Evaluation of geogenic cadmium bioavailability in soil-rice system with high geochemical background caused by black shales

Journal of Soils and Sediments - Recently, the cadmium (Cd) accumulation in the black shale area has attracted increasing attentions, due to its extensive distribution and extremely high background...     

莫拉克台风引发台湾南部之降雨与崩塌

为了解2009年8月莫拉克台风的强大降雨在台湾南部地区引发严重的崩塌,造成500多人死亡的灾害情况.采用ArcGIS判释卫星影像崩塌地,统计分析降雨条件包括降雨强度、累积降雨量、降雨延时及重现期距等,对高屏溪流域在莫拉克台风期间之降雨与崩塌进行探讨.结果表明:1)莫拉克台风的降雨特性为长降雨延时(平均为3.3d)、高累积降雨量(平均为1 677 mm)及高降雨强度(平均为80.5 mm/h);2)尾寮山雨量站在48 h之累积降雨量(2319 mm)接近台湾降雨量纪录(2361 mm);3)尾寮山、御油山与溪南雨量站降雨延时在10～72 h之间,降雨强度皆大于尾寮山雨量站200 a之重现期距;4)风灾后新增崩塌面积及新增崩塌率分别为141.24 km2及4.92％,当累积降雨量达500 mm或降雨强度达55 mm/h时,崩塌地明显增加,崩塌率随累积降雨量及降雨强度的增加而有上升的趋势.     

影响PCR-SSCP的因素分析

ＰＣＲ－ＳＳＣＰ是一种基于ＰＣＲ的单链构象多态性（ｓｉｎｇｌｅ－ｓｔｒａｎｄｅｄ ｃｏｎｆｏｒｍａｔｉｏｎ ｐｏｌｙｍｏｒｐｈｉｓｍ）分析技术,是ＤＮＡ已知突变的检测或未知变异分析中十分常用和实用的技术之一,本研究从非变性聚丙烯酰胺凝胶的配制、样品的变性处理、电泳条件,显色方法和结果分析等方面对影响ＰＣＲ－ＳＳＣＰ实验室操作的因素进行了分析,并结合作者的经验给出了大小在１００～２００ｂｐ范围以内的     

Effects of sheet and rill erosion on soil aggregates and organic carbon losses for a Mollisol hillslope under rainfall simulation

Purpose

Characterizations of soil aggregates and soil organic carbon (SOC) losses affected by different water erosion patterns at the hillslope scale are poorly understood. Therefore, the objective of this study was to quantify how sheet and rill erosion affect soil aggregates and soil organic carbon losses for a Mollisol hillslope in Northeast China under indoor simulated rainfall.

Materials and methods

The soil used in this study was a Mollisol (USDA Taxonomy), collected from a maize field (0–20 cm depth) in Northeast China. A soil pan with dimensions 8 m long, 1.5 m wide and 0.6 m deep was subjected to rainfall intensities of 50 and 100 mm h^?1. The experimental treatments included sheet erosion dominated (SED) and rill erosion dominated (RED) treatments. Runoff with sediment samples was collected during each experimental run, and then the samples were separated into six aggregate fractions (0–0.25, 0.25–0.5, 0.5–1, 1–2, 2–5, >?5 mm) to determine the soil aggregate and SOC losses.

Results and discussion

At rainfall intensities of 50 and 100 mm h^?1, soil losses from the RED treatment were 1.4 and 3.5 times higher than those from the SED treatment, and SOC losses were 1.7 and 3.8 times greater than those from the SED treatment, respectively. However, the SOC enrichment ratio in sediment from the SED treatment was 1.15 on average and higher than that from the RED treatment. Furthermore, the loss of <?0.25 mm aggregates occupied 41.1 to 73.1% of the total sediment aggregates for the SED treatment, whereas the loss of >?0.25 mm aggregates occupied 53.2 to 67.3% of the total sediment aggregates for the RED treatment. For the organic carbon loss among the six aggregate fractions, the loss of 0–0.25 mm aggregate organic carbon dominated for both treatments. When rainfall intensity increased from 50 to 100 mm h^?1, aggregate organic carbon loss increased from 1.04 to 5.87 times for six aggregate fractions under the SED treatment, whereas the loss increased from 3.82 to 27.84 times for six aggregate fractions under the RED treatment.

Conclusions

This study highlights the effects of sheet and rill erosion on soil and carbon losses at the hillslope scale, and further study should quantify the effects of erosion patterns on SOC loss at a larger scale to accurately estimate agricultural ecosystem carbon flux.

     

甘蓝型油菜种子主要脂肪酸气象生态效应及数学模型的研究

在长江下游地区采用分纬度种植的方法,应用积分回归、相关和偏相关,逐步回归等统计手段,定量地探讨长江下游地区甘蓝型油菜的主要脂肪酸含量与当地气象因子间的基本关系和规律。结果表明,种子形成期是影响主要脂肪酸含量的关键生育期;获得1.6％以下芥酸含量的气象指标临界值为:种子形成期日平均温度大于19℃、日照时数长于6.5h/d.同时,还建立了预测各种主要脂肪酸含量的数学模型,也讨论了低芥酸油菜育种基地的选择依据,对优质油菜的区划具有重要的参考价值。     

新农村建设中乡镇企业发展路径探究

乡镇企业是源于中国城市与农村相分离的二元经济结构的一种具有独特性质的经济组织,经过二十多年的发展已经成为我国乡村工业化和乡镇经济的主体.在新型工业化和新农村建设的大背景下,乡镇企业如何定位自身角色并确定新型发展模式,以适应新形势是亟待解决的问题.本文以此为出发点,剖析在新形势下乡镇企业对新农村建设的重要性以及目前存在的问题,并提出相关建议,以利于乡镇企业进一步发展.     

云南特有野生果树资源及其分布特点

 云南有各类野生果树资源约500 余种, 其中云南特有的164种, 分属35科54属, 多为热带、亚热带果树和浆果类果树, 形成滇南—滇东南、滇西—滇西北和滇中—滇东北3个特有野生果树集中分布中心。这些果树资源用途广泛, 优异性状明显, 有待深入研究和综合开发利用。     

Protection of pigs against post-weaning multisystemic wasting syndrome by a recombinant adenovirus expressing the capsid protein of porcine circovirus type 2

Post-weaning multisystemic wating syndrome (PMWS) associated with PCV2 was one of the most costly diseases currently faced by the swine industry. In order to develop a vaccine to control this disease, we previously constructed a recombinant adenovirus expressing the capsid of PCV2. Here, we examined the protection of swine against PMWS by the recombinant adenovirus. Eighteen 32-day-old pigs were assigned to three groups each with six. Group 1 was vaccinated subcutaneously with rAd-Cap and boosted 2 weeks later. Thirty-seven days after first vaccination, Groups 1 and 2 were oronasally challenged with virulent PCV2 isolate, 4 and 7 days later, intramuscularly exposed to keyhole limpet hemocyanin (KLH). Group 3 remained unchallenged but with KLH. The results showed that high level of PCV2-specific ELISA antibody and neutralizing antibody could be induced at 37 days after first vaccination. After challenge, pigs in vaccinated group had no clearly clinical signs, although some of them had increased rectal temperatures (>/=40 degrees C) for short time. The pyrexic phase in vaccinated group was significantly lighter than that in challenge-control group (P<0.05). The relative daily weight gain in vaccinated-challenged group was similar to that in empty control group. But it was significantly high compared to the challenge-control group (P<0.05). Mean while the pathological lesions and virema presented in vaccinated group were milder than those in control group. It indicated that the recombinant adenovirus was able to confer significant protection against clinical disease and reduce pathogenic lesions induced by PCV2 challenge, even though it could not provide complete virological protection. The recombinant adenovirus might be an attractive candidate vaccine for preventing the disease associated with PCV2 infection.     

论木槿属树种及其在园林绿化中的应用

 木槿属树种在中国有着悠久的栽培利用历史,尤其是木槿在晋代就作为重要的观赏花木普遍栽植。本文依据相关文献,概述了木槿属丰富的种质资源,着重归纳总结了木槿、木芙蓉、扶桑3个乡土树种的文化内涵,指出了在园林绿化中的主要应用形式,并阐述了综合开发利用的价值。     

低蛋白·低铜·低锌饲料对杜梅商品猪生产性能的影响

将低蛋白、低铜、低锌生态饲料添加到杜梅商品猪日粮中,探索符合杜梅猪品种特点和营养需要的绿色无抗专用饲料。选取平均体重在20 kg左右的杜梅商品仔猪120头,随机分为试验组和对照组,研究低蛋白、低铜、低锌饲料对杜梅商品猪生长性能的影响。结果表明,试验组和对照组中都有猪发病与死亡。与对照组相比,试验组全程平均日增重和全程平均饲料转化率均较好,但2组间所有生长性能均无显著差异(P>0.05)。与对照组相比,试验组2个生长阶段猪粪便中氮、锌的含量均显著下降(P<0.05)。