Arsenic accumulation and speciation in Japanese paddy rice cultivars

We examined arsenic (As) accumulation and speciation in the major cultivars currently grown in Japan, because differences in grain As levels among cultivars may influence dietary As exposure in Japanese people. Ten major cultivars (Oryza sativa L.) were grown under flooded conditions in a paddy field with a background level of As (low-As soil) or in pots filled with soil containing a high level of As (high-As soil). In the low-As soil, the total grain As ranged from 0.11 to 0.17?mg?kg^?1, with a mean concentration of 0.14?mg?kg^?1, and inorganic As was the major species in all cultivars. There were few genotypic differences in the levels of either total As or inorganic As in the grain. In the high-As soil, total grain As increased to a mean level of 2.4?mg?kg^?1 in the 10 cultivars, with markedly increased levels of dimethylarsinic acid. The genotypic variations among cultivars in the levels of both total As and dimethylarsinic acid were statistically significant. However, the genotypic variability of inorganic As levels was quite small, and these levels remained low (at about 0.2?mg?kg^?1) even when total As levels increased markedly. These results suggest that differences in grain As levels among Japanese cultivars may not influence dietary As exposure, because there is little genotypic difference in the accumulation of inorganic As, which is considered more toxic than organic As to humans. We discuss the possible mechanism of As accumulation in Japanese paddy rice, in the context of the accumulation of As species in the developing grain and in other plant tissues.     

Arsenic speciation in xylem exudates of rice growing in arsenic-contaminated soil

Rice has a much enhanced arsenic (As) accumulation compared with other cereal crops. How As is transported in xylem exudates of rice growing in soil remains unknown. We quantified the chemical species of As in xylem exudates of rice growing in arsenic-contaminated soil (62.5 mg As per kg soil) under flooded and aerobic conditions. In the aerobic treatment, the predominant species of As in the xylem sap was arsenate [As(V)], accounting for 64–88%, and the remainder was arsenite [As(III)]. In the flooded treatment, dimethylarsinic acid (DMA) was detected in the xylem sap besides As(III) and As(V), and the percentages of the three species As was 11–20%, 26–77%, and 12–54%, respectively. As speciation in the soil solution was dominated by As(V) under aerobic conditions, and dominated by As(III) under flooded conditions. DMA was detected at low concentrations in some of the flooded solution samples. Our results show that As speciation in the xylem sap differs in different water management regimes and correlate with As speciation in the soil solution strongly.     

淡水鱼的连续式鱼鳞去除方法

为研究连续式鱼鳞的去除方法,以鲢鱼、鳊鱼、鲤鱼为试验对象,提出了一种以弹簧为主要去鳞结构的去鳞刷,并以弹簧外径、去鳞刷转速与去鳞刷直径等为主要因素,通过自制去鳞试验台研究了其对淡水鱼去鳞率和鱼体损伤的影响,表明弹簧外径、去鳞刷直径对淡水鱼去鳞率有显著影响,对鱼体损伤感官评价得分影响不显著,去鳞刷转速对去鳞率和鱼体损伤感官评价得分均有极显著影响。不同种鱼,其各自适宜的弹簧外径、去鳞刷直径与去鳞刷直径有所不同。确定了白鲢去鳞时弹簧外径、去鳞刷转速、去鳞刷直径的最优参数组合,即弹簧外径21 mm、去鳞刷转速1 120 r/min、去鳞刷直径90 mm。该研究可为连续式去鱼鳞机的研制提供依据。     

Arsenic toxicity and accumulation in turnip as affected by arsenic chemical speciation

Arsenic (As) uptake by turnip, growing under soilless culture conditions, was studied. A 4 x 3 factorial experiment was conducted with four As species [arsenite, arsenate, methylarsonic acid (MMAA), dimethylarsinic acid (DMAA)] and three As concentrations (1.0, 2.0, and 5.0 mg L(-)(1)). Arsenic phytoavailability and phytotoxicity were primarily determined by As speciation. Organic arsenicals, especially MMAA, were clearly phytotoxic to this turnip cultivar. Plant As concentrations significantly increased with increasing As application rates. Both organic arsenicals showed a higher upward translocation than their inorganic counterparts, contributing to the greater phytotoxicity and lower dry matter productions of these organic treatments. Both inner root and outer root skin As concentrations were above the maximum limit set for As content in food crops (1.0 mg kg(-)(1)). If turnip plants are exposed to a large pulse of As, as growth on contaminated nutrient solutions, they will accumulate residues at levels that are unacceptable for animal and human consumption.     

Arsenic mobilization and speciation during iron plaque decomposition in a paddy soil

Purpose  

Little information is available concerning the mobilization and speciation of arsenic (As) in paddy soils during iron plaque decomposition. It is important to investigate these processes since they affect As bioavailability and contaminate surface and ground water systems.     

基于鱼体特征点检测的淡水鱼种类识别

针对传统机器视觉技术对淡水鱼种类进行检测时特征提取过程复杂的问题,该研究提出了基于特征点检测的淡水鱼种类识别方法。以鳊、鳙、草鱼、鲢、鲤5种大宗淡水鱼为对象,构建了淡水鱼特征点检测数据集;以AlexNet模型为基础,通过减小卷积核尺寸、去除局部响应归一化、引入批量归一化、更换损失函数,构建了改进AlexNet模型用于特征点检测;并以特征点为依据提取特征值、构造特征向量,使用Fisher判别分析方法实现了淡水鱼的种类识别。试验结果表明：改进AlexNet模型在测试集上的归一化平均误差的均值为0.0099,阈值δ为0.02和0.03时的失败率F_0.02、F_0.03分别为2.50%和0.83%,具有较好的精准度和误差分布情况;基于该模型和Fisher判别分析的淡水鱼种类识别方法对5种淡水鱼的识别准确率为98.0%,单幅图像的平均识别时间为0.368 s,保证了时效性。由此可知,提出的改进AlexNet模型能实现淡水鱼的特征点检测并具有较高的精度,可为淡水鱼种类识别、尺寸检测、鱼体分割等提供条件,该方法可为淡水鱼自动化分类装置的研发奠定基础。     

Nickel induced hyperglycemia in the freshwater fish,Colisa fasciatus

Effect of nickel sulphate at the sublethal dose of 64 ppm (0.8 of LC50 96 hr) on the blood glucose levels of the freshwater fish, Colisa fasciatus, has been estimated from 3 to 96 hr. The blood glucose level exhibits a steady increase due to Ni toxicity. A maximum increase of 85.08% is observed at 96 hr (P < 0.001). It is suggested that the hyperglycemia in C. fasciatus, caused by exposure to nickel sulphate, is possibly a reflection of stress-induced hormone mediated response. It appears that the blood glucose level is a reliable indicator of Ni toxicity to fish.     

Development and intercalibration of methods in nordic freshwater fish monitoring

The awareness of the effects of transboundary pollution has increased the necessity to use comparable methods and to initiate joint studies between countries in environmental monitoring. In freshwater fish monitoring a number of different methods have been used, strongly reducing the possibilities to comparative assessments between countries. In 1990, a workshop on freshwater fish sampling was initiated in order to develop and intercalibrate methods used in freshwater fish studies in the Nordic countries. During a three year period, a new type of multi-mesh gillnet to be used for fish monitoring in Norway, Finland and Sweden have been developed. Comparative studies and gillnet-selectivity assessments show that these new multi-mesh gillnets better describe the actual population structure of European perch (Perca fluviatilis), roach (Rutilus rutilus) and Arctic char (Salvelinus alpinus) than do the traditional gillnet series used in the Nordic countries. Ageing of fish is central in most environmental studies, however, the comparability of analyses performed at different laboratories may be low. Comparative age analyses between the three countries have been performed for a number of fish species. The results of ageing E. perch, whitefish (Coregonus sp.) and roach indicate that differences between laboratories can be reduced by intercalibration. In the future, the workgroup will be focused on a further development of joint methods within studies of freshwater fish and on joint intemordic assessments on species distribution, abundance and life history characteristics in relation to airborne pollutants and liming.     

基于机器视觉技术的淡水鱼品种识别

为了后续加工便利,需要对打捞上来的淡水鱼进行分类,而且分类是淡水鱼加工前处理的重要工序之一。为了实现淡水鱼的自动分类,该研究通过收集常见的4种淡水鱼240条为试验样本,分别为鲢鱼、鲫鱼、鳊鱼和鲤鱼。通过运用机器视觉技术采集各种淡水鱼的图像,并运用数字图像处理技术对图像进行处理,提取其各个颜色分量及长短轴之比等特征值,最后运用该特征值建立有关淡水鱼的品种识别模型。研究表明,通过该识别模型可以完全实现对鲢鱼、鲫鱼、鳊鱼和鲤鱼这4种淡水鱼的品种的识别,准确率达到96.67%。机器视觉技术可以快速准确对常见的淡水鱼进行品种识别,具有较强的实际应用价值。     

Retention of ingested 60Co by a freshwater fish

The experiment was carried out on a group of 10 carp receiving the soft tissue of previously contaminated lymnaea as food. Ingestion by carp of 45 daily rations, distributed over a 63-day period, resulted in a low retention of the radionuclide. The contamination kinetics showed that the steady state should be reached after only 225 days. The ⁶⁰Co transfer factor was approximately 10^?2 and the retention factor about 3.3 x 10^?3. During the depuration phase, radiocobalt elimination by the carp developed in accordance with an exponential model based on the existence of two biological half-lives of 1.5 and 35 days which indicate a high Co turnover. During both phases of the experiment, urinary and branchial excretion appeared to be higher than faecal excretion.     

基于机器视觉技术的淡水鱼质量分级

为了便于淡水鱼后续加工,需要对其进行大小分级,而且分级是淡水鱼加工前处理的重要工序之一。该研究收集86条淡水鱼为试验样本,利用机器视觉技术获取淡水鱼样本图像,对样本图像进行灰度化、二值化、轮廓提取等预处理,获取长短轴、投影面积等特征值。通过试验研究,建立有关鱼的头部、腹部和尾部的长度以及质量关系,运用各部分所占总质量的比例对特征值面积进行一定的校正,最后通过回归分析建立鱼体质量的预测模型。试验结果为：鱼体质量与投影面积之间是高度相关,其决定系数R2为0.9878,并对质量预测模型进行验证,验证相对误差均值为3.89%,绝对误差均值为6.81 g。试验结果表明,利用机器视觉技术可以为淡水鱼质量分级方法提供参考。     

基于近红外光谱技术的淡水鱼品种快速鉴别

为探索淡水鱼品种的快速鉴别方法,该文应用近红外光谱分析技术,结合化学计量学方法,对7种淡水鱼品种的判别分类进行了研究。采集了青、草、鲢、鳙、鲤、鲫、鲂等7种淡水鱼,共665个鱼肉样品的近红外光谱数据,经过多元散射校正(multiplicative scatter correction,MSC)、正交信号校正(orthogonal signal correction,OSC)、数据标准化(standardization,S)等20种方法预处理,在1 000~1 799 nm范围内分别采用偏最小二乘法(partial least square,PLS)、主成分分析(principal component analysis,PCA)和BP人工神经网络技术(back propagation artificial neural network,BP-ANN)、偏最小二乘法和BP人工神经网络技术对7种淡水鱼原始光谱数据进行了鉴别分析。结果表明,近红外光谱数据,结合主成分分析和BP人工神经网络技术建立的淡水鱼品种鉴别模型最优,模型的鉴别准确率达96.4%,对未知样本的鉴别准确率达95.5%。模型具有较好的鉴别能力,采用该方法能较为准确、快速地鉴别出淡水鱼的品种。     

A dynamic model for radionuclide transfer from water to freshwater fish

A dynamic model for radionuclide transfer from water to fish is presented, from its design stages to its in situ validation. Four steps are proposed in order to apply the model, for predictive purposes, to ¹³⁷ Cs and ¹⁰⁶ Ru in case of the Rhone (S.E. France), downstream of the Marcoule fuel reprocessing plant. The first step consists of an experimental laboratory study conducted on a species which is representative of the second order trophic level (Cyprinus carpio L.). Compartmental analysis then allows construction of the conceptual model of the organism. The number of compartments necessary to represent the organism and the kinetic parameters quantifying the transfer studied are estimated using a standardized procedure for the statistical processing of results. A numerical method which allows consideration of all the fluctuations recorded in the radionuclide concentration in the water during the exposure phase is shown. Direct ¹³⁷Cs transfer is modeled on the basis of a single compartment, characterized by the exchange kinetics constants A₂=0.224 d^-1 and λ₂=0.0065 d^-1. For¹⁰⁶ Ru, two compartments are necessary in order to model the exchange kinetics. They are characterized by the constants A₁=1.319 d^-1 and λ₁=0.638 d^-1, A₂=0.198 d^-1 and λ₂=0.0261 d^-1. For a theoretical fish having zero growth, and for constant concentration in water, these transfer kinetics lead to concentration factor values of 34 L Kg w.w.^-1 for ¹³⁷Cs and 10 L Kg w.w.^-1 for ¹⁰⁶Ru. The corresponding long biological half- lives are 106 days and 27 days. A different transfer model expression is necessary based on the radionuclide tissue distribution differences within the organism. The major distribution of the ¹³⁷Cs in muscle which is a growth target tissue, implies building the conceptual transfer model on the assumption of the proportionality between the mass of water intervening in the transfer and the mass of the organism. For the ¹⁰⁶Ru preferentially accumulating in a low growth organ (digestive tract), the basic assumption is that of the intervention of a constant mass of water in the transfer. The entire model, i.e. the basic assumption on the influence of the growth of the organism, the number of compartments, the kinetic parameters, was validated by adapted in situ experimentation. The validation tested with a monthly time step was satisfactory for the two radionuclides.     

淡水鱼鱼鳞生物结合力与去鳞特性的试验研究

为研究影响淡水鱼去鳞难易程度的因素,以鲤鱼、草鱼、鲫鱼、鳊鱼4种淡水鱼为试验对象,利用TMS-PRO质构仪对鱼鳞与鱼体的生物结合力进行了测量,研究了鱼鳞所处部位、加载速率、死亡时间对鱼鳞生物结合力的影响。同时,测量了淡水鱼单位面积内的鱼鳞数目,淡水鱼的滑动摩擦角,进行了去鳞试验。在此基础上分析并验证了单位面积鱼鳞生物结合力对去鳞的影响,表明淡水鱼单位面积鱼鳞生物结合力越大,去鳞越难,为去鱼鳞设备的研制提供参考。     

淡水鱼头尾与腹背定向装置的设计与试验

为了给6PYL-305型剖鱼机制造一种自动喂料设备,该文设计了一种淡水鱼头尾与腹背定向装置,并以鲢鱼为定向对象,根据鲢鱼的摩擦特性,通过理论分析,分别对利用倾斜振动台面实现头尾定向和利用渐变滑道实现腹背定向过程的机理进行了探讨,并采用质量为0.75～1.0 kg的新鲜鲢鱼进行了试验研究。理论分析和试验结果均表明,该定向装置可以实现鲢鱼的头尾和腹背定向。并对影响鱼体头尾定向因素：进入振动台面的体位、电动机频率、激振力和筛面角,以及影响鱼体腹背定向因素：滑道夹角、电机频率、激振力和滑道倾斜角分别进行了试验研究,得出各因素对定位时间均具有显著的影响;头尾定向的总定位率达97.53%,定向动作可在0.65～3.75 s内完成;腹背定位的总定位率达97.5%,定向动作可在0.39～5.03 s内完成。研究结果可为淡水鱼连续化加工中定向连续喂料设备的产品开发提供技术依据。     

基于虚拟仪器的淡水鱼鲜度电子鼻测量系统

新鲜度是鱼类或鱼类制品质量的一个重要指标,可以通过测量鱼体气味来评价其新鲜度。该文分析了鱼体死亡后产生的特征挥发性气体,确定了TGS822乙醇类及有机溶剂型传感器、TGS825硫化氢型传感器、TGS826氨气及胺类型传感器以及TGS832 卤烃型气体传感器等4类传感器作为淡水鱼电子鼻的传感器阵列,并采用虚拟仪器平台开发了电子鼻测量系统,用该测量系统对不同新鲜度的鲢鱼鱼肉进行了气味检测。试验结果表明,电子鼻传感器阵列的响应随样品新鲜度的变化而变化,采用PCA（主成分分析）对试验数据进行聚类分析,可以将鱼体新鲜、次新鲜和腐败（包括半腐败）的样本正确区分,证实了自行研制电子鼻测量系统的可行性和适用性。     

光合细菌对鱼病原细菌生长的影响

从发病的棒花鱼（Abbottina rivularis）和鲫鱼（Carassius auratus）分离得到7株菌,经人工感染证实其中的B3、J1和J2等3株菌均为病原细菌。B3和J1鉴定为嗜水气单胞菌（Aeromonas hydrophila）,J2鉴定为豚鼠气单胞菌（Aeromonas caviae）。采用平板扩散法测定了光合细菌嗜酸红假单胞菌Y7（Rhodopseudomonas acidophila Y7）、球形红假单胞菌X3（R．spheroids X3）和桃红荚硫菌S（Tniocapsa roseopersicina S）对病原细菌B3和J2生长的影响。结果表明：在营养琼脂平板上3种光合细菌对两种病原细菌（B3和J2）无明显拮抗作用,但光合细菌能覆盖在病原细菌上生长;3种光合细菌对病原细菌生长有明显的抑制作用,其中球形红假单胞菌X3抑制作用最大,但X3代谢产物对病原细菌生长无明显抑制作用,说明X3对病原细菌的抑制作用来自菌体细胞。X3还能明显抑制水体中的病原菌B3和J2的生长。     

The fish fauna of mountain streams in South Korean national parks and its significance to conservation of regional freshwater fish biodiversity

The fish fauna of mountain streams in the Jiri (440 km²) and Seorak (373 km²) National Park areas of South Korea was investigated from September 1998 to May 2001. A total of 5979 fish were collected and classified into 22 families and 60 species from both national parks. At Jiri, 30 species in 12 families of fishes were collected, while at Seorak there were 42 species in 17 families. Zacco temmincki [relative abundance (RA) 47.9%] was dominant at both parks. Subdominant species were Rhynchocypris kumkangensis (RA 10.8%), Zacco platypus (RA 9.4%), and Pungtungia herzi (RA 5.3%). A total of 20 species were found to be Korean endemic species, representing seven families. The relative abundance of Korean endemic species was higher at Seorak (30.5%) than Jiri (18.5%). One exotic species (Oncorhynchus mykiss) and two species translocated outside their native catchments (Hypomesus nipponensis and Coreoperca herzi) were collected. The proportion of Korean endemic freshwater fish species in both parks (33.3%) was higher than the overall proportion on the Korean peninsula (23.6%). Within the 14 South Korean mountain-area national parks as a whole, larger parks tend to have higher fish diversity. We conclude that South Korean national parks are important for conservation of the regional fish fauna, especially for endemic and endangered species. Current threats to conservation of fishes within South Korean national parks are identified and management solutions are suggested.