棘洪滩水库沉积物对上覆水氮磷营养盐的影响

为了解青岛棘洪滩水库沉积物对水库水质的影响,分别在水库进水口（JSK）、库区中心（KX）和出水口（CSK）3个采样点采集库区沉积物,通过静态模拟吸附/释放实验,分析上覆水中氮磷营养盐含量变化.结果表明,除亚硝酸盐表现出微弱释放作用外,库区沉积物对氨氮、硝酸盐氮、总氮和总磷均表现出吸附作用,是氮磷营养盐的“汇”,并且不同采样点吸附能力也存在差异.其中出水口沉积物对总氮吸附作用最明显,吸附速率为4.80mg/（kg·d）,进水口沉积物对总磷吸附作用最强,吸附速率为0.06mg/（kg·d）.由此得出棘洪滩水库库区沉积物不会增加上覆水营养盐含量,库区水体营养盐可能主要来自引水.     

Performance evaluation of representative Wildfowl & Wetlands Trust constructed wetlands treating sewage

Data collected from five Wildfowl & Wetlands Trust constructed wetland systems offering a range of styles and inflow water types between 2005 and 2009 were examined and compared to identify long‐term trends in nutrient removal. Ammonia‐nitrogen concentrations were reduced between 31.9 and 96.8%. In contrast, the concentrations of nitrate‐nitrogen and total oxidised nitrogen in the effluent exceeded the influent in many of the systems. Reduction in ortho‐phosphate‐phosphorus and total phosphorous were between ?10.5 and 87.6%, and between 6.9 and 92.5%, respectively. Removal efficiencies of biochemical oxygen demand were between 0.0 and 87.3%, and reductions of total suspended solids ranged from ?249.3 to 57.6%. Ammonia‐nitrogen reduction was effective during summer. Long‐term nitrogen removal has been efficient and consistent. However, phosphorous reduction was only sufficient during the early stages of operation, and generally declined as the wetland aged.     

Mesocosm study of enhanced bioretention media in treating nutrient rich stormwater for mixed development area

A well-designed engineered soil for bioretention is important as it ensures that pollutant removal requirements are met. This laboratory study investigated the nutrient removal efficiency of bioretention media enhanced with 10% (by volume) additives from various waste materials (cockle shell, newspaper, printed paper, coconut husk and tyre crumb) and planted with Red Hot Chinese Hibiscus (Hibiscus rosa-sinensis), a common landscape shrub in tropical countries. The results showed that media enhanced with shredded newspaper demonstrated a significant improvement in total nitrogen (TN) removal (80.4%), compared to standard bioretention media (57.5%) without compromising total suspended solids (TSS) and total phosphorus (TP) removal, when dosed with actual runoff. The thick root system and rapid growth rate of the plant was proven to contribute to TN removal. This study concluded that shredded newspaper can be a potential addition to enhance bioretention media performance in treating stormwater, especially nutrient rich runoff from mixed development areas.     

The effect of beaver ponds on the nonpoint source water quality of a stream in Southwestern Wyoming

Currant Creek, a second order stream in southwestern Wyoming, has three large complexes of beaver ponds midway along its 32 km length. To determine whether these ponds improve the quality of water flowing through them, during spring and summer of 1984 and 1985 water samples were taken upstream from, within, and downstream from the pond complexes. During periods of high flow (i.e. spring runoff), concentrations of suspended solids (SS), total phosphorus (TP), sodium hydroxide-extractable phosphorus (NaOH-P, an index of biologically available P) and total Kjeldahl nitrogen (TKN) were reduced in water flowing through the beaver ponds. During low flow, beaver ponds had less effect on these parameters. Concentrations of nitrate nitrogen (NO₃-N) were reduced during both high and low flows, while concentrations of ortho-phosphate (ortho-P) did not appear to be affected by beaver ponds. Ammonia nitrogen almost always was at the limit of detection. Regression of NaOH-P versus [SS plus ortho-P] suggested that the primary source of NaOH-P was SS. In general, SS explained a large portion of the variation in TP, TKN, and NaOH-P, and often ortho-P was significantly correlated to TP. The increase in the concentration of most parameters below the area with dam complexes appears to reflect input from bank and channel erosion, and export of SS, TP, TKN and NO₃-N from beaver dam complexes was calculated to be less than that from stream sections above or below the dams. Thus the location of dams should be considered before using them to try and improve water quality. The apparent importance of bank and channel erosion as the primary source of nutrients to Currant Creek contrasts with many watersheds in agricultural areas.     

Material balances of organics and nutrients in an oxidation pond

A series of experiments concerning a tertiary oxidation pond was performed from 10 January to 12 November 1979, using a model oxidation pond of 21 m² in capacity. The concentrations of organics and nutrients in influent and pond water were measured so as to consider the conversion of water quality in a tertiary oxidation pond. The sedimentation rates were measured weekly, and the final sediments were analyzed at the end of experiments, so that the material balances in respect to carbon, nitrogen and phosphorus were calculated and the various transition reactions were evaluated quantitatively. The result of the material balances showed that there were three main reactions in pond: the assimilation to algae; the sedimentation of suspended substance; and the decomposition of sediments. The regeneration rates of nutrients from sediments were so active that the removal of nutrients by algal solidification were not effective. Consequently, the overall removal efficiency of nutrients was 45% in total nitrogen and 43% in total phosphorus by a tertiary oxidation pond with 16 days detention time.     

Effect of nitrate concentration in lake water on phosphate release from the sediment

Thirty-one Danish eutrophic lakes were investigated routinely over 1 year during the period 1978–1980. Nine lakes were dimictic with anoxic hypolimnia and 22 were very productive and shallow, polymictic lakes. Phosphate release from the sediment resulted in large increases in phosphate concentrations in anoxic hypolimnion, if concentrations of oxidized nitrogen in hypolimnion were less than about 0.1 g N m⁻³. If concentration of oxidized nitrogen (mainly nitrate) in hypolimnion was about 1 g N m⁻³ or higher, no release of phosphate from the sediment to anoxic hypolimnion occurred. In lakes with no summer stratification a release of phosphate from the sediment to the well oxygenated water resulted in summer maxima of phosphate in the lake water, when nitrate concentration in the water was less than about 0.5 g N m⁻³, but no release took place if nitrate concentration exceeded about 0.5 g N m⁻³. This effect of oxidized nitrogen in preventing phosphate release from the sediment demonstrates the ability of oxidized nitrogen to buffer the redox potential of the surface sediment at a level high enough to prevent a release of phosphate. Thus, among the efforts to limited phytoplankton biomass in lakes an artificial enrichment with nitrate may in some cases be an important supplement to the usually necessary reduction in phosphorus loading, but the possibility of a stimulation of phytoplankton growth through the addition of nitrate must be carefully considered.     

Nutrient release from integrated constructed wetlands sediment receiving farmyard run‐off and domestic wastewater

Constructed wetland sediments are frequently contaminated with nitrogen and phosphorus. There is a risk that accumulated pollutants can either be remobilised or reach the groundwater. Five identical mesocosms, which were filled with subsoil collected from full‐scale integrated constructed wetland (the first cell receives the most contaminated influent), were set up to examine nutrient removal within sediment layers. The results indicated that accumulated nutrients leached out into inflow water and that the sediment capacity of nutrient retention decreased as the wetlands aged. Furthermore, the mesocosm planted with Phragmites australis achieved better treatment results compared with the one planted with Agrostis stolonifera. The risk of contamination to groundwater does not exist because none of the treated water reached the bottom outlet during the study period. Both the bentonite (clay) and biogeochemical processes taking place within sediments proved to be efficient in preventing polluted water from infiltrating into lower lying soils.     

Enhanced nutrient removal by biological treatment systems

The importance of nitrogen and phosphorus in stimulating eutrophic conditions in receiving waters has been well documented. As a result, over the last decade an increased emphasis has been placed on limiting these elements in wastewater effluents. In the future, new discharge permits will include limits on both of these elements.

In 1985 a research program was initiated to conduct a pilot plant study of an anoxic/anaerobic/aerobic treatment train using primary effluent. The facility was operated at varying flow and Qr/Q ratios, and at effective mixed liquor suspended solids (MLSS) concentrations of 3100 mg/L. The results of the first 13 month operational phase indicated that the effluent concentrations of total BOD₅, TSS and nitrate nitrogen were less than 5 mg/L. Ammonia nitrogen was less than 0.2 mg/L. The solids settleability was excellent, and foaming due to Norcadia, was effectively controlled. The average overall phosphorus removal was 48%. Influent BOD₅ concentrations of less than 100 mg/L significantly reduced the system's ability to remove phosphorus. A strong relationship between the amount of carbon source in the influent, phosphorus release in the anoxic and anaerobic tanks and phosphorus uptake in the aeration basin was established.     

生态绿地控制初期雨水径流污染的研究

研究了生态绿地对初期雨水径流污染物的控制效果。生态绿地通过滤层过滤、植物吸收和生物降解的多重作用,实现了对SS、TN和TP的高效去除,而过滤介质和植物根系的缓冲作用,使得对CODMn保持了比较稳定的去除效果。生态绿地通过对初期高污染的雨水径流进行收集及后期洁净雨水的溢流实现了对雨水径流污染物的高效控制,对每场降雨中CODMn、TP、TN和SS的平均控制量分别为41.0、0.697、24.5和239mg/m2。生态绿地收集的雨水通过毛细作用到达表层土壤,提高了土壤的含水率,供给植物生长需求,对降雨量的利用率可达20%。生态绿地在有效控制雨水径流污染物的同时,还实现了对雨水的高效利用,可广泛应用于雨水径流面源污染的控制。     

Causes of low oxygen in a lowland, regulated eutrophic river in Eastern England

In the River Brett, Eastern England, over the period 1955-1998 there was a significant long-term decline in dissolved oxygen (DO), as well as increases in TON (total oxidised nitrogen) and SRP (soluble reactive phosphorus). Flow decreased from 1963 to 1998. Field studies in 1998-2000 showed increased pH and a gradient of DO beneath the filamentous alga Cladophora glomerata. DO decreased through the summer. Macrophytes accounted for 45% of community respiration at the study site, while sediment accounted for 36%. In container studies, muddy sediments had the highest maximum sediment oxygen demand (SOD), but canopies of C. glomerata and Lemna minor together increased the SOD by up to 90% over control samples. During periods of high temperature, abundant growths of C. glomerata and/or L. minor would increase the SOD of organic mud in river areas with shallow, ponded water, eventually leading to anoxic conditions and the release of nutrients from the sediment. If a river had large areas of mud, these processes could dramatically affect the river's oxygen budget, and hence its ecology.     

Nutrient and sediment removal by stormwater biofilters: a large-scale design optimisation study

A large-scale column study was conducted in Melbourne, Australia, to test the performance of stormwater biofilters for the removal of sediment, nitrogen and phosphorus. The aim of the study was to provide guidance on the optimal design for reliable treatment performance. A variety of factors were tested, using 125 large columns: plant species, filter media, filter depth, filter area and pollutant inflow concentration. The results demonstrate that vegetation selection is critical to performance for nitrogen removal (e.g. Carex appressa and Melaleuca ericifolia performed significantly better than other tested species). Whilst phosphorus removal was consistently very high (typically around 85%), biofilter soil media with added organic matter reduced the phosphorus treatment effectiveness. Biofilters built according to observed 'optimal specifications' can reliably remove both nutrients (up to 70% for nitrogen and 85% for phosphorus) and suspended solids (consistently over 95%). The optimally designed biofilter is at least 2% of its catchment area and possesses a sandy loam filter media, planted with C. appressa or M. ericifolia. Further trials will be required to test a wider range of vegetation, and to examine performance over the longer term. Future work will also examine biofilter effectiveness for treatment of heavy metals and pathogens.     

Microalgae growth-promoting bacteria as "helpers" for microalgae: a novel approach for removing ammonium and phosphorus from municipal wastewater

A combination of microalgae (Chlorella vulgaris or C. sorokiniana) and a microalgae growth-promoting bacterium (MGPB, Azospirillum brasilense strain Cd), co-immobilized in small alginate beads, was developed to remove nutrients (P and N) from municipal wastewater. This paper describes the most recent technical details necessary for successful co-immobilization of the two microorganisms, and the usefulness of the approach in cleaning the municipal wastewater of the city of La Paz, Mexico. A. brasilense Cd significantly enhanced the growth of both Chlorella species when the co-immobilized microorganisms were grown in wastewater. A. brasilense is incapable of significant removal of nutrients from the wastewater, whereas both microalgae can. Co-immobilization of the two microorganisms was superior to removal by the microalgae alone, reaching removal of up to 100% ammonium, 15% nitrate, and 36% phosphorus within 6 days (varied with the source of the wastewater), compared to 75% ammonium, 6% nitrate, and 19% phosphorus by the microalgae alone. This study shows the potential of co-immobilization of microorganisms in small beads to serve as a treatment for wastewater in tropical areas.     

Effects of water sample preservation and storage on nitrogen and phosphorus determinations: implications for the use of automated sampling equipment

The effects of freezing, acidification, refrigeration and extended storage without refrigeration on measured concentrations of forms of nitrogen and phosphorus were assessed in water samples taken from polluted and unpolluted streams in dry and wet weather. Emphasis was placed on likely changes associated with the use of automatic samplers in field conditions. The response of measured nutrient concentrations to different preservation methods and to extended storage without preservation varied widely between samples. For polluted streams where nutrient concentrations were high (ammoniacal nitrogen >0.1 mg l⁻¹; oxidised nitrogen, total Kjeldahl nitrogen, total and filterable phosphorus >1 mg l⁻¹), there was generally little proportional change in nutrients other than ammoniacal nitrogen after up to 6 d of storage without preservation. Where nutrient concentrations were low, up to 90% of ammoniacal nitrogen, 50% of oxidised nitrogen, 84% of total Kjeldahl nitrogen and 67% of total phosphorus was lost after 6 d. If samples cannot be retrieved immediately, automatic samplers should be refrigerated where possible. Acidification is a suitable alternative for preservation of nitrogen. Samples for filterable phosphorus should be filtered as soon as possible after collection. In some circumstances, unpreserved samples may provide an acceptable level of accuracy for evaluation of broad temporal trends or estimation of nutrient loadings.     

The phosphorus content of fluvial sediment in rural and industrialized river basins

The phosphorus content of fluvial sediment (suspended sediment and the < 63 microm fraction of floodplain and channel bed sediment) has been examined in contrasting rural (moorland and agricultural) and industrialized catchments in Yorkshire, UK. The River Swale drains a rural catchment with no major urban and industrial areas, and the total phosphorus (TP) content of fluvial sediment is generally within the range 500-1,500 microg g(-1). There is little evidence of any major downstream increase in TP content. In contrast, fluvial sediment from the industrialized catchments of the Rivers Aire and Calder exhibits both higher levels of TP content and marked downstream increases, with values of TP content ranging from < 2,000 microg g(-1) in headwater areas upstream of the main urban and industrial areas, to values > 7,000 microg g(-1) at downstream sites. These elevated levels reflect P inputs from point sources, such as sewage treatment works (STWs) and combined sewer overflows. The influence of STWs is further demonstrated by the downstream increase in the inorganic P/organic P ratio from < 2 in the headwaters to > 4 in the lower reaches. Comparison of the P content of suspended sediment with that of the <63 microm fraction of potential source materials suggests that topsoil from upland moorland/pasture and from cultivated areas, and channel bank material are likely to be the main sources of particulate P (PP) in the River Swale and in the headwaters of the Rivers Aire and Calder. In the middle and lower reaches of the Rivers Aire and Calder, inputs associated with urban and industrial land uses, such as STWs, industrial effluents and street dust, are likely to represent the dominant sources of PP. During high flow events, such urban inputs may be diluted by inputs from moorland and agricultural land in the headwaters. Consequently, for all three rivers, there are inverse relationships between the TP content of suspended sediment and both discharge and suspended sediment concentration, reflecting changes in sediment and P sources during high flow events. Spatial variations in the P contents of the < 63 microm fraction of overbank floodplain deposits and channel bed sediment evidence a similar pattern as those for suspended sediment, with relatively low levels of TP in the River Swale and elevated levels in the middle and downstream reaches of the Rivers Aire and Calder. The PP concentrations associated with floodplain and channel bed sediment are, however, lower than equivalent values for suspended sediment, and this primarily reflects the differences in the particle size composition between the three types of sediments. Rates of floodplain deposition and the amounts of fine-grained sediment stored in the river channels are relatively high, and suggest that such environments may represent important sinks for PP. Based on the sediment samples collected from the study basins, a simple four-fold classification which relates the TP content of suspended sediment to upstream land use has been established. Both the range and the absolute values of TP content tend to increase with an increase in the level of urbanization and industrialization.     

Life form dependent impacts of macrophyte vegetation on the ratio of resuspended nutrients

The effects of floating-leaved and submerged macrophytes on sediment resuspension and on the ratio of resuspended nitrogen and phosphorus were studied by sediment traps in the Kirkkojärvi basin in southern Finland. The effect of submerged macrophytes on preventing sediment resuspension was stronger than the effect of floating-leaved plants. On average, among submerged plants the resuspension rate of suspended solids was 43%, and among floating-leaved plants 87% of that in the open water. The floating-leaved Nuphar lutea had a reductive effect on P resuspension but no significant effect on N resuspension. The impact on P resuspension was strong, because root uptake by Nuphar lutea reduced the P content of the sediment. N:P ratio in resuspended nutrients was 6.7 among the plants and 4.1 in the open water. Among suzbmerged plants, sediment N content was strongly increased but P content was not affected due to the pleustophytic life form of the dominant plants (Ceratophyllum demersum, Ranunculus circinatus). The effect of pleustophytes on sediment nutrients was weak, because their nutrient uptake is mostly foliar. The N:P ratio of resuspended nutrients was 7.9 among the submerged plants and 7.0 in the open water. The results suggested that depending on the life form, macrophytes can modify the flux of N and/or P to the water column through their effects on nutrient resuspension and possibly modify phytoplankton communities via their effects on the N:P ratio. If the overall nutrient level is the most important factor for the dominance of cyanobacteria, submerged macrophytes can have stronger effects on phytoplankton community structure than floating-leaved species. If N:P ratio is of importance, the effects of floating-leaved species may be more pronounced.     

Suppression of phosphorus release from lake sediments by the addition of nitrate

An assessment was made of the effectiveness of nitrate in reducing phosphorus release from the anoxic sediments of a small dimictic lake, White Lough, N. Ireland. Laboratory experiments on sediment cores showed that nitrate delayed and reduced phosphorus release with an input of 61 gN m⁻² causing complete suppression. The addition of 24 gN m⁻² of nitrate to the sediment of White Lough resulted in a delay and reduction of phosphorus release similar to that observed in the laboratory core experiments. Sediment release of iron in the lake was also delayed and reduced but manganese release and the rate of hypolimnetic deoxygenation were unaffected by the nitrate addition. Ammonium release rates in the sediment cores and in the whole lake experiment did not vary with nitrate input. Comparing the costs of using nitrate or iron/aluminium salts to suppress sediment phosphorus release indicated that the nitrate method was at least 80% more expensive.     

Phosphorus recovery from dairy manure wastewater by fungal biomass treatment

Polyphosphate accumulating fungi was cultured to remove and recover the excessive phosphorus from dairy manure wastewater (DMW). The microbial treatment removed 83.9% of phosphorus in 20‐fold diluted DMW by the fungal biomass in 12 h. At the meantime, 33.6% of chemical oxygen demand, 46.5% of total nitrogen, and 89.4% of total ammonia nitrogen were removed as well. At seventh reuse batch, the cells could still remove 50.4% of phosphorus from the diluted wastewater. The average phosphorus removal efficiency in seven reuse batches was calculated as 62.1%, the nitrogen‐to‐phosphorus ratio in DMW increased from 3.6 : 1 to 6.3 : 1. With the treatment, DMW will be more suitable for farmland irrigation, with the better nutritional ratio to support crop growth, and it will help mitigate phosphorus pollution to water bodies caused by over‐applied phosphorus in the farmland.     

Some observations on the occurrence of phosphorus in recent sediments from western Europe

Near shore and fluvial sediments from the Netherlands and surrounding areas are composed of org-P, FeAl phosphorus and Ca-phosphorus. In marine sediments the org-P constitutes about 25% of the total phosphorus in the sediments. In Lake Yssel higher concentrations of organic phosphorus are found, whereas in fluvial sediments concentrations tend to be lower. The phosphorus in the highly contaminated river Rhine is mainly present as FeAl phosphorus. In sediments from the Dollard area (Wadden Sea), a diagenetic recycling of phosphorus takes place which results in high concentrations of phosphorus in the oxidised surface layer of the sediment. The phosphorus in this layer becomes reprecipitated as FeAl phosphate.The oxidised surface layer may act as a chemical barrier against the upward flow of some metals and nutrients from the interstitial water to the surface waters.     

Seasonal variation of denitrification rate in sediment determined by use of N

A laboratory method of determination of sediment denitrification capability is described. The determination of nitrogen gas evolved from ¹⁵N-labelled nitrate is based on the principle of isotope dilution. The gas evolved is spiked with unlabelled dinitrogen and the ¹⁵N-enrichment of the resulting gas mixture is measured by optical spectrometry.The amount of nitrate reduced to ammonia and organic nitrogen is determined simultaneously. Measurements performed on sediment from a shallow Danish lake indicated first order kinetics of denitrification with respect to nitrate concentration. Great seasonal variation of rate constant was found with maximum value in late August. This variation is probably governed by the pattern of accumulation of decomposable organic matter in sediment.Calculation based on measured rate constants and nitrate concentrations during the year indicate that approximately 10% of the total nitrogen loading of the lake is denitrified.     

Seasonal variation of denitrification rate in sediment determined by use of 15N

A laboratory method of determination of sediment denitrification capability is described. The determination of nitrogen gas evolved from ¹⁵N-labelled nitrate is based on the principle of isotope dilution. The gas evolved is spiked with unlabelled dinitrogen and the ¹⁵N-enrichment of the resulting gas mixture is measured by optical spectrometry.The amount of nitrate reduced to ammonia and organic nitrogen is determined simultaneously. Measurements performed on sediment from a shallow Danish lake indicated first order kinetics of denitrification with respect to nitrate concentration. Great seasonal variation of rate constant was found with maximum value in late August. This variation is probably governed by the pattern of accumulation of decomposable organic matter in sediment.Calculation based on measured rate constants and nitrate concentrations during the year indicate that approximately 10% of the total nitrogen loading of the lake is denitrified.