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The Alliance for Coastal Technology (ACT) conducted a sensor verification study of in situ nutrient analyzers during 2016 to characterize performance measures of accuracy, precision and reliability. The verification including a week of laboratory testing along with three moored field deployments in freshwater, estuarine, and oceanic coastal environments. Laboratory tests of accuracy, precision, and range were conducted at the University of Maryland’s Chesapeake Biological Laboratory (CBL) in Solomons, MD. A series of five tests were conducted to evaluate performance under controlled challenge conditions including: concentration range, temperature, salinity, turbidity, and dissolved organic carbon. All laboratory tests were conducted in 250 L polypropylene tanks using RO water as the initial matrix, within a temperature controlled room. Instruments sampled from a common, well-mixed, test tank maintained at a documented level of known challenge condition. Instruments were set-up by the manufacturer daily prior to the start of each individual laboratory tests, exposed to each test condition for a period of three hours, and programmed to sample at a minimum frequency of 30 minutes. Reference samples were collected every 30 minutes for five timepoints during corresponding instrument sampling times for each test. For the laboratory concentration range challenge the absolute difference between the Systea-PO4 and reference measurement across all timepoints for trials C0 – C5 ranged from 0.0067 to 0.0277 mgP/L, with a mean of 0.0041 ±0.0091 mgP/L. There was a small but significant increase in the measurement difference with increasing concentration as determined by linear regression (p=0.02; r2=0.20). However, the change in accuracy mostly occurred at the highest two test concentrations (0.406 and 1.87 mgP/L) with absolute measurement errors of 0.022 and 0.171 mgP/L, respectively. An assessment of precision was performed by computing the standard deviations and coefficients of variation of the five replicate measurements for C1 – C5 concentration trials. The standard deviation of the mean ranged from 0.0005 to 0.0040 mgP/L across the five trials, and the coefficient of variation ranged from 0.93 to 4.75 %. For the laboratory temperature challenge with testing at 5 oC, the absolute difference between instrument and reference measurement across all timepoints for trials C2 – C4 ranged from -0.0026 to 0.0170 mgP/L, with a mean of 0.010 ±0.005 mgP/L. Measurement differences were significantly higher at 5 oC versus 20 oC for each of three concentration test with the increased offset being 0.007, 0.005 and 0.017 mgP/L greater, respectively, for C2, C3, and C4. Similar to test results at 20 oC, there was a much larger offset at the C4 level compared to the lower two concentrations for the 5 oC test. For the laboratory salinity challenge performed at the C3 concentration level, the absolute difference between instrument and reference measurement across all timepoints for the three added salinity levels ranged from 0.0030 to 0.0333 mgP/L, with a mean of 0.0205 ±0.0078 mgP/L. There was a statistically significant response to increased salinity with measurement offsets increasing (over-predicted) as salinity increased. A linear regression of the measurement differences versus salinity was significant (p10x maximum reference). The average and standard deviation of the differences between instrument and reference readings over the entire deployment (n=63 out of a possible 63) were -0.0004 ± 0.002 mgP/L, with a total range of -0.0058 to 0.0044 mgP/L. There was a small but statistically significant trend in the measurement difference over time (p=0.0003; r2 = 0.247) during the deployment, with a slope of 0.0001 mgP/L/d. A linear regression of the instrument versus reference data was highly significant but with a low regression coefficient (p=0.001; r2 = 0.209). The regression had a slope of 0.999 and y intercept of -0.0004. Under and over predictions were fairly evenly distributed Published Refereed Current Particulate matter Best Practice Standard Operating Procedure

The Alliance for Coastal Technology (ACT) conducted a sensor verification study of in situ nutrient analyzers during 2016 to characterize performance measures of accuracy, precision and reliability. The verification including a week of laboratory testing along with three moored field deployments in freshwater, estuarine, and oceanic coastal environments. Laboratory tests of accuracy, precision, and range were conducted at the University of Maryland’s Chesapeake Biological Laboratory (CBL) in Solomons, MD. A series of five tests were conducted to evaluate performance under controlled challenge conditions including: concentration range, temperature, salinity, turbidity, and dissolved organic carbon. All laboratory tests were conducted in 250 L polypropylene tank using RO water as the initial matrix, within a temperature controlled room. Instruments sampled from a common, well-mixed, test tank maintained at a documented level of known challenge condition. Instruments were set-up by the manufacturer daily prior to the start of each individual laboratory test, exposed to each test condition for a period of three hours, and programmed to sample at a minimum frequency of 30 minutes. Reference samples were collected every 30 minutes for five timepoints during corresponding instrument sampling times for each test. For the laboratory concentration range challenge the absolute difference between the NOCPO4 and reference measurement across all timepoints for trials C0 – C5 ranged from -0.0153 to 0.0025 mgP/L, with a mean of -0.0027 ±0.0043 mgP/L. There was a small but significant increase in the measurement difference with increasing concentration as determined by linear regression (p=0.008; r2=0.27). However, the change in accuracy mostly occurred at the highest test concentration (0.406 mgP/L) with measurement difference of -0.0103 mgP/L. An assessment of precision was performed by computing the standard deviations and coefficients of variation of the five replicate measurements for C1 – C5 concentration trials. The standard deviation of the mean ranged from 0.0002 to 0.0050 mgP/L across the five trials, and the coefficient of variation ranged from 1.25 to 5.25 percent. For the laboratory temperature challenge with testing at 5 oC, the absolute difference between instrument and reference measurement across all timepoints for trials C2 – C4 ranged from -0.0095 to -0.0004 mgP/L, with a mean of -0.0045 ±0.0031 mgP/L. There was no significant difference in measurement accuracy at the C2 concentration level. However, measurement differences were significantly more negative (under-predicted) for the C3 and C4 concentration trials at 5 oC then at 20 oC, with offsets of -0.0050 and -0.0071, respectively. For the laboratory salinity challenge performed at the C3 concentration level, the absolute difference between instrument and reference measurement across all timepoints for the three added salinity levels ranged from -0.0021 to 0.0125 mgP/L, with a mean of 0.004 ±0.0051 mgP/L. There was no statistically significant response between measurement accuracy and salinity across all trials (p=0.32; r2=.08). For the laboratory turbidity challenge, performed at the C3 concentration level, the absolute difference between instrument and reference measurement across all timepoints for the two added turbidity levels ranged from -0.0033 to 0.0014 mgP/L, with a mean of -0.0007 ±0.0017 mgP/L. A linear regression of the measurement differences versus turbidity was not significant (p

The Alliance for Coastal Technology (ACT) conducted a sensor verification study of in situ nutrient analyzers during 2016 to characterize performance measures of accuracy, precision and reliability. The verification including a week of laboratory testing along with three moored field deployments in freshwater, estuarine, and oceanic coastal environments. Laboratory tests of accuracy, precision, and range were conducted at the University of Maryland’s Chesapeake Biological Laboratory (CBL) in Solomons, MD. A series of five tests were conducted to evaluate performance under controlled challenge conditions including: concentration range, temperature, salinity, turbidity, and dissolved organic carbon. All laboratory tests were conducted in 250 L polypropylene tanks using RO water as the initial matrix, within a temperature controlled room. Instruments sampled from a common, well-mixed, test tank maintained at a documented level of known challenge condition. Instruments were set-up by the manufacturer daily prior to the start of each individual laboratory test, exposed to each test condition for a period of three hours, and programmed to sample at a minimum frequency of 30 minutes. Reference samples were collected every 30 minutes for five timepoints during corresponding instrument sampling times for each test. For the laboratory concentration range challenge the absolute difference between the Real Tech Real-NO3 and reference measurement across all timepoints for trials C0 – C5 ranged from 0.217 to 0.490 mgN/L, with a mean of 0.185 ±0.168 mgN/L. A linear regression of the measurement difference versus concentration was significant (p=0.0192; r2=0.193), but with a low regression coefficient due to a reversal in direction for the C4 trial. In general, the Real-NO3 increasingly over-predicted concentrations as they increased in the test. An assessment of precision was performed by computing the standard deviations and coefficients of variation of the five replicate measurements for C1 – C5 concentration trials. The standard deviation of the mean ranged from 0.010 to 0.022 mgN/L across the five trials, and the coefficient of variation ranged from 0.20 to 6.47 percent. For the laboratory temperature challenge at 5 oC, the absolute difference between instrument and reference measurement across all timepoints for trials C2 – C4 ranged from -0.0880 to 0.4381 mgN/L, with a mean of 0.056 ±0.115 mgN/L. Measurement differences at both C2 and C3 were significantly lower at 5 oC (0.017 and 0.058) versus 20 oC (0.020 and 0.237) (p25 mgN/L) and 318 values were missing from the inoperable period. The average and standard deviation of the measurement difference between instrument and reference NO3 measurements for each matched pair (n=47 of a possible 51 observations) over the total deployment was 0.312 ± 1.029 mgN/L with a total range of -3.35 to 1.15 mgN/L. There was no significant trend in measurement difference over time as estimated by linear regression (p= 0.28; r2=0.026). A linear regression of instrument versus reference measurement was highly significant (p

International audience; The Antarctic Vostok ice core provided compelling evidence of the nature of climate, and of climate feedbacks, over the past 420,000 years. Marine records suggest that the amplitude of climate variability was smaller before that time, but such records are often poorly resolved. Moreover, it is not possible to infer the abundance of greenhouse gases in the atmosphere from marine records. Here we report the recovery of a deep ice core from Dome C, Antarctica, that provides a climate record for the past 740,000 years. For the four most recent glacial cycles, the data agree well with the record from Vostok. The earlier period, between 740,000 and 430,000 years ago, was characterized by less pronounced warmth in interglacial periods in Antarctica, but a higher proportion of each cycle was spent in the warm mode. The transition from glacial to interglacial conditions about 430,000 years ago (Termination V) resembles the transition into the present interglacial period in terms of the magnitude of change in temperatures and greenhouse gases, but there are significant differences in the patterns of change. The interglacial stage following Termination V was exceptionally long--28,000 years compared to, for example, the 12,000 years recorded so far in the present interglacial period. Given the similarities between this earlier warm period and today, our results may imply that without human intervention, a climate similar to the present one would extend well into the future.