Relationship between nutrient pollutants and suspended sediments in upper reaches of Yangtze River

In order to study the relationship between nutrient pollutants and suspended sediments(SS) in the upper reaches of the Yangtze River and two tributaries, water samples were collected from September 1, 2010 to September 30, 2011 at the Zhutuo, Cuntang, Beibei, Wulong, Qingxichang,Wanxian, and Fengjie cross-sections. In the laboratory, the SS concentration and the concentration of SS whose particle size was smaller than0.02 mm were measured. The phosphorus(P), nitrogen(N), and permanganate index(CODMn) concentrations in the natural water sample, the settled water sample, and two types of filtered water samples obtained through filter membranes with pore sizes of 0.02 mm and 0.45 mm were monitored synchronously. The results show that there are strong relationships between the P and CODMnconcentrations and the SS concentration. P mainly exists in particulate form, while N mainly exists in dissolved form. SS whose particle size is smaller than 0.02 mm accounts for a high proportion of sediments in the Yangtze River and has a strong effect on water quality. At the seven cross-sections, the amounts of P, N, and CODMnin particulate form in the wet season are higher than in the dry season and the adsorption amounts of P, N, and CODMnper unit mass of sediment are higher in the dry season than in the wet season.     

Groundwater-surface water interactions and agricultural nutrient transport in a Great Lakes clay plain system

Nutrient export from agricultural land to surface waters is a significant environmental concern within the Great Lakes Basin (GLB). A field-based watershed-scale study was completed to investigate spatial and temporal variations of phosphorus and nitrate to assess nutrient transport pathways and groundwater-surface water interactions in an agriculturally dominated clay plain system. This was conducted in the 127 km² Upper Parkhill Watershed, near Lake Huron in southwestern Ontario, Canada. Data collection occurred from June 2018 to May 2019 via continuous sensor deployment and discrete sampling of stream water, groundwater, hyporheic zone, and tile drainage water. Samples were analyzed for various nutrient species (total, total dissolved, soluble reactive, and particulate phosphorus, and nitrate-N) to examine the hydrological dynamics of principal transport pathways of agriculturally-derived nutrients. Total phosphorus and nitrate concentrations in stream water ranged from 0.007 to 0.324 mg/L and 0.32 to 13.13 mg NO₃^?-N/L, respectively. Tile drainage water total phosphorous concentrations varied from 0.006 to 0.066 mg/L. Groundwater total dissolved phosphorus concentrations ranged from <0.003 to 0.085 mg/L. Transport of phosphorus through tile drainage was observed to be greater than through groundwater over the study period. No distinct relationship was observed between nutrient concentrations in the hyporheic zone and the vertical hydraulic gradient within this zone in the studied stream reach. Preliminary correlations were discerned between water quality observations and recognized land management practices. Given the elevated stream nutrient concentrations, these results are consequential for the continual improvement of strategies and programs devised to conserve water resources within the GLB.     

Tracking changes in nutrient delivery to western Lake Erie: Approaches to compensate for variability and trends in streamflow

Tracking changes in stream nutrient inputs to Lake Erie over multidecadal time scales depends on the use of statistical methods that can remove the influence of year-to-year variability of streamflow but also explicitly consider the influence of long-term trends in streamflow. The methods introduced in this paper include an extended version of Weighted Regressions on Time, Discharge, and Season (WRTDS) modeling that explicitly considers nonstationary streamflow by incorporating information on changes in the frequency distribution of daily measured streamflow (discharge) over time. Soluble reactive phosphorus (SRP) trends in annual flow-normalized fluxes (loads) at five long-term monitoring sites in the western Lake Erie drainage basin show increases of 109 to 322% over the period 1995 to 2015. About one-third of the increase appears attributable to increasing discharge trends, while the remaining two-thirds appears to be driven by changes in concentration versus discharge relationships reflecting higher concentrations for any given discharge during recent years. Trends in total phosphorus and three nitrogen parameters (total nitrogen, nitrate-nitrite, and total Kjeldahl nitrogen) at the 10 sites analyzed were much less pronounced, and commonly show decreases in concentration-discharge relationships accompanied by increases in discharge, resulting in little net change in total flux. Trends in monthly SRP fluxes and discharge, dissolved versus particulate fractions of nutrients, and N:P flux ratios were also evaluated. The methods described here provide tools to more clearly discern the effectiveness of nutrient-control strategies and can serve as ongoing measures of progress, or lack of progress, towards nutrient-reduction goals.     

Balancing nutrient inputs to Lake Kivu

The primary production in meromictic Lake Kivu is sustained by external nutrient inputs and by internal loading due to upwelling caused by sub-aquatic sources. We present here the results of external loading of phosphorus (P), nitrogen (N) and silica (Si) by rivers and atmospheric deposition measured from 2006 to 2008. These external inputs are compared to internal loading. The input of soluble-reactive P (SRP), supplied in equal parts from rivers and atmospheric deposition, adds up to 230 t P yr^− 1, 20 times less than total P load. Ammonium (mainly via rainwater) and nitrate (mainly via rivers) are primary sources of the dissolved N load (5400 t N yr^− 1), with both species contributing ∼ 50%. Dissolved Si input (40,000 t Si yr^− 1) is unique in that only ∼ 60% enters by rivers, while the remaining ∼ 40% comes from sub-aquatic sources and atmospheric deposition is negligible. Based on the molar nutrient ratios, we identify P as the limiting factor for algae production. Despite the strong anthropogenic impact on the catchment and the high particle erosion (74 t km^− 2 yr^− 1), the area-specific nutrient mobilization is rather low. The external nutrient input is therefore not the cause for the reported increase of methane production in the last decades. External loading to the epilimnion plays a lesser role for all three nutrients (∼ 10% for SRP, ∼ 25% for dissolved N and ∼ 45% for dissolved Si), as compared to the lake-internal loading by upwelling (90%, 75% and 55%, respectively). Lake Kivu, therefore, is similar to other East African large lakes in that the internal loading exceeds the external loading. Despite the substantial uncertainty of the load estimates of up to 50%, we can conclude that the observed nutrient input is consistent with the primary production of 260 g C m^− 2 yr^− 1 recently measured by Sarmento et al. (2006) and also consistent with the lake-internal fluxes established by Pasche et al. (in press).     

赣江流域土地利用迁移变化分析

土地利用/覆被变化是人类与自然环境相互作用的重要表征,其变化特征深刻影响着区域的生态安全和社会经济可持续发展。基于赣江流域1980—2018年土地利用数据,利用ArcGIS空间分析方法,分析赣江流域土地利用的时空变化特征。结果表明:赣江流域1980—2018年土地类型以林地和耕地为主,林地和耕地面积呈减少趋势,建设用地面积不断增加;流域土地利用综合指数呈增加态势,表明土地利用变化加快;土地利用转换类型以耕地和林地向建设用地转移、林地和草地相互转移以及林地向耕地转移为主,部分耕地转化为水域;草地、水域、建设用地重心变化较明显,草地的重心在向西偏北方向迁移,水域的重心在向西偏南方向迁移,建设用地重心在向东偏南方向移动,移动速度均具有阶段性。可为赣江流域生态环境保护、水土资源规划与管理提供科学依据。     

Use of manure nutrients from concentrated animal feeding operations

Over the past few decades, there has been a nationwide trend away from small livestock farms and toward large Concentrated Animal Feeding Operations (CAFOs). This shift results in concentrated manure production and introduces potential problems associated with its disposal. We analyzed data from 13 permitted CAFOs in southeastern Michigan, including 1187 occurrences of manure application from 12 of the CAFOs with available field-level data. CAFOs applied excess manure nutrients to cropland by applying to fields with soil phosphorus test levels >50?ppm (42% of all cases), applying to soybeans (7% of all cases), over-estimating crop yields in calculating plant nutrient requirements (67% of all cases), and applying beyond what is allowed by state permits (26% of all cases). This represents significant potential for redistribution of manure nutrients. The total amount of manure from all instances of over-application could be redistributed to fertilize over 4775?ha (11,800?acres) per year. Significant barriers to redistribution of manure exist, however, including cost, land availability, crop and soil need, transport logistics, and farmers' reluctance to use manure instead of inorganic fertilizer due to its variable composition. These findings are relevant to the harmful algal bloom and hypoxia issues in Lake Erie, which are driven by excess nutrients, and can be used to better inform science, modeling, and policy in the region.     

稳定塘对制浆废水中羟基芳族化合物去除的试验研究

研究稳定塘对造纸制浆废水中羟基芳族化合物的去除效果,以及氮、磷和填料三因素对厌氧塘去除效果的影响。试验采用三因素二次饱和设计,找出处理效果最佳的氮、磷及填料水平的组合与出水经基芳族化合物的关系。分别建立了厌氧塘出水中羟基芳族化合物,厌氧塘一级反应速率常数K(以羟基芳族化合物为底物)与氮、磷、填料的回归方程,并找出了最优处理效果的氮水平和磷水平。结果显示在平衡阶段,出水羟基芳族化合物与氮正相关,与磷二次项正相关,与磷一次项负相关。     

三峡库区湖北片土地利用动态变化研究

根据1986年和2000年2期卫星影像,运用"3S"技术对三峡库区湖北境内的巴东、秭归、兴山和宜昌4县1986年和2000年的土地利用状况进行了动态监测.全面分析了土地利用的变化情况,揭示了该地区各类土地利用类型数量变化的幅度、速度和区域差异,阐明了该地区土地利用变化的区域特点.成果可为三峡库区的水土保持和土地可持续利用提供有效的决策支持.     

Dynamics of the relative nitrogen and phosphorus concentrations in a reservoir situated in a semi-arid zone (Sahela,Morocco)

Fluctuations in total nitrogen and phosphorus concentrations and in the N/P ratio (i.e. in terms of mass) were measured at the entry and exit of the Sahela Reservoir (Morocco) throughout an annual cycle. Particulate N and P concentrations in sedimenting particles in the reservoir itself were also measured. The results obtained showed that the spring floods were a major source of N and P inputs, this being especially pronounced for phosphorus that was present mainly in particulate form. In all the compartments of the reservoir analysed, the N/P ratios were high (means between 81 and 314), especially in summer (the only season when the reservoir was emptied) when the supply of P was apparently limited by the drought. However, the values of this ratio in the sedimenting particles remained lower (mean = 21), at levels characteristic of natural communities. This implies that the reservoir's biological communities preferentially store phosphorus, no doubt to maximise their activity in an environment where a large proportion of this element is not bioavailable. Furthermore, it appeared that the quantity of particulate N and P sequestrated by the sediments and the total quantities of N and P leaving the reservoir were greater than the inputs of these nutrients, underlining the importance of lateral and internal nutrient supplies. One spot measurement, made in a single month, showed that nutrient release activity from the sediments was in fact quite considerable.     

土地利用遥感分类方法研究进展

遥感技术已经广泛的应用于土地利用与土地覆盖数据获取中。现综合分析了目前主要的遥感图像分类方法, 将遥感图像分类方法归纳为:基于传统统计分析的分类方法、神经网络分类方法、模糊分类方法、决策树分类方法、专家系统分类方法,并对各种方法的应用情况进行了综述,并总结出各种分类方法应用特点。     

Hungarian Experiences with Public Participation in Water Management

Abstract

The paper reviews the experience of public participation in water management decisions since the political transition in Hungary. Ongoing practices of public participation are examined through the critical analysis of three cases: (i) the Gabcikovo-Nagymaros dam project which has been known as the source of Europe's longest and most complex transboundary environmental conflict; (ii) the development of water quality legislation by the national government; and (iii) an integrated land use planning project in the region of the Szentendrei-island. Based on the above cases, factors promoting and hindering effective public participation are identified. Key promoting factors include the activity and professionalism of civil society organizations, the financial support provided by international funding agencies and other foreign sponsors, the methodological support provided by professional organizations, and the social learning process taking place in the society. Factors hindering effective public participation include the resistance to public participation on the part of several public officials and planners, the lack of methodological knowledge to manage public participation procedures effectively, the lack of interest and passivity on the part of the public, the lack of trust between various stakeholders, and some recent negative trends in the development of civil society. It is concluded that although the existence of a legal framework, which allows for the possibility of public involvement, is a necessary precondition for comprehensive public participation, but it must be supplemented by other elements that facilitate public participation.