kit to detect anti-T. gondii antibodies. Overall, 24 out of 816 horses (2.9%) were seropositive for T. gondii. The result was analyzed by age, gender, breed and region. Significant differences were observed according to breed and region (P<0.05). This is the first nationwide serological investigation of T. gondii in horses reared in Korea. The study results reveal that T. gondii occurs nationwide in Korean horses.     

Allelopathic potential of K21, selected as a promising allelopathic rice

The agronomic characteristics of a newly bred potent allelopathic rice, K21, including morphological appearance, resembled its female parent, Dongjinbyeo, except for 8 days' earlier heading and 9 cm shorter plant height. The water extract of K21 showed a greater inhibitory effect on the shoot and root growth of barnyardgrass than its female parent, but less than the male parent, Kouketsumochi. At the highest extract concentration of 5.0%, the inhibitory effect of K21 on the shoot growth of barnyardgrass was ≈ 64%, similar to its male parent. The dry weight of the barnyardgrass shoot was reduced by 13.0% when grown with K21 and 30.2% when grown with its male parent. There was no inhibitory effect on the shoot dry weight of barnyardgrass when grown with the female parent. The activity of cinnamic acid 4-hydroxylase in K21 was ≈ 1.8-fold higher than that of the female parent, but significantly lower than that of the male parent. The ρ-coumaric acid content in K21 was ≈ 60% higher than that of the female parent, but it was about half of the male parent. The total amount of phenolic compounds in K21 was ≈ 11.5% higher than in the female parent, but about half of the male parent. The results obtained suggest that the newly bred K21 contains desirable allelopathic traits derived from the male parent, Kouketsumochi, and acceptable agronomic traits from its female parent, Dongjinbyeo.     

The Study and Prospect of the Secondary Clarifier Models in Wastewater Treatment

The paper reviews the research status of the secondary clarifier model from one-dimensional model to three-dimensional model. The one-dimensional model based on solid flux theory was outlined by discussing how to choose model parameters such as settling velocity function and the number of layers. Based on the achievement of actived sludge model and the development of wastewater treatment technology, it is suggested that the development of the secondary clarifier model should focus on the establishment of some clarifier model including biological processes and the enrichment of hydraulics phenomena modeling.     

Trade Reorientation and Its Effects on Regional Port Systems: The Korea‐China Link along the Yellow Sea Rim

ABSTRACT Owing to its competitive labor costs, its open‐market policy, and a substantial amount of capital investments, China has become a global manufacturing pole and an export‐based economy replicating the conventional Asian model but on a much wider scale. This is creating acute competition on other Asian export‐based economies such as Korea that have to adapt to the “China effect.” Consequently, many Korean manufacturing companies have repositioned their capital and equipment in China to enlarge their market potential as well as to reduce their production costs. Because Korea is adjacent to China—both are sharing the Yellow Sea Rim—this shift is creating a unique geographical dimension with a high level of functional integration of Sino‐Korean manufacturing supply chains. This transition has also brought substantial changes in the regional logistic network by organizing new flows of raw materials, parts, and final products, most of them along the Yellow Sea Rim. New logistic flows have given substantial influences on regional port competition by creating diverse links. These changes are bringing a reorientation of the regional maritime industry and of the port system.     

SWAT模型之初步探讨

由美国农业部农业研究中心（USDA-ARS）研发的分布式水文模型:水土评估工具（SWAT）,具有强大的物理机制。近年来,它被认为是最适合模拟在不同土壤、土地利用和管理大流域中,长期土地管理对于水、土沙、营养物质及农业化学物质的影响。介绍SWAT模型的原理及基础数据库之建立,并搜集SWAT模型应用研究之文献（1999-2008年）,以统计分析SWAT模型目前的研究现况,作为日后应用SWAT模型进行相关研究之参考。     

Stochasticity dominates assembly processes of soil nematode metacommunities on three Asian mountains

Nematodes play an important role in ecosystems; however, very little is known about their assembly processes and the factors influencing them. We studied nematode communities in bulk soils from three Asian mountain ecosystems to determine the assembly processes of free-living nematode metacommunities and their driving factors. On each mountain, elevations span a range of climatic conditions with the potential to reveal assembly processes that predominate across multiple biomes. A phylogenetic nu...     

NATURAL REGENERATION OF VEGETATION AS AN ALTERNATIVE FOR GREENING SAND-FILLED RECLAIMED LAND IN SINGAPORE

Land reclamation projects have been implemented in Singapore to increase the republic's land area. Not all reclaimed lands have been used to date, and some of those that remain idle have been allowed to regenerate. This paper examines one such sand-filled reclaimed area and studies the pattern of, and factors favouring, the natural regeneration of Casuarina equisetifolia whose seeds come mainly from a row of established mother trees planted by the roadside nearby. Based on the extent of coverage of this species over the reclaimed land and the mean trunk-wood volume build-up after 14 years, natural regeneration of this kind appears to be an effective alternative to the greening of sand-filled reclaimed land, or any derelict land of this nature, at very low cost. © 1997 John Wiley & Sons, Ltd.     

The genesis and classification of soils on wet terraces and moraines in New Zealand

Six soils on glacial outwash terraces and one on moraine are discussed; four are formed partly in loess of unknown age. Evidence of podzolization is apparent in all profiles, but the vertical drainage under very high rainfall is insufficient to remove surplus water. Gley processes appear to dominate, in a perched-water environment.
Podzolic B horizons were identified in the same five profiles following both the Canadian system and that used by the Soil Survey of England and Wales. However, only three of these profiles could be allocated to existing podzolic subgroups in the latter system. Spodic horizons were identified in a different group of five profiles. Differences in classification are discussed with reference to the criteria used and in relation to proposals for revision of the New Zealand Soil Classification.     

土壤NO_x气体释放研究进展

营养元素的迁移转化是生态学及环境科学研究领域的一个重要课题,土壤微生物活动产生的NOx气体作为大气中NOx的重要排放源之一,日益受到人们的关注。NOx在大气中具有很强的化学活性,通过参与大气中光化学反应而影响到其它温室气体的浓度,且在对流层O3和OH自由基的光化学反应中起着决定性作用,同时也是酸沉降中HNO3的生成源,在平流层NOx是消耗臭氧层的痕量气体之一。本文综合分析了土壤NOx产生及排放机理;影响土壤NOx排放的主要因素;土壤NOx气体排放通量的测定及其模型估算方法。并在此基础上,提出今后应把土壤微生物系统以及土壤硝化、反硝化作用机理作为以后的研究重点,运用同位素技术和各种模型手段进行较大范围的时空尺度上的连续观测研究。     

不同土壤水分对赤松光合作用与水分利用效率的影响研究

在不同土壤水分条件下研究了赤松光合特征及其水分利用效率的变化。结果表明,不同土壤水分处理对赤松幼苗净光合速率、气孔导度、蒸腾速率、水分利用效率等生理指标及其日变化均产生明显影响;中度水分胁迫时赤松幼苗的光合午休比对照提前1h且午休时间长,其净光合速率和气孔导度的下降平行进行,而且,日平均水分利用效率的下降幅度比日平均净光合速率的下降幅度小。