基于SWAT模型的汤浦水库流域非点源污染模拟

在对汤浦水库流域内污染调查的基础上,建立了基于GIS技术的SWAT模型,建立了汤浦水库流域非点源污染空间和属性信息基础数据库,在GIS技术和ArcScene、Arcview等软件支持下,研究流域非点源污染分布规律、主要污染因子、各溪各镇的污染贡献率以及流域污染负荷总量等。结果表明,在空间尺度上,南溪和双江溪流域营养物质贡献量最高,泥沙量较大;不同土地利用类型污染流失负荷不同,灌溉水田是总氮负荷的主要来源,水田和茶园是总磷负荷的主要来源,其次是居民点,最小是林地。在时间尺度上,年内总氮、总磷负荷随季节呈不规     

洋河水库流域面源污染负荷空间分布特征

为探究洋河水库流域面源污染的空间分布特征,基于气象、土地利用、农业管理等数据资料,计算2013年洋河水库流域农村生活污水、固体废弃物、畜禽养殖流失、化肥流失、水土流失污染和城镇地表径流污染6种污染来源中总氮（TN）、总磷（TP）、氨氮（NH3-N）、化学耗氧量（COD）4个污染物指标排放负荷,并通过GIS空间分析反映流域内的污染分布情况。结果表明,畜禽养殖污染物排泄量对研究区污染负荷贡献最大,年产生量约51621.34 t,入河量2961.52 t,占比分别为92%和85%;从总量上看,洋河水库流域的面源污染负荷分布在西洋河支流区域范围;单位面积负荷量最大的区域是迷雾河支流区域范围。据此确定了西洋河和迷雾河流域为今后洋河水库流域面源污染重点治理的区域,此研究结果可为洋河水库流域面源污染防治及消减提供理论依据。     

基于ArcSWAT模型的老鹳河流域面源氮识别和分析

进行老鹳河流域面源氮污染负荷估算和关键源、区识别,推进流域面源污染的溯源和控制,为流域非点源氮污染控制和治理提供理论支撑。通过模型数据库构建、流域空间单元划分以及参数率定和验证建立老鹳河流域氮污染过程的ArcSWAT模型;以2017年的气象资料为背景,设置4种情景模式,模拟估算流域不同面源氮的入河量,分析和识别不同污染源的关键期以及不同土地利用类型的关键污染源。结果表明,化学氮肥施用和大气沉降是老鹳河流域面源氮的主要污染源,分别贡献了47.6%和38.6%;大气沉降、畜禽养殖和化学氮肥施用入河氮量最大值均出现在3月,农村生活入河氮量最大值出现在8月,而4类污染源入河氮量的最小值均出现在12月;雨季是老鹳河流域控制面源污染氮的关键期;减控的关键污染源旱地、园地和水田是化学氮肥施用,林地和人居地分别是大气沉降和农村生活。应分时、分区、分类制定老鹳河流域面源氮污染减控方案,对于人为氮源（化学氮肥施用、畜禽养殖和农村生活）还要关注在作物播种期和生长季节进行减控。     

松华坝水库上游牧羊河氮、磷主要来源研究

牧羊河是昆明松华坝水库的一条重要支流,其水质的好坏直接关系到松华坝水库的水质。面源污染是影响水库水质的主要因素。通过对流域内农田径流、农村生活污水以及牧羊河丰水期与枯水期水质的测定,对总氮、总磷指标进行了评价和分析,得出了牧羊河氮、磷主要来源于松华坝水源区面源污染,且流域内面源污染对牧羊河水体总氮含量影响较大。     

基于GIS技术的濑溪河流域泸县境内农村非点源污染评估

通过地理信息系统(Geographic Information System,GIS)技术对濑溪河流域泸县境内进行水系提取及流域划分,并利用GIS空间技术分析了各乡镇污染贡献度。选取城镇居民生活污水、城镇地表径流、畜禽散养、农村生活污水以及化肥流失5大污染源,计算各镇总等标污染负荷比。结果表明,研究区内农村畜禽散养、化肥流失、生活污水的污染源总和比重高达69.71%,福集镇占研究区乡镇总污染的31.17%,导致泸县濑溪河水质差的主要原因是农村非点源污染,并提出了针对性的污染防治对策。     

高州水库集水区内污染源污染负荷研究

为探究高州水库集水区内污染状况,根据2008年污染源的调查结果,利用排污系数法和输出系数法,结合现场资料调查分别对该地区点源和非点源污染负荷(COD、NH3-N、TN、TP)进行估算,并应用地理信息系统(GIS)技术对集水区内污染源空间分布特征及来源构成进行分析。研究结果表明,高州水库集水区内COD、NH3-N、TN、TP污染物输出总量分别为8192.83、394.13、1137.38、94.29 t/a,其中非点源污染COD、NH3-N、TN、TP输出量为7114.79、336.91、1060.21、88.08 t/a,占污染物输出总量的比例分别为87%、85%、93%、93%。COD、TN和TP均以农林种植源排放为主,占总输出量的比例分别为50%、52%、50%。NH3-N以农村生活源排放为主,占总输出量的比例为63%。在空间分布上,每年不同乡镇单位面积COD负荷强度为47.08~144.63 kg.hm-2,NH3-N负荷强度2.43~5.24 kg.hm-2,TN负荷强度6.70~20.34 kg.hm-2;TP负荷强度0.60~1.73 kg.hm-2,其中以临近库区的平山镇COD、NH3-N、TN、TP污染负荷强度均最高。在来源构成上,集水区各镇COD、NH3-N、TN、TP污染负荷的70%~94%来源于非点源。因此,为保护高州水库水环境,应将集水区内非点源(农村生活、散养畜禽、农林种植)作为重点控制源,同时根据其空间分布特征进行分区防治,重点防治控制区为平山镇。     

高州水库集水区污染源分布特征及污染负荷研究

为探究高州水库集水区的污染状况,根据2008年污染源的调查结果,利用排污系数法和输出系数法,结合现场资料调查,分别对该地区点源和非点源污染负荷(COD、NH_3-N、TN、TP)进行估算,并应用地理信息系统(GIS)技术对集水区内污染源空间分布特征及来源构成进行分析。结果表明,高州水库集水区内COD、NH_3-N、TN、TP污染物输出总量分别为8 192.83、394.13、1 137.38、94.29 t/a,其中非点源污染COD、NH_3-N、TN、TP输出量为7 114.79、336.91、1 060.21、88.08 t/a,占污染物输出总量的比例分别为87%、85%、93%、93%。COD、TN和TP均以农林种植源排放为主,占总输出量的比例分别为50%、52%、50%。NH_3-N以农村生活源排放为主,占总输出量的比例为63%。在空间分布上,每年不同乡镇单位面积COD、NH_3-N、TN、TP的负荷强度分别为47.08~144.63、2.43~5.24 kg/hm~2、6.70~20.34 kg/hm~2、0.60~1.73 kg/hm~2,其中此4项指标的污染负荷强度均以临近库区的平山镇最高。在来源构成上,集水区各镇COD、NH_3-N、TN、TP污染负荷的70%~94%来源于非点源。为保护高州水库水环境,应将集水区内非点源(农村生活、散养畜禽、农林种植)作为重点控制源,同时根据其空间分布特征进行分区防治,重点防控区域为平山镇。     

海河流域农业非点源污染评价

伴随着我国经济的快速增长,人类活动和资源环境的矛盾加剧,水资源短缺和水环境污染的形势严峻。海河流域是中国的政治、经济和文化中心,在国民经济中具有重要的战略地位,然而它却是中国水污染最严重的流域。本文通过分析评价现有大尺度流域非点源污染负荷估算方法,建立了适合现有数据条件并有一定精确性的大尺度流域农业非点源污染负荷估算方法一“三维”系数估算法,估算农业非点源污染负荷量,评价农业非点源污染对水体污染的影响,并在此基础之上,提出了介于环境资源的公共物品属性决定了控制农业非点源污染必须由政府主导、公众广泛参与。海河流域要重点抓好畜禽养殖污染的控制,大力推广生态畜牧业。积极推进“农村清洁工程”,改善农村生活条件。     

大伙房水库主要营养物物流平衡研究

根据1980～2003年对大伙房水库及上游流域水质调查情况,对库区主要营养物(N、P)等进行了分析。结果表明:水库主要污染物为氮、磷。上游流域的种、养殖、生活污水是水库氮、磷污染的主要因子。论述了水库营养物(N、P)物流来源及平衡关系和污染份额。确立了水库汇水区内存在的问题和治理对策。     

蓄水前后三峡水库营养盐收支计算

根据近10年来长江三峡库区江段氮、磷营养盐的历史数据,以及三峡库区支流、大气降水、地表径流、淹没土壤释放、工农业排放等主要形式的氮、磷营养盐负荷数据,并结合现场调杏的结果,采用箱式模型对蓄水(135～139m)前后三峡水库营养盐进行收支计算,以期为三峡成库后三峡江段生源要素生物地球化学过程以及长江营养盐输送过程提供研究基础.结果表明:上游输入的总氮、总磷是三峡水库氮、磷营养盐的主要来源,占入库负荷的80%～90%;蓄水后入库营养盐负荷种类增加,主要是淹没土壤的释放作用.蓄水前总氮、总磷入库负荷与出库负荷相等,蓄水后入库营养盐有约18%的总氮和15%的总磷滞留于水库中,而溶解无机氮、溶解无机磷受蓄水因素影响较小.颗粒氮磷营养盐的沉降、生物吸收以及残体的沉降作用是导致出库营养盐减少的主要原因,其过程有待进一步深入研究.     

Association between the interannual variation in the oceanic environment and catch rates of bigeye tuna (Thunnus obesus) in the Atlantic Ocean

The environmental processes associated with variability in the catch rates of bigeye tuna in the Atlantic Ocean are largely unexplored. This study used generalized additive models (GAMs) fitted to Taiwanese longline fishery data from 1990 to 2009 and investigated the association between environmental variables and catch rates to identify the processes influencing bigeye tuna distribution in the Atlantic Ocean. The present findings reveal that the year (temporal factor), latitude and longitude (spatial factors), and major regular longline target species of albacore catches are significant for the standardization of bigeye tuna catch rates in the Atlantic Ocean. The standardized catch rates and distribution of bigeye tuna were found to be related to environmental and climatic variation. The model selection processes showed that the selected GAMs explained 70% of the cumulative deviance in the entire Atlantic Ocean. Regarding environmental factors, the depth of the 20 degree isotherm (D20) substantially contributed to the explained deviance; other important factors were sea surface temperature (SST) and sea surface height deviation (SSHD). The potential fishing grounds were observed with SSTs of 22–28°C, a D20 shallower than 150 m and negative SSHDs in the Atlantic Ocean. The higher predicted catch rates were increased in the positive northern tropical Atlantic and negative North Atlantic Oscillation events with a higher SST and shallow D20, suggesting that climatic oscillations affect the population abundance and distribution of bigeye tuna.     

Growth performance,digestive enzyme activity and immune response of Japanese sea bass,Lateolabrax japonicus fed with fructooligosaccharide

In this experiment, a feeding trial was performed to determine the effects of fructooligosaccharide (FOS) on growth performance, digestive enzyme activity and immune response of Japanese sea bass, Lateolabrax japonicus juveniles (initial weight 38.3 ± 0.5 g), and the fish were examined following feeding with six levels of FOS (0, 0.5, 1, 2, 4 and 6 g/kg) for 28 days. Significant enhancement of weight gain (WG) and specific growth rate (SGR) was found in fish fed 1 g/kg FOS incorporated diets (p < .05), while the feed conversion ratio (FCR) in the 1, 2 g/kg FOS groups reduced significantly compared with the control (p < .05). Besides, the crude lipid in the 4, 6 g/kg FOS groups increased significantly compared with the control (p < .05). On the other hand, the erepsin and lipase activities significantly elevated in intestine of fish fed 2 g/kg FOS (p < .05) and the lysozyme activity in serum of fish fed 2 g/kg FOS were significantly higher than that in the control (p < .05). Moreover, the alkaline phosphatase activities in serum of fish fed 0.5, 1, 2 g/kg FOS were significantly higher than in control (p < .05). Regression analysis showed that the relationships between dietary FOS levels and either SGR, FCR, erepsin or lysozyme activities were best expressed by regression equations, and the optimal inclusion levels are 1.37, 1.80, 3.06, 3.11, 1.93 and 1.80 g/kg for SGR, FCR, erepsin, lipase, lysozyme and total superoxide dismutase activities, respectively. Overall, this study revealed that FOS incorporated diets could beneficial for L. japonicus culture in terms of increasing the growth, digestion and immune activities. Under the present experimental condition, the optimal supplementary level of FOS in the diet of L. japonicus is 1–3 g/kg.     

Rare serotype occurrence and PFGE genotypic diversity of Streptococcus agalactiae isolated from tilapia in China

Previously, we reported 10 PEGE types of 85 tilapia Streptococcus agalactiae(GBS), which shifted from Streptococcus iniae in China, by using PEGE method. Presently, larger and more representative tilapia GBS were isolated, for the ?rst time in China, to characterize their serotypes and genetic diversities more precisely than had done before. 168 GBS strains were distributed in ?ve provinces of China, in which Guangdong, Guangxi and Hainan were the major ones, holding36.9%(62/168), 37.5%(63/168) and 19.6%(33/168), respectively. Serotypes, Ia, Ib and III, were observed in these strains and the most predominant one was Ia(95.2%), which mainly distributed in Guangdong, Guangxi and Hainan. Ia initially occurred in 2009, it shoot up to 32.1% in 2010,but decreased to 16.1% in 2011 before went up to 45.2% in 2012. Ib sporadically occurred during2007–2011, III onlyoccurred in 2012. 14 different PFGE types, including 4 new types(N, O,P and Q), were observed, in which B, D, F and G were the predominant types, holding 83.9%(141/168) of the total GBS strains. Ia corresponded to 11 PFGE types(A–H, N–P), in which type D predominated(51%). Ib represented 3 genotypes(I, J and Q) and III harbored only 2genotypes(N and F). Type N and Fsynchronously presented in Ia and III. In summary, the genetic diversity of tilapia GBS varied by serotypes and changed with geographical locations and years.Although Iastillpredominated, new rareserotypeIII alreadyoccurred in China.     

Evaluation of a Fast Method Based on the Presence of Two Restriction Sites in the Mitochondrial ND5 (mt ND5) Gene for the Identification of Scomber Species

The purpose of this work was to evaluate the suitability of a method based on the presence of two restriction sites (for Hae III and Hindf I) in the mitochondrial NADH dehydrogenase subunit 5 (mt ND5) gene to identify Scomber species. The evaluation was performed on 144 reference and market samples by sequencing of the entire 505-bp fragment of the mt ND5 gene and of a 464-bp fragment of the Kocher fragment of the cytochrome b gene (mt Cytb). Sequence analysis of any of the two fragments allows the identification of each of the four Scomber species, but S. japonicus and S. colias had the same restriction sites at the ND5 amplicon and would not have been differentiated by this analysis. Similarly, loss of the Hae III site in some S. scombrus individuals would have misidentified them as not being Scomber. All the market products were correctly labeled except one acquired in Spain labeled as originating in the Atlantic and containing S. japonicus.     

Growth hormone (GH) and reproduction: a review

Interaction between growth and reproduction occurs in many vertebrates and is particularly obvious at certain stages of the life cycle in fish. Endocrine interactions between the gonadotropic axis and the somatotropic axis are described, the potential role of GH being emphasised. A comparative analysis of these phenomena in mammals, amphibians and fish, suggests a specific role of GH in the physiology of puberty, gametogenesis and fertility. It also shows the original contribution made by studies on the fish model in this field of investigations.     

Purification and partial characterization of GtHs (cfLH and cfFSH) from Indian walking catfish (Clarias batrachus) (L.) and development of a homologous ELISA for cfLH

Two gonadotropins (GtH; Qa and Qb) were purified by gel filtration and ion exchange chromatography from the pituitaries of Indian walking catfish (Clarias batrachus). The presence of GtH during purification was assessed by in vitro oocyte maturation and in vivo steroidogenic activity, and their identities were determined by elution profiles, molecular weight, biological activities and yield. The molecular weights of Qa and Qb were 37 and 42 kDa, respectively, and composed of distinct subunits (Qa: 20 and 14 kDa and Qb: 26 and 18 kDa). Polyclonal antibodies raised against Qa immunostained Qa, Qb and pituitary GtH cells. A competitive Qa‐ELISA was developed whose sensitivity was 6.25 ng mL^?1 (1.25 ng well^?1) with intra‐ (3.5%) and inter‐ (12.4%) assay coefficients of variation. Displacement curves parallel to the standard were obtained with plasma and pituitary extracts of catfish, Qb and carp GtHII. The assay was validated by measuring the plasma Qa levels after LHRH treatment and in relation to ovarian growth in the female catfish during different reproductive phases. Based on the results, Qa and Qb corresponded to fish LH and FSH respectively. The findings will increase the knowledge of the mechanisms controlling fish reproduction and identification of sensitive phases in fish in captivity for hormonal manipulation.     

The optimal dietary protein level of juvenile silver sillago Sillago sihama at three dietary lipid levels

A 5 × 3 factorial growth trial was conducted to evaluate optimal dietary protein and lipid levels (dietary protein level, DP; dietary lipid level, DL) for juvenile Sillago sihama (S. sihama) (2.0 ± 0.02 g, initial weight). Fish were fed 15 diets containing 5 DPs (350, 400, 450, 500 and 550 g/kg) and 3 DLs (60, 90 and 120 g/kg) for 8 weeks. The interaction between proteins and lipids significantly influenced the feed conversion ratio, condition factor, body composition, antioxidant indices and lipase activity (p < .05). DP 450 g/kg showed the highest average final body weight. DPs 500 and 550 g/kg significantly decreased the protein efficiency ratio (p < .05). DL 120 g/kg showed the highest percentage weight gain. The low feed conversion ratio was found in diets P45L12, P55L9 and P55L12. Diet P45L12 showed high superoxide dismutase activities. DP 450 g/kg showed the lowest average malondialdehyde content. Lipase activity was increased by increasing DP (p < .05) with a fall at DP 550 g/kg. Under the present experimental conditions, the optimal DP for S. sihama was 450 g/kg under the DL 120 g/kg.