基于神经网络模型的千岛湖清洁水体叶绿素a遥感反演研究

叶绿素a浓度值是水体水质评价的重要指标,研究基于高分一号(GF-1)卫星遥感影像,利用神经网络模型,选用6节点的隐含层设置,构建了千岛湖清洁水体叶绿素a浓度反演模型,对其叶绿素a浓度值时空特征进行分析,并与其他常规反演方法精确度进行比较.研究结果表明,利用神经网络模型对千岛湖清洁水体叶绿素a浓度值进行反演是可行的,且与其他常规方法相比,该模型对于叶绿素a含量低的内陆清洁水体反演有着更高的相关性(R2 = 0.921 8);在空间分布上,千岛湖区域水体叶绿素a浓度整体较低,高叶绿素a浓度区域主要集中易受人类活动干扰的西南及东北区域;年际变化分析表明,千岛湖区域水体叶绿素a浓度稳定,且波动较小,平均叶绿素a浓度值皆维持在1.70～1.75 pg/L之间,清洁水体特征显著.     

湖北省农业地质灾害及防治对策

本文论述了湖北省农业地质灾害的类型、分布、危害,并提出了防治对策。     

金属加工过程中应力状态的分析方法

分析简单地拉伸、压缩和扭转的情况时,应力状态能容易地被确定.但是,实际上在金属加工过程中材料是承受复杂的应力状态,在模具——工件接触面上增加有摩擦力.而且,这些应力和摩擦力一般地沿着接触面变化.准确的计算或预测载荷、力、应力和温度,不但对设计适宜的设备是重要的,而且对研究工艺期间材料的变化过程也是重要的.本文将讨论材料变形过程中所运用的主要分析方法及其优缺点.     

金属探测器的现状与发展前景

目前,随着科学技术的不断发展,犯罪分子和恐怖分子也利用高新技术制造出新式的武器、爆炸物等.各个国家也对安检越来越重视.通道式安检门在整个安检过程中扮演着一个十分重要的角色.目前,在国内这个领域,国外产品占了很大一部分.国内产品与国外产品相比还有一定的技术差距.主要体现在漏报和误报.漏报是因为灵敏度达不到,误报是因为抗干扰能力较差.而国外产品在这方面却有很大的优势,因此很大一部分政府机关、企业、大型活动组织者都倾向于购买国外产品.衡量一个安检门的优势除了误报和漏报两个重要指标外,还有其它一些技术性能,也是衡量一个门质量好坏的重要参数.     

生态示范区内生态工业建设模式探讨

生态工业建设为生态示范区建设的重要内容之一 ,是一项涉及到地区经济发展、人地关系协调的重大举措。从生态示范区建设中生态工业的基本定义出发 ,对生态工业建设层次进行详尽分析 ;并结合代表江苏省苏南、苏中和苏北不同社会经济发展水平的三个地区——吴县市、邗江县和邳州市的具体案例 ,通过对其产业构成、主导产业、消费结构以及经济发展总量与人均水平的对比分析 ,指出经济发展水平较低的地区要立足当地农业资源 ,实施末端治理并逐步推广清洁生产这种较低层次的生态工业建设模式 ;而经济发展较好的地区其生态工业的建设则要采用生态企业以及生态工业园区这种较高层次的建设模式。为确保生态工业建设的顺利实施 ,最后从政府、企业、市场和公众四方面提出了生态工业建设的驱动机制     

Diffusion pollution from livestock and poultry rearing in the Yangtze Delta,China

BACKGROUND: The Yangtze Delta is one of the most developed regions in China and includes Shanghai, eight cities in Jiangsu province and eight cities in Zhejiang province. Meat consumption in this region has increased with economic growth, and most of the consumed meat is produced locally. The water quality of surface waters has deteriorated in recent years. An example was the huge blue-green algae bloom in Tai Lake in late May 2007, which affected millions of people's daily drinking water. However, animal husbandry is considered to be one of the main pollution sources. METHODS: Pollutants (NH3-N, total phosphorus (TP), and total nitrogen (TN)) excreted by livestock and poultry, and the resultant COD (chemical oxygen demand) and BOD (biochemical oxygen demand), were estimated using two different methods based on different data sets. RESULTS: The number of livestock and poultry has remained stable in the Yangtze Delta over the four years from 1999 to 2002, with the average number of pigs, cattle, sheep and poultry being 21.1 M, 0.4 M, 7.7 M and 597.6 M, respectively. Pollutants in livestock and poultry excreta estimated by Method I were: 0.12 Mt NH3-N, 0.11 Mt TP and 0.29 Mt TN, resulting in COD and BOD of 1.34 Mt and 1.30 Mt, respectively, while the estimations based on Method II were: 0.18 Mt NH3-N, 0.15 Mt TP and 0.40 Mt TN, resulting in COD and BOD of 1.95 Mt and 1.80 Mt, respectively. DISCUSSION: Pollutants excreted annually by livestock and poultry in the Yangtze Delta are estimated to be: 0.17 Mt NH3-N, 0.16 Mt TP and 0.42 Mt TN, giving rise to a COD of 1.86 Mt and a BOD of 1.72 Mt. Approximately 25% of this pollution was estimated to enter water bodies, which means that the annual pollutant load is 43,700 t NH3-N, 39,400 tTP, 104,600t TN with a COD of 465,000 tand a BOD of 430,100 t. Pollutants from animal husbandry were similar in magnitude to those from industrial wastewater. Pigs produced the most pollution, followed by poultry, cattle and sheep. The pollution load from animal husbandry in the Yangtze Delta is about twice the average level of the whole of China. CONCLUSIONS: Domestic wastewater was the main pollution source in the Yangtze Delta, followed by pollution from raising livestock and poultry and from industrial wastewater. The pollution load in Shanghai and Jiaxing were the greatest, followed by 7 cities of Jiangsu province (except Suzhou) and other cities of Zhejiang province and Suzhou. Pigs and poultry produced about 90% of the total pollutants from animal husbandry. RECOMMENDATIONS AND PERSPECTIVES: The local governments, especially in Shanghai and Jiaxing, should focus their attention on the pollution produced by livestock and poulrry. Controlling pollution from pigs and poultry will have the greatest impact in this region. Control of pollution will be facilitated by the development of large-scale livestock and poultry farming units and a shift away from small scale husbandry.     

不同轮作模式下作物根际土壤养分及真菌群落组成特征

为研究宁夏中部干旱带不同轮作模式下土壤养分及真菌群落组成的特征,以谷子轮作大豆（MRG）、轮作籽粒苋（MRA）、轮作藜麦（MRQ）及谷子连作（CK）为对象,测定了土壤养分含量,并利用Illumina MiSeq高通量测序平台测定了土壤真菌的ITS变异区序列.结果表明,不同轮作模式对土壤养分的影响存在差异.3种轮作模式下土壤pH和电导率均有所下降,土壤全氮、全钾、全磷和有机质含量均上升,OTUs数和α多样性指数均高于连作.真菌群落组成研究结果显示,子囊菌门（Ascomycota）为4种模式下的优势菌群.聚类分析显示MRA和MRG的真菌属组成最为相似,其次是MRQ,CK与3种轮作模式相差较大.相关性分析显示,土壤养分与几种优势真菌属呈显著相关性（P<0.05或P<0.01）,土壤全氮、全钾、硝态氮和有机质含量是影响土壤真菌群落最主要的因子.主成分分析（PCA）表明,MRG轮作模式优于MRA和MRQ模式.综上所述,轮作提高了真菌群落多样性指数,改变了土壤真菌群落结构,改善了土壤肥力状况,其中以谷子与大豆轮作效果最佳,建议将谷豆轮作作为中部干旱带杂粮产业中主要的轮作模式之一进行推广.     

Identification of potential electrotrophic microbial community in paddy soils by enrichment of microbial electrolysis cell biocathodes

Electrotrophs are microbes that can receive electrons directly from cathode in a microbial electrolysis cell (MEC). They not only participate in organic biosynthesis, but also be crucial in cathode-based bioremediation. However, little is known about the electrotrophic community in paddy soils. Here, the putative electrotrophs were enriched by cathodes of MECs constructed from five paddy soils with various properties using bicarbonate as an electron acceptor, and identified by 16S rRNA-gene based Illumina sequencing. The electrons were gradually consumed on the cathodes, and 25%–45% of which were recovered to reduce bicarbonate to acetic acid during MEC operation. Firmicutes was the dominant bacterial phylum on the cathodes, and Bacillus genus within this phylum was greatly enriched and was the most abundant population among the detected putative electrotrophs for almost all soils. Furthermore, several other members of Firmicutes and Proteobacteria may also participate in electrotrophic process in different soils. Soil pH, amorphous iron and electrical conductivity significantly influenced the putative electrotrophic bacterial community, which explained about 33.5% of the community structural variation. This study provides a basis for understanding the microbial diversity of putative electrotrophs in paddy soils, and highlights the importance of soil properties in shaping the community of putative electrotrophs.     

Metabolomic modulations in a freshwater microbial community exposed to the fungicide azoxystrobin

An effective broad-spectrum fungicide, azoxystrobin (AZ), has been widely detected in aquatic ecosystems, potentially affecting the growth of aquatic microorganisms. In the present study, the eukaryotic alga Monoraphidium sp. and the cyanobacterium Pseudanabaena sp. were exposed to AZ for 7 days. Our results showed that 0.2–0.5 mg/L concentrations of AZ slightly inhibited the growth of Monoraphidium sp. but stimulated Pseudanabaena sp. growth. Meanwhile, AZ treatment effectively increased the secretion of total organic carbon (TOC) in the culture media of the two species, and this phenomenon was also found in a freshwater microcosm experiment (containing the natural microbial community). We attempted to assess the effect of AZ on the function of aquatic microbial communities through metabolomic analysis and further explore the potential risks of this compound. The metabonomic profiles of the microcosm indicated that the most varied metabolites after AZ treatment were related to the citrate cycle (TCA), fatty acid biosynthesis and purine metabolism. We thereby inferred that the microbial community increased extracellular secretions by adjusting metabolic pathways, which might be a stress response to reduce AZ toxicity. Our results provide an important theoretical basis for further study of fungicide stress responses in aquatic microcosm microbial communities, as well as a good start for further explorations of AZ detoxification mechanisms, which will be valuable for the evaluation of AZ environmental risk.     

生态调控后贵州花溪水库浮游植物群落结构的变化特征及影响因素

为了解生态调控后花溪水库浮游植物功能群变化特征与环境因子的关系,基于浮游植物功能群、NMDS（非度量多维尺度分析）、RDA（冗余分析）、Pearson相关性分析方法,于2017年3月-2018年3月逐月对浮游植物群落结构与水环境指标进行采样分析.结果表明:①生态调控前,花溪水库共鉴定浮游植物4门18种,共归类出10个功能群,且功能群H1占绝对优势,其代表藻种为水华束丝藻（Aphanizomenon flosaquae）;生态调控后,共鉴定浮游植物6门66种,共归类出20个功能群,主要优势功能群为B/Lo,其代表藻种为小环藻（Cyclotella sp.）和多甲藻（Peridinium sp.）.②生态调控后,花溪水库优势功能群结构发生了变化,其变化特征为B/Lo（春季）→D/B/Lo/X2/N/P（夏季）→D/B/Lo/N（秋季）→D/MP/B/Lo/W1/W2（冬季）.功能群B的生物量在春季达到峰值（3 056.3 μg/L）,与其对低营养环境有良好的耐受性有关;功能群Lo的生物量在秋季达到峰值（2 900.9 μg/L）,与组成功能群Lo的甲藻特性有关.③RDA结果表明,生态调控前影响浮游植物生长的环境因子为SD（透明度）、ρ（DIN）（DIN为无机氮）;生态调控后影响浮游植物生长的环境因子为WT（水温）、ρ（DO）、ρ（DIN）.研究显示,生态调控后花溪水库功能群结构发生了明显变化,影响功能群变化的主要环境因子为WT和ρ（DO）.