湖泊富营养化相关物理量的定量关系

湖水中总磷、总氮、叶绿素a、透明度、均温层氧亏量是与水体富营养化密切相关的几个物理量。研究结果表明,它们之间有一定的相关关系,可用数学公式定量表示。本文针对这些关系进行了概括和整理。     

Water Quality Functions of Riparian Forest Buffers in Chesapeake Bay Watersheds

/ Maryland, Virginia, and Pennsylvania, USA, have agreed to reduce nutrient loadings to Chesapeake Bay by 40% by the year 2000. This requires control of nonpoint sources of nutrients, much of which comes from agriculture. Riparian forest buffer systems (RFBS) provide effective control of nonpoint source (NPS) pollution in some types of agricultural watersheds. Control of NPS pollution is dependent on the type of pollutant and the hydrologic connection between pollution sources, the RFBS, and the stream. Water quality improvements are most likely in areas of where most of the excess precipitation moves across, in, or near the root zone of the RFBS. In areas such as the Inner Coastal Plain and Piedmont watersheds with thin soils, RFBS should retain 50%-90% of the total loading of nitrate in shallow groundwater, sediment in surface runoff, and total N in both surface runoff and groundwater. Retention of phosphorus is generally much less. In regions with deeper soils and/or greater regional groundwater recharge (such as parts of the Piedmont and the Valley and Ridge), RFBS water quality improvements are probably much less. The expected levels of pollutant control by RFBS are identified for each of nine physiographic provinces of the Chesapeake Bay Watershed. Issues related to of establishment, sustainability, and management are also discussed.KEY WORDS: Riparian forest buffers; Chesapeake Bay; Nonpoint source pollution; Nitrogen; Phosphorus; Sediment     

Effect of phosphate releasing in activated sludge on phosphorus removal from municipal wastewater

Aluminum and ferric salts are commonly used in municipal wastewater treatment plants(WWPTs) for phosphorus(P) removal. In this study, on-site jar tests were conducted to determine the removal of different P species from the fresh samples in the presence and absence of activated sludge(AS) with different doses of alum, poly-aluminum chloride,and ferric chloride at different p H. The soluble P(SP) concentration in the samples was about 0.63 mg/L. When the mixed liquor containing AS was treated with 8 mg/L of Al, SP could be reduced to 0.13 mg/L, while it was reduced to 0.16 mg/L with only 1 mg/L of Al after sedimentation removal of AS from sample. Chemical analysis determined that AS contained 59.8 mg-P/g-TSS and 43.8 mg-Al/g-TSS and most of the P was associated with the aluminum hydroxide. We discovered that the phosphate in the AS could readily be released from it, which was mainly responsible for ineffective removal of P to low levels in mixed liquor even with very high alum dose. This study provides new insight into the behavior and fate of P in the wastewater treatment plants that use alum to enhance P removal in the final effluent.     

A Daily Time Series Analysis of StreamWater Phosphorus Concentrations Along an Urban to Forest Gradient

During a 1-year period, we sampled stream water total phosphorus (TP) concentrations daily and soluble reactive phosphorus (SRP) concentrations weekly in four Seattle area streams spanning a gradient of forested to urban-dominated land cover. The objective of this study was to develop time series models describing stream water phosphorus concentration dependence on seasonal variation in stream base flows, short-term flow fluctuations, antecedent flow conditions, and rainfall. Stream water SRP concentrations varied on average by ±18% or ±5.7 μg/L from one week to another, whereas TP varied ±48% or ±32.5 μg/L from one week to another. On average, SRP constituted about 47% of TP. Stream water SRP concentrations followed a simple sine-wave annual cycle with high concentrations during the low-flow summer period and low concentrations during the high-flow winter period in three of the four study sites. These trends are probably due to seasonal variation in the relative contributions of groundwater and subsurface flows to stream flow. In forested Issaquah Creek, SRP concentrations were relatively constant throughout the year except during the fall, when a major salmon spawning run occurred in the stream and SRP concentrations increased markedly. Stream water SRP concentrations were statistically unrelated to short-term flow fluctuations, antecedent flow conditions, or rainfall in each of the study streams. Stream water TP concentrations are highly variable and strongly influenced by short-term flow fluctuations. Each of the processes assessed had statistically significant correlations with TP concentrations, with seasonal base flow being the strongest, followed by antecedent flow conditions, short-term flow fluctuations, and rainfall. Times series models for each individual stream were able to predict ∼70% of the variability in the SRP annual cycle in three of the four streams (r² = 0.57–0.81), whereas individual TP models explained ∼50% of the annual cycle in all streams (r² = 0.39–0.59). Overall, time series models for SRP and TP dynamics explained 82% and 76% of the variability for these variables, respectively. Our results indicate that SRP, the most biologically available and therefore most important phosphorus fraction, has simpler and easier-to-predict seasonal and weekly dynamics.     

磷的沉积物-水界面反应

本文对磷在水中和沉积物中的赋存状态进行了简单介绍;对磷在沉积物-水界面的反应机制作了详细的介绍;且认为有必要对磷进行更深入地研究.     

Regional Lake Trophic Patterns in the Northeastern United States: Three Approaches

N   = 11,076). Results were compared to a large, nonrandomly sampled data set for the same area compiled by Rohm and others and contrasted with lake trophic state information published in the National Water Quality Inventory: 1994 Report to Congress [305(b) report. Lakes across the entire Northeast were identified by EMAP data as 37.9% (±8.4%) oligotrophic, 40.1% (±9.7%) mesotrophic, 12.6% (±7.9%) eutrophic, and 9.3% (±6.3%) hypereutrophic. Lakes in the ADI and NEU generally are at a low, nearly identical trophic state (96% oligotrophic/mesotrophic), while those in the CLP are much richer (45% eutrophic). EMAP results are similar to results of the Rohm data set across the entire region. In the CLP, however, EMAP identified approximately 45% of the lakes as eutrophic/hypereutrophic, while the Rohm data set identified only 21% in these categories. Across the entire Northeast, the 305(b) report identified a much higher proportion (32.2%) of lakes in eutrophic condition and a much smaller proportion (19.8%) in oligotrophic condition than did the EMAP survey data (12.5% ± 7.9% and 37.9% ± 8.5%, respectively). Probability sampling has several advantages over nonrandom sampling when regional resource condition assessment is the goal.     

Adapting regional eutrophication targets for surface waters—influence of the EU Water Framework Directive, national policy and climate change

Large amounts of waterborne nutrients are major problems for society since they can cause harmful algal blooms in surface water bodies. Consequently, there are a variety of national and international guidelines, e.g. Swedish National Environmental Quality Objectives and the EU Water Framework Directive, which include targets to be achieved within a certain time frame. This paper uses the example of a large Swedish lake to show that national and international targets must be adapted to the local situations. Despite decreasing nutrient concentrations, cyanobacterial blooms in the lake have increased over recent years. We found that these blooms coincide with depleted nitrate–nitrogen concentrations and increased water temperatures. We propose a simple model with water temperature, nitrate–nitrogen and total phosphorus concentrations as input variables as a basis for formulation of regional eutrophication targets. Political decisions should be preceded by open discussion between policymakers and scientists to differentiate between real knowledge, assumptions or feelings. For optimal results, recommendations for reducing nutrient load should consider all sources, including urban stormwater and wastewater from rural houses, and should be founded on a balanced reduction in emissions of algae-available nutrients. In addition, climate change calls for more effective environmental policy to protect surface water resources.     

Biosynthesis of iron nanoparticles and their application in removing phosphorus from aqueous solutions

This paper reports the biosynthesis of nanoscale zero-valent iron (nZVI) using the extracts of Shirazi thyme leaf (Th-nZVI) and pistachio green hulls (P-nZVI). Scanning electron microscopy verified the successful synthesis of the poorly crystalline nZVI with a spherical shape and diameter in the range of 40–70 nm. According to X-ray diffraction and Fourier transform infrared spectroscope analyses, the synthesised nZVI were composed of iron oxides nanoparticles and ployphenol obtained from Shirazi thyme leaf and pistachio green hulls extracts acting as both reducing and capping agents. The phosphorus removal efficiency of Th-nZVI and P-nZVI increased with time and reached equilibrium at about 4 and 2h, respectively. Sorption of phosphorus on both sorbents was observed to be pH-dependent with maximum phosphorus removal occurring in the pH range of 2–5. Langmuir, Freundlich, Redlich–Peterson, and Temkin models were used to describe phosphorus sorption at pH 5 and maximum sorption capacity for Th-nZVI and P-nZVI was about 40.52 and 29.33?mg?g^?1, respectively. Correlation coefficient (R²) and standard errors of estimate showed that the Elovich model was better than other models at describing the kinetic data. These results suggested that the synthesised nZVI with Shirazi thyme leaf and pistachio green hulls extracts could be employed as an efficient sorbent for the remediation of phosphorus from contaminated water sources.     

Role of microorganisms and macrofauna in benthic phosphorus dynamics in the po river--Adriatic Sea frontal system: An experimental approach

Sediment biotic and abiotic attributes were determined during the PRISMA II oceanographic campaigns in the northern and central Adriatic Sea. The radiotracer orthophosphate 32 P was used under laboratory conditions to analyse the role of micro- and macrofauna in phosphorus dynamics at the water-sediment interface. Effects of infaunal suspensivores on microfungal growth were also investigated. Our findings emphasised: 1) significant differences in sediment 32 P uptake as related to the sampling area, occurrence of the pelagic frontal system, sediment grain size, microbial activity, and anoxia; 2) the crucial role played in 32 P dynamics by different tropho-functional groups r - r i.e ., infaunal filter-feeders and epifaunal detritivore characterising the benthic community of the northern Adriatic basin. The significant changes in ergosterol concentration (adopted as an index of microfungal growth) observed in sediments subjected to infaunal activity, eventually provided a comprehensive insight into macrofauna-microorganism interactions. The potential impact of macrofaunal activity in phosphorus dynamics in the Adriatic benthic system is discussed.     

Removal of nitrogen and phosphorus by eight strains of microalgae and their growth characteristics in Penaeus vannamei sewage北大核心CSCD

Microalgae are the most important primary productive forces in shrimp aquaculture systems. Microalgae not only provide oxygen and natural food for aquaculture objects, but they also absorb nitrogen (N) and phosphorus (P) to reduce water eutrophication. However, there are great differences in N and P absorption among different strains of microalgae. To maintain the sustainable development of shrimp aquaculture, the growth performances of eight microalgal strains in Penaeus vannamei sewage and N and P removal rates were investigated under laboratory conditions. The results indicated that the eight microalgal strains could reduce the N and P content in P. vannamei sewage to some extent. Microcystis aeruginosa, Chlamydomonas sp., and Chlorella pyrenoidosa grew very well, with average growth rates of 0.309 3, 0.246 9, and 0.215 5, respectively. There were significant differences in the removal efficiency among the different strains. The removal rates of total N by M. aeruginosa, Chlamydomonas sp., and C. pyrenoidosa were 74%, 69%, and 60%, respectively, at the end of the experiment, which were higher than the other species. M. aeruginosa and Chlamydomonas sp. had better total P removal efficiency than those of the other microalgal strains and removal rates were greater than 60%, and the second highest total P removal efficiency was by C. pyrenoidosa. Different types of microalgal strains had different absorption rates of different morphological nitrogen. M. aeruginosa and Chlamydomonas sp. had the highest nitrate nitrogen removal rate (approximately 70%). Chlamydomonas sp. had a fast and persistent removal rate of ammonia nitrogen, with the removal rate being as high as 100%. The removal efficiency of M. aeruginosa and C. pyrenoidosa were a little slower, and those of Scenedesmus obliquus, Synedra sp., and Navicula graciloides were the slowest. After 16 d, the removal rate reached more than 90%. Cryptomonas obovate and C. pyrenoidosa displayed the best removal rate of nitrite nitrogen, and the removal rate reached 80% on day 8, and the removal rate of C. obovata was more persistent. These results can provide scientific reference for the orientation and use of microalgae to remove pollutants in tailings water from shrimp aquaculture systems. © 2018 Science Press. All rights reserved.