Spatio-temporal variations of selected pesticide residues in the Kurose River in Higashi-Hiroshima city,Japan

ABSTRACT

This study investigated spatio-temporal variations of selected pesticide residues in the Kurose River in Higashi-Hiroshima city (Hiroshima Prefecture), Japan. Water samples were collected from the river at seven sites every month for 1 year (March 2016 to February 2017). Pesticide residues were extracted from the samples by a solid phase extraction using Sep Pack C₁₈ cartridges. Once extracted, the samples were analyzed for cyanazine, simetryn, fenarimol, isoprothiolane, and diazinon using a reversed-phase high-performance liquid chromatography ultraviolet visible (HPLC-UV Vis) system. The limits of detection were 3.60, 4.10, 2.80, 6.50, and 7.30 ng L^-1 for cyanazine, simetryn, fenarimol, isoprothiolane, and diazinon, respectively. Good recovery rates (88%–102%), and mean percent relative standard deviation range (1.00%–5.70%) (n = 6) were obtained with a spiking at 0.20 µg L^-1. The maximum concentrations of 282, 391, 60, 1086, and 1194 ng L^-1 were obtained for cyanazine, simetryn, isoprothiolane, fenarimol, and diazinon, respectively. Cyanazine was the most frequently detected pesticide (64% of the samples, n = 84), followed by simetryn (58%), and then diazinon (57%). The highest and lowest pesticide concentrations were measured during the periods May–June, and January–February, respectively. Principal component analysis revealed three principal components in which the pesticides were linked to dissolved organic matter and total suspended solids. The major water quality parameters (electrical conductivity, pH, Na⁺, K⁺, Mg²⁺, Ca²⁺, NH₄⁺, NO₃^?, Cl^?, SO₄^2?, NO₂^?, and temperature) showed no clear trends for these pesticides. The presence of simetryn and isoprothiolane was largely attributed to rice paddy farms, whereas diazinon was associated mostly with vegetable farms and orchards. The diazinon and isoprothiolane patterns were consistent with their use of controlling insects and fungi in the prefecture. The maximum diazinon concentration detected was higher than the human safe level specified by the European Union (100 ng L^-1) in Council Directive 98/83/EC. This is of concern because of the bioconcentration potential of these residues in fish and other marine animals consumed by humans.     

南苕溪支流锦溪水质时空变化特征分析

综合运用灰色聚类法、综合污染指数法、等级聚类法就南苕溪支流锦溪近年水质时空变化特征进行分析。结果表明,锦溪入青山水库断面水质2005—2009年逐年改善,2007年后达到灰色聚类等级Ⅲ类水质要求;2009年秋季至2010年夏季期间秋、冬两季的污染程度高于春、夏季节;枯水期综合污染指数最高,但TN、TP污染分指数在丰水期最高,表明污染源中面源污染已占相当比例。空间变化方面从玲珑桥到江桥锦溪水质的综合污染指数不断提升,到江桥时达到极值13.25,锦溪末端三眼桥断面水质较江桥断面有所改善;SPSS空间聚类分析可分为轻污染区(从玲珑桥到冬韵桥)、重污染区(从群利桥到江桥)和中度污染区(从江桥到三眼桥)。锦溪上游农业区对河水中的COD、TN和TP的贡献率分别为66%、54%和49%,农业面源污染已成为制约锦溪水质改善的主要因素。     

胶州湾水质及主要营养盐季节性变化分析

于2010年4个季度对胶州湾水质进行了调查,根据单因子污染指数法,利用计算机软件绘制了水质分区图,分析了胶州湾水质的最新状况及不同季节的水质变化情况,同时对胶州湾主要营养盐无机氮和活性磷酸盐的变化进行了分析。调查结果显示,2010年胶州湾水质定性评价为差,无机氮和活性磷酸盐的平均浓度分别为0.393 mg/L、0.018 mg/L,高值区主要分布在胶州湾东北角,无机氮和活性磷酸盐的平均浓度及空间分布随着季节的变化而呈现了一定的变化。     

个人特征、家庭特征对农村非农就业影响的实证

工业化对于一个国家或地区经济腾飞的重要性,已经被西方发达国家的经验和道路所证实。在实现工业化的过程中,农村劳动力转移是世界各国都曾经或必将面对的重要课题。本文运用行为主义研究方法,利用2003-2006年全国农村固定观察点的数据,建立Probit模型实证分析了农民个体特征和农户家庭特征对农村非农就业的影响。研究发现:就样本个人特征而言,户主或家庭主要经营者、男性、文化程度较高、身体健康的农民从事农村非农就业的意愿更强,职业教育或培训对于农村非农就业有明显的促进作用,而是否农业户口对农村非农就业的影响并不明显。就样本家庭特征而言,家庭类型会影响农民在农村的非农就业倾向,同时,乡村干部户从事非农产业的倾向性更强,少数民族户和信教户从事非农产业的倾向性较弱,"是否国家干部职工户"、"是否党员户"对农村非农就业的影响并不显著。重视农民的个人特征和家庭特征差异,大力发展农村非农产业,促进农村非农就业是我国政府解决农村剩余劳动力转移问题的重要战略选择。     

The Future of Baltic Sea Populations: Local Extinction or Evolutionary Rescue?

Environmental change challenges local and global survival of populations and species. In a species-poor environment like the Baltic Sea this is particularly critical as major ecosystem functions may be upheld by single species. A complex interplay between demographic and genetic characteristics of species and populations determines risks of local extinction, chances of re-establishment of lost populations, and tolerance to environmental changes by evolution of new adaptations. Recent studies show that Baltic populations of dominant marine species are locally adapted, have lost genetic variation and are relatively isolated. In addition, some have evolved unusually high degrees of clonality and others are representatives of endemic (unique) evolutionary lineages. We here suggest that a consequence of local adaptation, isolation and genetic endemism is an increased risk of failure in restoring extinct Baltic populations. Additionally, restricted availability of genetic variation owing to lost variation and isolation may negatively impact the potential for evolutionary rescue following environmental change.     

Geographic variation in tissue accumulation of endocrine disrupting compounds (EDCs) in grazing sheep

Muscle tissue was collected from ewes and lambs derived from farms throughout Scotland and sample concentrations of five endocrine disrupting compound groups were determined. Farms of origin were categorised according to geographic region. There were few statistically-significant differences with region or distance from cities. However, the magnitude of the difference between the highest and lowest mean values in ewe muscle from different regions exceeded 30% for 13 of the 15 compounds that were consistently detected in muscle, with animals derived from the industrialised region having the highest mean values for 11 of the 13 compounds. A less marked trend was apparent in the lamb muscle (8 of 13 highest were in the industrialised region). The physiological effects of such small differences in exposure to mixtures of pollutants remain to be determined.     

Growth, leaf traits and litter decomposition of roadside hybrid aspen (Populus tremula L.× P. tremuloides Michx.) clones

Road traffic contributes considerably to ground-level air pollution and is therefore likely to affect roadside ecosystems. Differences in growth and leaf traits among 13 hybrid aspen (Populus tremula × P. tremuloides) clones were studied in relation to distance from a motorway. The trees sampled were growing 15 and 30 m from a motorway and at a background rural site in southern Finland. Litter decomposition was also measured at both the roadside and rural sites. Height and diameter growth rate and specific leaf area were lowest, and epicuticular wax amount highest in trees growing 15 m from the motorway. Although no significant distance × clone interactions were detected, clone-based analyses indicated differences in genotypic responses to motorway proximity. Leaf N concentration did not differ with distance from the motorway for any of the clones. Leaf litter decomposition was only temporarily retarded in the roadside environment, suggesting minor effects on nutrient cycling.     

Binational school-based monitoring of traffic-related air pollutants in El Paso, Texas (USA) and Ciudad Juárez, Chihuahua (México)

Paired indoor and outdoor concentrations of fine and coarse particulate matter (PM), PM2.5 reflectance [black carbon(BC)], and nitrogen dioxide (NO₂) were determined for sixteen weeks in 2008 at four elementary schools (two in high and two in low traffic density zones) in a U.S.-Mexico border community to aid a binational health effects study. Strong spatial heterogeneity was observed for all outdoor pollutant concentrations. Concentrations of all pollutants, except coarse PM, were higher in high traffic zones than in the respective low traffic zones. Black carbon and NO₂ appear to be better traffic indicators than fine PM. Indoor air pollution was found to be well associated with outdoor air pollution, although differences existed due to uncontrollable factors involving student activities and building/ventilation configurations. Results of this study indicate substantial spatial variability of pollutants in the region, suggesting that children’s exposures to these pollutants vary based on the location of their school.     

太湖蓝藻水华分级及其时空变化

根据MODIS影像和实地监测叶绿素a浓度数据,采用太湖蓝藻水华分级评估方法,对2004~2008年太湖不同类型蓝藻水华类型进行评估并统计分析,探求太湖蓝藻水华特征及其时空变化规律,以期为太湖蓝藻水华预防和预警提供支持。结果表明：（1）2004~2008年,全湖共发生蓝藻水华414次,以小型蓝藻水华为主,发生333次,占总次数的80.43%;随着蓝藻水华级别的增加,发生次数逐渐减少;（2）空间上,蓝藻水华主要发生在太湖的北部和西部区域,并且蓝藻水华发生级别由高到低基本上沿西北-东南方向分布;（3）年际变化上,蓝藻水华发生次数呈逐渐增加趋势,蓝藻水华级别较高、次数较多的年份主要集中于2006年和2007年;（4）年内变化上,4~8月份,蓝藻水华发生次数呈增加趋势,8~11月,蓝藻水华发生次数逐渐减少。并且,蓝藻水华主要集中于5月和7~10月份,尤其是8~10月。     

Unusual Salinity Conditions in the Yangtze Estuary in 2006: Impacts of an Extreme Drought or of the Three Gorges Dam?

During the extreme dry year of 2006, abnormal salinity conditions in the Changjiang Estuary of the Yangtze River occurred in partial coincidence with the second impoundment phase of the TGD (Three Gorges Dam). Analysis of discharge observations in the upper reaches of the estuary and of salinity observations in the estuary as a whole reveals that in 2006 salinity was over 100 mg/l during 275 days, over 250 mg/l during 75 days and over 400 mg/l during 48 days. It is well known that this is due to extreme low discharges from the upper catchment area into the estuary. Moreover, large amounts of water consumed along the lower reaches of the Yangtze River can also aggravate the low discharges that lead to stronger saltwater intrusion in the estuary. Of the 75 days that salinity was over 250 mg/l, the low discharge was decreased further by 10 to 20% due to water consumption. The additional impact of the impoundment phase of the TGD (lasting 37 days in autumn) was noticeable only during 7 days in 2006. During that period, the relative contributions of the TGD and the water consumption in the lower reaches of the Yangtze River amounted to 70 and 30%, respectively. It may be concluded that the impact of the second impoundment phase of the TGD on salinity intrusion in the estuary was modest, while the extreme drought of 2006 was the dominant cause.