Competitive Arsenate and Phosphate Adsorption on Ferrihydrite as Described by the CD-MUSIC Model

The solubility and bioavailability of arsenic in the environment are to a large extent governed by adsorption reactionswith iron (hydr)oxides, the extent of which is affected by competitive interactions with other ions, for example, phosphate. Here,batch experiments were performed with ferrihydrite suspensions to determine the adsorption of arsenate [As(V)] and phosphate(PO4)atdifferent As(V)-PO4ratios. A surface complexation model based on the Charge Distribution MUltisite Ion Complexation(CD-MUSIC) concept (the"Ferrihydrite CD-MUSIC model") was developed to describe these interactions in a way consistent withresults from spectroscopic studies. For this purpose, several previously published data sets on As(V) and PO4adsorption inferrihydrite suspensions were reviewed, including a number of systems containing other major ions (CO32-and Ca2+), and newsurface complexation constants were derived. During model development, it was found that the inclusion of ternary complexes wasnot needed to describe the observed Ca2+-PO4interactions. For both As(V) and PO4, the resulting model predicts the presence ofcorner-sharing bidentate complexes as well as monodentate complexes, with the latter being important particularly at low pH. Theexperimental results showed that As(V) and PO4displayed similar adsorption patterns in the single-ion systems studied, which wereconducted using a constant anion-to-Fe ratio of 0.2. Even so, As(V) was preferentially adsorbed over PO4in competitive systems,particularly at low As(V)-to-PO4ratios when theKdvalues for As(V) were up to 2.1 times as high as those for PO4. The model,which described these patterns very well, suggests that adsorbed As(V) consists of a larger fraction of bidentate complexes than inthe case of PO4. This causes aflatter adsorption isotherm for As(V), which leads to a stronger As(V) adsorption as the As(V)-to-Feratio decreases, compared to that for PO

Supply and removal of phosphorus in grassland

Syftet med studien är att ta upp de problem som finns med de fosforrestriktioner som finns i samband med organisk gödsling i vallodling. Idén till arbetet kom från rådgivarna på Växa i Halland som har upplevt att flera av deras kunder har problem med att uppfylla fosforrestriktionerna. Det finns en lag som säger att det inte är tillåtet att sprida mer än 22 kg fosfor från organisk gödsel ha-1 (hektar per år) spridningsareal under en 5-årsperiod. Gårdar med mycket djur kan få ytterligare fosforrestriktioner beroende på fältens fosforinnehåll. Syftet med arbetet är att belysa de problem som finns kring fosforrestriktionerna. Målet är att få fram verkliga siffror för 5 utvalda gårdars till- och bortförsel av fosfor. I litteraturgenomgången framförs de viktigaste punkterna som berör fosforrestriktionen. De punkter som tas upp är fosforns betydelse för vallen, hur kretsloppet ser ut för fosforn, upptaget av fosforn i vallen, hur restriktionerna ser ut och läckaget av fosfor. Läckaget av fosfor är den stora anledningen till att fosfor är ett problem i dagens jordbruk. Fosforn läcker ut i sjöar och vattendrag genom utlakning och ytavrinning. Det största läckaget sker vid stora nederbördsmängder vilket är svårt att förhindra som lantbrukare. Dock finns det förebyggande insatser som gör att läckaget kan minska. Att förhindra markpackning, strukturkalka och mylla ner gödseln är några exempel på hur en lantbrukare kan minska fosforläckaget. Arbetet innehåller två delar, en del där den litteratur som finns inom området behandlas och en resultatdel där 5 halländska mjölkgårdars grovfoderanalyser, gödselplaner, P-AL tal och gödselanalyser har blivit analyserade. De gårdar som varit med i arbetet blev utvalda för att samtliga hade alla de analyser som behövdes och för att de på ett eller annat sätt har problem med fosforrestriktioner. Analyserna har bearbetats så att ett resultat där till- och bortförsel av fosfor har kunnat ställas mot varandra. På grund av tidsbrist har skördarnas storlek endast uppskattats av lantbrukarna och deras rådgivare. Resultatet av studien visar på att det finns större bortförsel av fosfor än de 22 kg fosfor från organiskt gödsel som lantbrukarna får sprida. Dock har de gårdar som varit med i undersökningen alla spridit över 22 kg fosfor från organisk gödsel. Vilket medfört att 3 av 5 gårdar fick en högre tillförsel än bortförsel. De som hade högre bortförsel än tillförsel var de gårdar som hade spridit minst fosfor. Det framkom att sambandet mellan hög tillförsel av fosfor och överskott av fosfor var stort. Utifrån resultatet kan inte några direkta slutsatser dras, men undersökningen tyder på att en högavkastande vall för bort mer fosfor än 22 kg ha-1. För att kunna säkerställa de resultat som denna studie visar behövs en mer omfattande studie där fler gårdar från olika delar av landet ingår. Det bör också göras mer noggranna mätningar av skördestorleken.The aim of this study is to illustrate the problem with the restrictions regarding phosphorus in organic manure for fertilization in grasslands. The introduction of this subject came from advisors from the company Växa, located in the county Halland. These advisors have observed problems with restrictions regarding phosphorus in organic fertilization at the dairy farmers in the area. The farmers are restricted to apply a maximum of 22 kg organic phosphorus hectare-1 during a five year period. Additional restrictions are added considering large farms with high amount of animals dependent on the phosphorus level in the soil. The main purpose of this study is to examine the problem with the phosphorus restrictions. The goal is to obtain real numbers of supply and removal of phosphorus from five different dairy farms in Halland. The most important issues of the phosphorus restrictions are presented within the literature study.. The issues pointed out within this study that focus on grasslands are, the cycle of phosphorus, uptake of phosphorus in grasslands, the restrictions of phosphorus and the leakage of phosphorus. The leakage of phosphorus is the main problem in today´s agriculture, because the phosphorus leaks to nearby lakes and rivers through surface-and groundwater leakage. The primary leakage is caused by heavy rainfall and is therefore impossible for farmers to prevent. The farmers can partly prevent the leakage with efforts like avoiding soil compaction, adding lime to improve the soil structure and use injector equipment on the manure machinery to mix the manure with the soil. The study is divided in two parts, one literature part where the current literature is processed and one part where the result from the five dairy farms roughage analysis, P-AL analysis, plan for fertilization and manure analysis are presented. The farms were selected because they had all necessary analyses and they also had problems with phosphorus restrictions. The analyses have been processed in such a way that the results for supply and removal of phosphorus can be compared. Due to lack of time the farmers and their advisors have estimated the yield size. The result of the study shows a bigger removal of phosphorus than the 22 kg organic phosphorus which the farmers today are allowed to spread. Despite the fact that all the farms in this study have applied more than 22 kg organic phosphorus, three of five farms had higher phosphorus supply than removal. The farms with higher phosphorus removal than supply were the ones with the lowest application of phosphorus. This indicate that no general conclusions could be set, but the study indicates that a high-yield grassland remove more phosphorus than 22 kg hectare-1. In order to ensure what this study emphasizes, a future study that includes more farms is needed. In such a study accurate yield-size needs be measured

Bismuth(III) Forms Exceptionally Strong Complexes with Natural Organic Matter

The use of bismuth in the society has steadily increased during the last decades, both as a substitute for lead in hunting ammunition and various metallurgical applications, as well as in a range of consumer products. At the same time, the environmental behavior of bismuth is largely unknown. Here, the binding of bismuth(III) to organic soil material was investigated using extended X-ray absorption spectroscopy (EXAFS) and batch experiments. Moreover, the capacity of suwannee river fulvic acid (SRFA) to enhance the solubility of metallic bismuth was studied in a long-term (2 years) equilibration experiment. Bismuth(III) formed exceptionally strong complexes with the organic soil material, where >99% of the added bismuth(III) was bound by the solid phase, even at pH 1.2. EXAFS data suggest that bismuth(III) was bound to soil organic matter as a dimeric Bi3+ complex where one carboxylate bridges two Bi3+ ions, resulting in a unique structural stability. The strong binding to natural organic matter was verified for SRFA, dissolving 16.5 mmol Bi per gram carbon, which largely exceeds the carboxylic acid group density of this compound. Our study shows that bismuth(III) will most likely be associated with natural organic matter in soils, sediments, and waters

Etiska fondförvaltares påverkan på företagens hållbarhetsredovisning

Syfte: Vårt syfte är att utreda om svenska förvaltare av etiska fonder påverkar utvecklingen av hållbarhetsredovisningen hos svenska börsföretag. I den mån de påverkar ska vi dessutom utreda vad de påverkar och hur. Metod: Uppsatsen är kvalitativ, deskriptiv och genomförs med användande av grundad teori (Glaser & Strauss). Empiriinsamlingen har huvudsakligen skett genom intervjuer. Teoretiska perspektiv: Det teoretiska ramverket består av de vidareutvecklingar av intressentteorin som utvecklats inom forskningsområden som angränsar vårt, institutionell teori efter bland andra Jönsson samt Porters och Chuas teorier om kvalitativ och kvantitativ information. Empiri: Två empiriska undersökningar genomförs. Den första utreder om och hur förvaltarna av etiska fonder försöker påverka företagens hållbarhetsredovisning. Den andra genomförs med företagen i fokus och utreder om dessa anammar fondförvaltarnas önskemål. Resultat: Förvaltare av etiska fonder påverkar i viss mån företagens hållbarhetsredovisning. Direkt påverkan rör vanligen önskemål om mer kvantitativ information och övrig påverkan sker främst genom synpunkter på företagens hållbarhetsarbete och ett allmänt önskemål om transparens

Методика производства измерений напряженности электрического поля в соответствии с требованиями санитарных правил

Материалы XVII Междунар. науч.-техн. конф. студентов, аспирантов и молодых ученых, Гомель, 27–28 апр. 2017 г

Where does all the phosphorus go? Mass balance modelling of phosphorus in the Swedish long-term soil fertility experiments

To gain insights into phosphorus (P) dynamics in soils and the ability to predict soil responses to varying fertilizer inputs, mass balance models prove to be valuable tools. In this study, a new dynamic mass balance model, PBalD8, was used to describe the change in extracted P in the A horizon of soils subjected to diverse fertilizer treatments over a period of 50 to 60 years in five soil fertility experiments. The model employed a Freundlich equation to describe soil-solution partitioning of P and assumed that acid-lactate-extractable P represented a labile pool of P in instant equilibrium with soil solution P. Additionally, oxalate-extractable inorganic P was presumed to comprise the sum of the labile and stable pools of P, with mass flux to and from the latter described by Fick's first law. The model was evaluated using results from extractions and P K-edge XANES spectroscopy. Notably, organic P, as revealed by P K-edge XANES, did not substantially contribute to long-term changes in soil P content and was therefore excluded from consideration. In general, the model offered reasonable fits to the extracted P concentrations. However, for the P-depleted treatments, a prerequisite was that the P removal through harvest was lower compared to measurements. Conversely, in three of the soils, the modelled fertilizer inputs needed to be reduced to 70 % to 85 % of the known additions. These discrepancies may be attributed to the involvement of deeper soil horizons, including deep crop uptake and mixing with lower soil layers, although other factors such as lateral dispersion and inaccuracies in estimating applied fertilizers cannot be discounted. These results underscore the necessity of gaining a more comprehensive understanding of how deeper soil horizons influence P mass balances in agricultural soils. In one of the soils, Fja center dot rdingslo center dot v, P K-edge XANES results demonstrated the formation of calcium phosphate over time in the highest fertilization treatment, consistent with the model. Additionally, in two soils, Kungsa center dot ngen and the P-depleted Vreta Kloster soil, the model predicted a significant contribution from mineral weathering. However, the PBalD8 model also projected higher P leaching rates than those observed, suggesting that the model may not fully capture this P output term

Cloning of the β-phycocyanin gene from Anacystis nidulans

AbstractThe β-phycocyanin gene, pcyB, of Anacystis nidulans was isolated from an Escherichia coli λ-phage bank by the use of synthetic oligonucleotides derived from the 170 amino acid sequence of the β-phycocyanin protein. Two positive, overlapping λ-clones were found. Partial DNA sequencing of one of the clones gave a deduced amino acid sequence which was in full agreement with a portion of the published sequence of A. nidulans β-phycocyanin. A comparison with the published DNA sequence for β-phycocyanin from Agmenellum quadruplicatum shows a DNA sequence homology of 70.4% over the sequenced region

Accelerated planning for urban housing infills: coordination strategies

The outcome of local policies to satisfy residential demand by accelerating urban planning and development is studied here for an infill programme with about 30 plans and a target of 7,000 new suburban dwellings, launched by a mid-sized Swedish city, Gothenburg. Interviews with developers and officials, questionnaires, policy and planning documents including appeals have been analyzed. Three municipal strategies for acceleration were applied: interdepartmental coordination, collaboration with developers and parallel processing of plans and permits. Plans were produced more rapidly, but the goal of parallel work on building permits was seldom achieved. A complex pattern of delay causes has been found and is discussed in the light of coordination strategies. Strong initial focus on the physical design in the detailed development plan overshadowed the need for an early identification of coordination issues throughout the stages of implementation. This emerges as one reason why developers have been reluctant or unable to start detailed design early on, instead of embracing the principle of parallel planning and preparation for a building permit

Immobilizing arsenic in contaminated anoxic aquifer sediment using sulfidated and uncoated zero-valent iron (ZVI)

Arsenic (As) is carcinogenic and of major concern in groundwater. We collected sediment material from a contaminated anoxic aquifer in Sweden and investigated the immobilization of As by four commercial zero-valent iron (ZVI) particles. Solid-phase As and Fe speciation was assessed using X-ray absorption spectroscopy (XAS) and solution-phase As speciation using chromatographic separation. Without ZVI addition, arsenite dominated in solution and As(V) species in the solid phase. Adding ZVI caused a sharp increase in solution pH (9.3-9.8), favoring As oxidation despite a lowered redox potential. ZVI greatly improved As retention by complex binding of arsenate to the Fe(III) (hydr)oxides formed by ZVI corrosion. Uncoated ZVI, both in nano-and microscale, performed better than their sulfidated counterparts, partly due to occlusion of As by the Fe(III) (hydr) oxides formed. The effect of particle size (micro vs. nano ZVI) on As immobilization was small, likely because immobilization was related to the corrosion products formed, rather than the initial size of the particles. Our results provide a strong geochemical background for the application of ZVI particles to remove As in contaminated aquifers under anoxic conditions and illustrate that immobilization mechanisms can differ between ZVI in As spiked solutions and sediment suspensions.Environmental implication: Arsenic ranks first on the list by the US ATSDR of substances posing a threat to human health and the WHO considers groundwater the riskiest source for human intake of As. However, dealing with As contamination remains a scientific challenge. We studied the immobilization of groundwater As by commercially available ZVI particles at field-realistic conditions. Arsenic immobilization was highly efficient in most cases, and the results suggest this is a promising in situ strategy with long-term performance. Our results provide a strong geochemical background for using ZVI to remove As in contaminated anoxic aquifers