The necessity to saline and sodic waters is sometimes used for irrigating agricultural activities under certain circumstances, but it is important to note that the use of these waters comes with specific consideration...The necessity to saline and sodic waters is sometimes used for irrigating agricultural activities under certain circumstances, but it is important to note that the use of these waters comes with specific considerations and limitations. One way to decrease undesirable effects of sodic waters on the physical and chemical properties of soils is to apply organic and chemical amendments within the soil. This study aimed to assess the effectiveness of saline water on soil acidity, alkalinity and nutrients leaching in sandy loamy soil at Bella flower farm, in Rwamagana District, Rwanda. The water used was from the Muhazi Lake which is classified as Class I (Saline water quality). Column leaching experiments using treated soils were then conducted under saturated conditions. The soil under experimental was first analyzed for its textural classification, soil properties and is classified as sandy loamy soil. The t-test was taken at 1%, 5% and 10% levels of statistical significance compared to control soil. The results indicated that the application of saline water to soils caused an increase in some soil nutrients like increase of Phosphorus (P), Potassium (K<sup>+</sup>), Magnesium (Mg2<sup>+</sup>), Sulphur (S), CN ratio and Sodium (Na<sup>+</sup>) and decreased soil texture, physical and chemical properties and remained soil nutrients. Consequently, the intensive addition of saline water leachates to soil in PVC pipes led to decreased of soil EC through leaching and a raiser Soluble Sodium Percentage (SSP). The rate of saline water application affected the increase accumulation of SAR and Na% in the top soil layers. The study indicated that saline water is an inefficient amendment for sandy soil with saline water irrigation. The study recommends further studies with similar topic with saline water irrigation, as it accentuated the alkalinity levels.展开更多
In Saint-Louis, Senegal, a constructed wetland with horizontal flow reed beds (FHa and FHb) has demonstrated significant efficacy in treating municipal wastewater. Analyzing various treatment stages, the system showed...In Saint-Louis, Senegal, a constructed wetland with horizontal flow reed beds (FHa and FHb) has demonstrated significant efficacy in treating municipal wastewater. Analyzing various treatment stages, the system showed only a slight temperature variation, from an influent average of 26.3°C to an effluent of 24.7°C. Electrical conductivity decreased from 1331 mS/cm to 974.5 mS/cm post-primary treatment, with suspended solids (SS) dramatically reduced from 718.9 mg/L to 5.7 mg/L in the final effluent. Biochemical oxygen demand (BOD5) and chemical oxygen demand (COD) saw a notable decrease, from initial levels of 655.6 mg/L and 1240 mg/L to 2.3 mg/L and 71.3 mg/L, respectively. Nitrogenous compounds (N-TN) and phosphates () also decreased significantly, indicating the system’s nutrient removal capacity. Microbiological analysis revealed a reduction in fecal coliforms from 7.5 Ulog/100ml to 1.8 Ulog/100ml and a complete elimination of helminth eggs. The presence of Phragmites and Typha was instrumental in enhancing these reductions. The system’s compliance with the Senegalese standards for disposal into natural environments, WHO recommendations for unrestricted water reuse in irrigation, and the European legislation for water reuse was established. The effluent quality met the stringent criteria for various classes of agricultural reuse, illustrating the system’s potential for sustainable water management. This wetland model presents a robust solution for water-stressed regions, ensuring environmental protection while supporting agricultural needs. The study calls for ongoing research to further refine the system for optimal, reliable wastewater treatment and water resource sustainability.展开更多
Desert ephemeral plants play an important role in desert ecosystem.Soil water availability is considered as the major restrictive factor limiting the growth of ephemeral plants.Moreover,arbuscular mycorrhizal fungi(A...Desert ephemeral plants play an important role in desert ecosystem.Soil water availability is considered as the major restrictive factor limiting the growth of ephemeral plants.Moreover,arbuscular mycorrhizal fungi(AM fungi) are widely reported to improve the growth of desert ephemerals.The present study aimed to test the hypothesis of that AM fungi could alleviate drought stress of desert ephemeral Plantago minuta,and AM fungal functions reduced with the improvement of soil water content.A pot experiment was carried out with three levels of soil water contents(4.5%,9.0%,and 15.8%(w/w)),and three AM inoculation treatments(Glomus mosseae,Glomus etunicatum and non-inoculation).The results indicate that mycorrhizal colonization rate decreased with the increase of soil water availability.Inoculation improved plant growth and N,P and K acquisition in both shoots and roots regardless water treatments.When comparing the two fungi,plants inoculated with G.mosseae performed better than those inoculated with G.etunicatum in terms of plant growth and nutrient acquisition.These results showed that ameliorative soil water did not suppress arbuscular mycorrhizal fungal functions in improving growth and nutrient acquisition of desert ephemeral Plantago minuta.展开更多
Faced with rapid population growth and fresh water scarcity, reuse of reclaimed water is growing worldwide and becoming an integral part of water resource management. Our objective was to determine the fate of nutrien...Faced with rapid population growth and fresh water scarcity, reuse of reclaimed water is growing worldwide and becoming an integral part of water resource management. Our objective was to determine the fate of nutrients, trace metals, bacteria, and legacy organic compounds (organochlorine pesticides) in the recycled water from five commercial nursery ponds in Florida. The pH of recycled water at all sites was 8.1 - 9.3, except one site (6.5), while the electrical conductivity (EC) was 0.31 - 0.36 dS/m. Concentrations of trace metals in recycled water were low: Fe (0.125 - 0.367 mg/L), Al (0.126 - 0.169 mg/L), B (0.104 - 0.153 mg/L), Zn (0.123 - 0.211 mg/L), and Mn (<0.111 mg/L). Total phosphorus (P) and total nitrogen (N) in the recycled water were 0.35 - 1.00 mg/L and 1.56 - 2.30 mg/L, respectively. Among organochlorine pesticides, endrin aldehyde was the only pesticide detected in all nursery recycled water ponds, with concentrations from 0.04 to 0.10 μg/L at four sites and 1.62 μg/L at one site. Other detected pesticides in recycled water were methoxychlor, endosulfan sulfate, dichlorodiphenyldichloroethylene (DDE) and α-chlorodane, with concentrations < 0.20 μg/L. Total coliforms and Escherichia coli (E. coli) in recycled water were 20 - 50 colony forming units (CFU)/100 mL. We conclude that the concentrations of various inorganic and organic compounds in recycled water are very low and do not appear to be problematic for irrigation purposes in Florida’s nursery recycled water ponds.展开更多
Root function in uptake of nutrients and the effect of soil water on the transfer and distribution of NO3^--N in arable soil were studied using summer maize (Zea mays L. var. Shandan 9) as a testing crop. Results sh...Root function in uptake of nutrients and the effect of soil water on the transfer and distribution of NO3^--N in arable soil were studied using summer maize (Zea mays L. var. Shandan 9) as a testing crop. Results showed that root growth and water supply had a significant effect on NO3^--N transfer and made NO3^--N distributed evenly from bulk soil to rhizosphere soil. Under a natural condition with irrigation, the difference of NO3^--N concentration at different distance points from a maize plant was smaller, while obvious difference of NO3^--N concentration was observed under conditions of limited root growth space without irrigation. Whether root growth space was restricted or not, the content of soil NO3^--N decreased gradually from 10 to 0 cm from the plant, being opposite to the root absorbing area in soils. When root-grown space was limited, changes of NO3^--N concentration at different distances from a plant were similar to that of water content in tendency. Results showed that NO3^--N could be transferred as solute to plant root systems with water uptake by plants. However, the transfer and distribution of NH4^--N were not influenced by root growth and soil water supply, being different to NO3^--N.展开更多
A study was carried out to determine the temporal and spatial distribution of nutrients and Harmful Algal Blooming species (HABs) to establish the relationship between nutrient concentrations and HABs density in the c...A study was carried out to determine the temporal and spatial distribution of nutrients and Harmful Algal Blooming species (HABs) to establish the relationship between nutrient concentrations and HABs density in the coastal water of Kota Belud, Sabah, Malaysia. Eight stations were set up in four transects (each transect had two stations;one 500 meters seawards from shoreline, and another five kilometers seawards from shoreline) along the Kota Belud coastal area. Phytoplankton samples, water samples and in situ environmental parameters were collected during dry and wet seasons. Altogether nine HABs species were identified from the study area, where six species (Pyrodinium bahamense, Prorocentum micans, Neoceratium furca, Prorocentum sigmoides, Dinophysis caudate, and Neoceratium fursus) belonged to Dinophyceae and three species (Thalassionema nitzchoioides, Chatoceros affinis, Rhizosolenia sp.) belonged to Bacillariophyceae. Among nine species, Chatoceros affinis was the most abundance composed of 80.6% of total species recorded from all stations during study period. Among the toxic producing Dinoflagellate, Pyrodinium bahamense bloom (>10<sup>3</sup> cells/l) was observed during study period. Trong linear relationship (r<sup>2</sup> = 0.80) was observed between the cell density and concentration of nitrate nitrogen. Relationship between cell density and phosphate phosphorus was poor (r<sup>2</sup> = 0.51). The study showed that increasing in nutrient concentrations resulted in the increasing of HABs density. Nitrate was seen to be more important than phosphate in Kota Belud water as limiting factor of the growth of HABs.展开更多
Sudangrass and ryegrass rotation is a new type of cropping system in Jianghan Plain,which develops very fast in recent years.So,it is essential to work out the optimal nutrients and water management measures in this n...Sudangrass and ryegrass rotation is a new type of cropping system in Jianghan Plain,which develops very fast in recent years.So,it is essential to work out the optimal nutrients and water management measures in this new system.The effect of NPK fertilizer on yield of forage grass,nutrients and water utilization under sudangrass and ryegrass rotation was studied through continuous pot experiments for three years.The results showed that NPK combination could significantly improve the yield of forage grasses.The total yields during the periods of 2005-2006,2006-2007 and 2007-2008 were 1 690.0,2 091.3 and 1 770.7 g/pot,respectively.The yields in PK treatment were 700.7,1 256.9 and 856.3% lower than those of NPK treatment,while the yields in NK treatment were 426.3,384.9 and 792.3% lower than those of NPK treatment,respectively.Similarly,the yields in NP treatment were 15.9,4.4 and 10.6% lower than those of NPK treatment,respectively.The NPK combination was found to improve the nutrients uptake,and the total N uptakes during the above periods were 10.0,14.8 and 10.6 times higher than that of PK treatment,respectively,and 3.7,1.8 and 5.1 times higher than those of NK treatment,respectively,but,were similar to NP treatment.The total P uptakes were 4.6,6.8 and 5.3 times higher than those of PK treatment,and were 2.4,2.3 and 2.9 times higher than those of NK treatment,respectively,but were similar to NP treatment.The total K uptakes were 5.2,8.4 and 4.9 times higher than that of PK treatment,3.9,2.3 and 3.9 times higher than those of NK treatment,and 80.9,57.4 and 200.5% higher than those of NP treatment,respectively.Water productivity for three years time periods were 16.5,16.1 and 16.2 kg m-3,and were 3.8,5.4 and 4.2 times higher than those of PK treatment,2.3,1.3 and 2.6 times higher than those of NK treatment,and were 16.4,8.8 and 22.4% higher than those of NP treatment,respectively.The soil pH was decreased and soil organic matter was increased in all treatments with increase in the time of sudangrass and ryegrass rotation system.The total soil N was increased in NP,NK and NPK treatments,while it was stable in PK treatment.The available P in NP,PK and NPK treatments was increased significantly,while it was stable in NK treatment.The slow releasing K and available K were increased significantly in NK and PK treatments,but decreased in NP and NPK treatments.The treatment with NPK combination was found to improve the yield of forage,nutrient uptake and soil fertility in sudangrass and ryegrass rotation system.展开更多
An understanding of nutrient movement in soil is important for developing management strategies to minimize nutrient leaching and surface movement, thus improving nutrient uptake by plants, maintaining a sustainable s...An understanding of nutrient movement in soil is important for developing management strategies to minimize nutrient leaching and surface movement, thus improving nutrient uptake by plants, maintaining a sustainable soil system, and even protecting groundwater quality. Polyacrylamide (PAM) is known as one of soil conditioner that functions to stabilize soil structure, increase infiltration, and reduce surface runoff. This study assesses the effects of PAM on the vertical movement of soil-water and major/minor nutrients (NO3-N, NH3-N, T-N, PO4-P, T-P, K, Ca, Mg, and Fe) in soils. Saturated hydraulic conductivity (Ksat) increases with increasing PAM concen- trations up to 10 mg·L-1 for sand and 20 mg·L-1 for a mixture of sand and clay. Decreases in the loss of soluble nutrients, particularly NH3-N, PO4-P and T-P, are observed as PAM concentrations increase. In contrast, PAM concentration has no effect on nitrate and minor nutrient levels. These results indicate that the application of PAM may be a viable method for protecting water bodies from excessive nutrients and improving nutrient availability for plants.展开更多
The distribution of nitrate, nitrite, ammonia, phosphate and silicate in pore-water and their exchange between sediments and overlying waters (benthic flux) were determined at nine locations on the shelve of Huangha...The distribution of nitrate, nitrite, ammonia, phosphate and silicate in pore-water and their exchange between sediments and overlying waters (benthic flux) were determined at nine locations on the shelve of Huanghai and East China Seas. On the basis of the redox potential of sediments and nutrients distributions in the pore-waters, it is found that the benthic sediments are being in a suboxic to anoxic environment in the Huanghai and East China Seas. The nutrients distribution in the pore-waters is mainly controlled by the sediment environment, and ammonia is the major inorganic nitrogen in the pore-waters. On the basis of benthic fluxes of nutrients calculated us- ing Fick's first law, there is remarkable efflux of ammonia, dissolved inorganic nitrogen(DIN), phosphate and silicate from the sediments to the overlying waters in the study area, and their benthic fluxes are 299.3-2 214.8, 404.4-2 159.5 , 5.5-18.8 and 541.3-1 781.6 μmol/(m^2·d) respectively, and perhaps they are the major source of dissolved inorganic nitrogen, phosphate and silicate for the overlying water. At most stations, the nitrate flux was from the overlying waters to the sediments, which suggests that suboxic organic matter decomposition via denitrification is dominated in the most area of Huanghai and East China Seas. High benthic fluxes appearing in the coastal area and relatively low benthic fluxes occurring in the shelf area are found and are consistent with pri- mary productivity zoning in the study area. On the other hand, the ammonia flux displays an exponential decrease with water depth increase and an exponential increase with the bottom water temperature. However, others do not display this trend.展开更多
The profiles of nutrient salts in the interstitial water of sediment were analyzed in the Zhu- jiang Estuary in the summer of 1999, and based on the profiles of content and characteristic of nutri- ents, the relations...The profiles of nutrient salts in the interstitial water of sediment were analyzed in the Zhu- jiang Estuary in the summer of 1999, and based on the profiles of content and characteristic of nutri- ents, the relationship between nutrients in the interstitial water and organic matter decomposition in sediment was discussed. The results showed that ammonium with high content was the main existence form of nutrients in the interstital water of sediment, and the organic matter decomposition was com- pleted in anaerobic condition. The increase of ammonium content in the bottom water resulted from the decomposition of organic matter and release of metabolic production, and the ammonium bottom flux was an important resource for nutrients geochemistry in the Zhujiang Estuary.展开更多
During the storage of water and the initial running of a reservoir, part of the dissolved nutrients released from the soil in water will effect water quality. Taking Qinglongshan Reservoir as an example, estimating th...During the storage of water and the initial running of a reservoir, part of the dissolved nutrients released from the soil in water will effect water quality. Taking Qinglongshan Reservoir as an example, estimating the value of the contribution of dissolved nutrients to the water quality and analyzing the trend or level of the dissolved nutrients effecting on the water quality under the soil nutrient inquiring, the soil nutrient monitoring, and the dissolving experiment of nutrients released from soil, also according to the capacity curve of Qinglongshan Reservoir.展开更多
Filter-feeding shellfish are common benthos and significantly affect the biogeochemical cycle in the shallow coastal ecosystems.Ark clam Scapharca subcrenata is one of the widely cultured bivalve species in many coast...Filter-feeding shellfish are common benthos and significantly affect the biogeochemical cycle in the shallow coastal ecosystems.Ark clam Scapharca subcrenata is one of the widely cultured bivalve species in many coastal areas owing to its tremendous economic value.However,there is little information regarding the effects of the bioturbation of S.subcrenata on the fluxes of nutrient exchange in the sediment-water interface(SWI).In this regard,S.subcrenata was sampled during October 2016 to determine the effects of its bioturbation activity on the nutrient exchange flux of the SWI.The results showed that the biological activity of S.subcrenata could increase the diffusion depth and the rate of the nutrients exchange in the sediments.The bioturbation of S.subcrenata could allow the nutrients to permeate into the surface sediments at 6-10cm and increase the release rate of nutrients at the SWI.The releasing fluxes of DIN and PO43−-P in the culture area were found to be around three times higher than that in the non-cultured region.The culture of S.subcrenata has been proved to be an important contributor to nutrient exchange across the SWI in the farming area of Haizhou Bay.Nutrients exchange in the SWI contributes a part of 86%DIN,71%PO43−-P and 18%SiO32−-Si for the aquaculture farm.展开更多
Investigations of sediment-water fluxes of nutrients in the Bohai Sea were carried out in September - October 1998 and April - May 1999. The exchange fluxes of nutrients between sediment and sea water were determined ...Investigations of sediment-water fluxes of nutrients in the Bohai Sea were carried out in September - October 1998 and April - May 1999. The exchange fluxes of nutrients between sediment and sea water were determined by incubating the core-top sediments with overlying water aerated with air. The benthic fluxes of NO3- , NO2- , NH4+ , DIN, DON and TON in the first cruise and the flux-es of NO3 , NO2- , NH4+ , DIN, DON, TDN, PO43- , DOP and TDP in the second cruise were measured. The exchange fluxes of nutrients in fall were higher than in spring. The benthic nutrient fluxes represented 15% -55% of nutrient budgets in the Bohai Sea.展开更多
The concentration and profile characters of nutrients in sediment pore water of the South Ocean, sampled during the cruise of CHINARE-18 of the austral summer 2001/02 were determined. The results show that the content...The concentration and profile characters of nutrients in sediment pore water of the South Ocean, sampled during the cruise of CHINARE-18 of the austral summer 2001/02 were determined. The results show that the content of SiO3-Si and NH4- N were much higher than other nutrients. The profile of SiO3-Si was characterized with sharp gradients near the sediment-water interface, profile distribution of silicate show that during the diagenetie reaction of silicate, dissolution was the main part. The organic matter decomposition was occurred under the anaerobic condition. Benthic fluxes of SiO3-Si, NH4-N were from pore water to overlying water, and regeneration of silicate and ammonium were the main part of the nutrient regeneration from the pore water of the study area.展开更多
Material fluxes (e.g., nutrients) from coastal waters to offshore areas play an important role in controlling the water quality of the adjacent sea areas not only by increasing nutrient concentration hut also by cha...Material fluxes (e.g., nutrients) from coastal waters to offshore areas play an important role in controlling the water quality of the adjacent sea areas not only by increasing nutrient concentration hut also by changing nutrient structures. In this study, naturally occurring isotopes, ^226Ra and ^228Ra, were measured with the alpha spectrometry in the Wenjiao-Wenchang and Wanquan estuaries and adjacent sea areas along the east coast of Hainan Island. The excess ^226Ra and ^228Ra activities were observed by comparison with the values derived from the conservative mixing of freshwater and seawater end-members in both estuaries. Using a one-dimensional diffusion model, the horizontal eddy diffusion coefficient of 3.1 6 × 10^5 cm^2/s, for nutrients diffusing from their sources, was derived from 228Ra activities. Consequently, the corresponding nutrient fluxes flowing into the coastal waters were assessed. The results can provide useful information for the study of the mixing and exchange processes of coastal waters as well as dissoluble pollutant transport in this sea area.展开更多
We conducted a study on a model drinking water distribution system to evaluate the impact of nutrient in the form of sodium acetate on the growth and survival of coliform and heterotrophic plate count (HPC) bacteria f...We conducted a study on a model drinking water distribution system to evaluate the impact of nutrient in the form of sodium acetate on the growth and survival of coliform and heterotrophic plate count (HPC) bacteria for a maximum of 21 days residence time of water in pipes. Our results show that, besides the nutrient added and the absence of any additional source of contamination and additional supply of nutrient, there was significant growth of the above mentioned bacteria in the pipes and bottles for a couple of days, after which the bacterial population began to decrease. The results indicate that the bacteria used the nutrient to grow and multiply until the nutrient was totally consumed and became depleted in the bulk water phase, after which the bacterial population reached a near stationary level and subsequently declined. This suggests the death of some of the bacteria and their dead cells were used by other bacteria for growth and survival. Using a detection limit of 3.3 CFU/100 mL for the coliforms, the study shows that after sometime, no bacteria were found in the water phase of the pipe, however, the biofilm in the pipes still harbored some of the bacteria. The results have revealed that the bacteria also have the tendency to move from the water phase to the biofilm since the latter provides a more suitable environment for bacteria to thrive on and grow, thus prolonging their survival in the system.展开更多
Wastewater treatment plays a crucial role in preserving water quality in receiving streams;however, continuous nutrient enrichment can diminish the retention capacity of rivers. The objectives of this study were to ev...Wastewater treatment plays a crucial role in preserving water quality in receiving streams;however, continuous nutrient enrichment can diminish the retention capacity of rivers. The objectives of this study were to evaluate the effects of wastewater treatment plant effluent and river discharge on water chemistry and determine the retention efficiency of nutrients added in the effluent along a 6.1-km reach of a 5th-order stream in the Ozark Highlands of northwest Arkansas. From 2006 through 2007, effluent discharge increased river nitrite, soluble reactive P (SRP), and total organic C (TOC) and conductivity. As river discharge increased, DO and turbidity increased, but water temperature, conductivity, and TOC decreased. Net nutrient uptake lengths were inconsistent for NO3-N, NH4-N, and SRP. Results indicated that the fluvial channel acted as both a sink and a source of NO3-N and SRP, but the channel always acted as a sink for NH4-N with a significantly positive retention coefficient that indicated only 12% of added NH4-N was retained in the study reach. The effluent discharge increased the concentrations of seven water quality parameters, and it appears the long-term enrichment has rendered the immediate-downstream reach ineffective as a nutrient sink. Nutrients added in the effluent were generally transported with little to no uptake or transformation, thus river chemical concentrations beyond the study reach have likely been influenced by this effluent discharge.展开更多
文摘The necessity to saline and sodic waters is sometimes used for irrigating agricultural activities under certain circumstances, but it is important to note that the use of these waters comes with specific considerations and limitations. One way to decrease undesirable effects of sodic waters on the physical and chemical properties of soils is to apply organic and chemical amendments within the soil. This study aimed to assess the effectiveness of saline water on soil acidity, alkalinity and nutrients leaching in sandy loamy soil at Bella flower farm, in Rwamagana District, Rwanda. The water used was from the Muhazi Lake which is classified as Class I (Saline water quality). Column leaching experiments using treated soils were then conducted under saturated conditions. The soil under experimental was first analyzed for its textural classification, soil properties and is classified as sandy loamy soil. The t-test was taken at 1%, 5% and 10% levels of statistical significance compared to control soil. The results indicated that the application of saline water to soils caused an increase in some soil nutrients like increase of Phosphorus (P), Potassium (K<sup>+</sup>), Magnesium (Mg2<sup>+</sup>), Sulphur (S), CN ratio and Sodium (Na<sup>+</sup>) and decreased soil texture, physical and chemical properties and remained soil nutrients. Consequently, the intensive addition of saline water leachates to soil in PVC pipes led to decreased of soil EC through leaching and a raiser Soluble Sodium Percentage (SSP). The rate of saline water application affected the increase accumulation of SAR and Na% in the top soil layers. The study indicated that saline water is an inefficient amendment for sandy soil with saline water irrigation. The study recommends further studies with similar topic with saline water irrigation, as it accentuated the alkalinity levels.
文摘In Saint-Louis, Senegal, a constructed wetland with horizontal flow reed beds (FHa and FHb) has demonstrated significant efficacy in treating municipal wastewater. Analyzing various treatment stages, the system showed only a slight temperature variation, from an influent average of 26.3°C to an effluent of 24.7°C. Electrical conductivity decreased from 1331 mS/cm to 974.5 mS/cm post-primary treatment, with suspended solids (SS) dramatically reduced from 718.9 mg/L to 5.7 mg/L in the final effluent. Biochemical oxygen demand (BOD5) and chemical oxygen demand (COD) saw a notable decrease, from initial levels of 655.6 mg/L and 1240 mg/L to 2.3 mg/L and 71.3 mg/L, respectively. Nitrogenous compounds (N-TN) and phosphates () also decreased significantly, indicating the system’s nutrient removal capacity. Microbiological analysis revealed a reduction in fecal coliforms from 7.5 Ulog/100ml to 1.8 Ulog/100ml and a complete elimination of helminth eggs. The presence of Phragmites and Typha was instrumental in enhancing these reductions. The system’s compliance with the Senegalese standards for disposal into natural environments, WHO recommendations for unrestricted water reuse in irrigation, and the European legislation for water reuse was established. The effluent quality met the stringent criteria for various classes of agricultural reuse, illustrating the system’s potential for sustainable water management. This wetland model presents a robust solution for water-stressed regions, ensuring environmental protection while supporting agricultural needs. The study calls for ongoing research to further refine the system for optimal, reliable wastewater treatment and water resource sustainability.
基金funded by the Foundation for University Key Teacher by Henan Educational Committee (2013GGJS070)the National Basic Research Program of China (2014CB954202)+1 种基金the National Natural Science Foundation of China (40971150)the China Scholarship Council (201208410020)
文摘Desert ephemeral plants play an important role in desert ecosystem.Soil water availability is considered as the major restrictive factor limiting the growth of ephemeral plants.Moreover,arbuscular mycorrhizal fungi(AM fungi) are widely reported to improve the growth of desert ephemerals.The present study aimed to test the hypothesis of that AM fungi could alleviate drought stress of desert ephemeral Plantago minuta,and AM fungal functions reduced with the improvement of soil water content.A pot experiment was carried out with three levels of soil water contents(4.5%,9.0%,and 15.8%(w/w)),and three AM inoculation treatments(Glomus mosseae,Glomus etunicatum and non-inoculation).The results indicate that mycorrhizal colonization rate decreased with the increase of soil water availability.Inoculation improved plant growth and N,P and K acquisition in both shoots and roots regardless water treatments.When comparing the two fungi,plants inoculated with G.mosseae performed better than those inoculated with G.etunicatum in terms of plant growth and nutrient acquisition.These results showed that ameliorative soil water did not suppress arbuscular mycorrhizal fungal functions in improving growth and nutrient acquisition of desert ephemeral Plantago minuta.
文摘Faced with rapid population growth and fresh water scarcity, reuse of reclaimed water is growing worldwide and becoming an integral part of water resource management. Our objective was to determine the fate of nutrients, trace metals, bacteria, and legacy organic compounds (organochlorine pesticides) in the recycled water from five commercial nursery ponds in Florida. The pH of recycled water at all sites was 8.1 - 9.3, except one site (6.5), while the electrical conductivity (EC) was 0.31 - 0.36 dS/m. Concentrations of trace metals in recycled water were low: Fe (0.125 - 0.367 mg/L), Al (0.126 - 0.169 mg/L), B (0.104 - 0.153 mg/L), Zn (0.123 - 0.211 mg/L), and Mn (<0.111 mg/L). Total phosphorus (P) and total nitrogen (N) in the recycled water were 0.35 - 1.00 mg/L and 1.56 - 2.30 mg/L, respectively. Among organochlorine pesticides, endrin aldehyde was the only pesticide detected in all nursery recycled water ponds, with concentrations from 0.04 to 0.10 μg/L at four sites and 1.62 μg/L at one site. Other detected pesticides in recycled water were methoxychlor, endosulfan sulfate, dichlorodiphenyldichloroethylene (DDE) and α-chlorodane, with concentrations < 0.20 μg/L. Total coliforms and Escherichia coli (E. coli) in recycled water were 20 - 50 colony forming units (CFU)/100 mL. We conclude that the concentrations of various inorganic and organic compounds in recycled water are very low and do not appear to be problematic for irrigation purposes in Florida’s nursery recycled water ponds.
基金the National Natural Science Foundation of China (NSFC) (30230230).
文摘Root function in uptake of nutrients and the effect of soil water on the transfer and distribution of NO3^--N in arable soil were studied using summer maize (Zea mays L. var. Shandan 9) as a testing crop. Results showed that root growth and water supply had a significant effect on NO3^--N transfer and made NO3^--N distributed evenly from bulk soil to rhizosphere soil. Under a natural condition with irrigation, the difference of NO3^--N concentration at different distance points from a maize plant was smaller, while obvious difference of NO3^--N concentration was observed under conditions of limited root growth space without irrigation. Whether root growth space was restricted or not, the content of soil NO3^--N decreased gradually from 10 to 0 cm from the plant, being opposite to the root absorbing area in soils. When root-grown space was limited, changes of NO3^--N concentration at different distances from a plant were similar to that of water content in tendency. Results showed that NO3^--N could be transferred as solute to plant root systems with water uptake by plants. However, the transfer and distribution of NH4^--N were not influenced by root growth and soil water supply, being different to NO3^--N.
文摘A study was carried out to determine the temporal and spatial distribution of nutrients and Harmful Algal Blooming species (HABs) to establish the relationship between nutrient concentrations and HABs density in the coastal water of Kota Belud, Sabah, Malaysia. Eight stations were set up in four transects (each transect had two stations;one 500 meters seawards from shoreline, and another five kilometers seawards from shoreline) along the Kota Belud coastal area. Phytoplankton samples, water samples and in situ environmental parameters were collected during dry and wet seasons. Altogether nine HABs species were identified from the study area, where six species (Pyrodinium bahamense, Prorocentum micans, Neoceratium furca, Prorocentum sigmoides, Dinophysis caudate, and Neoceratium fursus) belonged to Dinophyceae and three species (Thalassionema nitzchoioides, Chatoceros affinis, Rhizosolenia sp.) belonged to Bacillariophyceae. Among nine species, Chatoceros affinis was the most abundance composed of 80.6% of total species recorded from all stations during study period. Among the toxic producing Dinoflagellate, Pyrodinium bahamense bloom (>10<sup>3</sup> cells/l) was observed during study period. Trong linear relationship (r<sup>2</sup> = 0.80) was observed between the cell density and concentration of nitrate nitrogen. Relationship between cell density and phosphate phosphorus was poor (r<sup>2</sup> = 0.51). The study showed that increasing in nutrient concentrations resulted in the increasing of HABs density. Nitrate was seen to be more important than phosphate in Kota Belud water as limiting factor of the growth of HABs.
基金supported by the International Plant Nutrition Institute (Hubei-22)
文摘Sudangrass and ryegrass rotation is a new type of cropping system in Jianghan Plain,which develops very fast in recent years.So,it is essential to work out the optimal nutrients and water management measures in this new system.The effect of NPK fertilizer on yield of forage grass,nutrients and water utilization under sudangrass and ryegrass rotation was studied through continuous pot experiments for three years.The results showed that NPK combination could significantly improve the yield of forage grasses.The total yields during the periods of 2005-2006,2006-2007 and 2007-2008 were 1 690.0,2 091.3 and 1 770.7 g/pot,respectively.The yields in PK treatment were 700.7,1 256.9 and 856.3% lower than those of NPK treatment,while the yields in NK treatment were 426.3,384.9 and 792.3% lower than those of NPK treatment,respectively.Similarly,the yields in NP treatment were 15.9,4.4 and 10.6% lower than those of NPK treatment,respectively.The NPK combination was found to improve the nutrients uptake,and the total N uptakes during the above periods were 10.0,14.8 and 10.6 times higher than that of PK treatment,respectively,and 3.7,1.8 and 5.1 times higher than those of NK treatment,respectively,but,were similar to NP treatment.The total P uptakes were 4.6,6.8 and 5.3 times higher than those of PK treatment,and were 2.4,2.3 and 2.9 times higher than those of NK treatment,respectively,but were similar to NP treatment.The total K uptakes were 5.2,8.4 and 4.9 times higher than that of PK treatment,3.9,2.3 and 3.9 times higher than those of NK treatment,and 80.9,57.4 and 200.5% higher than those of NP treatment,respectively.Water productivity for three years time periods were 16.5,16.1 and 16.2 kg m-3,and were 3.8,5.4 and 4.2 times higher than those of PK treatment,2.3,1.3 and 2.6 times higher than those of NK treatment,and were 16.4,8.8 and 22.4% higher than those of NP treatment,respectively.The soil pH was decreased and soil organic matter was increased in all treatments with increase in the time of sudangrass and ryegrass rotation system.The total soil N was increased in NP,NK and NPK treatments,while it was stable in PK treatment.The available P in NP,PK and NPK treatments was increased significantly,while it was stable in NK treatment.The slow releasing K and available K were increased significantly in NK and PK treatments,but decreased in NP and NPK treatments.The treatment with NPK combination was found to improve the yield of forage,nutrient uptake and soil fertility in sudangrass and ryegrass rotation system.
文摘An understanding of nutrient movement in soil is important for developing management strategies to minimize nutrient leaching and surface movement, thus improving nutrient uptake by plants, maintaining a sustainable soil system, and even protecting groundwater quality. Polyacrylamide (PAM) is known as one of soil conditioner that functions to stabilize soil structure, increase infiltration, and reduce surface runoff. This study assesses the effects of PAM on the vertical movement of soil-water and major/minor nutrients (NO3-N, NH3-N, T-N, PO4-P, T-P, K, Ca, Mg, and Fe) in soils. Saturated hydraulic conductivity (Ksat) increases with increasing PAM concen- trations up to 10 mg·L-1 for sand and 20 mg·L-1 for a mixture of sand and clay. Decreases in the loss of soluble nutrients, particularly NH3-N, PO4-P and T-P, are observed as PAM concentrations increase. In contrast, PAM concentration has no effect on nitrate and minor nutrient levels. These results indicate that the application of PAM may be a viable method for protecting water bodies from excessive nutrients and improving nutrient availability for plants.
基金supported by the Major State Basic Research Program of China under contract No.G1999043704the National Natural Science Foundation of China under contract No.40206012.
文摘The distribution of nitrate, nitrite, ammonia, phosphate and silicate in pore-water and their exchange between sediments and overlying waters (benthic flux) were determined at nine locations on the shelve of Huanghai and East China Seas. On the basis of the redox potential of sediments and nutrients distributions in the pore-waters, it is found that the benthic sediments are being in a suboxic to anoxic environment in the Huanghai and East China Seas. The nutrients distribution in the pore-waters is mainly controlled by the sediment environment, and ammonia is the major inorganic nitrogen in the pore-waters. On the basis of benthic fluxes of nutrients calculated us- ing Fick's first law, there is remarkable efflux of ammonia, dissolved inorganic nitrogen(DIN), phosphate and silicate from the sediments to the overlying waters in the study area, and their benthic fluxes are 299.3-2 214.8, 404.4-2 159.5 , 5.5-18.8 and 541.3-1 781.6 μmol/(m^2·d) respectively, and perhaps they are the major source of dissolved inorganic nitrogen, phosphate and silicate for the overlying water. At most stations, the nitrate flux was from the overlying waters to the sediments, which suggests that suboxic organic matter decomposition via denitrification is dominated in the most area of Huanghai and East China Seas. High benthic fluxes appearing in the coastal area and relatively low benthic fluxes occurring in the shelf area are found and are consistent with pri- mary productivity zoning in the study area. On the other hand, the ammonia flux displays an exponential decrease with water depth increase and an exponential increase with the bottom water temperature. However, others do not display this trend.
基金This study was supported by the Science and Technology University of Hong Kong and the State Oceanic Administrationof China.
文摘The profiles of nutrient salts in the interstitial water of sediment were analyzed in the Zhu- jiang Estuary in the summer of 1999, and based on the profiles of content and characteristic of nutri- ents, the relationship between nutrients in the interstitial water and organic matter decomposition in sediment was discussed. The results showed that ammonium with high content was the main existence form of nutrients in the interstital water of sediment, and the organic matter decomposition was com- pleted in anaerobic condition. The increase of ammonium content in the bottom water resulted from the decomposition of organic matter and release of metabolic production, and the ammonium bottom flux was an important resource for nutrients geochemistry in the Zhujiang Estuary.
文摘During the storage of water and the initial running of a reservoir, part of the dissolved nutrients released from the soil in water will effect water quality. Taking Qinglongshan Reservoir as an example, estimating the value of the contribution of dissolved nutrients to the water quality and analyzing the trend or level of the dissolved nutrients effecting on the water quality under the soil nutrient inquiring, the soil nutrient monitoring, and the dissolving experiment of nutrients released from soil, also according to the capacity curve of Qinglongshan Reservoir.
基金supported by the Young Orient Scholars Programme of Shanghaithe Doctoral Scientific Research Starting Foundation of Shanghai Ocean University+2 种基金the Shanghai Special Research Fund for Training College’s Young Teachersthe Fund for Ministry of Agriculture Readjusting the Industrial Structure: Sea Farming Demonstration Project of Haizhou Bay in Jiangsu Province (Nos. D-8006-12-0018, D8006-15-8014)the Special Fund for Agro-Scientific Research in the Public Interest (No. 201303047)
文摘Filter-feeding shellfish are common benthos and significantly affect the biogeochemical cycle in the shallow coastal ecosystems.Ark clam Scapharca subcrenata is one of the widely cultured bivalve species in many coastal areas owing to its tremendous economic value.However,there is little information regarding the effects of the bioturbation of S.subcrenata on the fluxes of nutrient exchange in the sediment-water interface(SWI).In this regard,S.subcrenata was sampled during October 2016 to determine the effects of its bioturbation activity on the nutrient exchange flux of the SWI.The results showed that the biological activity of S.subcrenata could increase the diffusion depth and the rate of the nutrients exchange in the sediments.The bioturbation of S.subcrenata could allow the nutrients to permeate into the surface sediments at 6-10cm and increase the release rate of nutrients at the SWI.The releasing fluxes of DIN and PO43−-P in the culture area were found to be around three times higher than that in the non-cultured region.The culture of S.subcrenata has been proved to be an important contributor to nutrient exchange across the SWI in the farming area of Haizhou Bay.Nutrients exchange in the SWI contributes a part of 86%DIN,71%PO43−-P and 18%SiO32−-Si for the aquaculture farm.
基金This study was supported by the special Funds from National Key Basic Research Program of China under contract No. G1999043705
文摘Investigations of sediment-water fluxes of nutrients in the Bohai Sea were carried out in September - October 1998 and April - May 1999. The exchange fluxes of nutrients between sediment and sea water were determined by incubating the core-top sediments with overlying water aerated with air. The benthic fluxes of NO3- , NO2- , NH4+ , DIN, DON and TON in the first cruise and the flux-es of NO3 , NO2- , NH4+ , DIN, DON, TDN, PO43- , DOP and TDP in the second cruise were measured. The exchange fluxes of nutrients in fall were higher than in spring. The benthic nutrient fluxes represented 15% -55% of nutrient budgets in the Bohai Sea.
基金funded by the:"National Key Technology R&D Program project (2006BAB18B04)""The scientific research fund of the Second Institute of Oceanography,SOA(JT0706)"Polar stratagem fund"The mechanism of biogenic silica preservation in the Prydz Bay and its biogeochemical significance"
文摘The concentration and profile characters of nutrients in sediment pore water of the South Ocean, sampled during the cruise of CHINARE-18 of the austral summer 2001/02 were determined. The results show that the content of SiO3-Si and NH4- N were much higher than other nutrients. The profile of SiO3-Si was characterized with sharp gradients near the sediment-water interface, profile distribution of silicate show that during the diagenetie reaction of silicate, dissolution was the main part. The organic matter decomposition was occurred under the anaerobic condition. Benthic fluxes of SiO3-Si, NH4-N were from pore water to overlying water, and regeneration of silicate and ammonium were the main part of the nutrient regeneration from the pore water of the study area.
基金supported by the Natural Science Foundation of China (Grant No.41021064)the Sino-German Cooperation Project of Ministry of Science and Technology of China (Grant No.2007DFB20380)the Ph. D. Program Scholarship Fund of East China Normal University (Grant No.2010047)
文摘Material fluxes (e.g., nutrients) from coastal waters to offshore areas play an important role in controlling the water quality of the adjacent sea areas not only by increasing nutrient concentration hut also by changing nutrient structures. In this study, naturally occurring isotopes, ^226Ra and ^228Ra, were measured with the alpha spectrometry in the Wenjiao-Wenchang and Wanquan estuaries and adjacent sea areas along the east coast of Hainan Island. The excess ^226Ra and ^228Ra activities were observed by comparison with the values derived from the conservative mixing of freshwater and seawater end-members in both estuaries. Using a one-dimensional diffusion model, the horizontal eddy diffusion coefficient of 3.1 6 × 10^5 cm^2/s, for nutrients diffusing from their sources, was derived from 228Ra activities. Consequently, the corresponding nutrient fluxes flowing into the coastal waters were assessed. The results can provide useful information for the study of the mixing and exchange processes of coastal waters as well as dissoluble pollutant transport in this sea area.
文摘We conducted a study on a model drinking water distribution system to evaluate the impact of nutrient in the form of sodium acetate on the growth and survival of coliform and heterotrophic plate count (HPC) bacteria for a maximum of 21 days residence time of water in pipes. Our results show that, besides the nutrient added and the absence of any additional source of contamination and additional supply of nutrient, there was significant growth of the above mentioned bacteria in the pipes and bottles for a couple of days, after which the bacterial population began to decrease. The results indicate that the bacteria used the nutrient to grow and multiply until the nutrient was totally consumed and became depleted in the bulk water phase, after which the bacterial population reached a near stationary level and subsequently declined. This suggests the death of some of the bacteria and their dead cells were used by other bacteria for growth and survival. Using a detection limit of 3.3 CFU/100 mL for the coliforms, the study shows that after sometime, no bacteria were found in the water phase of the pipe, however, the biofilm in the pipes still harbored some of the bacteria. The results have revealed that the bacteria also have the tendency to move from the water phase to the biofilm since the latter provides a more suitable environment for bacteria to thrive on and grow, thus prolonging their survival in the system.
文摘Wastewater treatment plays a crucial role in preserving water quality in receiving streams;however, continuous nutrient enrichment can diminish the retention capacity of rivers. The objectives of this study were to evaluate the effects of wastewater treatment plant effluent and river discharge on water chemistry and determine the retention efficiency of nutrients added in the effluent along a 6.1-km reach of a 5th-order stream in the Ozark Highlands of northwest Arkansas. From 2006 through 2007, effluent discharge increased river nitrite, soluble reactive P (SRP), and total organic C (TOC) and conductivity. As river discharge increased, DO and turbidity increased, but water temperature, conductivity, and TOC decreased. Net nutrient uptake lengths were inconsistent for NO3-N, NH4-N, and SRP. Results indicated that the fluvial channel acted as both a sink and a source of NO3-N and SRP, but the channel always acted as a sink for NH4-N with a significantly positive retention coefficient that indicated only 12% of added NH4-N was retained in the study reach. The effluent discharge increased the concentrations of seven water quality parameters, and it appears the long-term enrichment has rendered the immediate-downstream reach ineffective as a nutrient sink. Nutrients added in the effluent were generally transported with little to no uptake or transformation, thus river chemical concentrations beyond the study reach have likely been influenced by this effluent discharge.