Analysis of Nitrification in Agricultural Soil and Improvement of Nitrogen Circulation with Autotrophic Ammonia-Oxidizing Bacteria

Accumulations of inorganic nitrogen (NH₄ ⁺, NO₂ ^?, and NO₃ ^?) were analyzed to evaluate the nitrogen circulation activity in 76 agricultural soils. Accumulation of NH₄ ⁺ was observed, and the reaction of NH₄ ⁺?→?NO₂ ^? appeared to be slower than that of NO₂ ^??→?NO₃ ^? in agricultural soil. Two autotrophic and five heterotrophic ammonia-oxidizing bacteria (AOB) were isolated and identified from the soils, and the ammonia-oxidizing activities of the autotrophic AOB were 1.0?×?10³–1.0?×?10⁶ times higher than those of heterotrophic AOB. The relationship between AOB number, soil bacterial number, and ammonia-oxidizing activity was investigated with 30 agricultural soils. The ratio of autotrophic AOB number was 0.00032–0.26 % of the total soil bacterial number. The soil samples rich in autotrophic AOB (>1.0?×?10⁴ cells/g soil) had a high nitrogen circulation activity, and additionally, the nitrogen circulation in the agricultural soil was improved by controlling the autotrophic AOBs.     

A new tool for inorganic nitrogen speciation study: simultaneous determination of ammonium ion, nitrite and nitrate by ion chromatography with post-column ammonium derivatization by Nessler reagent and diode-array detection in rain water samples

The paper presents a new method for a simultaneous determination of inorganic nitrogen species in the oxidized (NO₂⁻, NO₃⁻) and reduced (NH₄⁺) form in rain water samples. The method is based on a system of nitrogen species separation employing ion exchange and diode-array detection. The ions are separated in a strong ion-exchanger, nitrites and nitrates are determined directly at 208 and 205 nm, respectively, while the ammonium ions are determined in the column hold-up time after a post-column derivatization by the Nessler reagent, at 425 nm. The use of a diode-array detector permits a simultaneous identification of the inorganic nitrogen species in 8 min. The detection limits obtained are: NO₂⁻, 0.1 mg L⁻¹; NO₃⁻, 0.05 mg L⁻¹; NH₄⁺, 1 mg L⁻¹. The method proposed has been successfully used for speciation analysis of inorganic nitrogen in precipitation.     

阴阳离子双隔膜三室电解槽电渗析处理垃圾渗滤液

采用阴阳离子双隔膜三室电解槽,将电渗析技术与Ｆｅｎｔｏｎ试剂法结合,去除垃圾渗滤液中氨氮和ＣＯＤ_Ｃｒ。垃圾渗滤液中的氨氮通过电渗析技术富集到阴极液中,随后用化学沉淀法加以去除。同时,在铁阳极上生成的Ｆｅ^２＋离子,与滴加入阳极液中的Ｈ_２Ｏ_２反应生成Ｆｅｎｔｏｎ试剂,降解有机物,降低ＣＯＤ_Ｃｒ。实验结果表明,模拟废水中的氨氮透过率达８０％,垃圾渗滤液中氨氮浓度和ＣＯＤ_Ｃｒ由原来的１９８２和２２４８ ｍｇ／Ｌ分别降至２００和１２７ ｍｇ／Ｌ。     

On‐site sampling of inorganic contamination on the metal surface and analysis with capillary electrophoresis

Pipes are the primary structural elements used for transporting fluid in various industries. The most common damage mechanism is corrosion, which occurs in pipes surface of turbine. The corrosive compounds for pipes are inorganic ion (Na⁺, Cl^?, NH₄⁺, NO₃^?, etc.) and grinding oil. For rapid and quantitative detection of inorganic ions on site, more reliable and reproducible analytical methods are demanded. A highly efficient solid–liquid sampling collection system is introduced in this work. Papering on the sample surface, inorganic cations and anions were simultaneously collected and analyzed by capillary electrophoresis with indirect ultraviolet detection. As a result, five cations (Na⁺, K⁺, NH₄⁺, Ca²⁺, Mg²⁺) and three anions (Cl^?, NO₃^?, SO₄^2?) were completely separated. The efficiency of the sampling and ability of capillary electrophoresis analysis were presented by the determination of trace‐level (mg/m²) contaminants. The recoveries of cations and anions on the paper from metal surface were between 86.6 and 107.2%, and the relative standard deviations were less than 12.85%.     

Kinetics and mechanism of the reduction of monochloramine by hydroxylamine and hydroxylammonium ion

The kinetics and mechanism by which monochloramine is reduced by hydroxylamine in aqueous solution over the pH range of 5–8 are reported. The reaction proceeds via two different mechanisms depending upon whether the hydroxylamine is protonated or unprotonated. When the hydroxylamine is protonated, the reaction stoichiometry is 1:1. The reaction stoichiometry becomes 3:1 (hydroxylamine:monochloramine) when the hydroxylamine is unprotonated. The principle products under both conditions are Cl^–, NH⁺₄, and N₂O. The rate law is given by ?[d[NH₂Cl]/dt] = k₊[NH₃OH⁺][NH₂Cl] + k₀[NH₂OH][NH₂Cl]. At an ionic strength of 1.2 M, at 25°C, and under pseudo‐first‐order conditions, k₊= (1.03 ± 0.06) ×10³ L · mol^?1 · s^?1 and k₀=91 ± 15 L · mol^?1 · s^?1. Isotopic studies demonstrate that both nitrogen atoms in the N₂O come from the NH₂OH/NH₃OH⁺. Activation parameters for the reaction determined at pH 5.1 and 8.0 at an ionic strength of 1.2 M were found to be ΔH? = 36 ± 3 kJ · mol^–1 and Δ S? = ?66 ± 9 J · K^?1 · mol^?1, and Δ H? = 12 ± 2 kJ · mol^?1 and Δ S? = ?168 ± 6 J · K^?1 · mol^?1, respectively, and confirm that the transition states are significantly different for the two reaction pathways. © 2005 Wiley Periodicals, Inc. Int J Chem Kinet 38: 124–135, 2006     

A portable lab‐on‐a‐chip instrument based on MCE with dual top–bottom capacitive coupled contactless conductivity detector in replaceable cell cartridge

A new design for a compact portable lab‐on‐a‐chip instrument based on MCE and dual capacitively coupled contactless conductivity detection (dC⁴D) is described. The instrument is battery powered with total dimension of 14 × 25 × 8 cm³ (w × l × h), and weighs 1.2 kg. The device consists of a front electrophoresis compartment which has the chip holder and the chip, the associated high‐voltage electrodes for electrophoresis injection and separation and the detector. The detection cell is integrated into the device housing with an exchangeable plug‐and‐play cartridge format. The design of the dC⁴D cell has been optimized for maximum performance. The cartridge includes the top–bottom excitation and pick up electrodes incorporated into the cell and connected to push‐pull self‐latching pins that are insulated with plastic. The metal frame of the cartridge is grounded completely to eliminate electronic interferences. The cartridge is designed to clamp a thin fluidic chip at the detection point. The cartridges are replaceable whereby different cartridges have different detection electrode configurations to employ according to the sensitivity or resolution needed in the specific analytical application. The second compartment consists of all the electronics, data acquisition card, high‐voltage modules of up to ±5 kV both polarity, and batteries for 10 h of operation. The improved detector performance is illustrated by the electrophoresis analysis of six cations (NH₄⁺, K⁺, Ca²⁺, Na⁺, Mg²⁺, Li⁺) with a detection limit of approximately 5 μM and the analysis of the anions (Br^?, Cl^?, NO₂^?, NO₃^?, SO₄^2?, F^?) with a detection limit of about 3 μM. Analytical capabilities of the instrument for food and medical applications were evaluated by simultaneous detection of organic and inorganic acids in fruit juice and inorganic cations and anions in rabbit blood samples and human urine samples are also demonstrated.     

Adsorption of Li by a lithium ion-sieve using a buffer system and application for the recovery of Li from a spent lithium-ion battery

A lithium ion-sieve manganese oxide (MO) derived from Li-enriched MO was prepared by the glycolic acid complexation method. The Li adsorption performance in a LiCl–NH₃·H₂O–NH₄Cl buffer solution, simulated a spent lithium-ion battery (LIB) processing solution, and actual spent LIB processing solution were studied. An adsorption capacity of 27.4 mg/g was observed in the LiCl–NH₃·H₂O–NH₄Cl buffer solution (Li concentration of 0.2 mol/L, pH?=?9), and the adsorption behavior conformed to the Langmuir adsorption isotherm equation with a linear correlation coefficient (R²) of 0.9996. An adsorption capacity of 19 mg/g was observed in the simulated buffer spent battery solution (Li concentration of 0.15 mol/L, pH?=?7), and an adsorption capacity of 17.8 mg/g was observed in the actual spent battery solution (Li concentration of 0.15 mol/L, pH?=?7). X-ray diffraction, scanning electron microscope, and infrared spectrum results revealed that the structure and morphology of MO are stable before and after adsorption, and the adsorption of MO in all of the abovementioned buffer systems conforms to the Li⁺–H⁺ ion-exchange reaction mechanism. The lithium ion-sieve MO demonstrates promise for the recovery of lithium from spent LIBs.     

Amperometric detection studies of Nafion/indium hexacyanoferrate film for the determination of electroinactive cations in ion chromatography

An amperometric detector based on the chemical modification of Nafion and indium (III) hexacyanoferrate (II, III) thin film (Nafion/In-CN-Fe) onto a glassy carbon (GC) electrode, was first successfully used for the determination of electroinactive cations (Li⁺, Na⁺, K⁺, Rb⁺, Cs⁺, NH₄ ⁺) in single column ion chromatography (IC). A set of well-defined peaks of electroinactive cations was obtained. The detection limits of the cations are 8.9 × 10^–6 mol/L for Li⁺, 2.3 × 10^–6 mol/L for Na⁺, 5.2 × 10^–6 mol/L for K⁺, 4.8 × 10^–6 mol/L for Rb⁺, 4.0 ׶10^–6 mol/L for Cs⁺ and 5.3 × 10^–6 mol/L for NH₄ ⁺ at a single-to-noise ratio of 3. The proposed method was quick, sensitive and simple. The cations in rainwater and mineral water were successfully analyzed by this method.     

Effect of inorganic anions on the titanium dioxide-based photocatalytic oxidation of aqueous ammonia and nitrite

In this study, we investigated the effects of four inorganic anions (Cl⁻, SO₄²⁻, H₂PO₄⁻/HPO₄²⁻, and HCO₃⁻/CO₃²⁻) on titanium dioxide (TiO₂)-based photocatalytic oxidation of aqueous ammonia (NH₄⁺/NH₃) at pH ∼ 9 and ∼10 and nitrite (NO₂⁻) over the pH range of 4–11. The initial rates of NH₄⁺/NH₃ and NO₂⁻ photocatalytic oxidation are dependent on both the pH and the anion species. Our results indicate that, except for CO₃²⁻, which decreased the homogeneous oxidation rate of NH₄⁺/NH₃ by UV-illuminated hydrogen peroxide, OH scavenging by anions and/or direct oxidation of NH₄⁺/NH₃ and NO₂⁻ by anion radicals did not affect rates of TiO₂ photocatalytic oxidation. While HPO₄²⁻ enhanced NH₄⁺/NH₃ photocatalytic oxidation at pH ∼ 9 and ∼10, H₂PO₄⁻/HPO₄²⁻ inhibited NO₂⁻ oxidation at low to neutral pH values. The presence of Cl⁻, SO₄²⁻, and HCO₃⁻ had no effect on NH₄⁺/NH₃ and NO₂⁻ photocatalytic oxidation at pH ∼ 9 and ∼10, whereas CO₃²⁻ slowed NH₄⁺/NH₃ but not NO₂⁻ photocatalytic oxidation at pH ∼ 11. Photocatalytic oxidation of NH₄⁺/NH₃ to NO₂⁻ is the rate-limiting step in the complete oxidation of NH₄⁺/NH₃ to NO₃⁻ in the presence of common wastewater anions. Therefore, in photocatalytic oxidation treatment, we should choose conditions such as alkaline pH that will maximize the NH₄⁺/NH₃ oxidation rate.     

Identification of Thermal Decomposition Products and Reactions for Liquid Ammonium Nitrate on the Basis of Ab Initio Calculation

This work analyzed the thermal decomposition of ammonium nitrate (AN) in the liquid phase, using computations based on quantum mechanics to confirm the identity of the products observed in past experimental studies. During these ab initio calculations, the CBS‐QB3//ωB97XD/6–311++G(d,p) method was employed. It was found that one of the most reasonable reaction pathways is HNO₃ + NH₄⁺ → NH₃NO₂⁺ + H₂O followed by NH₃NO₂⁺ + NO₃^– → NH₂NO₂ + HNO₃. In the case in which HNO₃ accumulates in the molten AN, alternate reactions producing NH₂NO₂ are HNO₃ + HNO₃ → N₂O₅ + H₂O and subsequently N₂O₅ + NH₄⁺ → NH₂NO₂ + H₂O. In both scenarios, HNO₃ plays the role of a catalyst and the overall reaction can be written as NH₄⁺ + NO₃^– (AN) → NH₂NO₂ + H₂O. Although the unimolecular decomposition of NH₂NO₂ is thermodynamically unfavorable, water and bases both promote the decomposition of this molecule to N₂O and H₂O. Thus AN thermal decomposition in the liquid phase can be summarized as NH₄⁺ + NO₃^– (AN) → N₂O + 2H₂O.     

Kinetics of oxidation and comproportionation reactions involving an oxammonium ion,benzyl alcohol and methyltrioxorhenium(VII)

The reactions of 4‐hydroxy‐2,2,6,6‐tetramethylpiperidinium N‐oxide, an oxammonium ion abbreviated R₂NO⁺, have been studied. The previously unreported triflate salt was used in this study because the anions of the usual chloride and bromide salts can themselves be oxidized. Reactions between R₂NO⁺ and alcohols produce ketones and aldehydes; the rate constant for PhCH₂OH is 4.4 × 10⁻³ L mol⁻¹ s⁻¹ in acetonitrile at 298 K. The immediate product is the hydroxylamine, R₂NOH, but its further comproportionation reaction with R₂NO⁺ yields the stable piperidinyl oxyl radical, R₂NO^·. The rate constant of this reaction is 1.78 × 10³ L mol⁻¹ s⁻¹ at 298 K. The possibility of using R₂NO⁺ and MTO as co‐catalysts for the oxidation of alcohols was explored, but the competitive rates are such that the resultant is not particularly attractive. © 1999 John Wiley & Sons, Inc. Int J Chem Kinet 31: 381–385, 1999     

Determination of Total Selenium in Human Urine and Serum by Graphite-Furnace Atomic-Absorption Spectrophotometry with Palladium-Nickel-Ammonium Nitrates as a Matrix Modifier

After human urine or serum was diluted (1 + 9) with HNO₃ (0.2%, v/v) and standard additions of Se solution (100 μ L^?1), the diluted sample (10 μL) was introduced into the graphite cuvette. The matrix modifier [10μL, containing Pd (0.6 μg) + Ni (25 μg) + NH₄NO₃ (80 μg) in HNO₃ (0.2%, v/v) for urine, or Pd (0.3 μg) + Ni (30 μg) + NH₄NO₃ (80 μg) + Triton X-100 (0.04%) in HNO₃ (0.2%, v/v) for serum, respectively] was added and the mixture was heated according to a temperature program. The matrix modifier containing NH₄NO₃ in a suitable amount and a small amount of Pd enhanced the sensitivity for Se. The method detection limits (3σ) after dilution were about 4.9 ± 0.8 and 2.36 ± 0.18 μg L^?1 for urine and serum, respectively. The accuracy of this method was tested with SRM #2670 human urine Se and Seronorm Trace Elements #116 human serum Se, respectively, and the results of 97.6 – 101% and 100 – 104% were obtained with precision ± 0.3% and ± 2%, respectively. This method can be applied easily and accurately to the determination of concentration of total Se in human urine and serum.     

The determination of low lead levels in the bone of lead-depleted mice by graphite furnace atomic absorption spectrometry

Low lead levels in the femurs of mice fed with a lead-depleted diet have been determined by use of electrothermal atomic absorption spectrometry with Zeeman-effect background correction. The method is based on the use of Mg(NO₃)₂/Pd as matrix modifier which enables significant reduction of the spectral interferences prevalent if chemical modifiers based on NH₄H₂PO₄ with either Ca or Mg are used for samples rich in Ca₃(PO₄)₂ matrix. The method was developed and validated by use of the NIST standard reference material 1486 bone. Bones were decomposed in a pressurized microwave-heated system using 70% nitric acid. Forty-three mice femurs, with a mass of 74.62 ± 12.54 mg, were dissolved in concentrated nitric acid. The lead results found in SRM 1486 (1.25 ± 0.15 μg g^–1, n = 9) were in good agreement with the certificate (1.335 ± 0.014 μg g^–1). Recoveries of 200 ng lead added to the SRM before or after digestion were 99.0 ± 1.4% and 98.5 ± 1.6%, respectively. The lead detection limit in bone samples is 0.06 μg g^–1 dry mass. This method is, therefore, suitable for the determination of very low lead levels (0.06–0.20 μg Pb kg^–1 bone) in the femurs of mice fed a diet with lead level of < 20μg kg^–1.     

Rapid separation of post‐blast explosive residues on glass electrophoresis microchips

This study describes the development of an analytical methodology based on the use of microchip electrophoresis (ME) devices integrated with capacitively coupled contactless conductivity detection (C⁴D) for the separation and detection of inorganic anions in post‐blast explosive residues. The best separation condition was achieved using a running buffer composed of 35 mmol/L lactic acid, 10 mmol/L histidine and 0.070 mmol/L cetyl(trimethyl ammonium) bromide. For C⁴D measurements, the highest sensitivity was obtained applying a 700 kHz sinusoidal wave with excitation voltage of 20 V_pp. The separation of Cl^?, NO₃^?, NO₂^?, SO₄^2?, ClO₄^? and ClO₃^? was performed within ca. 150 s with baseline resolution and efficiencies between 4.4 × 10⁴ and 1.7 × 10⁵ plates/m. The found limits of detection ranged between 2.5 and 9.5 μmol/L. Last, real samples of post‐blast explosive residues were analyzed on the ME‐C⁴D devices obtaining successfully the determination of Cl^?, NO₃^? and SO₄^2?. The achieved concentration values varied between 12.8–72.5 mg/L for Cl^?, 1.7–293.1 mg/L for NO₃^? and 1.3–201.3 mg/L for SO₄^2?. The data obtained using ME‐C⁴D devices were in good agreement with the concentrations found by ion chromatography. The approach reported herein has provided short analysis time, instrumental simplicity, good analytical performance and low cost. Furthermore, the ME‐C⁴D devices emerge as a powerful and portable analytical platform for on‐site analysis demonstrating to be a promising tool for the crime scene investigation.     

Polydiphenylamine-dodecyl sulfate films for the simultaneous amperometric determination of electroinactive anions and cations in ion-exclusion cation-exchange chromatography

An amperometric detector with two working electrodes both modified with polydiphenylamine-dodecyl sulfate (PDPA-DS) was successfully used for the simultaneous determination of electroinactive anions (SO₄ ^2–, Cl^–, NO₃ ^–) and cations (Na⁺, NH₄ ⁺ and K⁺) in single-column ion-exclusion cation-exchange chromatography (IEC-CEC). The PDPA-DS chemical modified electrode (CME) was based on the incorporation of dodecyl sulfate (DS) into PDPA by electropolymerization of diphenylamine in the presence of sodium dodecyl sulfate. The electrochemical responses against the anions and cations at the PDPA-DS CME in differential pulse voltammetry were studied. A set of well-defined peaks of electroinactive anions and cations were obtained. The anions and cations were detected conveniently and reproducibly in a linear concentration range 0.01–5.0 mmol/L and their detection limits were in the range 5–9 μmol/L at a signal-to-noise ratio of 3 (S/N = 3). The proposed method was quick, sensitive and simple and was successfully applied to the analysis of lake water samples. The working electrode was stable over one week period of operation with no evidence of chemical and mechanical deterioration.     

Synthesis and Crystal Structure of Alkali Metal and Ammonium Nitratocuprates(II): M3[Cu(NO3)4](NO3) (M = K,NH4, Rb) and Cs2[Cu(NO3)4]

Blue crystals of metal nitratocuprates(II), M₃[Cu(NO₃)₄](NO₃) (M = K ( I ), NH₄ ( II ), Rb ( III )) and Cs₂[Cu(NO₃)₄] ( IV ) were synthesized from Cu(NO₃)₂ · 3 H₂O and MNO₃ by heating at 100–140 °C during 3–12 h. X-ray single crystal structures for isotypic I and II reveal the presence of the [Cu(NO₃)₄]^2– and NO₃^– anions and M⁺ cations. Structure IV contains [Cu(NO₃)₄]^2– and Cs⁺. In structures I , II , and IV , Cu atoms have a square-planar coordination [CuO₄] with short Cu–O distances of 1.92–2.00 Å, the oxygen atoms belonging to four different NO₃ groups. Each coordinated NO₃ group is a nonsymmetrical bidentate ligand with the second, longer Cu–O distance from 2.38 to 2.74 Å. Rubidium derivative III was shown to be isotypic to I on the basis of unit cell dimensions and symmetry. Eight-coordinate metal(II) environment in tetranitrates is compared for transition metals with different electronic configurations.     

Use of zwitterionic micelles in the eluent II: a new approach to ion chromatographic analysis of inorganic cations in biological fluids with direct sample injection

A new ion chromatographic (IC) technique has been developed for the determination of inorganic cations in biological fluids with direct sample injection. This involved the use of a mixed zwitterionic-micelle/electrolyte solution as an eluent. The proteins in the sample became bound to the zwitterionic micelles in the eluent and were thus eliminated from the column. The cations were separated by cation exchange. This method is ideal for the on-line, simultaneous determination of common inorganic cations (Na⁺, NH₄ ⁺, K⁺, Mg²⁺, and Ca²⁺) in urine and serum samples. Such an application was demonstrated experimentally. Non-suppressed conductivity was used for analyte detection. The detection limits obtained using this IC system were 2.94, 5.22, 34.9, 32.6, and 56.7 μg/L for Na⁺, NH₄ ⁺, K⁺, Mg²⁺, and Ca²⁺, respectively.     

Electrical Pulse-Driven Periodic Self-Repair of Cu-Ni Tandem Catalyst for Efficient Ammonia Synthesis from Nitrate

Electrocatalytic nitrate reduction sustainably produces ammonia and alleviates water pollution, yet is still challenging due to the kinetic mismatch and hydrogen evolution competition. Cu/Cu₂O heterojunction is proven effective to break the rate-determining NO₃⁻-to-NO₂⁻ step for efficient NH₃ conversion, while it is unstable due to electrochemical reconstruction. Here we report a programmable pulsed electrolysis strategy to achieve reliable Cu/Cu₂O structure, where Cu is oxidized to CuO during oxidation pulse, then regenerating Cu/Cu₂O upon reduction. Alloying with Ni further modulates hydrogen adsorption, which transfers from Ni/Ni(OH)₂ to N-containing intermediates on Cu/Cu₂O, promoting NH₃ formation with a high NO₃⁻-to-NH₃ Faraday efficiency (88.0±1.6 %, pH 12) and NH₃ yield rate (583.6±2.4 μmol cm⁻² h⁻¹) under optimal pulsed conditions. This work provides new insights to in situ electrochemically regulate catalysts for NO₃⁻-to-NH₃ conversion.     

Chemical ionization mass spectrometry using ammonia reagent gas. Selective protonation of conjugated ketones

Studies using ammonia as a selective reagent gas in chemical ionization mass spectrometry were extended to conjugated ketones. Their proton affinities were in the range of most nitrogen-containing compounds (> 207 ± 3 kcal/mole), thereby permitting proton transfer from [NH₄]⁺-, leading to well stabilized protonated molecular ions as the most abundant ion products.     

Depth profiles of 129I species in the Bothnian Sea

The Bothnian Sea which is located between Finland and Sweden represents an important source of fresh water to the Baltic Sea. We here present new data on the radioactive isotope ¹²⁹I species from water samples collected in December 2009 at different depths in the Bothnian Sea. Concentrations of ¹²⁹I^? (iodide) in the Bothnian Sea range from 14 × 10⁸ to 32 × 10⁸ atoms/L, while ¹²⁹IO₃ ^? (iodate) concentrations are relatively low and fluctuating at 1 × 10⁸ atoms/L. For nutrients data determined in the same samples as ¹²⁹I, significant correlations could be found between ¹²⁹I^? and total P, NO₃–N, SiO₃–Si, but rather poor with NH₄–N. The correlations suggest comparable source pathway of ¹²⁹I^? and nutrient parameters, while the source of NH₄–N may be different. The small amounts and negligible change of ¹²⁹IO₃ ^? indicate prevailing extensive reduction of iodate in the Baltic Sea.