Experimental study on the influence of dissolved organic matter in water and redox state of bottom sediment on water quality dynamics under anaerobic conditions in an organically polluted water body

To understand aquatic environmental deterioration due to the anoxic state in an organically polluted water body, water quality dynamics under anaerobic conditions were examined through beaker-scale water quality monitoring. This study focused on the dynamic properties of NO₃–N, NH₄–N, PO₄–P, and sulfide from the biochemical reactions point of view, and based on anaerobic respiration activities, such as denitrification, iron reduction, and sulfate reduction. The specific aims of this study were to quantitatively estimate the impacts of the oxidative/reductive state of the sediment surface and the high/low concentrations of dissolved organic matter on the dynamic properties of water quality under anaerobic conditions. The beaker-scale water quality monitoring was carried out through continuous measurements of dissolved oxygen and oxidation–reduction potential (ORP), as well as periodic observations of water quality parameters for six cases that are composed from combinations of three experimental conditions: (1) concentration of dissolved organic carbon (DOC); (2) redox state of the sediment; and (3) concentration of NO₃–N. As a result, the temporal changes in ORP under anaerobic conditions exhibited a five-step process of decline without these conditions. Also, high DOC concentrations and oxidative states of the bottom mud accelerated the release of PO₄–P and sulfide generation through promoting biological iron reduction and sulfate reduction, because these conditions increase respiratory substrates for anaerobic microorganisms, such as iron and sulfate-reducing bacteria. It was concluded that our results would provide important information about the mechanisms of aqueous environmental deterioration due to organic pollution in closed water bodies.     

Anoxification recovery using underwater LED irradiation and influence of its optical spectrum on water quality improvement

Paddy and Water Environment - This study focuses on a method for improving water quality via anoxification recovery using underwater LED treatment in an organically polluted reservoir. The main aim...     

鱼塘种稻对养殖水体营养物质的去除作用研究

以黄颡鱼精养塘为例,探索鱼塘种植高秆型水稻对精养池塘水体氮磷养分等水质指标的修复作用。结果表明,在水稻生长期,种稻黄颡鱼精养塘水体氮、磷养分含量显著低于单养鱼池塘。在水稻收获期,单养鱼塘水体总氮(TN)和总磷(TP)含量高达11.98mg/L和0.52mg/L,超过了《淡水池塘养殖水排放要求》标准;而种稻鱼塘水体中TN、TP含量则仅为0.49mg/L和0.08mg/L,达到《淡水池塘养殖水排放要求》一级排放标准。种稻鱼塘水体中TN、NH4+-N、NO3--N、TP和PO43--P含量比不种稻单养鱼塘分别降低95.95%、98.09%、98.07%、84.47%和64.57%。种稻鱼塘COD含量和pH值低于单养鱼塘。可见,种稻能有效降低水体养分含量,改善养殖水体水质。     

Effect of N-fertilizer application on return flow water quality from a terraced paddy field in Northern Taiwan

Intensive use of chemical fertilizer for crops may be responsible for nitrogen and phosphate accumulation in both groundwater and surface waters. The return flow polluted by nutrients not only results in the limitation of water reuse goals but also creates many environmental problems, including algal blooms and eutrophication in neighboring water bodies, posing potential hazards to human health. This study is to evaluate the N-fertilizer application of terraced paddy fields impacting return flow water quality. Water quality monitoring continued for two crop-periods around subject to different water bodies, including the irrigation water, drainage water at the outlet of experimental terraced paddy field, and shallow groundwater were conducted in an experimental paddy field located at Hsin-chu County, Northern Taiwan. The analyzed results indicate that obviously increasing of ammonium-N (NH₄ ⁺-N) and nitrate-N (NO₃ ^?-N) concentrations in the surface drainage water and ground water just occurred during the stage of basal fertilizer application, and then reduced to relatively low concentrations (<0.1 mg/l and <3 mg/l, respectively) in the remaining period of cultivation. The experimental results demonstrate the potential pollution load of nitrogen can be reduced by proper drainage water control and fertilizer application practices.     

不同拦截植物对小流域农田排水沟渠氮磷消纳效果差异研究

构建生态沟渠消纳水体氮磷是防控农业面源污染的重要措施.为筛选出适应湘北洞庭湖区农区沟渠生长的高富集氮、磷植物,选取津市市毛里湖稻区沟渠作为研究对象,进行生态沟渠拦截试验.于2016~2017年连续监测,系统研究狐尾藻、珍珠梅、海寿花等水生植物及组合对小流域农田排水中氮、磷的去除效果.结果表明:2年观测期(4~8月)内,拦截植物对农田排水总氮、铵态氮、硝态氮及总磷的去除率效应极显著(p<0.01),且去除率具有生长变化趋势.不同拦截植物及组合对总氮、铵态氮、硝态氮及总磷的去除率大小表现为狐尾藻+海寿花>海寿花>珍珠梅>狐尾藻>自然植被.其中,狐尾藻+海寿花组合平均总氮、铵态氮、硝态氮及总磷的去除率2016年分别为53.57%、77.35%、51.74%和61.06%,2017年分别为34.67%、66.53%、39.51%和46.05%.研究区生态沟渠对氮、磷污染物有较好的拦截效应,单种植物以海寿花的水体氮磷消纳效果较好,在此基础上混种狐尾藻,效果更佳.     

The effect of phosphorus fertilization on the chemical quality of Katahdin potatoes

The influence of phosphorus fertilization on the content of ascorbic acid, lipids, total nitrogen, protein, and non-protein nitrogen of Katahdin potatoes was investigated. Phosphorus in the form of mono ammonium phosphate was applied at rates of 0, 56, 112, and 168 Kg/ha (0, 50, 100, and 150 lb/acre). Ascorbic acid, total nitrogen, protein and non-protein nitrogen content were significantly increased (p<.01) and the phospholipid content was significantly reduced (p<.01) by phosphorus application.     

Evaluation of the water-quality dynamics in a eutrophic agricultural pond by using a one-box ecosystem model considering several algal groups

The Okubo pond is an agricultural pond located in the Itoshima area of Fukuoka Prefecture, Japan. It was constructed for irrigating a nearby cultivated area. A monitoring program from August 11 to November 26, 2008, suggested the risk of eutrophication in the water body. The high total nitrogen concentration (1.34 mg/l), high total phosphorus concentration (0.06 mg/l) and extreme oxygen depletion (2 mg/l on 5 November 2008) exceeded the Japanese standards for paddy irrigation water. Furthermore, luxuriant algal blooming in October indicated a hypereutrophic status according to the OECD (1982) criteria. In this study, a one-box ecosystem model was developed to obtain an insight into the seasonal variations in the algal concentrations and chemical components of the Okubo pond with the aims of protecting its aquatic ecosystem and maintaining its water quality. The model was based on a completely mixed system and included 12 water-quality indices: green algae, blue-green algae, diatoms and dinoflagellates, cryptophytes, zooplankton, particulate organic matter, dissolved organic matter, phosphate–phosphorus, ammonia–nitrogen, nitrite–nitrogen, nitrate–nitrogen, and dissolved oxygen. The monitoring data were used to verify the model simulation. Model evaluation suggested good agreement between the predicted and the observed data for the seasonal variations in the algal, nutrient, and dissolved oxygen concentrations. To determine the sensitivity of the model parameters, a sensitivity analysis was conducted leading to the conclusion that the optimal temperature, growth rate, and respiratory rate of the four algal groups, especially the ideal temperature for blue-green and green algae are the most influential factors determining the variability affecting the model inference. From the model simulation, the water temperature and nutrient concentration were considered to be the key limiting factors controlling alternative algal blooms in this period.     

转基因大豆种植对根际土壤酶活性和养分的影响

采用盆栽试验,以耐草甘膦大豆M88、抗虫耐草甘膦大豆ZB及常规大豆中黄13为研究对象,比较分析转基因大豆对根际土壤酶活性和养分含量的影响。结果表明,在大豆成熟期时,与常规大豆中黄13相比, M88、ZB根际土壤碱性磷酸酶活性、过氧化氢酶活性、速效磷含量无显著差异,硝态氮含量显著下降。根际土壤脲酶活性、铵态氮含量则表现不同,其变化随大豆品种的不同而不同。相较于常规大豆中黄13, M88根际土壤脲酶活性和铵态氮含量无显著差异; ZB根际土壤脲酶活性显著下降,而铵态氮含量则显著上升。      

淹涝胁迫和氮形态对苗期玉米营养特性的影响

采用砂培培养方法,比较研究两种水分条件和3种供氮形态处理对苗期玉米根、茎鞘、叶生物量干重及其氮、磷、钾含量及分配的影响。结果表明,非淹涝胁迫条件下铵硝态氮混合处理(AN)玉米生物量干重及氮、磷、钾累积量最高;淹涝胁迫条件下铵硝态氮混合处理(ANF)的叶片、总生物量以及硝态氮处理(NF)的根系、叶片和总生物量干重明显降低。淹涝胁迫降低3种氮形态处理叶片氮累积量,明显降低铵硝态氮混合处理和硝态氮处理植株氮、钾累积量,降低磷在铵硝态氮混合处理茎鞘、叶中的分配比例、磷在硝态氮处理根、叶中的分配比例以及钾在铵硝态氮混合处理茎鞘、叶中的分配比例。淹涝胁迫下铵态氮处理(AF)叶片含氮量、植株含钾量呈降低趋势;非淹涝胁迫下铵态氮处理(A)具有相对较高的植株氮、磷含量,且淹涝胁迫对氮、磷、钾在植株不同部位分配的影响相对较低。因此,本试验供应铵态氮苗期玉米具有相对较强的耐淹涝胁迫能力。     

Ecosystem health evaluation of agricultural reservoirs using multi-metric lentic ecosystem health assessment (LEHA) model

The objectives of this study were to determine the trophic state of agricultural reservoirs within the four major watersheds and evaluate ecosystem health using a multi-metric fish modeling approach of the lentic ecosystem health assessment (LEHA) in South Korea. Fish survey for the LEHA model was sampled twice from 12 reservoirs (oligotrophic to hypereutrophic reservoirs) during 2008–2010 along with data analysis of water quality monitored by the Ministry of Environment, Korea. The fish sampling gears used in the field were fyke net, trammel net, casting net, and kick net. A regression analysis of N:P ratios showed a negative linear function with total phosphorous (TP) values but not with total nitrogen. The greater relationship to TP was due to low variability and high ambient concentrations of N relative to P. The plots of “TSI (CHL)–TSI (TP)” and “TSI (CHL)–TSI (SD)” suggest that other factors other than phosphorus limited algal biomass (CHL–TP < 0), and that non-algal particles dominated light attenuation (CHL–SD < 0). Nutrients input into the reservoirs during the Asian monsoon exceeded actual nutrient availability for phytoplankton growth. A regression model of the fish trophic components against log-transformed TP showed that the proportions of omnivore and insectivore fish had a positive linear function and negative relationship with TP, respectively. According to the multi-metric LEHA model for agricultural reservoirs, the model value averaged 26 ± 6.5, indicating a “Fair” condition. Overall, ecosystem health was directly influenced by organic matter pollution and high algal production. This new tool appeared particularly relevant to detect the contamination effects on fish communities in reservoirs. The new national biological monitoring methodology in lentic ecosystem would be used as a key tool for ecological restorations and species conservations in Korean lentic ecosystems.     

聚磷酸铵溶液在春玉米上的施用效果研究

通过在东北典型黑土上设置聚磷酸铵新型液体氮磷复合肥溶液的不同用量田间试验,研究其对玉米产量、磷肥利用效率及农田磷素盈余状况的影响,明确聚磷酸铵溶液在玉米施用上的最佳施用量.两年试验结果表明,磷养分投入量在75 kg/hm2时,玉米产量、干物质量及磷素积累量均处于较高水平,两年的磷肥利用率分别为25.0％和24.5％;当...     

Application of USLE for the prediction of nutrient losses in soil erosion processes

Soil erosion in agricultural fields affects not only land productivity but also water environment down stream. Many investigations have been made for the prediction of soil erosion processes. The Universal Soil Loss Equation (USLE) has been applied broadly for the prediction of average annual soil loss from upland fields. However, there are few reports concerning the prediction of nutrient (N, P) losses based on the USLE. Thus, the objective of this study is to propose the prediction equation of nitrogen and phosphorus losses during soil erosion processes on the basis of the USLE. In order to predict total nitrogen and phosphorus losses, the coefficients for total nitrogen or phosphorus transfer are derived on the basis of results from experimental field plots. Three bare-cover USLE plots with different amounts of granular chemical fertilizer were installed in an experimental upland field. There was a tendency for the coefficient of total nitrogen or phosphorus transfer to increase with the average concentration of total nitrogen or phosphorus in the soils. It follows that the more granular chemical fertilizer applied caused a higher coefficient of total nitrogen or phosphorus transfer in the calculations. Moreover, the coefficients in heavily fertilized plots were higher than 1.0. Through this investigation, it became clear that the nutrient losses during soil erosion could be predicted on the basis of the coefficient of total nitrogen or phosphorus transfer along with other soil erosion parameters.     

Impact of Rice-Catfish/Shrimp Co-culture on Nutrients Fluxes Across Sediment-Water Interface in Intensive Aquaculture Ponds

Exchange of nitrogen and phosphorus across sediment-water interface plays an important role in the management of nutrient recycling in the aquaculture pond. In this study, a plot experiment was conducted to study the effect of rice-catfish/shrimp co-culture on the micro-profile of oxygen(O_2), p H and nutrient exchange across sediment-water interface in the intensive culture ponds. The results showed that rice-catfish co-culture increased the concentration and penetrating depth of O_2, but decreased the p H value across the sediment-water interface, compared with catfish monoculture. Additional rice cultivation significantly reduced the flux rates of ammonium(NH_4~+) and nitrate(NO_3~-) across sediment-water interface in the catfish and shrimp ponds. The flux rates of NO_2~- and soluble phosphorus(PO_4~(3-)) showed no significant difference between rice-catfish/shrimp co-culture ponds and catfish/shrimp monoculture ponds. Rice only affected the dissolved inorganic nitrogen and phosphorus fractions in the sediment. The concentrations of NH_4~+ were significantly lower in the sediment of co-culture ponds than in the monoculture ponds. Additional rice cultivation also significantly reduced the content and percentage of dissolved inorganic phosphorus in the sediment of catfish ponds.     

Seasonal characteristics of surface water quality in the wastewater catchment system of an urbanizing basin

Vientiane, Lao PDR, has been subject to extensive and ongoing urbanization plans, including development of natural marshes and residentialization of paddy fields into suburban areas, despite natural marshes playing a vital role in treating wastewater from urban areas. Therefore, it is important to understand the current situation regarding the nutrient balance in these natural wastewater treatment systems to predict future conditions and design appropriate measures against water quality deterioration. However, limited data are available in Vientiane on the hydrological characteristics of water and nutrient runoff that flow into marshes through drainage canals. In this study, we conducted a periodic survey of drainage canals and Mak Hiao River in the wastewater catchment system surrounding Vientiane during the rainy and dry seasons. We monitored the discharge of surface water at 21 observation sites and analyzed water quality of nitrogen, phosphorus, and total organic carbon. These observations revealed that the concentrations of dissolved nitrogen and phosphorus were significantly higher at sites in urban areas, followed by sites in the main river basin and those in agricultural areas. Dissolved nitrogen and phosphorus concentrations varied with runoff discharge, especially in urban and river basin sites, with lower concentrations in the rainy season and higher concentrations in the dry season. On the other hand, we found no significant differences between the rainy and dry seasons in nutrient concentrations in the agricultural basin. Finally, we proposed measures to counteract the deterioration of water quality during dry seasons and simulated the impact of these measures.     

Long-term evaluation of the BMPs scenarios in reducing nutrient surface loads from paddy rice cultivation in Korea using the CREAMS-PADDY model

Curbing nutrient loads from rice cultivation has been an issue for the water quality management of surface water bodies in the Asian monsoon region. The objectives of this study were to develop paddy BMP scenarios and to evaluate their effectiveness on nutrient loads reduction using long-term model simulation. Totally five BMP scenarios were developed based on the three paddy farming factors of drainage outlet height, fertilizer type, and application amount and were compared with conventional practices. CREAMS-PADDY model was chosen for the paddy nutrient simulation, and two-year field experimental data were used for the model calibration and validation. The validated model was used to evaluate the developed BMP scenarios for the 46 years of simulation period. The observed nutrient loads were 15.2 and 1.45 kg/ha for nitrogen and phosphorus, respectively, and mainly occurred by early season drainage and rainfall runoff in summer. The long-term simulation showed that the soil test-based fertilization and drainage outlet raising practice were the two most effective methods in nutrient loads reduction. The combination of these two resulted in the greatest loads reduction by 29 and 37 % for T-N and T-P, respectively (p value < 0.001). Overall the effectiveness of the BMP scenarios was decreased in the wet season. As the conclusion, outlet height control and soil nutrient-based fertilization were suggested as the effective practices in paddy loads reduction and their combination can be a practicable BMP scenario for the paddy nutrient management.     

磷胁迫下氮形态对苗期玉米氮素吸收与分配的影响

采用营养液培养的方法,比较Ca_3(PO_4)_2模拟磷胁迫条件时3种氮处理(NO_3~--N、NH_4~+-N、NO_3~--N+NH_4~+-N)对玉米氮素吸收与分配的影响。结果表明,与KH_2PO_4处理相比,磷胁迫处理时,硝态氮、铵态氮及铵硝混合营养处理的玉米整株生物量分别降低38.1%、17.4%和20.8%;与此同时,铵态氮处理的玉米植株全氮、氮素累积量、有机氮及硝态氮含量显著升高,而硝态氮处理时全氮、氮素累积量、有机氮显著降低,硝态氮含量无明显变化;此外,与硝态氮及铵硝混合处理相比,铵态氮处理的玉米叶中可溶性蛋白含量下降幅度最大,而游离氨基酸、脯氨酸含量下降幅度最小。因此,本试验中,铵态氮处理的玉米更耐磷胁迫,表现为增加了氮的吸收和积累以及增强可溶性蛋白降解为氨基酸的过程。     

Numerical modeling of environmental behavior and fate of tributyltin in a semi-closed bay

The environmental behavior and fate of tributyltin (TBT) in the northern Ariake Sea, resulting from the use of TBT-containing antifouling paints on hulls of ships, pleasure crafts and docking facilities, was assessed by numerical simulations. First, a mathematical model was devised on the basis of a non-steady state equilibrium, one box multi-compartment model consisting of the surface micro-layer, the water column, the mud-layer, and the bottom sediment compartments. The movement of TBT among the four compartments was modeled by resuspension of bottom mud, deposition of suspended sediment, film penetration and water advection in each compartment. Furthermore, a one-dimensional diffusion equation was introduced into the bottom sediment compartment to calculate profile distribution of TBT. The reactivity of TBT considered within the compartments included biological degradation, adsorption to particulate matter and diffusion. Next, the optimal amount of past TBT loads, reflecting the recent observations of TBT concentration in the waters and sediments of the northern Ariake Sea, was searched by a simple genetic algorithm. The relative sensitivity of various model parameters were also determined to identify the more important parameters for estimating the environmental behavior and fate of TBT. Finally, the future status of TBT contamination of the northern Ariake Sea was predicted assuming the discontinued use of TBT-containing antifouling paints. Despite its simple model structure relative to hydraulics, it was concluded that this multi-compartment model adequately estimated the environmental behavior and fate of TBT.     

不同种类磷肥对果蔗的有效性研究

通过室内盆栽试验,以不施磷作为对照,分别选用钙镁磷肥、聚磷酸铵和磷酸一铵进行施磷处理,研究施用不同类型磷肥对黑皮果蔗生物量、根系形态及磷吸收特性的影响。结果显示,施磷处理能够显著促进果蔗生长,与未施磷处理的相比较,钙镁磷肥、聚磷酸铵和磷酸一铵处理的果蔗地上部生物量分别增加了67.00%、58.38%、50.65%。在同一施磷水平下,钙镁磷肥处理的果蔗生物量显著高于聚磷酸铵和磷酸一铵处理。在不同类型磷肥处理下,果蔗的根系形态特征有显著差异。钙镁磷肥处理的果蔗根系总根长和总根系表面积均比其他两种磷肥处理有显著增加;钙镁磷肥和聚磷酸铵处理的果蔗根平均直径和根总体积之间无显著差异。不同类型磷肥处理下,果蔗地上部和根系的磷含量无显著差异;但钙镁磷肥处理的果蔗磷积累量显著高于磷酸一铵处理。     

Does intercropping winter wheat (Triticum aestivum) with red fescue (Festuca rubra) as a cover crop improve agronomic and environmental performance? A modeling approach

The introduction of a living cover crop during a cash crop growth cycle (relay intercropping) and its maintenance after the cash crop harvest may help to preserve biodiversity, increase soil organic matter content and carbon sequestration and provide other ecosystem services, such as natural pest regulation or nutrient recycling, by increasing useful biotic interactions within the agroecosystem. We studied the impact of various approaches to manage a red fescue cover crop in a winter wheat crop in terms of light, water and nitrogen competition, using the STICS crop model adapted for intercropping. The STICS model for wheat/fescue intercropping was first evaluated on two years of experimental data obtained in the field. It gave satisfactory statistical results for the prediction of dry matter, leaf area index (LAI) and nitrogen accumulation in the two species, and for nitrogen and water dynamics in the soil. By simulating unmeasured variables, such as transpiration, the model improves our understanding of the performance of the intercrop in the field. For example, we showed that the intercropping system was more efficient that wheat grown as a sole crop, in terms of nitrogen accumulation and decreasing soil nitrogen levels before the leaching period. However, it also resulted in lower wheat yields. We then used the STICS model to compare four intercropping management scenarios differing in terms of the date of red fescue emergence, over 35 climatic years. We found that, in most climatic scenarios, the emergence of the fescue crop during the late tillering phase of the wheat crop gave the best compromise between wheat yield overall nitrogen accumulation and radiation interception.     

不同施氮量对单季稻养分吸收及氨挥发损失的影响

 以杂交晚粳浙优12为材料,研究了不同氮素用量对单季晚稻养分吸收和氨挥发损失的影响。结果表明,施氮量在0~330  kg/hm2范围内水稻植株氮积累量、磷积累量及钾积累量均表现为随施氮量的增加而增加,施氮水平超过270  kg/hm2后增施氮肥反而降低水稻对氮磷钾的吸收。施氮量在150  kg/hm2时增施有机肥有助于杂交粳稻浙优12对土壤中氮素、磷素以及钾素的吸收利用。水稻拔节期至抽穗期为吸氮量最大时期,施氮量在0~270  kg/hm2范围内杂交粳稻浙优12各生育期植株氮积累量随着施氮量增加而增加。相关分析表明,水稻产量与水稻植株全生育期氮积累量、磷积累量和钾积累量极显著正相关,其中,与水稻吸氮总量的相关系数最大。氨挥发速率、累计氨挥发量随施氮量的增加而增加,以施用基肥阶段氨挥发速率最快,累计氨挥发量最高。在基肥氮肥和分蘖肥氮肥施入后,高施肥水平(270  kg/hm2、330  kg/hm2)下氨挥发速率均远高于其他处理,其中,施氮量330  kg/hm2处理施基肥后测得的累计氨挥发量占基肥施氮量的23.9%。