Relationship between the variation of water quality in rivers and the characteristics of watershed at Miyun,Beijing, China

Based on the characteristics of land use and drainage network of the upper watershed of the Miyun Res-ervoir, Beijing, 26 monitoring and sampling sites were selected in different sub-catchments. Temporal and spatial variations in nutrient loss were dealt with in this paper in terms of the monitoring data on the water quality of the main tributaries flowing into the Miyun Reservoir. In combination with the monitoring data on water quality, the impacts of watershed characteristics including land-use type, landscape pattern, and drainage density were assessed, The concentrations of nutrients in the rainy season are higher than those in other seasons, and the concentrations of NO3--N are linearly related to those of total N which is the main form of nitrogen present in the fiver water. The concentrations of nitrogen become higher toward the reservoir along the main rivers. The seasonal variation of ni-trogen in the watershed affected by intensive human activities is very obvious; in the watershed with steady or low water flow, the seasonal variation of nitrogen is less obvious. Forest land and grassland can trap and filter nitrogen effectively. Land-use pattern also has important impacts on the loss of nitrogen. The concentrations of nitrogen and phosphorus in the water bodies show great temporal and spatial variations. On a temporal scale, the concentrations of TN and TP in the rainy reason are higher than those in other seasons. On a spatial scale, the concentrations of TN and NO3--N in the Qingshui River and Chaohe River are highest all the time. The spatial variation of TP is distinct, being obvious at sampling sites near villages. The form of nitrogen and phosphorus loss varies in different hydrological seasons. Dissolved nitrogen and phosphorus are the main forms in streams in non-rainy seasons, the dissolved nitro-gen and total nitrogen decrease in percentage in the rainy season. Particulate nitrogen and phosphorus are the main forms in some rivers. The concentrations of TN and NO3--N from orchards and villages are high whereas those from forest land are lowest. Land-use pattern has impacts on TN and NO3--N losses, at the sampling sites near the source landscape, the concentrations are higher than those at the sampling sites near the sink landscape. Water quality of the rivers which flow into the Miyuan Reservior is influenced by the composition of adjacent soils.     

基于GIS的西平县土地利用变化分析

在遥感和地理信息系统软件支持下,通过2002年的ETM＋和2007年的CBERS遥感图像分析,利用马尔科夫链的元胞自动机模型与构建土地利用适宜性图层,模拟西平县2012年土地利用变化。结果表明：到2012年,西平县城镇及工矿用地将在原有基础上向四周辐射发展,交通运输用地将在原来基础上拓宽,村镇居民点及公路周围的耕地将减少,林地、其他用地也将减少。     

Modeling Research of the 27-day Forecast of 10.7 cm Solar Radio Flux (I)

Adopting the autoregressive method for time-series modeling, we have made a study on the medium-term forecast of solar 10.7 cm radio flux (F10.7). The result of forecast experiments and the error analysis indicate that when the solar activity is at a rather low level and the 27-day periodicity of F10.7 is apparent, the autoregressive forecast method has a high accuracy and relatively ideal effectiveness, but when a large active region appears or disappears on the solar dusk, the forecast effectiveness is not ideal. This means that the autoregressive method for the time-series modeling can reflect well the 27-day periodicity of F10.7, and that it has certain applicability for building a mediumterm forecast model of F10.7. By comparing the forecast results in the period from 21th September 2005 to 7th June 2007, it is demonstrated that the accuracy of the autoregressive forecast method is equivalent to that of the forecast made by the American Air Force.     

Screening and characterization of the alkaline protease isolated from PLI-1, a strain of Brevibacillus sp. collected from Indonesia’s hot springs

A total of 69 strains of thermophilic bacteria were isolated from water, soil and sediment samples from three Indonesia’s hot spring areas (Pantai cermin, Kalianda and Banyu wedang) by using Minimal Synthetic Medium (MSM). The extreme thermophile Brevibacillus sp. PLI-1 was found to produce extracellular thermophilic alkaline protease with optimal activity at 70℃ and pH 8.0-9.0. The molecular weight of the protease was estimated to be around 56 kD by SDS-PAGE. The maximum activity of the protease was 26.54 U mL-1. The protease activity did not decrease after 30 min and still retained more than 70% of relative activity after 60 min at 70℃ and pH 8.0. The ion Mg2+ was found to promote protease activity at both low and high concentrations, whereas Cu2+ and Zn2+ could almost completely inhibit the activity. Divalent cation chelator EDTA inhibited the enzyme activity by 55.06% ± 0.27%, while the inhibition caused by PMSF, Leupeptin, Pepstain A and Benzamidine were 66.78% ± 3.25%, 52.37% ± 0.25%, 62.47% ± 2.96% and 50.99% ± 0.24%, respectively. Based on these observations, the enzyme activity was conspicuously sensitive to the serine and cysteine protease inhibitors. All these results indicated that the protease isolated from the strain PLI-1 was a thermophilic protease and had a high-temperature stability and a pH stability.     

THERMAL EFFECTS OF BUILDING＇S EXTERNAL SURFACES IN CITY——Characteristics of Heat Flux into and out of External Wall Surfaces

This study examined the thermal effects of building‘s external wall surfaces, using observational data of spatial-temporal distribution of surface temperature, air temperature, and heat flux into and out of external surface. Results indicate that external wall surface temperature and nearby air temperature vary with the change of orientation, height and season. In general, the external wall surface temperature is lower near the ground, and is higher near the roof, than nearby air temperature. But north wall surface temperature is mostly lower than nearby air temperature at the same height; south wall surface temperature during the daytime in December, and west wall surface temperature all day in August, is respectively higher than nearby air temperature. The heat fluxes into and out of external wall surfaces show the differences that exist in the various orientations, heights and seasons. In December,south wall surface at the lower sites emits heat and north wall surface at the higher sites absorbs heat. In April, all external wall surfaces, emit heat near the ground and absorb heat near the roof. In August, west wall surface all day emits heat, and other wall surfaces just show the commensurate behavior with that in April.     

Identification of paralytic shellfish toxin-producing microalgae using machine learning and deep learning methods

Journal of Oceanology and Limnology - Paralytic shellfish poisoning (PSP) microalgae, as one of the harmful algal blooms, causes great damage to the offshore fishery, marine culture, and marine...     

Simulation Study of Potential Impacts of Tidal Farm in the Eastern Waters of Chengshan Cape,China

The sea area east of Chenshan Cape has peak tidal current flows that exceed 2.3 m s-1, which make it a promising site for the development of tidal current energy. Before these resources can be exploited, a comprehensive assessment is needed of the potential environmental impacts of the extraction of this energy. In this paper, we describe our construction of a three-dimensional hydrodynamic model of the waters near Chengshan Cape, and verify the performance of the model using continuous data measured in situ. We modeled the potential impacts of the exploitation of these resources on the flow field by adding a momentum loss term in the governing equation of the model. Simulation results show that an assumed tidal farm with an estimated power output of 20.34 MW would have a significant impact on the surrounding water level, especially next to the farm, where fluctuation could reach 6 cm. The maximum drop in the flow velocity in the wake of the farm was predicted to be more than 0.8 m s-1, and this influence would extend 10 km downstream.     

枣庄市台儿庄区小龚庄岩溶地下水水源地允许开采量计算评价

科学有效的地下水资源评价是可持续开发地下水资源的关键,其中地下水资源可开采量的评价是地下水资源评价的核心内容。该文在对枣庄市台儿庄区小龚庄水源地水文地质条件、岩溶塌陷发育情况等进行详细分析的基础上,采用开采试验法对小龚庄水源地岩溶地下水允许开采量进行了计算,计算结果为11354m~3/d。根据已发生岩溶塌陷情况,设定岩溶塌陷预警水位,利用非稳定流Theis公式计算了安全开采量范围在11187～13150m~3/d之间,对开采试验法计算结果进一步进行评价。根据评价结果最终确定以11354m~3/d作为小龚庄水源地的允许开采量是可靠的,可以保证水源地最大限度的开采地下水资源,同时又保证水源地运行时不易引发岩溶塌陷的环境地质问题。该方法为同类型水源地地下水允许开采量的计算评价提供了一定的借鉴。     

Identification of Suitable Hydrologic Response Unit Thresholds for Soil and Water Assessment Tool Streamflow Modelling

Use of a non-zero hydrologic response unit(HRU) threshold is an effective way of reducing unmanageable HRU numbers and simplifying computational cost in the Soil and Water Assessment Tool(SWAT) hydrologic modelling. However, being less representative of watershed heterogeneity and increasing the level of model output uncertainty are inevitable when minor HRU combinations are disproportionately eliminated. This study examined 20 scenarios by running the model with various HRU threshold settings to understand the mechanism of HRU threshold effects on watershed representation as well as streamflow predictions and identify the appropriate HRU thresholds. Findings show that HRU numbers decrease sharply with increasing HRU thresholds. Among different HRU threshold scenarios, the composition of land-use, soil, and slope all contribute to notable variations which are directly related to the model input parameters and consequently affect the streamflow predictions. Results indicate that saturated hydraulic conductivity, average slope of the HRU, and curve number are the three key factors affecting stream discharge when changing the HRU thresholds. It is also found that HRU thresholds have little effect on monthly model performance, while evaluation statistics for daily discharges are more sensitive than monthly results. For daily streamflow predictions, thresholds of 5%/5%/5%(land-use/soil/slope) are the optimum HRU threshold level for the watershed to allow full consideration of model accuracy and efficiency in the present work. Besides, the results provide strategies for selecting appropriate HRU thresholds based on the modelling goal.