松嫩草地40余年气温、降水变化及其若干影响研究

分析了松嫩草地４０余年气温、降水的变化,评估了这些变化对土壤水分及草地生产力的影响。继而根据大气环流模式ＣＯ２倍增“平衡试验”结果评估了未来大气ＣＯ２加倍条件下降水、气温的变化对松嫩草地土壤水分及草地生产力可能产生的影响。     

沙土地夏玉米灌溉方式的试验研究

在豫北耕作层保水能力较差的砂壤土地带,围绕节水和增收,开展了夏玉米沟灌、常规畦灌及减少生育期内灌水次数的试验研究,每次畦灌定额控制在630~682.5m³·hm^-2,而沟灌条件下平均灌水量仅为442.5m³·hm^-2。研究结果表明,反映夏玉米生长速率的株高、叶面积指数等性状均是以抽雄期为界,之前增长迅速;抽雄时植株高度达2.50m左右,之后增长速率明显减慢;而抽雄至灌浆初期,叶面积指数保持在5.40~5.92的最高值,往后急剧地下降。不同灌水处理下生长速率的变化则是随着供水总量的增加呈同步增长趋势。在干旱年份,畦灌夏玉米全生长期耗水4278m³·hm^-2,沟灌及减少灌水次数的处理,耗水量分别为3762m³·hm^-2和3348m³·hm^-2。按生长阶段比较,抽雄~开花期日耗水强度最大,为66.75~76.50m³·hm^-2;其次是拔节~抽雄期,平均为65.50m³·hm^-2;播种~出苗期间日耗水强度仅为13.35m³·hm^-2。不同的灌溉方式与灌水量对夏玉米的穗粒重、千粒重及粒占穗重的百分比都有影响。对于宽行稀植作物采用沟灌方式,灌溉用水量小(平均为442.5m³·hm^-2),所供的水能集中于植株的根际附近,棵间蒸发的无效损耗少,穗粒重和千粒重都较高,产量达9616.5 kg·hm^-2,比畦灌条件下节省22.8%的灌溉用水,水分生产率提高16.9%。减少夏玉米生长期内的灌水次数,在降低水量消耗的同时,易造成较大幅度的减产(13.7%),因此,在夏玉米生长过程中,遇到偏旱年份,要特别注意防止缺水而引起的水分胁迫。     

Nutrient Behavior and Productivity in a River System Affected by Fishpond Effluents

The expanding culture of fish in coastal areas has raised issues concerning resource use conflicts and water quality problems. A major concern is pollution resulting from nitrogen and phosphorus lost to the environment from feed wastage and fish excretion. The purpose of the study was to assess the environmental conditions in a river system affected by fishponds. Nutrient fluxes and productivity measurements were obtained from Sta. Rita River, a river estuary used as a discharge and an irrigation area of approximately 316 ha of fishponds. During the dry season, when freshwater influence is absent, salinity values inside the river were higher than outside (in the bay). Nutrient trends during ebb and flood periods were similar except for some lag in the profiles that indicate tidal oscillation. The absence of river flow during the dry period resulted in a negligible flux of nutrients along the river. During the wet season, the increase in nitrate concentrations indicates river inputs while the decrease in phosphate values imply less of freshwater influence but more from ponds and domestic wastes. Similarity in productivity estimates signifies good agreement between direct and indirect methods. The absence of flushing during the dry season translates to trapping of nutrients discharged from the ponds in the drainage canals.     

Relationship between species richness of small mammals and primary productivity of arid and semi-arid grasslands in north China

We studied the relationship between primary productivity and species richness of small mammals at both large and small spatial scales in the arid and semi-arid grasslands of north China. The productivity (x)–species richness (y) pattern at a large spatial scale can be described by a unimodal quadratic regression curve (y=7·41+0·1^*x−0·0003^*x²,p =0·008, r²=0·788). At a small spatial scale, however, neither linear nor quadratic regression fit the data for 1980 and 1994 (p>0·25). Primary productivity may not be an appropriate predictor of the species richness of small mammals at a small spatial scale. We conclude, therefore, that the primary productivity–species richness pattern of small mammals may be scale-dependent in the arid and semi-arid grasslands of north China. Landscape complexity should be considered in future studies of productivity–richness relationships.     

桑沟湾水域浮游植物的光量子产值

于1989－1990年对山东半岛的桑沟湾水域进行了综合调查,利用对自然水域现场测量的方法,对浮游植物兀合色素对光的吸收及其光量子产值进行了4个季度月的测量和计算,目的是研究这种浅海养殖生态系统初级生产过程中的能量流动状况。结果表明,该海区光量子产值的范围为0.189×10-2molC／E－6．019×10-2molC／E;浮游植物吸收的光能占海面总吸收光能的0.9％－5.5％;浮游植物的光利用率为0.026％－0.101％,与其他海区相比,较为偏低。     

象山港潮滩底栖微型藻类现存量和初级生产力

作者于1992年2、5、6、8和10月在象山港湖头渡,5月和6月在大佳河（港顶部）、西沪港（港中部）和横山（近港口区）4条断面潮滩进行了底栖微型藻现存生物量和初级生产力的观测研究．结果表明,潮滩表层叶绿素a浓度分布具有明显的空间区域性和时间变异性特征．港顶部的浓度高于港中部和近港口区;滩面表层的平均叶绿素a浓度,5月[（10．36±8．08）μg／g湿重]高于6月[（2．94±1．21）μg／g湿重]．由于光的限制,沉积物中的叶绿素a主要分布在表层0～1cm,随深度的增加浓度下降,但其降解产物──脱镁叶绿素的浓度却增大．松软、平整、稳定的滩面有利于底栖微型藻类的生长,5、6月湖滩表层平均初级生产力为（45．1±46．8）mg／（m2·h）（C）．湖头渡潮滩叶绿素a浓度以夏季最高,春、秋季次之,冬季最低;初级生产力仍以夏季最高,春、冬季较低,秋季最低．     

Environmental geochemistry of the Pichavaram mangrove ecosystem (tropical), southeast coast of India

 Spatial and temporal geochemical variations of various parameters in the water and sediment of a relatively small mangrove situated on the southeast coast of India were examined in detail for the first time. The water quality generally reflects the impact of seawater and the Vellar estuary (mixing effect) aided by evaporation and in situ biological productivity. The depletion and fluctuation of dissolved silica are controlled by biological processes. Nitrate and phosphate are contributed by fertilizer input from adjoining agriculture fields. Total suspended matter (TSM) shows an erratic range and trend due to deforestation and resuspension processes. Sand and silt constitute 70–90% of the sediments. Statistical analysis of the sediments shows the prevalence of a moderately high-energy environment with very effective winnowing activity. Organic matter content is higher in the mangrove sediments in comparison to adjacent estuaries. Water and sediment show fluctuations in their chemical concentration, but no specific trends could be identified. Heavy metals are also enriched in the mangrove sediments, indicating their unique chemical behavior and the existence of trapping mechanisms. Factor analysis and correlation analysis of water and sediments show the complexity of the system and the multitude of contributing sources. The core sediment chemistry suggests the depletion of metal input due to the damming of the detrital inputs. The Pichavaram mangrove seems to be relatively unpolluted, since the anthropogenic signal observed is small and acts as a sink for heavy metals contributed from a multitude of sources without an adverse effect. Received: 5 November 1997 · Accepted: 30 March 1998     

新疆金刚石原生矿成矿地质条件及其找矿方向

塔里木地台是我国寻找原生金刚石矿较有远景的地区之一。通过对塔里木地台及其周边４个古老陆块成矿地质条件的分析以及与国内外已知原生金刚石矿床产出地质条件的对比研究,指出新疆塔里木周边的库鲁克塔格－星星峡、铁克力克、阿尔金和柯坪４个断降具有寻找原生金刚石矿的前景,提出在上述４个地区开展原生金刚石矿的具体找矿工作建议。     

初论金刚石原生矿床成矿系列

目前所知产金刚石的岩石类型包括金伯利岩、钾镁煌斑岩、榴辉岩、蛇绿岩套、碱性超基性杂岩、碱性超基性煌斑岩和橄榄岩类(方辉橄榄岩、纯橄榄岩等) 等偏碱性超镁铁质岩石, 而有经济价值的金刚石原生矿床仅见于金伯利岩和钾镁煌斑岩中, 除此之外的其他岩石类型中仅见有少量微粒金刚石.金伯利岩和钾镁煌斑岩都起源于地幔深部, 就此意义上讲, 二者是同源的, 但其岩石化学成分、主要矿物组成、产出大地构造背景以及同位素资料等, 却存在着比较明显的差异.由此构成了金刚石原生矿床的两个成矿系列: 金伯利岩成矿系列和钾镁煌斑岩成矿系列.金伯利岩成矿系列又可以根据其化学成分划分为3个亚系列, 即: 高Cr, Ti, Mg成矿亚系列, 低Cr, Ti, Mg成矿亚系列和介于二者之间的一种具有复杂化学成分的成矿亚系列.钾镁煌斑岩成矿系列则可以根据其主要矿物组成, 划分出橄榄石钾镁煌斑岩成矿亚系列、白榴石钾镁煌斑岩成矿亚系列以及介于两者之间的白榴石-橄榄石钾镁煌斑岩成矿亚系列共3种次级成矿系列.与此同时, 无论是金伯利岩成矿系列, 还是钾镁煌斑岩成矿系列, 又都可以根据其野外地质产状, 划分为以下3个成矿亚系列(形成时间从早到晚) : (1) 火山沉积凝灰岩成矿亚系列; (2) 火山凝灰角砾岩成矿亚系列; (3) 火山-次火山侵入相成矿亚系列.      

Radiative transfer code: Application to the calculation of PAR

The production of carbon in the ocean, the so-called primary production, depends on various physicobiological parameters: the biomass and nutrient amounts in oceans, the salinity and temperature of the water and the light available in the water column. We focus on the visible spectrum of the solar radiation defined as the Photosynthetically Active Radiation (PAR). We developed a model (Chamiet al. 1997) to simulate the behavior of the solar beam in the atmosphere and the ocean. We first describe the theoretical basis of the code and the method we used to solve the radiative transfer equation (RTE): the successive orders of scattering (SO). The second part deals with a sensitivity study of the PAR just above and below the sea surface for various atmospheric conditions. In a cloudy sky, we computed a ratio between vector fluxes just above the sea surface and spherical fluxes just beneath the sea surface. When the optical thickness of the cloud increases this ratio remains constant and around 1.29. This parameter is convenient to convert vector flux at the sea surface as retrieved from satellite to PAR. Subsequently, we show how solar radiation as vector flux rather than P A R leads to an underestimate of the primary production up to 40% for extreme cases.