Edmondo Canelli

Mn/V ratio as a tracer of aerosol sulfate transport

Abstract Concentrations of SO 4 2− , Al, V and Mn were determined in airborne particles during July-August 1981 at five sites in New York State: for 6-h intervals at Mayville, Brewerton and Whiteface Mountain and for 24-h intervals at Oneonta and West Haverstraw. Episodic high [SO 4 2− ] were observed during 18–21 and 24–26 July and 1–4 August. Air trajectories showed that during the 18–21 July and 1–4 August episodes peak [SO 4 2− ] coincided with slow-moving air masses which had spent 1 or more days in the midwestern states of Indiana, Michigan, Ohio or Pennsylvania prior to entering New York. During the episodes [SO 4 2− ] decreased from west to east. No significant local sources of SO 4 2− exist at the 6-h sites. All these lines of evidence together show that during these episodes SO 4 2− were transported from the industrial Midwest. During the 24–26 July episode, peak [SO 4 2− ] at Mayville coincided with air masses entering the state from Ohio, but at Brewerton and Whiteface Mountain the highest [SO 4 2− ] occurred when air masses came from metropolitan New York City and the mid-Atlantic states. The average [SO 4 2− ] at Mayville were 2-fold higher than at Brewerton and Whiteface Mountain. The average manganese/vanadium ratio (Mn/V) in aerosols from the Midwest (1–10) has been suggested to be ~ 10 times that in the Northeast ( 4 2− ] were due to transport from the Midwest. On 25–26 July the average Mn/V was high at Mayville (2.8) but low at Brewerton (0.29) and Whiteface Mountain (

A study of heterogeneous oxidation of SO2 in summer clouds

Experimental determination of incloud oxidation of SO2 has been lacking because of an Inability to distinguish SO 2 in cloud water, derived from aerosol scavenging (i.e., produced from homogeneous gas phase oxidation), from that due to in-cloud SO 2 oxidation, (SO 4 ) in . A tracer technique has been developed in this laboratory that uses trace elements (M) to resolve the two SO 4 components

EFFECT OF THE SINKING RATE OF TWO DIATOMS (THALASSIOSIRA SPP.) ON UPTAKE FROM LOW CONCENTRATIONS OF PHOSPHATE1

The effect of the sinking rate, or rate of medium flow (φ) on the rate of phosphate incorporation (V) by the planktonic diatoms Thalassiosira fluviatilis Hust. and T. pseudonana Hasle & Heimdal in batch and chemostat cultures was determined by passing medium at defined flow rates (0.5–25.0 mm·min−1) over algae on membrane filters. At concentrations from 1 to 100 μg phosphorus·l−1 V, increases with increasing velocity of flow, approaching a maximum value (Vm) as described by the empirical relationship: where Kφ is the sinking rate value when V = 1/2 Vm+ Vo and Vo is the uptake at 0 rate of flow. By comparing uptake at controlled flow with uptake in a vigorously stirred medium, the phosphate concentration in the cell boundary layer can be determined. The sinking rate that reduces the phosphate concentration in the boundary layer to half of nominal concentration in the medium is much lower for the larger T. fluviatilis than for T. pseudonana. For both diatoms, it is inversely related to the nominal concentration.

An improved determination of chemical oxygen demand in water and wastes by a simplified acid dichromate digestion

Abstract A simplified and improved chemical oxygen demand (COD) procedure is suitable for water and waste water samples containing up to 1500 mg Cl l−1. Samples are digested with sulfuric acid, potassium dichromate, silver sulfate, mercury(II) sulfate and sulfamic acid in open glass tubes for 2 h at 140 ± 2°C without boiling, and excess dichromate is determined colorimetrically at 440 nm. The use of 49-position digestion racks, a large oven and a spectrophotometer fitted with a 1-cm flow cell allow analysis of ca. 12 samples h−1. A correction for chloride interference is not required in the 0–500 mg Cl l−1 range. The detection limit is 3 mg l−1, and the relative standard deviation at the 112 mg COD l−1 level is 4.3%. Thirty-five waste water samples were analyzed by the standard dichromate reflux method and by the proposed procedure. There was no significant difference between the two sets of data (P > 0.25). Recovery data for 15 major water pollutants including benzene, toluene and pyridine are presented.

Evaluation of a portable bare-electrode amperometric analyzer for determining free chlorine in potable and swimming-pool waters

Abstract Chlorine in the forms of HOCl or ClO− was determined rapidly and precisely in the range from 0.10 to 3.0 ppm chlorine, without titration, using a bare-electrode portable amperometric analyzer. The instrument was calibrated with a 1.00 ppm chlorine standard solution or an equivalent permanganate solution which is stable for at least 6 months. The detection limit was 0.10 ppm chlorine, and relative standard deviations (N = 10) were Analysis of solutions of hypochlorite with ammonium chloride or selected organic nitrogen compounds indicated that various N-chloro compounds may interfere. In the presence of N-chloroglycine (2.70 ppm chlorine) the amperometric signal was about 5% of that for the equivalent concentration of hypochlorite, but higher relative responses were obtained with NH2Cl, NHCl2 or NCl3 (19, 42 and 70% at 2.60, 1.20 or 1.00 ppm chlorine respectively). Chlorinated urea (2.2 ppm N, 2.90 ppm chlorine), chlorinated bovine albumin (10 ppm albumin, 2.00 ppm chlorine) or monochloroisocyanurate (1.30 ppm chlorine) produced amperometric signals (76, Twenty potable water samples were analyzed for free chlorine by the DPD and amperometric procedures. Statistical analysis showed no significant differences between the two sets of results (P 0.005). This discrepancy was associated with the probable presence of chlorinated urea, whose signal by amperometry is lower than that by the DPD method. The advantages of this simple procedure must be weighed against possible inaccurate results in the presence of NH2Cl, NHCl2 or NCl3.

Determination of total particulate sulfur at Whiteface mountain, New York, by pyrolysis microcoulometry

Abstract Total paniculate sulfur (TPS) in air samples can be determined by a technique based on thermal volatilization at 1000°C, followed by controlled oxidation of sulfur compounds to SO 2 and coulometric titration of SO 2 with iodine. Calibration curves are linear within 5% from 0.1 to 10 μgS, the detection limit is 0.10μg S (equivalent to 20ng Sm −3 when ~ 1800m 3 of air are filtered), and the relative standard deviations ( n = 10) are 48 and 5.1% at the 0.10 and 4.0 μgS levels. Recoveries for 20 organic and inorganic compounds, including refractory sulfates, elemental sulfur, sulfides, sulfites, sulfonates and sulfones, vary from 79 to 88%. No interferences are observed for a number of non-sulfur-containing compounds, including nitrates, benzene, acetone, glucose, cellulose, silicates and carbonates. The technique was also used to determine the presence of non-sulfates and of non-water-soluble sulfates. Both TPS, using this technique, and water-soluble sulfate (WSS), using the methyl thymol blue method, were determined in daily air particulate samples collected at Whiteface Mountain, NY during both winter and summer. Comparision of TPS and WSS values showed that WSS could usually account for all of the sulfur present in the samples. The TPS concentrations ranged from 0.1 to 9.7μg Sm −3 and the contribution from acid-soluble sulfites and sulfides, elemental sulfur and volatile, S-containing organic compounds was negligible ( −3 ).

Simultaneous automated determination of chloride, nitrite, nitrate, and ammonia in water and wastewater

An automated system capable of simultaneous determination of chloride, nitrite, nitrate, and ammonia in about 2 ml of fresh water or wastewater is described. The four compounds are determined using modifications of established colorimetric procedures. Results can be reported at a true rate of five samples per hour with a relative standard deviation at optimum concentrations of less than 2%. Detection limits are 1 ppm Cl for chloride and 1, 5, and 5 ppb N for nitrite, nitrate, and ammonia, respectively. Sample pH adjustment is not required from 0.0002 N H2SO4 (pH 3.7) to 0.005 N NaOH (pH 11.2). Fresh water and wastewater samples were analyzed for nitrite and ammonia by the proposed procedure and by the manual sulfanilic-naphthylamine and nesslerization method. Analysis by the student t-test showed no significant difference between the paired sets of data (P > 0.5). When potable and wastewater samples were spiked with sodium chloride, potassium nitrate, sodium nitrite, and ammonium chloride and analyzed, average recoveries were 99 to 103%.

A semiautomated procedure for the determination of phosphorus in water, waste waters and particulates

Abstract Improved procedures for the determination of total dissolved phosphorus (TDP), particulate phosphorus (PP) and dissolved inorganic orthophosphate (DP) are described. Organic particulate material is solubilized in 5 n NaOH, and phosphorus compounds are oxidized and mineralized to orthophosphate by persulfate digestion. DP is determined by an improved automated molybdenum blue procedure that does not require sample pH adjustment or a correction for silicate interference in the 0–50 mg Si 1 −1 range. The use of 36-position digestion racks allows 32 TDP or PP samples to be digested in ca . 1 and 4 h respectively. Detection limits in μg of phosphorus 1 −1 are DP, 2; TDP, 5; and PP. 1. Waste water samples were analyzed for TDP and PP by the nitric acid-sulfuric acid procedure and by the proposed method. There was no significant difference between the two sets of data (P > 0.45).