Reintroducing wood to streams in agricultural landscapes: changes in velocity profile,stage and erosion rates

Historically, perceived increases in erosion and flooding levels have been attributed to in‐stream wood and used to justify its removal from streams and rivers around the world. More recently, recognition of the adverse morphological and biological impacts caused by this removal has led to rehabilitation projects that actively reintroduce wood to streams. However, a perception remains amongst some members of the general community that wood additions increase the likelihood of flooding and erosion in the target streams. To test whether there was a basis for this perception, we experimentally added wood to eight streams across southwest Victoria and Gippsland, Australia. The velocity, stage and bed and bank erosion rates were compared with those of unaltered reaches. We detected localized changes in the velocity and stage parameters but that these were unlikely to operate at the reach‐scale. Bed erosion rates, where maximum erosion was assumed if pins were not recovered, showed increased erosion due to wood additions but this was not supported by channel shape analyses, which identified short‐term increases in the variability of the channel shape, followed by longer‐term stability at treatment sites. We found no clear evidence of increased longer‐term rates of erosion or flooding associated with the introduction of wood to streams over the 18‐month study period. It remains important to carefully design rehabilitation works, but the lack of adverse effects on stream morphology and increased variability of the in‐stream environment suggests improved habitat diversity, supporting the use of wood addition as a stream rehabilitation technique. Copyright © 2008 John Wiley & Sons, Ltd.     

Periphytic algal biomass as a bioindicator of phosphorus concentrations in agricultural headwater streams of southern Ontario

Algal blooms in Lake Erie have worsened in recent decades and are driven by diffuse export of phosphorus (P) from a large stream network that drains predominately agricultural land. Given the diffuse nature of nonpoint source pollution, best management practices (BMPs) must target areas where P levels are high. This requires long-term watershed-wide monitoring programs that do not currently exist in many jurisdictions. Instead of conventional nutrient analyses that can be costly and time-consuming, we propose the use of periphyton biomass as a bioindicator of trophic status in low-order streams, where agricultural runoff first enters watercourses. We carried out 2-week in-stream bioassays to measure periphytic algal biomass (CHL_peri) in 19 low-order streams in southern Ontario across an agricultural gradient (8 % to 89 %). CHL_peri was significantly related to total P (TP) concentration (r² = 0.46; p = 0.0015) but was not significantly related to soluble reactive P (SRP). A relationship between TP and turbidity (r² = 0.52; p = 0.0007) is consistent with previous observations of increasing SRP uptake in streams draining agriculturally-dominated landscapes. Stream temperature (°C) was correlated with the proportion of agricultural land (R = 0.55; p = 0.019) and may reflect the warming effects of the sun in unshaded agricultural streams. This method involving substrate rods (Peristix) is cost-effective, requires very little training, and yielded data that were significantly related to TP concentrations in agricultural streams. We recommend that environmental agencies and landowners use this bioassay to identify areas for implementing BMPs to reduce P export from the Lake Erie watershed.     

Development of habitat suitability criteria for trout in small streams

We observed 2863 trout in the wild to determine habitat utilization in small streams of the Kings River basin in California's Sierra Nevada mountains. The habitat utilization data were used to develop habitat suitability functions that provide input variables to the instream flow incremental methodology (IFIM) habitat assessment model of the U.S. Fish and Wildlife Service. Observations of habitat utilization of rainbow trout (Salmo gairdneri), brown trout (Salmo trutta), and brook trout (Salvelinus fontinalis) were obtained during the summer months of 1983 and 1984. The observations were made in small streams with discharges ranging from 0.7 m³ s^?1 to 0.03 m³ s^?1. The streams are at elevations of 1250 to 2530 m. Equal effort was applied to observing undisturbed trout in all habitat types. Snorkeling proved to be the most effective method of observation. Individual trout of all species and life stages were most often observed in the lower half of the water column, utilizing low-velocity currents of less than 3.0 cm s^?1. From the depth and velocity utilization data, several forms of habitat suitability functions were developed and evaluated:

• 1 Univariate depth and velocity functions derived from frequency histogram analysis.
• 2 Univariate depth and univariate velocity exponential polynomial models.
• 3 Bivariate depth and velocity exponential polynomial models.

Univariate exponential polynomial models provided the best fit to the data for each species, based on visual comparisons of response surfaces and contour plots, and comparisons of computed sums of squared errors. Bivariate models fitted to the data resulted in greater sums of squared errors than multiplicative aggragation of univariate models, and frequently predicted utilization at zero depth. The habitat suitability functions derived from the univariate exponential polynomial models provided the best input to the IFIM habitat assessment models.     

基于GIS的鄂州市氮、磷农业面源污染时空分布研究

近年来,鄂州市农药、化肥的不合理施用以及畜禽粪便的不适当处理,造成农业面源污染日益严重。以统计数据为基础,结合GIS技术,对鄂州市2015、2020、2030年农业面源污染中的氮、磷入河量进行分析。结果表明,农药、化肥源中的总氮入河量由2015年的2850. 40 t下降到到2020年的2382. 02 t再到2030年的1590. 74 t,总磷入河量由2015年的1305. 59 t下降到2020年的850. 78 t到2030年的503. 84 t。畜禽养殖源中的总氮入河量由2015年的618. 17 t下降到2020年的313. 17 t再到2030年的604. 37 t,总磷入河量由2015年的351. 71 t下降到2020年的45. 59t再到2030年的145. 75 t。空间上,葛华新城、涂家垴镇的化肥、农药污染削减明显,主城区、葛华新城、东沟镇、沼山镇、杨叶镇的畜禽养殖污染削减明显。畜禽养殖源2030年比2020年污染物入河量增加,这是因为在2020年以前,非规模养殖场关停,规模畜禽养殖逐年增加。利用GIS对污染物入河量的展布,从空间上,能够清晰地反映不同水平年鄂州市污染物入河量的效果,为鄂州市有针对性的农业面源污染的防治提供依据。     

国外传统农业水适应经验及水适应景观

古代人类在长期水资源管理及与各种水灾害斗争过程中,积累了朴素的具有生态价值的农业生产经验,表现在造田方式、作物类型、水资源管理等方面的适应性景观。研究表明,水适应景观内容和形式受气候干湿类型、地形特征等因素影响。当前,传统农业水适应景观研究已从传统的水利工程设施要素研究转向综合研究,探讨水景观的复杂结构和复合功能。现代水利技术背景下,如何借鉴传统水适应景观经验,探讨新的环境条件下水适应的途径和方法,是值得深入研究的方向。在水适应景观概念的框架下,对不同气候类型、不同地形特点下农业水景观的内容、形式及区域差异的研究,也是值得国内学者借鉴的研究方向。     

仙女湖流域农业面源总氮和总磷入河污染负荷分析

农业水价综合改革是缓解水资源短缺、推进节水农业发展的重要途径。自2016年下半年起,南京市江宁区率先开展农业水价综合改革试点工作,取得了显著成效。立足于江宁区实际情况,从改革具体措施、问题及成效入手,分析总结了江宁区农业水价综合改革过程中的经验与教训,并提出了相关对策和建议,为下一步更好地常态化开展农业水价改革工作提供参考借鉴。     

仙女湖流域农业面源总氮和总磷入河污染负荷分析

本文采用输出系数法分析仙女湖流域各县区农业面源污染的总氮和总磷入河量,结果显示流域内主要农业污染源为畜禽养殖排污及农田化肥流失,二者总氮和总磷入河量占比超80%,各县区中袁州区是流域内总氮和总磷的主要污染来源,总氮和总磷入河量占比为59%。     

丁坝型挡板调控农田溪流暂态氮磷滞留能力的模拟研究

选择Na Cl作为保守性示踪剂、NH4Cl和KH2PO4为添加营养盐,在巢湖流域的二十埠河某一农田源头溪流段,采用恒定连续投加示踪剂的方式,开展野外示踪实验。通过对不同情景下暂态存储参数和营养螺旋指标模拟结果的比较,解析丁坝型挡板对于溪流暂态存储和氮磷滞留能力的调控效果。结果表明:丁坝型挡板使溪流交换系数α显著增大,其中间距为2.5 m的α值较无挡板情景高出132.36%,1.5 m和3.0 m间距则分别高出825.37%和641.29%;相对于无挡板情景,设置挡板的溪流交换长度Ls明显下降,水力持留因子Rh、行进时间中值F200med及过水断面面积和暂态存储区断面面积的比值As/A等出现不同程度的增大;设置挡板的氮磷吸收长度Sw较无挡板情景显著下降,吸收速度Vf则有不同程度的提高。丁坝型挡板对于农田溪流暂态存储和氮磷滞留能力具有很好的调控效果。     

BICT biological process for nitrogen and phosphorus removal.

An updated biological nitrogen and phosphorus removal process--BICT (Bi-Cyclic Two-Phase) biological process--is proposed and investigated. It is aimed to provide a process configuration and operation mode that has facility and good potential for optimizing operation conditions, especially for enhancing the stability and reliability of the biological nutrient removal process. The proposed system consists of an attached-growth reactor for growing autotrophic nitrifying bacteria, a set of suspended-growth sequencing batch reactors for growing heterotrophic organisms, an anaerobic biological selector and a clarifier. In this paper, the fundamental concept and operation principles of BICT process are described, and the overall performances, major operation parameters and the factors influencing COD, nitrogen and phosphorus removal in the process are also discussed based on the results of extensive laboratory experiments. According to the experimental results with municipal sewage and synthetic wastewater, the process has strong and stable capability for COD removal. Under well controlled conditions, the removal rate of TN can reach over 80% and TP over 90% respectively, and the effluent concentrations of TN and TP can be controlled below 15 mg/L and 1.0 mg/L respectively for municipal wastewater. The improved phosphorus removal has been reached at short SRT, and the recycling flow rate of supernatant between the main reactors and attached-growth reactor is one of the key factors controlling the effect of nitrogen removal.     

Model assumptions limit implications for nitrogen and phosphorus management

A recent Science paper concluding “phosphorus load reduction will make Erie more toxic” is misleading because it ignores historical lake behavior, and is based on a cellular-level model that excludes lake-level processes which influence phytoplankton community composition and toxicity. The inferences made from models are inherently limited by the assumptions underlying those models. We identify major assumptions, several of which are implicit, that were involved in extrapolating this cellular-level model to make lake-level inferences. An active adaptive management program will evaluate future nutrient load modifications if emerging evidence from well-vetted data and models indicate updates are appropriate.     

极限学习机在湖库总磷、总氮浓度预测中的应用

基于传统BP人工神经网络模型训练速度慢、参数选择困难、易陷入局部极值等问题,提出极限学习机(ELM)的水质预测模型。以云南某水库为例,选取NH₃-N、NO₂^--N、NO₃^--N、COD_Mn和水体透明度作为网络输入,TP、TN作为输出, 构建基于ELM的湖库TP、TN预测模型,并将ELM预测结果与传统BP、GA-BP、RBF人工神经网络模型模拟结果进行比较。结果表明,ELM模型预测精度高于传统BP和RBF模型模拟结果,甚至略高于GA-BP模型的预测精度,并且ELM模型具有参数选择简便、训练速度快、不会陷入局部最优值等特点,有着较大的计算优势。     

青岛棘洪滩水库氮磷营养盐分析

根据棘洪滩水库2000—2009年水质监测数据,分析该水库水体中总氮(TN)、总磷(TP)及叶绿素(Ch-l a)等水质指标的变化情况,并进行富营养化评价。结果表明:TN质量浓度超出地表水Ⅴ类标准,TP质量浓度满足地表水Ⅱ类标准,ρ(TN)/ρ(TP)值为80.6～246.2,水库属于磷(P)限制型。TN质量浓度冬季、春季较高,夏季、秋季逐渐降低;TP、Ch-la质量浓度在夏末和秋季较高,春季和冬季较低。水库营养盐主要来源是引水,水库水质2000—2009年近10年的营养程度均为中营养。     

减少氮、磷流失的多目标控制排水模型

运用多目标决策技术,减少农田排水氮、磷输出,保持适宜作物生长的土壤含水量,探讨地表控制排水的控制时间。通过田间试验和SPSS回归模拟,应用均值土壤一维垂直入渗Philip公式计算累计入渗量,研究田间尺度降雨排水中氮、磷浓度的变化规律,拟合控制排水氮、磷浓度对数函数模拟方程。建立减少氮、磷流失和排涝、除渍的多目标控制排水模型,提出求解模型的非劣解和均衡解的方法。     

潘家口水库氮与磷营养盐的时空变化及滞留效应分析

潘家口水库是华北地区的重要水源,对保障区域供水安全发挥着重要作用。本文以该水库为研究对象,分析了建库以来水库氮、磷营养盐的时空变化特征、滞留效应。结果表明：建库以来水库TP浓度呈上升趋势,最高达到0.37 mg/L;库区TN、硝酸盐的浓度较高,年际变化小,近15年平均浓度分别为4.4 mg/L、3.5 mg/L,氨氮浓度基本低于0.5 mg/L。库区氮、磷以滞留为主,其浓度主要受来水影响;磷的滞留效率呈下降趋势,近5年滞留效率为-6%;氨氮滞留效率一直较高,近5年滞留效率为72%;硝酸盐滞留效率呈增加趋势,近5年滞留效率为20%,硝酸盐和磷的滞留效应呈显著的负相关关系。结合垂向水质监测的分析表明,近年来库底存在内源污染的显著释放和反硝化脱氮。潘家口水库库底沉积物污染严重,内源污染将是未来水库水质恶化的潜在风险。为了保证水库的供水水质,抑制库区内源污染的释放,建议水库尽量保持高水位运行。     

Catchment characteristics predicting nitrogen and phosphorus losses in Finland

Empirical relationships between catchment properties and nutrient losses are often derived from spatially restricted data, which hampers the ability to more widely generalize the results. In this study, we regressed the catchment characteristics and the losses of total nitrogen (TN) and total phosphorus (TP) for all monitored catchments in Finland with adequate data (n = 59, from the year 2000 to 2011). TN loss was found to increase with the percentage of arable land and amount of point source loading and to decrease with increasing lake percentage. TP loss also increased not only with the percentage of arable land but also with fine‐grained soils (Cambisols) in the catchment and decreased with the percentage of lakes. Urban areas, scattered settlements, and N deposition were not significant explanatory variables, possibly due to their spatial covariation with arable land in Finland. Despite the fact that only a few significant explanatory variables were identified, the models explained the TN and TP losses by up to 91% and 92%, respectively.     

洞庭湖氮、磷平衡研究

对洞庭湖营养盐成分磷和氮进行了全面的调查分析，查明了各种途径入湖、出湖情况。结果表明：①入湖氮、磷总量分别为754940．93t/a和60178．7t/a，其中河道入湖与生活污染占的比例最大，二者占总量的95％以上；②每年滞留湖内的营养盐总磷量为7780．35t, 总氮量为107003．23t，总磷与总氮的滞留系数分别为12．93％和14．17％；③生活污染是湖泊营养盐输入的主要来源，占入湖总磷量的57．55％和入湖总氮量的41．37％，洗衣粉排磷的贡献率也比较大。所以，防止洞庭湖的富营养化应把重点放在解决生活污染和禁止或限制使用含磷洗衣粉上。     

Cascade macroinvertebrate assemblages for in‐stream flow criteria and biomonitoring of tropical mountain streams

Few comprehensive studies on stream assessment and biomonitoring have been conducted in tropical, freshwater watersheds. Currently under threat from climate change, urbanization and increasing freshwater demands, there is a need for innovative approaches to tropical watershed assessment and management. This study investigated cascade habitat macroinvertebrate communities among four tropical mountain streams with the goal of enhancing future efforts to identify flow biocriteria for watersheds of Polynesia. Cascade macroinvertebrate communities were compared between streams of differing size and magnitude of flow removal to evaluate the biological effects of water withdrawal on benthic communities. Two cascade microhabitats, identified as torrenticolous and amphibious, were evaluated for macroinvertebrate community differences and presence of native taxa among watersheds. Cascade habitat in general was reduced, by as much as 98%, in downstream reaches, having a significant impact on the stream ecosystem physical template important for native stream communities. In addition, two‐way ANOVA results revealed no main effects, but significant interactions of watershed size and flow removal on mean macroinvertebrate density for torrenticolous microhabitats; however, the opposite was true for the amphibious microhabitat. Diversity was significantly higher under undiverted flow conditions (t = 4.21, df = 272, p = 0.0004) and in torrenticolous microhabitats (t = 3.86, df = 272, p < 0.0001) over the entire study period. The amphibious microhabitat was composed of 39% native taxa, while the torrenticolous microhabitat contained <7%. This study provides new options for biomonitoring of native populations in Polynesian watersheds. Further studies that support the development of in‐stream flow criteria to preserve cascades are important to understanding the role of this habitat in tropical stream ecosystem function. Copyright © 2010 John Wiley & Sons, Ltd.     

传统活性污泥法污水处理厂脱氮除磷改造技术研究

随着受纳水体富营养化日益严重,污水处理厂尾水N、P排放成为迫切需要解决的问题.针对传统活性污泥工艺的实际情况,在脱氮除磷改造中,最大限度地利用原有处理构筑物,提出增加厌氧池或缺氧池以确保生物除磷或脱氮效果.改造采用基于两段A/O的生物处理工艺,工艺论证采用IWA使用的ASMs系列模型进行模拟,模型参数使用污水处理厂多年运行数据进行率定,模拟结论可信.此方法可广泛运用于污水处理厂的改造和设计中,特别是对污水处理运行诊断和实际运行节能减排过程优化具有优势.通过合理调整运行工艺参数,改造后污水处理厂尾水可达到<城镇污水处理厂污染物排放标准(GB 18918-2002)二级标准.     

瓦埠湖沉积物中氮与磷赋存形态分析

利用连续提取法研究了瓦埠湖沉积物中磷的赋存形态和氮的组成特征。结果显示:瓦埠湖沉积物中总磷含量为293～874 mg/kg,平均为470 mg/kg,总磷主要由无机磷组成;在沉积物的提取磷中铁结合态磷为主要赋存形态;铁磷、钙磷、铝磷的相对百分含量指示出该湖泊的磷源自污染较少的区域。瓦埠湖沉积物中总氮的含量为208～464 mg/kg,平均为265 mg/kg,氮的主要组成为有机氮,有机氮、有机指数等显示该湖泊属于清洁类型,未遭受污染。瓦埠湖流域的社会与自然状况的调查结果、湖泊底泥的有机碳氮比等均表明湖泊营养物质来自面源,各指标含量在空间分布的特点与相关性的差异,说明了物质沉积存在重力分离与水动力作用的过程。