卤虫虾片对水体pH值的影响

通过喂养中国对虾幼体试验，分别以卤虫虾片试验组和传统饵对照组进行。试验表明，在幼体成活率方面，前者稍优于后者，在养殖水体的最主要指标PH方面，二者差别不大。说明投喂卤虫虾片对中国对虾幼体的成活率和水质无良影响，用低值的卤虫虾片代替部分或全部高价的活体饵料是切实可行的，能够满足育苗需要。     

耕作制度对稻田土壤有机碳季节变化的影响 —以海南省定安县为例

为了解耕作制度对稻田土壤有机碳时间变化的影响,选择了海南省定安县4种不同耕作制度下的稻田(一熟制、二熟制、三熟制和撂荒地)为研究对象,对比分析其表层土壤在2019年冬季(1月)、春季(4月)、夏季(7月)和秋季(10月)的有机碳和易氧化有机碳含量差异.结果表明,研究区稻田土壤有机碳含量在四个季节都表现为二、三熟制高,一熟制和撂荒地低,且在春季和夏季差异较大,夏季差异最为显著.各耕作制度下稻田土壤有机碳含量年内变化不明显.研究区不同耕作制度下稻田土壤易氧化有机碳含量都在春季时最高,一熟制和二熟制稻田土壤易氧化有机碳含量在土壤总有机碳中的占比年内变化明显,三熟制和撂荒地易氧化有机碳占比则较稳定.研究区稻田土壤有机碳和易氧化有机碳总体呈正相关关系,但由于耕作制度的不同使得其在不同季度两者之间的相关性存在一定差异.可见稻田耕作制度对土壤有机碳的累积和固定有一定影响.     

Control of soil solution interferences in an automated nitrate method

Abstract

An AutoAnalyzer method for nitrate nitrogen based on hydrazine reduction followed by diazotization was re‐examined after certain soil solutions had given poor recoveries. Modifications to the reaction parameters, particularly in the reduction stage improved the recovery of nitrate as nitrite. Soluble organic compounds in the samples were more critical than inorganic salts, but the proposed method allowed tolerance of up to 30 mgl^‐1 total organic carbon. Concentrations of various inorganic ions in soil solutions and natural waters were usually below the limits shown to be critical for the improved method.     

Waters HPLC检测蔬菜、水果中7种农药残留方法优化

参考现有方法,依据实验室条件,使用Waters2695 HPLC配2998 PDA检测器,检测蔬菜水果中吡虫啉、啶虫脒、多菌灵、除虫脲、灭幼脲、辛硫磷、阿维菌素7种农药残留。通过优化得到良好的分离效果,控制在30min内完成。外标定量分析时,标准曲线R2值在0.9996~0.9999,回收率在87.9%~105.1%,灵敏度和精密度满足分析要求。     

Relationship between coastal water properties and adult return of chum salmon (Oncorhynchus keta) along the Sanriku coast,Japan

We investigated the relationship between adult (age‐4) return rates for chum salmon (Oncorhynchus keta) originating from the Iwate Prefecture, Japan, and coastal environmental conditions during their early ocean life in coastal residency. We analyzed distributions of water properties via intensive hydrographic observations using a conductivity–temperature–depth profiler. Both the return rates and water properties vary strongly over interannual time scales. We found that the time when the return rate decreased drastically corresponded well to the time when the frequency of warm waters in the coastal residency increased.     

长江口九段沙附近水域浮游动物生态特征

根据1998-2000年长江口九段沙附近水域(30°~32°N,121°27′~122°30′E)丰水期枯水期6个航次的海洋调查资料,对长江口水域浅水Ⅲ型(网目孔径0.077 mm)和浅水Ⅰ型(网目孔径0.505mm)浮游动物生态特征的变动趋势进行了研究。结果表明:丰水期盐度与浮游动物总丰度有很显著的线性关系,总丰度随着盐度的增加而增加;枯水期盐度与总丰度的关系不明显。同一季节温度与总丰度之间的关系不明显,但从总丰度的季节变化可见,不同水温环境下总丰度的差异依然明显。各年多样性指数(H′)值均小于2;丰水期和枯水期大型浮游动物H′值无论涨潮还是落潮均要大于小型浮游动物。本调查水域浮游动物种类组成简单,种间分布不均匀,优势种突出,主要由淡水生态类型、河口半咸水生态类型、沿岸生态类型和外海生态类型的种类组成。     

林网化与水网化——中国城市森林建设理念

建设森林城市要求有足够的森林面积和通畅的水循环系统。本文以上海为例提出在人多地少与水系统不很通畅的中国发展城市林业必须走林网化和水网化的道路。为探索具有中国特色的城市森林发展新理念。作者从理念的内涵、依据、过渡和国内外比较研究等几方面作了阐述。       

Acoustic observations of fish schools and scattering layers in a Kuroshio warm-core ring and its environs

Biological sound scattering characteristics in a frontal region between warm and cold waters were examined at the southern edge of a Kuroshio warm-core ring off Sanriku, the northeast coast of Japan. The scattering strength was low in the surrounding cold water and high in the warm-core ring. The depth and thickness of sound-scattering layers changed in accordance with the vertical structure of the water mass during the day or at night. Intense, thick scattering layers were observed on the warm-water side of the front and farther inside the warm-core ring. Fish schools were distributed in the mixed layer warmer than 17°C at depths of 10-30m above the scattering layers on the warm-water side of the front.     

双岛湾海域人工鱼礁区水质状况及其季节变化特征

根据2011年夏季(8月)、秋季(11月)和2012年冬季(3月)、春季(5月)水环境调查资料,采用单因子污染指数法、营养指数法、营养状态指数法和有机污染综合指数法对威海双岛湾海域人工鱼礁区域的水质状况进行了评价.结果表明:(1)鱼礁区溶解氧、pH、无机氮、活性磷酸盐和COD污染指数均＜1.0,海水未受到上述因子的污染;(2)鱼礁区海水处于贫营养水平,水质指标季节变化不明显;(3)鱼礁区与鱼礁影响区、对照区比较,海水营养指数、营养水平和有机污染指数无显著差异,显示鱼礁短期内对水质改善作用不明显.     

Offshore currents explain the discontinuity of a fish community in the seagrass bed along the Japanese archipelago

Oceanographic conditions can affect spatial variability in fish community structures by influencing the temperature‐dependent latitudinal distribution of adult fishes and transport during their young stages. In order to examine latitudinal variability in the fish community structure within a single coastal ecosystem, quantitative sampling was conducted in the sub‐tidal zone of seagrass Zostera marina beds over a broad latitudinal scale (31.31–43.0°N: from subtropical to sub‐boreal zones, covering 80% of the latitudinal range of seagrass distribution in Japan) in the western North Pacific based on a uniform methodology. Cluster analysis with the similarity of fish communities showed that 13 sampling sites were divided into two clusters. The border between the two clusters corresponded with the area of mixing of two dominant currents, Oyashio and Kuroshio, which form a border between the warm temperate zone and the cool temperate zone off the Pacific coast of Japan. Oceanographic properties, such as major currents off the coast, are suggested to affect the latitudinal variability in the fish communities in the coastal ecosystem in the western North Pacific.