Interaction between inorganic nutrients and organic matter in controlling coral reef communities in Glovers Reef Belize

We studied the responses of algae, corals, and small fish to elevated inorganic fertilizer, organic matter, and their combination over a 49-day summer period in cages that simulated the coral reef in the remote Glovers reef atoll, Belize. The addition of organic matter reduced while fertilization had no effect on the numbers of herbivorous damsel and parrotfishes. All measures of algal biomass were influenced by fertilization. The combined inorganic and organic enrichment produced the highest algal biomass, which is most likely due to the combined effect of higher nutrients and lower herbivory. The cover of turf and total algae were influenced by all treatments and their interactions and most strongly and positively influenced by fertilization followed by organic matter and the combination of organic matter and inorganic fertilizer. The inorganic and combined treatments were both dominated by two turf algae, Enteromorpha prolifera and Digenia simplex, while the nonfertilized treatments were dominated by brown frondose algae Lobophora variegata, Padina sanctae, and Dictyota cervicornis. The organic matter treatment had greater cover of P. sanctae and D. cervicornis than the untreated control, which was dominated by Lobophora variegata, also the dominant algae on the nearby patch reefs. Crustose corallines grew slowly ( approximately 2.5 mm/49 days) and were not influenced by the treatments when grown on vertical surfaces but decreased on horizontal coral plates in the combined organic matter and fertilization treatment. No mortality occurred for the two coral species that were added to the cages. Porites furcata darkened in the fertilized cages while there was a mix of paling and darkening for a small amount of the coral tissue of Diploria labyrinthiformes. Inorganic fertilization stimulates small filamentous turf algae and Symbiodinium living in coral but inhibits brown frondose algae. Organic matter inhibits small herbivorous fish, L. variegata, and encrusting coralline algae when growing on horizontal surfaces.     

IP和电阻率对数假断面图

将野外测得的IP和电阻率数据表示成对数形式的假断面图,比目前常规绘制的假断面图更有意义,因为勘探深度是指数函数或对数函数,或者是幂函数.用双对数构制的IP和视电阻率图已有人讨论过,并不新奇.本文只是用图来简短说明所取得的成果. 静电等效性     

COMPUTER DEMODULATION TECHNIQUE FOR A DUAL-CHANNEL MICROWAVE RADIOMETER

The three stairstep output of the video amplifier has now been designed for the NOAA/WPL dual-channel radiometer in order to provide an analog input to one A/D converter instead of to two phase-detectors, and the synchronous detection for data and AGC is done in software. We put the new system into the dual-channel radiometer which was set in Boulder Atmospheric Observatory (BAO) to make experiments for three weeks and found the processor reliable and flexible.     

世界城市化进程

人口统计学原理具有重要的社会经济意义,尤其是对于城市化过程。整个世界正朝着更为城市化的生活方式发展,这个过程在发达国家已基本完成,而在第三世界的许多国家才刚刚起步。目前,越来越多的地方可以获取世界城市数量和规模的数据。联合国《人口统计年鉴》即是一个十分可靠的资料来源,它列出了所有1.0万人口以上的城市。从该数据库中选出一段时期内一百万人口以上的城市数据进行处理,便可以得出一个城市化的粗略指数。     

BOOK REVIEWS

TIMESLAB:A TIME SERIES ANALYSIS LABORATORY,by H.Joseph Newton,Wadsworth andBrooks/Cole Advanced Books and Software,Pacific Grove,CA,U.S.A.,1988.ISBN0-534-09198-9.Price:$49.95.TIMESLAB is the remarkable fusion of a text-book on the analysis of univariate and bivariatetime series and of software creating an interactive     

Delineating and quantifying ground water discharge zones using streambed temperatures

Streambed temperature mapping, hydraulic testing using minipiezometers, and geochemical analyses of interstitial water of the streambed were used to delineate the pattern of ground water discharge in a sandy streambed and to develop a flux-based conceptual model for ground water/surface water interactions. A new and simple empirical method was used to relate fluxes obtained from minipiezometer data to streambed temperatures. The relationship allowed flux to be calculated at locations where only streambed temperature measurements were made. Slug testing and potentiomanometer measurements at 34 piezometers indicated ground water discharge ranged from 0.03 to 446 L/m2/day (and possibly as high as 7060 L/m2/day) along a 60 m long by 11 to 14 m wide reach of river. Complex but similar plan-view patterns of flux were calculated for both summer and winter using hundreds of streambed temperatures measured on a 1 by 2 m grid. The reach was dominated by ground water discharge and 5% to 7% of the area accounted for approximately 20% to 24% of the total discharge. < 12% of the total area consisted of recharge zones or no-discharge zones. A conceptual model for ground water/surface water interactions consisting of five different behaviors was developed based on the magnitude and direction of flux across the surface of the streambed. The behaviors include short-circuit discharge (e.g., high-flow springs), high discharge (e.g., preferential flowpaths), low to moderate discharge, no discharge (e.g., horizontal hyporheic or ground water flow), and recharge. Geological variations at depth played a key role in determining which type of flow behavior occurred in the streambed.     

Conduit properties and karstification in the unconfined Floridan aquifer

Exchange of water between conduits and matrix is an important control on regional chemical compositions, karstification, and quality of ground water resources in karst aquifers. A sinking stream (Santa Fe River Sink) and its resurgence (River Rise) in the unconfined portion of the Floridan Aquifer provide the opportunity to monitor conduit inflow and outflow. The use of temperature as a tracer allows determination of residence times and velocities through the conduit system. Based on temperature records from two high water events, flow is reasonably represented as pipe flow with a cross-sectional area of 380 m2, although this model may be complicated by losses of water from the conduit system at higher discharge rates. Over the course of the study year, the River Rise discharged a total of 1.9 x 10(7) m3 more water than entered the River Sink, reflecting net contribution of ground water from the matrix into the conduit system. However, as River Sink discharge rates peaked following three rainfall events during the study period, the conduit system lost water, presumably into the matrix. Surface water in high flow events is typically undersaturated with respect to calcite and thus may lead to dissolution, depending on its residence time in the matrix. A calculation of local denudation is larger than other regional estimates, perhaps reflecting return of water to conduits before calcite equilibrium is reached. The exchange of matrix and conduit water is an important variable in karst hydrology that should be considered in management of these water resources.     

Monitoring chemical contamination levels in the Mediterranean based on the use of mussel caging

Within the framework of the biointegrator network (RINBIO), 92 man-made cages containing mussels (Mytilus galloprovincialis), distributed over 1800 km of the French Mediterranean coast, made it possible to assess chemical contamination by heavy metals (Cd, Hg, Zn, Pb, Cu, Ni, Cr, As) and organic compounds (DDT, PCBs, HAP). The caging technique was adopted to compensate for the scarcity of natural shellfish stocks in the Mediterranean and to enable comparison of the sites regardless of their physicochemical and trophic characteristics. Models linking a biometric parameter (the condition index) to pollutant levels make it possible to adjust raw data on contamination for a reference individual, by making a clear distinction between physiological factors (growth) and environmental ones. The results demonstrate significant levels of pollutants in sites heretofore unsampled; the pollution occurs at limited areas, and the sources have been identified. Moreover, average contamination levels are comparable to those measured in wild species and in other areas. Overall, the research demonstrates the reliability of this methodological approach for monitoring marine pollution, especially in the Mediterranean.     

Accumulation of hexavalent chromium by an exopolysaccharide producing marine Enterobacter cloaceae

An exopolysaccharide producing Enterobacter cloaceae (AK-I-MB-71a) was tested for its Cr (VI) tolerance. This isolate was not only resistant to this heavy metal but also showed enhanced growth and exopolysaccharide production in the presence of Cr (VI) at 25, 50 and 100 ppm concentrations. XRF analysis of both the biomass as well as the exopolysaccharide revealed that a sum total of about 60-70% chromium was accumulated by this bacterium. This indicated that this organism could prove to be a potential candidate in the field of bioremediation with respect to chromium removal.     

NOTE ON GORRELATION OF PHYSIOGRAPHIC STAGES

The definite nature of the faunal evidence afforded by the Nihowan beds is of importance in fixing the limits of the physiographic stages which till now have been somewhat hazily defined.