农田排水对沼泽湿地毛果苔草的影响及效应

随着三江平原沼泽湿地的垦殖,农田排水不断进入沼泽湿地,对湿地生态系统造成不同程度的影响。当一定氮、磷浓度的农田排水进入毛果苔草沼泽湿地后,水中TN、NH₄+-N、TP和PO₄3--P的含量均明显升高,8~9月份TN和NH₄+-N含量分别为自然沼泽湿地水体的1.51~2.10倍和1.53~3.02倍;TP和PO₄3--P含量分别为1.30~4.08倍和4.33~11.33倍。接受农田排水的毛果苔草根、茎叶生物量明显增高,相应的植物不同部分TN、TP含量也明显增高,其毛果苔草根部TN、TP含量与水中TN、TP含量的相关关系比自然湿地毛果苔草的这一相关关系更强,表明农田排水可促进毛果苔草的生长和对氮、磷的吸收。由于农田排水中磷的含量相对较高,造成湿地水系统N/P失衡,对湿地毛果苔草生态系统的稳定性和生物生产力形成潜在的威胁,因此应控制农田排水直接排入沼泽湿地。     

不同坡度缓冲带滞缓径流及污染物去除定量化

利用构建的东风港缓冲带现场试验基地和设计的径流流量测定装置,模拟上海地区农业面源污染物浓度和典型单次降雨历时及降雨量,对不同坡度缓冲带滞缓径流和农田氮磷污染物去除能力开展定量化试验研究。结果表明:相同植被缓冲带,坡度越小,其滞缓径流和土壤水力渗透的能力越强,19 m长的2%坡度缓冲带径流初始出水时间比5%坡度缓冲带延长了7.3 min,两者的渗流水量比值达到1.74;不同坡度缓冲带渗流氮磷污染物去除量显著高于径流,2%、3%、4%和5%坡度缓冲带对于氮磷污染物的渗流去除量与径流去除量的比值分别为2.32、2.15、1.82和1.64;坡度的变化对缓冲带净化面源氮磷污染物效果的影响显著,坡度越小,缓冲带渗流水量越大,其氮磷污染物的总去除率和单位面积去除负荷也越高,2%坡度缓冲带对氮磷污染的总去除率和单位面积污染去除负荷分别是5%坡度的1.56倍和1.66倍,2%坡度缓冲带对TN、NH₃--N、TP的单位面积去除负荷均最高,分别达到0.661 g/m2、0.672 g/m2和0.044 g/m2。     

土壤-含水层侧渗系统在净化河水中的应用——以郑州市索须河工程为例

由于降水较少以及地下水超采,北方地区大部分河流基流匮乏,河水主要来自未经深度处理的城市生活污水和工业废水,河水水质难以达标.在这些地区,利用河流漫滩土壤和含水层的天然净化能力,建立近自然土壤-含水层侧渗系统是净化河水的有效途径之一.在介绍侧渗系统净化机理及适用条件的基础上,通过室内试验和野外示范工程研究索须河土壤-含水层对河水中氨氮的去除效果.室内试验表明该处土壤及浅部含水层对氨氮的去除主要通过稀释、吸附和微生物等作用;通过对示范工程典型剖面上的监测井观测表明该系统对氨氮的去除效果良好,受降水补给的土壤和含水层使得河水中的氨氮硝化为亚硝酸盐和硝酸盐.硝酸盐在地下水中很难被去除,只有少部分通过反硝化作用转化成N2.土壤-含水层侧渗系统行之有效,可应用于类似索须河的北方河流.     

夏季长江河口潮间带反硝化作用和N2O的排放与吸收

采用培养箱乙炔抑制和现场静态箱法,于夏季(7月)在长江河口潮滩潮间带进行了采样,研究表明,长江河口潮滩水体自身N2O产生速率很低,在潮汐淹没期沉积物是上覆水体N2O的来源,其来自沉积物中反硝化、硝化等氮素循环的多个反应过程,沉积物中N2O自然产生速率在0.10～8.50μmol/(m2·h)之间,反硝化速率在21.91～35.87μmol/(m2·h)之间。退潮出露期中潮滩是大气N2O的排放源犤交换速率在-11.03～13.17μmol/(m2·h)之间犦,5～10cm地温是影响N2O排放速率的显著性因素;低潮滩-大气界面N2O排放、吸收速率在-5.75～0.49μmol/(m2·h)之间。总体上看,中潮滩是大气N2O的排放源;而低潮滩对大气N2O有明显的吸收作用。潮滩植被(海三棱草和底栖藻类)的光合作用明显抑制了N2O的排放并可能导致吸收,而其呼吸作用则增加了N2O的排放,潮间带-大气界面N2O的排放和吸收与CO2的排放、吸收有显著的正相关关系。     

再生水补水条件下土壤全氮空间分布特征

土壤中的氮素是植物生长发育的基础,由于城市湿地土壤受特殊水文条件影响,土壤全氮(TN)的分布规律和影响机制较为复杂,因此研究土壤TN的空间分布特征具有重大的生态意义。本文以再生水为主要补给水源的北京门城湖湿地公园为研究区,运用ArcGIS和地统计学对该区土壤TN的空间分布特征进行研究。结果表明:研究区土壤TN质量分数较高,差值明显,变异系数达47.35%;比较不同的植物群落区可知,香蒲群落区土壤TN质量分数最高。对影响研究区土壤TN分布的因素分析得出:土壤TN、全磷(TP)质量分数呈极显著正相关关系(r=0.81,P0.01);TN、土壤有机质(SOM)质量分数呈显著正相关关系(r=0.62,P0.05);气候因子中,湿度和温度对TN分布同样影响显著。水质参数中,再生水出水口处测得的土壤TN的指标数值更高,随出水口距离的增加,参数值总体呈下降趋势且逐步趋于稳定,说明植被对湿地土壤中氮素空间分布的调整具有重要作用。     

中国干旱内陆流域水体 N、P负荷特征与动态变化——以黑河流域为例

以黑河流域中游地区为研究区域，通过11年在不同河流断面的长期监测和区域内各类水体如地下水、泉水、水库和河流的空间选点取样分析，研究了干旱内陆流域水体 N、P等植物营养元素的负荷与时空分布及动态变化特征。浅层地下水与河水中NO₃-N含量普遍较高，含量超过 1．1 m g／L，大部分平原水库水中NH₄-N含量超过 0．3 m g／L；河水与浅层地下水TP、NH₄-N与NO₃-N含量均呈现沿流域从出山口至下游的显著递增变化，同时还具有明显的随时间递增趋势，其中NH₄-N含量在河流出山口及下游断面平均年增加幅度分别为 0．11 m g／L和 0．114 m g／L；流域水体 N、P含量的季节变化明显，黑河流域春季及春夏之交的枯水期大部分河段NH₄-N、NO₃-N和TP等要素含量为全年最高并出现水质超标污染。控制干旱内陆流域水域尤其是枯水期的 N、P污染，应成为干旱内陆流域水资源保护问题中值得关注的关键内容。     

农村家庭利用自酿米酒去除地下水中硝酸盐的初步研究

为去除农村家庭饮用地下水中的硝酸盐,以农村自酿米酒为碳源,利用简易的沙桶装置开展了反硝化去除硝酸盐的实验,对比了不同乙醇浓度下的反硝化效果。实验结果表明,以沙桶为实验装置,自酿米酒为碳源,在家庭中异位反硝化去除抽取地下水中的硝酸盐方法是有效果,易操作的。硝酸盐的去除率和C/N质量比有直接关系,当C/N质量比大于1.99时,硝酸盐去除率达99%,亚硝酸盐零积累,但易积累乙酸盐;当C/N质量比为0.89时,硝酸盐去除率达99%,生成物亚硝酸盐浓度远高于国家饮用水限值(1 mg/L);当C/N质量比为0.43时,反硝化过程不彻底,硝酸盐去除率不高,且易生成溶度较高的亚硝酸盐。溶解氧的存在不会对反硝化产生显著影响。米酒和硝酸盐之间的C/N最佳比例,宜大于本次实验的0.89,小于1.99,利用农村自酿米酒作为碳源去除地下水中硝酸盐是可行的。     

利用黑土洼沟净化官厅水库入库水水质研究

对高含沙、低污染永定河河水进行初步净化处理,是解决官厅水库水体污染,恢复水库向北京市供水功能的重要途径之一.示范工程研究表明,永定河水经黑土洼沟沉淀、大气富氧、增加水体停留时间等作用,对SS、COD、BODs、总氮TN、总磷TP的平均去除率分别达到87.4%、47%、36%、72%、73%,处理系统可大幅度减少入库污染物质总量,降低河湖富营养化发生的危险.     

云南岩溶断陷盆地植被演替土壤碳氮磷化学计量学特征

岩溶断陷盆地生态环境脆弱,石漠化严重,植被恢复是该地区生态重建、水土保持的有效措施。文章采用空间换时间的方法,以云南省泸西县岩溶断陷盆地5种不同演替阶段（玉米地、人工林、草地、灌木林、原始林）不同土层（0～10、10～20 cm）的土壤为研究对象,对比分析不同植被类型和不同深度条件下土壤C（碳）、N（氮）、P（磷）含量及化学计量比差异,旨在探明研究区土壤养分垂向分布及化学计量学特征,为该地区植被恢复管理及土地合理利用提供科学依据。结果表明：不同演替阶段、不同土壤深度土壤养分含量存在较大差异;随着演替年限的增长,土壤SOC（土壤有机碳）、TN（总氮）含量总体呈增长趋势且主要表现在0～10 cm深度土层上,而TP（总磷）含量存在波动,未表现出明显变化规律;各演替阶段0～10 cm土层的SOC、TN含量数值上均要高于10～20 cm土层,除原始林地以外,其余演替阶段不同土层间TP含量没有显著差异;在0～10 cm土层上,C/N、C/P、N/P均与土壤SOC含量呈显著正相关,C/P、N/P与土壤TN含量呈显著正相关,土壤TP含量与C/N、C/P和N/P无显著相关性;植被类型和土壤深度显著影响研...     

多层渗滤介质处理微污染水体的中试研究

对传统的渗滤系统进行改进,采用多层渗滤介质系统,以期增大人工土层对颗粒有机物的接触氧化表面积,同时设置曝气装置保证好氧过程的氧气供应,可以大大提高污水地下处理系统的水力负荷。以北京典型的细砂、中砂、粗砂和砾石为填充材料,处理北京市海淀区上庄水库的污染水体,远优于类似的系统。现场试验结果表明,改进后的系统能创造良好的好氧/厌氧环境,对污染物去除效果良好,COD_Cr、TN、NH⁺₄-N和TP去除率分别达到了48.57%~94.87%、18.49%~70.21%、20.51%~87.50%和5692%~80.65%,出水达到了地表水Ⅲ-Ⅳ类水质标准。多层渗滤介质系统通过微生物的硝化、反硝化作用实现生物脱氮是去除氮的主要途径;土壤的吸附与沉淀作用是去除磷的主要途径。      

Effects of plants development and pollutant loading on performance of vertical subsurface flow constructed wetlands

The influent concentration has a great effect on nutrients removal efficiency in vertical subsurface flow constructed wetland systems, but treatment performance response to different C: N: P ratios in the influent are unclear at present. At the first growing seasons, the effects of the plants present or not, season, the different C: N: P ratio in influent condition and their interaction on treatment performances were studied in the planted or the unplanted wetlands in greenhouse condition. Each set of units was operated at hydraulic loading rates of 40 L/d. Low, medium and high-strength (100, 200, 400 mg/L of chemical oxygen demand or 20, 40, 80 mg/L total nitrogen) synthetic sewage were applied as influent. According to the first growing season results, the average removal efficiencies for the unplanted and the planted wetlands were as follows: chemical oxygen demand (44–58 % and 55–61 % respectively), total nitrogen (26–49% and 31–54 %) and total phosphorus (36–64 % and 70–83 %). The both wetlands system was operated as an efficient treatment system of highest average removal rates of both chemical oxygen demand and total phosphorus when medium-strength synthetic sewage were applied. When high strength synthetic sewage was applied, the planted wetlands usually had a higher nutrients removal rates than the unplanted over the study period. The plants grew well under any high loading treatment over the study period. Anyhow, it also proved that the wetland systems have a good capacity to treat different strength wastewater in greenhouse condition.     

表面流人工湿地处理糠醛生产废水的应用

根据糠醛生产废水的特点,利用生产企业所处低洼盐碱地改造成表面流人工湿地,废水在湿地内以自然消耗的方式处理,无外排,处理的废水量等于湿地内废水的自然蒸发量、植物的蒸腾量与植物的贮存量。研究表明,经湿地处理后的废水COD去除率平均为94%,TN去除率平均为65%,TOC去除率平均为94.9%。处理后的废水pH值为6.22。     

Effects of discharge of municipal waste on water quality of the lower Mississippi River

The effects of discharge of municipal wastes on water quality within the lower Mississippi River below Old River have been reevaluated using published water quality data in the Louisiana reach of the river for the water years 1974–1984. A novel graphical technique has facilitated the evaluation of upriver controls on water quality and the identification of sources and sinks along the lower Mississippi. Comparison of calculated annual fluxes at different downstream monitoring stations has simplified some of the problems inherent in evaluating analyses of samples collected from different water masses during a typical sampling run. The absolute concentrations of chloride, nitrite plus nitrate, total phosphorous, dissolved oxygen, BOD, and COD are all strongly dependent on processes occurring upriver. Nonpoint influx of materials from agricultural wastes and natural plant debris may be the dominant upstream sources of N, P, BOD, and COD. Increases in chloride and phosphorous downstream within the Lower Mississippi appear to be caused by discharge of industrial wastes. Nitrogen fluxes decrease downriver, except where there is local discharge of high-N, high-P industrial waste water, possibly from fertilizer plants. Removal of N and increases in BOD may be due in part to biological uptake. High river discharge rates and efficient, natural processes of reaeration maintain high oxygen saturation levels. With the exception of an increase in bacterial count, the discharge of municipal waste into the Mississippi River in Louisiana appears to have had no significant effect on water quality, a finding consistent with the earlier U.S. Geological Survey study of Wells (1980). It would be highly desirable for future mass balance studies if existing water quality programs on the Mississippi River were to adopt a Lagrangian sampling approach.     

Tidal nitrogen exchanges across a freshwater wetland succession gradient in the upper Cooper River,South Carolina

Tidal freshwater sections of the Cooper River Estuary (South Carolina) include extensive wetlands, which were formerly impounded for rice culture during the 1,700s and 1,800s. Most of these former rice fields are now open to tidal exchange and have developed into productive wetlands that vary in bottom topography, tidal hydrography and vegetation dominants. The purpose of this project was to quantify nitrogen (N) transport via tidal exchange between the main estuarine channel and representative wetland types and to relate exchange patterns to the succession of vegetation dominants. We examined N concentration and mass exchange at the main tidal inlets for the three representative wetland types (submerged aquatic vegetation [SAV], floating leaf vegetation, and intertidal emergent marsh) over 18-21 tidal cycles (July 1998–August 2000). Nitrate + nitrite concentrations were significantly lower during ebb flow at all study sites, suggesting potential patterns of uptake by all wetland types. The magnitude of nitrate decline during ebb flow was negatively correlated with oxygen concentration, reflecting the potential importance of denitrification and nitrate reduction within hypoxic wetland waters and sediments. The net tidal exchange of nitrate + nitrite was particularly consistent for the intertidal emergent marsh, where flow-weighted ebb concentrations were usually 18–40% lower than during flood tides. Seasonal patterns for the emergent marsh indicated higher rates of nitrate + nitrite uptake during the spring and summer (> 400 μmol N m^-2 tide^-1) with an annual mean uptake of 248 ± 162 μmol m^–2 tide^–1. The emergent marsh also removed ammonium through most of the year (207 ± 109 μmol m^–2 tide^–1), and exported dissolved organic nitrogen (DON) in the fall (1,690 ± 793 μmol m^–2 tide^–1), suggesting an approximate annual balance between the dissolved inorganic N uptake and DON export. The other wetland types (SAV and floating leaf vegetation) were less consistent in magnitude and direction of N exchange. Since the emergent marsh site had the highest bottom elevation and the highest relative cover of intertidal habitat, these results suggest that the nature of N exchange between the estuarine waters and bordering wetlands is affected by wetland morphometry, tidal hydrography, and corresponding vegetation dominants. With the recent diversion of river discharge, water levels in the upper Cooper estuary have dropped more than 10 cm, leading to a succession of wetland communities from subtidal habitats toward more intertidal habitats. Results of this study suggest that current trends of wetland succession in the upper Cooper River may result in higher rates of system-wide inorganic N removal and DON inputs by the growing distributions of intertidal emergent marshes.     

长江口沉积物碳氮元素地球化学特征及有机质来源分析

根据对长江口水下三角洲上部(CJ16)和口门浅滩(CJ19)柱状样的粒度、总有机碳(TOC)、总氮(TN)和有机碳同位素(δ13C)以及长江口表层样TOC的测定,得出其粒度及碳氮元素特征,利用C/N和δ13C分析有机质来源及不同来源的贡献率。研究结果表明:(1)沉积物中有机碳含量在0.19%～1.17%之间,CJ16柱中有机碳含量比CJ19柱略高;总氮含量均比较少,且变化幅度小;C/N比值在5～17间变化;CJ16柱的δ13C值在24.70‰～22.86‰间变化,CJ19柱为24.88‰～22.37‰,且CJ19柱δ13C值在36 cm以上段较下段明显增大,推测可能与南汇边滩互花米草(C4植物)的引种有关;(2)长江口表层沉积物TOC的含量范围为0.17%～1.16%,平均值为0.52%;(3)粒度特征显示长江口主要以粉砂和粘土为主,砂含量较少,粒度与长江口TN、TOC含量有较好的相关性;(4)C/N和δ13C值的特征均显示该区有机质为陆源和海洋混合,利用C/N比值估算出来自陆源的有机碳比例在CJ16柱约为40%,而在CJ19柱中约为60%;根据δ13C值估算出CJ16柱陆源和海源两种有机质来源几乎是各占一半的比例,CJ19柱来自陆源的有机碳占总有机碳的60%,与用C/N比值法测得的结果较一致。上述结果显示长江口的不同空间位置碳氮元素分布特征不同,沉积记录受到粒度、河口区物源的影响,还受到陆源和海源不同有机质来源输入的影响。     

Ecosystem Functions of Tidal Fresh, Brackish, and Salt Marshes on the Georgia Coast

We examined patterns of habitat function (plant species richness), productivity (plant aboveground biomass and total C), and nutrient stocks (N and P in aboveground plant biomass and soil) in tidal marshes of the Satilla, Altamaha, and Ogeechee Estuaries in Georgia, USA. We worked at two sites within each salinity zone (fresh, brackish, and saline) in each estuary, sampling a transect from the creekbank to the marsh platform. In total, 110 plant species were found. Site-scale and plot-scale species richness decreased from fresh to saline sites. Standing crop biomass and total carbon stocks were greatest at brackish sites, followed by freshwater then saline sites. Nitrogen stocks in plants and soil decreased across sites as salinity increased, while phosphorus stocks did not differ between fresh and brackish sites but were lowest at salty sites. These results generally support past speculation about ecosystem change across the estuarine gradient, emphasizing that ecosystem function in tidal wetlands changes sharply across the relatively short horizontal distance of the estuary. Changes in plant distribution patterns driven by global changes such as sea level rise, changing climates, or fresh water withdrawal are likely to have strong impacts on a variety of wetland functions and services.     

Treatment of polluted river water by a new constructed wetland

A new constructed wetland was built to purify one polluted river in Taiwan, and this study was conducted to evaluate the treatment efficiency of the wetland. Due to the very limitation of available budget, several water quality items, which were stipulated by Taiwan’s Environmental Protection Administration for rivers, in the influent and effluent of wetland were analyzed and evaluated. These items included water temperature, pH, DO, BOD₅, TSS, and NH₄ ⁺-N. The results showed that the average removal rates of total (unfiltered) BOD₅, TSS and NH₄ ⁺-N were 36.9 %, 71.8 % and 47.1%, respectively. With the HRT more than 3.4 days, the wetland could treat the polluted river water effectively. Longer HRT in this wetland appeared no obvious improvement on the removal rate of TSS or NH₄ ⁺-N. However, BOD removal rate increased while the HRT (Hydraulic Retention Time) increased to about 5 days. In this wetland, the calculated mean first-order reaction rate constant (k_T) for BOD₅ was 0.15/day with a standard deviation of 0.13/day and for NH₄ ⁺-N was 0.24/ day with a standard deviation of 0.18/day. It is also concluded that there is a linear proportional relationship between BOD concentrations in the effluent of wetland and its influent mass loading rates, with the coefficient of determination (R²) of 0.6511. Similar result was seen for NH₄ ⁺-N as well, with the coefficient of determination (R²) of 0.5965. TSS removal rate was found to be linearly proportional to its influent mass loading rate, with the coefficient of determination (R²) of 0.4875.     

Mechanism of efficient nutrient removal and microbial analysis of a combined anaerobic baffled reactor–membrane bioreactor process

A combined ABR–MBR process consisting of an anaerobic baffled reactor (ABR) combined with an aerobic membrane bioreactor (MBR) treating municipal wastewater was investigated at controlled pH range 6.5–8.5 and at constant temperature 25 ± 1 °C. Total nitrogen (TN), ammonia (NH₄ ⁺–N), total phosphorus (TP), and chemical oxygen demand (COD) removal performances were evaluated by analyzing the mechanism for efficient nutrient removal. The results showed that the average removal rates of COD, NH₄ ⁺–N, TN, and TP reached 93, 99, 79, and 92 %, respectively, corresponding with the COD, NH₄ ⁺–N, TN, and TP effluent of 24 (18–31), 0.4 (0–0.8), 10.6 (8.8–12.9), and 0.31 (0.1–0.5) mg/L under the operational condition of hydraulic retention time (HRT) 7.5 h, recycle ratio 200 %, and dissolved oxygen 3 mg/L. The MBR enhanced NH₄ ⁺–N, TN, and TP removal rates of 13, 10, and 18 %, respectively, and the membrane retention reduced TP 0.17 mg/L. The process was able to maintain a stable performance with high-quality effluent. Analysis of the results by fluorescence in situ hybridization showed that the abundance of ammonia-oxidizing bacteria, nitrite-oxidizing bacteria, and phosphorus accumulating organisms as percentages of all bacteria in each compartment was stable. The enriched microorganisms in the system appear to be the main drivers of the process efficient for nutrient removal.     

Floating wetland mesocosm assessment of nutrient removal to reduce ecotoxicity in stormwater ponds

A grouped mesocosm study was conducted with different water holding capacities and conditions to determine nutrient removal efficiency using floating wetland macrophytes. Different scenarios were created by changing water depth, littoral vegetation, sorption media and area coverage to observe how they affect nutrient removal efficiencies. Plant species were screened and selected based on the literature, local availability and previously performed microcosm studies. Sorption media were warped using geotextile filter fostering microbial colonization in the rhizospheric zone to enhance denitrification and plant growth. Water quality parameters included total nitrogen, total phosphorus, orthophosphate, nitrate?Cnitrogen and ammonia?Cnitrogen in addition to in situ parameters such as pH, dissolved oxygen, temperature and chlorophyll-a. Composite samples across several locations were collected periodically to understand the spatial distribution or aggregation of nutrients. After 3?months of water quality monitoring, plants were analyzed for tissue nutrient concentrations, and the average uptake rate was calculated as 36.39 and 1.48?mg?m^?2?day^?1 for nitrogen and phosphorus, respectively, by the floating treatment wetland system. Finally, considering the higher nutrient aggregation in the rhizospheric zone, the removal rate with 5?% area coverage and water quality improvement by littoral zone, the optimized design, placement and maintenance of the whole system were recommended.