Long‐term water budget imbalances and error sources for cold region drainage basins

This study assessed the long‐term (1979–2008) water budget closures for 19 large cold region drainage basins in Canada using recently developed datasets for precipitation (P), land surface evapotranspiration and water surface evaporation, and observed streamflow. Total water storage (TWS) trends from the GRACE satellite observations were also used to assist the assessment. The objectives are to quantify the magnitudes and spatial patterns of the water budget imbalance (ε) and its source of errors for these cold region basins. Results showed that the water budget was closed within 10% of the P on average for all the basins. The ε showed a general pattern of positive values in the south and negative values in the north and mountainous regions over the country. Basins with large ε values were mostly found in the north. Uncertainties in the water budget variables, particularly P, were found to play a major role in the ε. Significant trends in TWS were found over 11 basins, which accounted for 31% of their ε on average. Improvements in the observation network, data quality assurance, and spatial models for P are critical for further improving the water budget closure for the cold region drainage basins. © 2014 Her Majesty the Queen in Right of Canada. Hydrological Processes. © John Wiley & Sons, Ltd.     

Physically-based hydrological modelling for non-point dissolved phosphorus transport in small and medium-sized river basins / Modélisation hydrologique à bases physiques et du transport de phosphore dissous diffus en bassins versants de petite et moyenne tailles

Abstract

Abstract Current research suggests that strategies to control sediment and phosphorus loss from non-point sources should focus on different runoff components and their spatial and temporal variations within the river basin. This is a prerequisite for determining effective management measures for reducing diffuse source pollution. Therefore, non-point source models, especially in humid climatic regions, should consider variable hydrologically active source areas. These models should be able to consider runoff generation by saturated overland flow, as well as Hortonian overland flow. A combination of the hydrological model WaSiM-ETH and the erosion and P-transport model AGNPS was chosen for this study. The models were run in the WaSiM runoff generation mode (Green & Ampt/TOPMODEL or Richards equation approach) and the SCS curve number mode to assess the effect of these different runoff calculation procedures on the dissolved phosphorus yield. A small and a medium-sized river basin, of the area of 1.44 and 128.9 km², respectively, in central Germany were selected for the investigation. The results show that the WaSiM–AGNPS coupling produces more accurate results than the SCS curve number method. For the spatial distribution, the more physically-based model approach computed a much more realistic distribution of water and phosphorus yield-producing areas.     

Using 137Cs measurements to establish catchment sediment budgets and explore scale effects

Growing awareness of the wider environmental significance of fine sediment transport by rivers and associated sediment problems linked to sediment–water quality interactions, nutrient and contaminant transfer, and the degradation of aquatic habitats has resulted in the need for an improved understanding of the mobilization and transfer of sediment in catchments to support the development of effective sediment management strategies. The sediment budget provides a key integrating concept for assembling information on the internal functioning of a catchment in terms of its sediment dynamics by providing information on the mobilization, transfer, storage and output of sediment. One key feature of a catchment sediment budget is the relationship between the sediment yield at the catchment outlet and rates of sediment mobilization and transfer within the catchment, which is commonly represented by the sediment delivery ratio. To date, most attempts to derive estimates of this ratio have been based on a comparison of the measured sediment yield from a catchment with an estimate of the erosion occurring within the catchment, derived from an erosion prediction procedure, such as the Universal Soil Loss Equation (USLE) or its revised version, RUSLE. There is a need to obtain more direct and spatially distributed evidence of the erosion rates occurring within a catchment and to characterize the links between sediment mobilization, transfer, storage and output more explicitly. In this context, fallout radionuclides have proved particularly useful as sediment tracers. This paper reports the results of a study aimed at exploring the use of caesium‐137 (¹³⁷Cs) measurements to establish sediment budgets for three catchments of different sizes and contrasting land use located in Calabria, southern Italy. Long‐term measurements of sediment output were available for the catchments, and, by using the estimates of gross and net rates of soil loss within the catchments provided by ¹³⁷Cs measurements, it was possible to establish the key components of the sediment budget for each catchment. By documenting the sediment budgets of three catchments of different sizes, the study provides a basis for exploring the effects of scale on catchment sediment budgets and, in particular, the increasing importance of catchment storage as the size of the catchment increases. The results of this study demonstrate a reduction in the sediment delivery ratio from 98 to 2% as catchment area increases from 1·47 ha to 31·2 km². Copyright © 2010 John Wiley & Sons, Ltd.     

辽河大伙房水库汇水区农业非点源污染入库模拟

利用输出系数法和SWAT模型,对大伙房水库汇水区农业非点源污染(ANSP)进行了入库模拟研究,并用2006—2009年的水文和水质监测数据对模型进行了校准和验证。研究结果表明:汇水区年均输入到水库的泥沙量、总氮和总磷负荷分别为82.65×103 t、1 873.49t和81.97t;月入库泥沙量、总氮和总磷负荷与径流量有着较强的相关性,ANSP的产生和迁移受降水、径流过程影响很大,每年7、8月份的氮、磷和泥沙流失量达到年内最大值,分别占全年流失总量的42.64%、44.42%和67.91%。水库汇水区各流域对水库氮、磷污染的贡献率由大到小依次为:浑河流域(清原段)、苏子河流域、社河流域和水库周边小流域。     

基于CLM4.5的高寒草地辐射收支和水热交换的数值模拟研究

利用那曲高寒气候环境观测研究站本部BJ观测点2014年6-8月的近地层观测资料,结合CLM4.5陆面模型,探究空气动力学粗糙长度、叶面积指数、植被覆盖度和热力学粗糙长度参数化方案的改变对陆面能水平衡的模拟结果产生的影响,并且探讨了粗糙度及植被状态指数影响陆面能水平衡模拟性能的机制.结果表明:(1)CLM4.5默认的热力...     

硅酸钙晶种法回收污水中磷的实验研究

实验研究了以钾长石水热分解的副产物沉淀硅酸钙为晶种,回收模拟污水中磷的效果。结果表明,晶种用量0.4 g/L、p H值为8、Ca/P(摩尔比)=2条件下反应2 h后,污水中剩余磷浓度为0.32 mg/L,低于我国污水综合排放一级A标准0.5 mg/L。沉淀硅酸钙重复使用60次后回收磷的效果仍然较好,回收率为79.5%以上。采用扫描电镜、红外光谱、粉晶X射线衍射等测试手段对回收产物进行的分析表明,回收磷产物以羟磷灰石形态存在,产物中P2O5含量在35%以上,达到了富磷矿的品位。沉淀硅酸钙有望成为回收磷的理想晶种材料。     

石灰性土壤中有效磷的电感耦合等离子体发射光谱法测定

方法采用0.5 mol/L NaHCO3浸提石灰性土壤中的有效磷,电感耦合等离子体原子发射光谱法测定。研究了土壤滤液的酸化、颜色、浸提温度以及振荡时间等对浸提结果的影响,方法检出限(3s)为0.18 mg/kg,定量限(6s)为0.36 mg/kg,通过对石灰性土壤有效态标准物质GBW07413a、GBW07459和GBW07460的12次测定,方法准确度和精密度均小于4.5%。     

Zeolite and fungi’s flocculability of simulated wastewater containing heavy metal ions or phosphorus

This paper focuses on the flocculability of simulated wastewater containing heavy metal ions (Fe3+, Cd2+) or phosphorus by zeolite, microbial flocculants (MBF) produced by Aspergillus niger and the composite flocculant composed of zeolite and MBF. The main results are presented as follows: zeolite was a good flocculant when the contamination of the three simulated wastewaters was low, but the treated water is of turbidness and the particles in it are hard to precipitate. The MBF have a good flocculability toward Fe3+ wastewater, as well as particulate matter. Significant changes in flocculability occurred after adding the composite flocculant in different simulated wastewaters, the best or least effect respective for Fe3+ and Cd2+ wastewater. The research we have done shows that the method by which the composite flocculant is used to treat the wastewater containing heavy metal ions or phosphorus provides important reference value for practical application.     

大口黑鲈(Micropterus salmoides)不同养殖模式氮磷收支及养殖效果研究

为了揭示池塘内循环流水养殖模式(Inner-Pond Raceway Aquaculture,IPRA)氮磷收支变化及养殖效果情况,阐明其生态特征及营养物质的来源与归宿,合理评价IPRA的经济与生态效益,通过定期采样计算氮磷的输入和输出项目,同时设置传统常规养殖池塘(usual pond aquaculture,UPA)为对照组。结果表明:(1)两种养殖模式中,饲料是池塘氮、磷输入的主要来源,分别占IPRA和UPA池塘氮输入的95.02%±2.31%和94.57%±1.82%,占两种模式磷输入的93.19%±2.75%和91.81%±4.44%;(2)底泥沉积是氮、磷输出的主要方式,占IPRA和UPA氮输出的45.16%±1.31%和53.98%±1.48%,占磷输出的40.28%±3.19%和59.59%±4.45%,差异显著(P0.05),其次是养殖产出,IPRA渔获物氮输出比例37.73%±0.91%高于UPA的35.07%±0.99%,差异不显著(P0.05),磷输出比例25.50%±1.77%显著高于UPA的20.78%±1.33%(P0.05);(3)IPRA对氮的绝对和相对利用率高于UPA,但差异不显著(P0.05),而对磷的利用率显著高于UPA (P0.05), IPRA提高了养殖对象对氮、磷的吸收利用率;(4) IPRA耗水系数、排水系数及排污系数均显著低于UPA (P0.05),但IPRA养殖效益显著高于UPA (P0.05)。综上所述, IPRA是一种清洁高效的新型养殖模式,可以进行推广应用。本研究旨在为今后更好地开展IPRA水质管理和科学养殖提供数据支撑,同时为IPRA模式在节水生态、经济效益等评价方面提供理论依据。     

水体富营养化状态对城市河道底泥吸附/释放P的影响 ——以江苏省苏州市河道试验研究为例

以苏州古城区内的河道为研究对象,采用静态培养的方式,研究了上覆水体不同富营养化程度对底泥中P释放/吸附的影响。研究结果表明：截断外源污染后,苏州河道底泥对水体中营养盐P呈现吸收状态;随着上覆水体磷酸盐浓度的增大,单位面积底泥累积吸收的磷酸盐就越多;上覆水与底泥比值越大,底泥对P的吸附率有减小的趋势。