宁夏回族自治区扬黄灌区密植高产玉米磷素吸收利用特征及适宜用量分析

利用田间试验的方法,研究磷肥(P_2O_5)施用量对宁夏扬黄灌区密植高产玉米产量、磷素吸收积累特征,明确宁夏扬黄灌区玉米生产适宜磷肥用量,以指导当地玉米生产。以正大12为供试材料,采用单因素随机区组设计,在玉米密度为9.75万株/hm~2条件下设置5个磷肥(P_2O_5)用量0、45、90、135和180 kg/hm~2,N 300.0 kg/hm~2和K_2O 75.0 kg/hm~2均一致。从磷肥(P_2O_5)对密植玉米产量、经济效益、土壤磷素平衡和磷肥利用效率的影响进行分析。结果表明:施用磷肥(P_2O_5)增加了玉米穗粒数和百粒重,增产率为3.1%～7.8%,通过产量获得磷肥(P_2O_5)效应方程为Y=-0.053 7x~2+15.803x+15 450(R~2=0.981 9~*),通过模拟计算最高产量P_2O_5用量为147.1 kg/hm~2,从实际最佳经济产量P_2O_5用量为112.2 kg/hm~2。经济效益角度分析P_2O_5用量在135 kg/hm~2时利润最高,比对照增收5.7%。施用磷肥(P_2O_5)促进了玉米磷素的吸收累积,籽粒、秸秆和地上部磷素累积量,100 kg籽粒需P_2O_5量均随磷肥(P_2O_5)用量的增加呈先升高后降低的趋势,均以施P_2O_5 135 kg/hm~2最高,较对照分别提高24.0%、19.3%、22.1%和15.7%。P_2O_5用量为135 kg/hm~2时磷肥利用效率最高为36.2%(P0.05),磷肥偏生产力、磷肥农学效率和生理利用效率均随着磷肥用量增加呈下降趋势。施P_2O_5量为45～135 kg/hm~2时耕层土壤速效磷均为当季匮缺。从玉米产量、经济效益、土壤磷素平衡和磷肥利用效率多个角度综合分析认为研究区域密植高产玉米磷肥(P_2O_5)用量适宜的范围为135～147 kg/hm~2。     

千岛湖森林康养基地发展路径探析 ——基于千岛湖龙川湾的调查研究

国家相关管理部门联合提出按照“环境优良、服务优质、管理完善、特色鲜明、效益明显”的要求建设一批国家森林康养基地。以浙江千岛湖龙川湾为例,分析其森林资源、地理区位、产业链、发展规模、社会合作、管理保障、三大效益等方面建设森林康养基地的优势,整合提升游憩观赏、研学文化、垂钓休闲、扶犁耕地、康养保健、疗养康复、健身拓展区域空间布局与发展举措,从康养体验、休闲体验、运动健身等方面增强千岛湖龙川湾森林康养基地功能,推进森林康养产业发展。     

洞庭湖烂泥湖水系洪涝灾害风险评估与应对措施

近年来,洪涝灾害是全球发生频繁、危害最严重的气象灾害之一,国内不少学者开始对洪涝灾害进行研究,目前对于洞庭湖区洪涝灾害风险的研究较少。采用综合评价法建立模型对洞庭湖区烂泥湖水系洪涝灾害风险进行评估并提出应对策略,结果表明:新泉寺闸内水位和滞涝水面率的不同导致暴雨对烂泥湖水系的影响程度也不同。同时采取提高滞涝水面率和降低内湖水位,基本可以消除一般年份处于高风险的范围,对于减少低风险范围、增加无风险范围效果更为显著;对于平均风险度为高风险的年份,能够消除大部分高风险区域。     

宁夏地区潜在蒸散发变化特征及成因分析

根据宁夏地区1962-2017年11个国家级气象站的逐日气象资料,采用Penman-Monteith公式计算宁夏地区潜在蒸散发(Potential evapotranspiration,ET₀)日值系列,采用气候倾向率、Mann-Kendall突变检验、ArcGIS反距离权重空间插值、敏感性分析和贡献率等方法对宁夏地区ET₀时空变化特征及影响因素进行分析.结果表明:宁夏地区1962-2017年多年平均ET₀为1 073 mm,其中,中部干旱带最高(1 135 mm),引黄灌区次之(1 095 mm),南部山区最低(893 mm); 宁夏地区ET₀在1986年发生了突变,突变前以0.571 mm/a的幅度下降,突变后以0.109 mm/a的幅度递增,整个周期内,以0.523 mm/a 幅度递增,但变化幅度均不显著.ET₀对不同区域气象要素的敏感性不同,引黄灌区和中部干旱带对最高温度最敏感,敏感性系数分别为0.41和0.43,南部山区为相对湿度(-0.45); 不同气象要素对ET₀的贡献率不同,引黄灌区和南部山区主导因子是最低温度,中部干旱带是平均风速.突变前后,对引黄灌区、中部干旱带和南部山区ET₀贡献率最高的气象要素分别由平均风速、相对湿度和最低温度,变为相对湿度、平均风速和最低温度.     

宁夏部分地区奶牛球虫感染情况调查与遗传进化分析

为了解宁夏地区奶牛球虫的感染现状与流行特征,以宁夏吴忠、石嘴山、贺兰地区5个不同规模化奶牛场采集的犊牛腹泻粪便样品为材料,利用饱和NaCl溶液飘浮法和麦克马斯特虫卵计数法观察统计球虫形态、种类与感染情况;并提取球虫卵囊基因组DNA,进行18S rRNA基因的扩增和测序,用DNAstar软件对奶牛球虫18S rRNA基因进行序列分析,并构建系统发育树。结果显示,在随机抽查的179份样品中,牛球虫病的平均感染率为56.98%,感染率的范围为40.00%~80.84%,平均每g粪便虫卵数(OPG)为1 358。孢子化卵囊呈圆形或椭圆形,初步确定该地区优势虫种为邱氏艾美尔球虫、牛艾美尔球虫,其大小为(25.7~36.0)μm×(21.4~27.1)μm。序列分析表明,宁夏地区所分离的虫株与其他虫株亲缘关系较远,但本地虫株之间有较近的亲缘关系。该研究丰富了奶牛球虫流行病学材料,也为该病的防治研究奠定了基础。     

Microsatellite analysis of genetic diversity and genetic structure of the Chinese freshwater mussel Solenaia carinata (Bivalvia: Unionidae)

1. The freshwater mussels (Unionidae) in the Yangtze River basin of China are among the most diverse assemblages on Earth. Freshwater mussels provide valuable ecosystem services (e.g. natural water filtration) and economic value (shell, pearls, and food), but are experiencing global declines as a result of pollution, habitat alteration, and overharvest.
2. Despite the diversity and value of freshwater mussels in the Yangtze River basin, relatively little is known about the biology of the many species endemic to the region. Solenaia carinata is an endemic and potentially imperilled freshwater mussel (Bivalvia: Unionidae) in China that is distributed in a single major tributary of the middle Yangtze; the Poyang Lake basin in Jiangxi Province.
3. This study represents the first analyses of the genetic diversity and population genetic structure of S. carinata. Solenaia carinata specimens (n=64) were collected from three sites in large tributary rivers of Poyang Lake.
4. Using 19 polymorphic microsatellite markers, the results showed that S. carinata had a moderate level of genetic diversity (PIC ranged from 0.464 to 0.484), limited evidence of a recent genetic bottleneck, little genetic differentiation (F_ST ranged from 0.021 to 0.045), high levels of gene flow (N_m ranged from 3.675 to 33.227) and limited genetic structure among the three sampling locations.
5. Given that S. carinata inhabits a highly interconnected system of large rivers and lakes, the results of low differentiation and high gene flow among geographically proximate sampling locations (sites separated by between 8 and 20 km of water) are not surprising. The results indicate that specimens can be used and moved from anywhere across the distribution of S. carinata for the purposes of captive propogation and translocation.

     

艾比湖湿地不同盐渍化土壤粒度组成及可蚀性研究

为了研究内陆干旱区不同盐渍化土壤的粒径组成及其可蚀性的空间分布,在不同盐渍化程度上探讨其与土壤中盐分含量的相互关系,本研究以新疆维吾尔自治区艾比湖湿地为研究靶区,利用2015年5月获取的66个表层土壤样品,对土壤的粒度组成、含盐量、分形维数和可蚀性因子K值进行了研究。结果表明:样品中盐土占比达到59.09%,平均含盐量达131.59 g/kg,研究区内盐渍化现象既普遍又严重;土壤颗粒以粉粒和砂粒为主,随着盐渍化程度的加剧黏粒含量不断增加,砂粒含量则相反;土壤颗粒的分形维数D值介于2.14~2.60,平均值为2.45;随着盐渍化程度加剧,分形维数逐渐变大,K值也随之逐渐增大,盐土的K值最大达0.093;土壤可蚀性因子K值与含盐量的相关性较高(r=0.596**),在一定程度上可以说明,土壤的含盐量水平越高,K值越大,越容易被侵蚀。     

Impact of short‐term climate effects and sea ice coverage variation on Japanese scallop aquaculture in Saroma Lake,Japan

Saroma Lake is the southernmost lagoon exhibiting seasonal sea ice coverage in the Northern hemisphere and one of the most important aquaculture areas for Japanese scallops (Mizuhopecten yessoensis). Under conditions of adequate food and appropriate temperature, scallops grow well from the time of ice melting in April to harvesting starting in July. However, over the past decade, Saroma Lake frequently has not been completely covered by ice in winter, and the production of Japanese scallops has shown significant changes. Therefore, this study integrated data from satellite remote sensing, buoys, and in situ observations with climatic events [the winter East Asian Monsoon (EAM) and El Niño/La Niña–Southern Oscillation events] to investigate the impact of ice coverage variations on scallop growth in Saroma Lake between 2007 and 2015. Daily ice conditions were detected using Moderate Resolution Imaging Spectroradiometer false colour images and an unsupervised classification method. The results indicated that EAM strongly influenced the ice coverage variation in Saroma Lake through their effects on temperature during winter. Ice coverage variations show a strong correlation with water temperature and spring phytoplankton blooms, which are the two most important environmental factors for scallop growth. In addition, extreme climate events could cause water temperature anomalies (as in 2015) which are unfavourable for scallop growth. Monitoring ice conditions should be considered when developing plans and management strategies for scallop aquaculture in Saroma Lake.     

汉阳地区五个湖泊沉水植物分布及富营养化现状

2011年7月—2012年4月对武汉市汉阳地区五个湖泊(后官湖,三角湖,南太子湖,墨水湖和龙阳湖)的水质及沉水植物进行了季节性调查,以了解湖泊富营养化现状及其对沉水植物的影响。结果显示:后官湖为中营养,而三角湖、南太子湖、墨水湖和龙阳湖为重度富营养,其中龙阳湖污染最重。共采集沉水植物7种,隶属于5科5属,主要种类为金鱼藻(Ceratophyllum demersum)、苦草(Vallisneria spiralis)和菹草(Potamogeton crispus)。沉水植物主要分布在后官湖沿岸带,其它四个湖泊中沉水植物已严重退化,仅在部分水域偶见。后官湖沉水植物盖度和生物量最大值出现在10月,分别为67.5%和5.58 kg/m~2,1月份较低,分别为29.3%和1.88 kg/m~2,优势种存在明显的季节更替。结果表明,汉阳地区湖泊沉水植物退化与富营养化引起的水下光照下降和高密度的水产养殖有关。     

Pansteatitis in polluted Olifants River impoundments: nutritional perspectives on fish in a eutrophic lake,Lake Loskop,South Africa

This study compares the aetiology of pansteatitis in Lake Loskop, relative to two other impoundments along the Olifants River. Macroscopic and microscopic pathology, age determination and analysis of stomach content, fatty acids and stable isotopes explain the high prevalence of pansteatitis in Oreochromis mossambicus (Peters) and several other species in Lake Loskop. All the dietary indicator comparisons between pansteatitis‐affected and healthy fish fail to support a systemic cause. Pansteatitis in Lake Loskop was linked to size and weight of O. mossambicus, but not to ontogenic age. Fish in Lake Loskop showed abnormally high omega‐3 to omega‐6 fatty acid ratios normally only found in marine fish with no significant difference in degree of assimilation of these fatty acids between pansteatitis‐affected and healthy fish. This explains the vulnerability to, but not the occurrence of, pansteatitis. As a cause for the pansteatitis, these results point towards sporadic vitamin E‐depleting trigger events, known sporadic fish die‐off occurrences that provide surviving fish with a rich source of rancid fats on which to scavenge. The mechanism ties pansteatitis to eutrophication and trophic cascade effects, the intrinsic drivers of the disease and suggests an adaptive management strategy that might be applied by relevant conservation authorities.