scholarly journals Methods for water quality sampling and load estimation in monitoring of Norwegian agricultural catchments

2006 ◽  
Vol 37 (1) ◽  
pp. 81-92 ◽  
Author(s):  
Trond Knapp Haraldsen ◽  
Per Stålnacke
Keyword(s):  
Water Quality ◽  
Suspended Solids ◽  
Sampling Strategy ◽  
Nordic Countries ◽  
Sampling Strategies ◽  
Composite Sampling ◽  
Point Sampling ◽  
Agricultural Catchments ◽  
Lower Load ◽  
Sampling Procedures

Different sampling procedures are applied to monitor water quality in agricultural catchments in the Nordic countries. The need for comparing monitoring results from the Nordic countries was the incentive for establishing a project aimed at comparing estimates of nutrient losses determined using different sampling strategies. Three different sampling methods were compared in three Norwegian catchments: weekly flow-proportional composite sampling (FPCS), weekly composite sampling with temporally equidistant subsampling every second hour (TECS) and temporally equidistant weekly point sampling (PS). Differences in load estimated between the three tested sampling strategies were smaller for nitrogen than for phosphorus or suspended solids. Point sampling tended to miss some of the peaks in concentrations of phosphorus and suspended solids, particularly during flow events, causing significantly lower load estimates for phosphorus and suspended solids by point sampling compared with composite sampling strategies. Flow-proportional composite sampling gave the most reliable data for event-responsible compounds or when the predictability of peaks was low. Based on this investigation, and similar studies in the other Nordic countries, a flow-proportional sampling strategy is recommended for studies of water quality in agricultural streams.

scholarly journals Performance and uncertainties of TSS stormwater sampling strategies from online time series

2018 ◽  
Vol 78 (6) ◽  
pp. 1407-1416
Author(s):  
Santiago Sandoval ◽  
Jean-Luc Bertrand-Krajewski ◽  
Nicolas Caradot ◽  
Thomas Hofer ◽  
Günter Gruber
Keyword(s):  
Time Series ◽  
Suspended Solids ◽  
Sampling Strategy ◽  
Sampling Strategies ◽  
Sampling Errors ◽  
Time Step ◽  
Sewer System ◽  
Time Intervals ◽  
Combined Sewer ◽  
One Year

Abstract The event mean concentrations (EMCs) that would have been obtained by four different stormwater sampling strategies are simulated by using total suspended solids (TSS) and flowrate time series (about one minute time-step and one year of data). These EMCs are compared to the reference EMCs calculated by considering the complete time series. The sampling strategies are assessed with datasets from four catchments: (i) Berlin, Germany, combined sewer overflow (CSO); (ii) Graz, Austria, CSO; (iii) Chassieu, France, separate sewer system; and (iv) Ecully, France, CSO. A sampling strategy in which samples are collected at constant time intervals over the rainfall event and sampling volumes are pre-set as proportional to the runoff volume discharged between two consecutive sample leads to the most representative results. Recommended sampling time intervals are of 5 min for Berlin and Chassieu (resp. 100 and 185 ha area) and 10 min for Graz and Ecully (resp. 335 and 245 ha area), with relative sampling errors between 7% and 20% and uncertainties in sampling errors of about 5%. Uncertainties related to sampling volumes, TSS laboratory analyses and beginning/ending of rainstorm events are reported as the most influent sources in the uncertainties of sampling errors and EMCs.

scholarly journals Development of Sampling Procedures Based Upon Satellite Derived Land Cover History for the NSF Digital African Cities Project

2003 ◽  
Vol 10 (1) ◽  
pp. 63
Author(s):  
Stuart E. Marsh ◽  
Thomas K. Park ◽  
Barbara A. Eiswerth ◽  
Mohamud H. Farah ◽  
Douglas S. Rautenkranz ◽  
...  
Keyword(s):  
Random Sampling ◽  
Urban Areas ◽  
Sampling Strategy ◽  
Sampling Bias ◽  
Relevant Information ◽  
Sampling Strategies ◽  
Sampling Frame ◽  
Simple Rules ◽  
Weighting Strategy ◽  
Sampling Procedures

This article discusses the sampling scheme employed by the Six Cities project to ensure that all areas of habitation have a chance of being selected, that we know what that chance is, and that we are able to critically evaluate the sampling strategy after it has been carried out. A weighting strategy that is slightly different from one used only to do research is therefore employed. The article describes a procedure for generating two kinds of random sample points for areas of change and of no change. Finally, a few simple rules for incorporating socioeconomic, demographic, and other relevant information into the sampling frame without introducing bias into the sample are discussed.Key words: sampling strategies; random sampling; sampling bias; local knowledge; Six Cities project; remote sensing; urban areas in Africa 

scholarly journals Spatial Variability of Suspended Sediments in San Francisco Bay, California

2021 ◽  
Vol 13 (22) ◽  
pp. 4625
Author(s):  
Niky C. Taylor ◽  
Raphael M. Kudela
Keyword(s):  
Remote Sensing ◽  
Water Quality ◽  
Spatial Variability ◽  
San Francisco ◽  
San Francisco Bay ◽  
Spatial Scales ◽  
Sampling Strategies ◽  
Point Sampling ◽  
Current Monitoring ◽  
Sentinel 2

Understanding spatial variability of water quality in estuary systems is important for making monitoring decisions and designing sampling strategies. In San Francisco Bay, the largest estuary system on the west coast of North America, tracking the concentration of suspended materials in water is largely limited to point measurements with the assumption that each point is representative of its surrounding area. Strategies using remote sensing can expand monitoring efforts and provide a more complete view of spatial patterns and variability. In this study, we (1) quantify spatial variability in suspended particulate matter (SPM) concentrations at different spatial scales to contextualize current in-water point sampling and (2) demonstrate the potential of satellite and shipboard remote sensing to supplement current monitoring methods in San Francisco Bay. We collected radiometric data from the bow of a research vessel on three dates in 2019 corresponding to satellite overpasses by Sentinel-2, and used established algorithms to retrieve SPM concentrations. These more spatially comprehensive data identified features that are not picked up by current point sampling. This prompted us to examine how much variability exists at spatial scales between 20 m and 10 km in San Francisco Bay using 10 m resolution Sentinel-2 imagery. We found 23–80% variability in SPM at the 5 km scale (the scale at which point sampling occurs), demonstrating the risk in assuming limited point sampling is representative of a 5 km area. In addition, current monitoring takes place along a transect within the Bay’s main shipping channel, which we show underestimates the spatial variance of the full bay. Our results suggest that spatial structure and spatial variability in the Bay change seasonally based on freshwater inflow to the Bay, tidal state, and wind speed. We recommend monitoring programs take this into account when designing sampling strategies, and that end-users account for the inherent spatial uncertainty associated with the resolution at which data are collected. This analysis also highlights the applicability of remotely sensed data to augment traditional sampling strategies. In sum, this study presents ways to supplement water quality monitoring using remote sensing, and uses satellite imagery to make recommendations for future sampling strategies.

Seagrass depth range and water quality in southern Moreton Bay, Queensland, Australia

1996 ◽  
Vol 47 (6) ◽  
pp. 763 ◽  
Author(s):  
EG Abal ◽  
WC Dennison
Keyword(s):  
Water Quality ◽  
Chlorophyll A ◽  
Suspended Solids ◽  
Light Attenuation ◽  
River Mouth ◽  
Total Suspended Solids ◽  
Quality Parameters ◽  
Depth Range ◽  
Moreton Bay ◽  
A Site

Correlations between water quality parameters and seagrass depth penetration were developed for use as a biological indicator of integrated light availability and long-term trends in water quality. A year-long water quality monitoring programme in Moreton Bay was coupled with a series of seagrass depth transects. A strong gradient between the western (landward) and eastern (seaward) portions of Moreton Bay was observed in both water quality and seagrass depth range. Higher concentrations of chlorophyll a, total suspended solids, dissolved and total nutrients, and light attenuation coefficients in the water column and correspondingly shallower depth limits of the seagrass Zostera capricorni were observed in the western portions of the bay. Relatively high correlation coefficient values (r2 > 0.8) were observed between light attenuation coefficient, total suspended solids, chlorophyll a, total Kjeldahl nitrogen and Zostera capricorni depth range. Low correlation coefficient values (r2 < 0.8) between seagrass depth range and dissolved inorganic nutrients were observed. Seagrasses had disappeared over a five-year period near the mouth of the Logan River, a turbid river with increased land use in its watershed. At a site 9 km from the river mouth, a significant decrease in seagrass depth range corresponded to higher light attenuation, chlorophyll a, total suspended solids and total nitrogen content relative to a site 21 km from the river mouth. Seagrass depth penetration thus appears to be a sensitive bio-indicator of some water quality parameters, with application for water quality management.

scholarly journals Assessment of the Impact of Small Hydropower Plants on the Ecological Status Indicators of Water Bodies: A Case Study in Lithuania

Water ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 433
Author(s):  
Laima Česonienė ◽  
Midona Dapkienė ◽  
Petras Punys
Keyword(s):  
Water Quality ◽  
Benthic Macroinvertebrates ◽  
Suspended Solids ◽  
Ecological Status ◽  
Fish Abundance ◽  
Water Bodies ◽  
Small Hydropower ◽  
Hydropower Plants ◽  
Physico Chemical ◽  
The Impact

Hydropower plants produce renewable and sustainable energy but affect the river’s physico-chemical characteristics and change the abundance and composition of the aquatic organisms. The impact of large HPPs on the ecological conditions of surface water bodies have been extensively studied, but less attention has been paid to environmental impact studies of small hydropower plants (SHPs). The impact of hydropeaking on both the river flow regime and ecosystems has been well-studied for peaking mode plants, mainly medium to large-sized ones. However, for small hydroelectric power plants, and especially for those in lowland rivers, the available information on water quality, benthic macroinvertebrates communities and fish abundance, and biomass is not sufficient. Ten small hydropower plants were selected, and the ecological status of water bodies was assessed in different parts of Lithuania. The studies were performed at the riverbed upstream from the SHPs, where the hydrological regime has not changed, and downstream from the SHPs. It was found that the small hydropower plants do not affect the physico-chemical values of the water quality indicators. This study demonstrated that the total number of benthic macroinvertebrates taxa (TS) is influenced by the concentration of nitrogen and suspended solids, the water flow, the river area, and the current speed; the number of EPT (Ephemeroptera (mayflies), Plecoptera (stoneflies), and Trichoptera (caddisflies)) taxa is influenced by the concentration of nitrogen and suspended solids. The studied indicators do not have a significant impact on biomass. The SHPs affect the fish abundance and biomass. The Lithuanian fish index (LFI) is influenced by the average depth and area of the river. Some SHPs operating in lowland areas may yield somewhat significant hydrograph ramping but more detailed investigation is needed to support the significance of this impact on the biological indices.

scholarly journals Limnology of Merbok estuary, Kedah, Malaysia

2015 ◽  
Vol 41 (1) ◽  
pp. 13-19
Author(s):  
Kaniz Fatema ◽  
Wan Maznah Wan Omar ◽  
Mansor Mat Isa
Keyword(s):  
Water Quality ◽  
Dissolved Oxygen ◽  
Suspended Solids ◽  
Total Suspended Solids ◽  
Quality Parameters ◽  
The Other ◽  
Wet Season ◽  
Hand Temperature ◽  
Do Concentration ◽  
Merbok Estuary

Water quality in three different stations of Merbok estuary was investigated limnologically from October, 2010 to September, 2011. Water temperature, transparency and total suspended solids (TSS) varied from 27.45 - 30.450C, 7.5 - 120 cm and 10 -140 mg/l, respectively. Dissolved Oxygen (DO) concentration ranged from 1.22-10.8 mg/l, while salinity ranged from 3.5-35.00 ppt. pH and conductivity ranged from 6.35 - 8.25 and 40 - 380 ?S/cm, respectively. Kruskal Wallis H test shows that water quality parameters were significantly different among the sampling months and stations (p<0.05). This study revealed that DO, salinity, conductivity and transparency were higher in wet season and TSS was higher in dry season. On the other hand, temperature and pH did not follow any seasonal trends.Bangladesh J. Zool. 41(1): 13-19, 2013

A comparison of soil sampling procedures used to monitor soil fertility in permanent pastures

Soil Research ◽  
1984 ◽  
Vol 22 (1) ◽  
pp. 81 ◽  
Author(s):  
DK Friesen ◽  
GJ Blair
Keyword(s):  
Sampling Method ◽  
Nutrient Status ◽  
Temporal Variations ◽  
Cluster Sampling ◽  
Soil Test ◽  
Sampling Strategies ◽  
Grazed Pasture ◽  
The Mean ◽  
Sampling Procedures ◽  
Bray 1

Soil testing programs are often brought in disrepute by unexplained variability in the data. The deposition of dung and urine onto grazed pasture brings about marked variation in the chemical status of soils which contributes to this variability. A study was undertaken to compare a range of sampling procedures to estimate Colwell-P, Bray-1 P, bicarbonate K and pH levels in adjacent low and high P status paddocks. The sampling strategies used consisted of 75 by 50 m grids; whole and stratified paddock zig-zag and cluster (monitor plot) samplings. Soil test means for the various parameters did not vary among sampling methods. The number of grid samples required to estimate within 10% of the mean varied from 121 for Bray-1 P down to 1 for soil pH. Sampling efficiencies were higher for cluster sampling than for whole paddock zig-zag path sampling. Stratification generally did not improve sampling efficiency in these paddocks. Soil test means declined as sampling depth increased, but the coefficient of variation remained constant for Colwell-P and pH. The results indicate that cluster sampling (monitor plots) is the most appropriate procedure for estimating the nutrient status of grazed pastures. This sampling method enables a more accurate measure to be taken of the nutrient status of a paddock and should allow more reasonable estimates to be made of the temporal variations in soil test.

Experiment of Polyester Wastewater Treatment by Aerobic Membrane Bioreactor and an Engineering Application

2012 ◽  
Vol 518-523 ◽  
pp. 2130-2137
Author(s):  
Si Hao Lv ◽  
Hui Chang ◽  
Zhi Hui Liang ◽  
Yan Yan Zeng ◽  
Hong Bo Fan
Keyword(s):  
Water Quality ◽  
Pilot Study ◽  
Membrane Bioreactor ◽  
Suspended Solids ◽  
Loading Rate ◽  
Engineering Application ◽  
Full Scale ◽  
Effluent Water ◽  
Small Influence ◽  
Volumetric Loading

A pilot study was carried out to evaluate the application of aerobic submerged MBR in treating polyester wastewater and a full scale system in which MBR was adopted as the key aspect was put forward to treat the polyester wastewater of Zhuhai Yuhua Polyester co., Ltd., China. The pilot study revealed that HRT could be affected by the influent COD, and a HRT larger than 36h was proposed for treating polyester wastewater by MBR. Volumetric loading rate and sludge loading rate ranged in 0.7-2.0 kgCOD/m3•d and 0.09~0.24 kgCOD/ kgMLSS•d respectively were of small influence on the COD removal. DO in the range of 2.5-4.0 mg/L seemed to be optimal for avoiding limitations due to oxygen concentration and creating an effective turbulence. The modified full scale system which includes anaerobic digesting tank and MBR followed by a stabilization pond was verified to be effective to treat the polyester wastewater in the latest two years. The results illustrated that the effluent water quality could meet the discharge limits of water pollutants (DB 44/26-2001) which was established in Guangdong, China. Observed sludge yield of the system fluctuated between 0.10-0.18 gMLSS/gCOD and averaged at 0.137 gMLSS/gCOD. The membrane permeate at around 10 L/m2h, TMP of less than 0.7bar, and total mixed liquor suspended solids (MLSS) between 6-7g/L were suitable to operate the MBR.

Development of a technically defensible soil gas sampling strategy for vapour intrusion assessments

2009 ◽  
Vol 46 (1) ◽  
pp. 102-113 ◽  
Author(s):  
Tai T. Wong ◽  
John G. Agar
Keyword(s):  
Human Health Risk ◽  
Sampling Strategy ◽  
Soil Gas ◽  
Assessment Process ◽  
Soil Conditions ◽  
Gas Monitoring ◽  
Gas Sampling ◽  
Monitoring Well ◽  
Sampling Procedures ◽  
Soil Gas Sampling

Soil vapour intrusion is now commonly evaluated as part of human health risk assessments at contaminated sites where buildings or other structures are located in close proximity to volatile organic chemicals (VOCs) in subsurface soils and groundwater. Investigation of the vapour intrusion pathway often requires that VOC concentrations in the soil gas adjacent to buildings and structures be characterized as part of the risk assessment process. This paper presents the design of a new soil gas monitoring well and a sampling procedure that effectively eliminate concerns about soil gas sample dilution due to short-circuiting of atmospheric air and help to ensure the collection of representative soil gas samples. The results of a parametric numerical modelling study that was applied to address the air short-circuiting issue and the technical rationale for the new soil gas monitoring well (SGMW) design are presented in this paper along with recommended soil gas sampling procedures in various soil conditions. The SGMW design rationale and methodology outlined in this paper considered the effects of soil moisture content and permeability, the depth to the sampling screen interval, and the soil gas sample extraction rate.

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