Estuary Water Samples Research Articles

Ultraviolet Spectroscopic Detection of Nitrate and Nitrite in Seawater Simultaneously Based on Partial Least Squares.

A direct, reagent-free, ultraviolet spectroscopic method for the simultaneous determination of nitrate (NO3−), nitrite (NO2−), and salinity in seawater is presented. The method is based on measuring the absorption spectra of the raw seawater range of 200–300 nm, combined with partial least squares (PLS) regression for resolving the spectral overlapping of NO3−, NO2−, and sea salt (or salinity). The interference from chromophoric dissolved organic matter (CDOM) UV absorbance was reduced according to its exponential relationship between 275 and 295 nm. The results of the cross-validation of calibration and the prediction sets were used to select the number of factors (4 for NO3−, NO2−, and salinity) and to optimize the wavelength range (215–240 nm) with a 1 nm wavelength interval. The linear relationship between the predicted and the actual values of NO3−, NO2−, salinity, and the recovery of spiked water samples suggest that the proposed PLS model can be a valuable alternative method to the wet chemical methods. Due to its simplicity and fast response, the proposed PLS model can be used as an algorithm for building nitrate and nitrite sensors. The comparison study of PLS and a classic least squares (CLS) model shows both PLS and CLS can give satisfactory results for predicting NO3− and salinity. However, for NO2− in some samples, PLS is superior to CLS, which may be due to the interference from unknown substances not included in the CLS algorithm. The proposed method was applied to the analysis of NO3−, NO2−, and salinity in the Changjiang (Yangtze River) estuary water samples and the results are comparable with that determined by the colorimetric Griess assay.

Atmospheric respiratory CO2 efflux by aquatic suspended particle-bound microbial communities: A laboratory experimental study

Natural sources of atmospheric CO2 are of increasing interest as possible contributors to global climate warming. This study documents the amount of respiratory CO2 contributed by microbial communities associated with suspended particulates in aquatic water columns. Microcosms containing three different sources of water (pond freshwater, NY East River estuary and Hudson River estuary) were used to experimentally determine the atmospheric respiratory CO2 released from particle-associated microbes. Two different approaches were used. In the first, finely powdered dried cereal leaves (alfalfa) were added to each of the three microcosms as a consistent source of particulate organic matter (POM). In the second, only Hudson River estuary water samples were used with natural densities of POM. Respiration rates associated with two sizes of particles were assessed: 1) ≥ 200 μm and 2) ≥ 50 μm but less than 200 μm. The total respiration rate for the three microcosms with cereal leaf POM ranged from 5.09 to 14.87 μmol CO2 min−1 L−1. Of this, the amount contributed by larger particulates was in the range of 55–63%; and for smaller particulates ranged from 18 to 32 %. Data for microcosms containing water from the Hudson River estuary, with natural particulates, was as follows: total respiration ranged from ∼3 μmol CO2 min−1 L−1 to ∼3.73 μmol CO2 min−1 L−1. Larger particulates contributed approximately 40% of total respiration, and that of smaller particulates was substantially less (4–5% of total). Overall, these results indicate that microbial communities associated with particulates in the water column (especially larger particulates) may contribute substantial amounts of CO2 to the atmosphere.

Microbiological Examination and Physicochemical Analysis of Estuary Water Used as a Point of Source Drinking Water

Introduction: Access to potable water is a fundamental human right. However, this is hardly the case in the rural areas of oil producing communities of the Niger Delta.
 Aim of Study: The primary aim of this study was therefore to evaluate the physicochemical and microbiological qualities of estuary water used as potable water.
 Method: Estuary water samples were collected from Eastern Obolo community in Akwa Ibom State, Niger Delta, Nigeria and analysed for physiochemical using standard techniques, and microbiological parameters using standard cultural and metagenomics techniques. Replicate data from microbiological and physicochemical analyses were analyzed using analysis of variance (ANOVA) while bioinformatic analyses were done using Vecton NTI suite 9 (InforMax, Inc.), NCBI-BLAST-2.2.24 and CLC bio Genomics workbench v7.5.1.
 Results: Physicochemical analysis showed that the levels of metals such as chromium, nickel, zinc and iron and as well as turbidity were significantly higher than acceptable standards. Bacterial counts ranged from 0.64 to 1.00 (x 105) cfu/ml. Fungal counts ranged from 2.00 to 4.00 (x 102) cfu/ml. Esherichia coli, Citrobacter, Bacillus, Micrococcus, Pseudomonas and Flavobacterium, Shigella, Salmonella and Vibrio species were isolated using cultural means. Total coliforms counts were higher in location E6 which was closest to the community. Metagenomics analysis gave a total of six kingdoms namely bacteria, unknown, protozoa, archae, plantae and fungi in decreasing order of read counts. Furthermore, it revealed a total of 16 phyla, 24 classes, 38 orders, 39 families and 209 species of bacteria. Some pathogens not captured by cultural means such as Clostridium species, Vibrio alginolyticus, Vibrio neresis, Staphylococcus kloosii, Corynebacterium diptheriae, and uncultured species such as uncultured Helicobacter were all captured by metagenomics.
 Conclusion: Although, cultural methods used in this study were able to capture water borne disease pathogens, metagenomics captured much more kingdoms and species. Where possible, both techniques should be used in the microbiological examination of water samples.

Aggregation Behavior of Dissolved Black Carbon: Implications for Vertical Mass Flux and Fractionation in Aquatic Systems.

The fluvial export of dissolved black carbon (DBC) is a major land-ocean flux in the global black carbon cycle, affecting the size of refractory carbon pool in the oceans. The aggregation behavior of DBC is a significant determinant of its transport and vertical mass flux. In this study, the aggregation kinetics and interaction energy of DBC leached from biochar were investigated. DBC was mainly stabilized by hydration force and underwent structural compacting in divalent cation solutions. Na+ and Mg2+ had limited impact on the colloidal stability of DBC due to the strong hydration of these cations. Ca2+ and Ba2+ readily destabilized DBC by forming inner-sphere complexes, reducing its hydrophilicity. Consistently, charge reversal of DBC was observed with high concentrations of Ca2+ and Ba2+. Simulated sunlight exposure led to photo-oxidation of DBC, increasing its colloidal stability. DBC behaved nonconservatively in laboratory mixing experiments using estuary water samples due to aggregation/sedimentation; while model aquatic humic acid behaved conservatively. Our results infer that there is a vertical mass flux of DBC and possible fractionation from the dissolved organic matter pool in the fluvial and estuarine systems, which have been overlooked in efforts to determine global carbon budgets and associated climate change implications.

Does the presence of caffeine in the marine environment represent an environmental risk? A regional and global study

Caffeine is an emerging contaminant considered to be an indicator of human contamination that has been widely detected in various aquatic systems, especially in continental waters. Nevertheless, the extent of its possible environmental impact is yet to be determined. This study determined the presence of caffeine, and evaluated the environmental hazard posed by this substance, in the “Rías Gallegas”, a series of costal inlets in north-west Spain which are of great ecological value and in which fishing and bivalve farming, are a significant source of income. Caffeine was found to be present at concentrations higher than the limit of quantification (LOQ=3.07ngL−1) in 15 of the 23 samples analysed, with the highest seawater concentration being 857ngL−1 (the highest measured in seawater in Spain). Six out of 22 seawater samples resulted in a hazard quotient (HQ) from chronic exposure higher than 1 with the highest being 17.14, indicating a high probability of adverse effects in the aquatic environment. Environmental Exposure Distributions (EEDs) generated from a literature review of caffeine levels reported previously in four out of the five continents, showed that 28% of all seawater samples, and 69% of all estuary water samples where caffeine has ever been measured resulted in HQ>1 for chronic exposure. Further studies into the potential adverse effects that may arise from exposure to caffeine in aquatic systems are still required. Indeed, the need to gain a more in-depth understanding of the long-term ecotoxicological effects of caffeine is essential to ensure the quality of our health and environment.

Microwave preservation method for DMSP, DMSO, and acrylate in unfiltered seawater and phytoplankton culture samples

AbstractA microwave‐preservation method was developed to quantify total dimethylsulfoniopropionate (DMSPT), dimethylsulfoxide (DMSOT), and acrylate (acrylateT) concentrations in unfiltered samples to alleviate problems associated with the acidification method when applied to samples containing Phaeocystis. Microwave‐ and acid‐preservation methods were compared using batch cultures of Phaeocystis antarctica and 11 other marine phytoplankton species for DMSPT, batch P. antarctica cultures for DMSOT and acrylateT, and unfiltered Delaware Estuary water samples for DMSPT to demonstrate the general applicability of this method. Acidification of P. antarctica culture samples resulted in the underestimation of DMSPT (42–69%) and overestimation of dimethylsulfide (DMS) (2156–3819%), DMSOT (9–101%), and acrylateT (71–249%). By comparison, DMSPT concentrations in microwaved samples agreed with non‐microwaved, non‐acidified controls. In contrast to P. antarctica results, the microwave‐ and acid‐preservation methods yielded DMSPT concentrations that were statistically indistinguishable for 11 other marine phytoplankton species and Delaware Estuary samples. Unfiltered samples stored frozen following microwave treatment or stored at room temperature if acidified after the microwaving step, resulted in no change in DMSPT or acrylateT; DMSOT concentrations increased slightly (∼ 15%) when they were not sparged to remove DMS prior to acidification and room temperature storage. Based on these findings, we propose microwaving small sample volumes (≤ 7 mL) of unfiltered seawater or culture samples as a general approach to preserve samples for subsequent DMSPT, DMSOT, and acrylateT analyses, especially when the phytoplankton composition of the samples is unknown.

Contamination of Estuary Water of Ship Breaking Activities in Sitakund Region, Bangladesh

The present study aimed to investigate hydrogeochemistry and its suitability for drinking and irrigation purposes and to determine the contamination of estuary water of ship breaking activities in Sitakunda region, Chittagong, Bangladesh. The study was carried out by in-situ field measurement of physical parameters while chemical parameters were followed by atomic absorption spectrometry (AAS) methods of laboratory analyses of 12 estuary water samples. The result shows that the P value was average 7.08 indicated neutral water while E, EC, TDS and TH value was average -24.65 mv, 8586.5 μS/cm, 5495.36 μS/cm and 432.41 mg/l respectively, indicated that the estuary water is not safe Original Research Article American Chemical Science Journal, 4(6): 934-951, 2014 935 and suitable for domestic and irrigation purposes. Inferential statistical results were depicted that a strong positive correlation (ρ) between the parameters such as EC, TDS, TH, Ca, Na, K, Cl, Br, SO4, PO4, NO3 while negative correlation (ρ) were existed between Mg and HCO3. According to most abundance of major cations were Na>Ca>Mg>K whereas major anions were Cl>SO4>HCO3>Br>NO3>PO4. The concentration of cations and anions in the study area exceeded drinking standards according to the World Health Organization (WHO) and the Directorate of Environment (DOE), Bangladesh. Irrigation quality index (SAR and PI) indicated that the quality of water is not suitable for irrigation. The origin of solutes in estuary water was influenced by chloride dissolution, although weathering of silicate and cation exchange also added to the water chemistry. This is not conclusive but it may be suggested that the sampled water is not ionically balanced and is highly contaminated due to ship breaking activities.

Improvements on bar adsorptive microextraction (BAμE) technique–Application for the determination of insecticide repellents in environmental water matrices

Bar adsorptive microextraction combined with micro-liquid desorption followed by large volume injection-gas chromatography-mass spectrometry operating in the selected-ion monitoring acquisition mode (BAµE-µLD/LVI-GC-MS(SIM)), is proposed for the determination of trace levels of three insecticide repellents (N,N-diethyl-meta-toluamide (DEET), cis and trans permethrin (PERM)) in environmental water matrices. By comparing different sorbent coatings (five activated carbons and six polymers) through BAµE, an activated carbon (AC2) proved to be the best compromise between selectivity and efficiency, even against polydimethylsiloxane through stir bar sorptive extraction. The novel improvement proposed on the back-extraction stage performed in a single step, by reducing the desorption solvent volume at the microliter level, demonstrated remarkable performance turning possible to save time, making easier the practical manipulation and more environmentally friendly. Assays performed by BAµE(AC2)-µLD/LVI-GC-MS(SIM) on 25 mL of ultrapure water samples spiked at the 1.0 μg/L level, yielded recoveries ranging from 73.8±8.8% (trans-PERM) to 96.4±9.9% (DEET), under optimised experimental conditions. The analytical performance showed convenient detection limits (8-20 ng/L) and good linear dynamic ranges (0.04-4.0 µg/L) with suitable determination coefficients (r(2)>0.9963, DEET). Excellent repeatability were also achieved through intraday (RSD<14.9%) and interday (RSD<11.9%) experiments. The novel improvement on downsizing the BAµE device to half-size proved to be either a promising option in forthcoming to reduce still more the desorption solvent volume without losing microextraction efficiency. By using the standard addition methodology, the application of the present analytical approach on tap, ground, river, swimming-pool and estuary water samples revealed good sensitivity at trace level and absence of matrix effects.

Chemometrics for the classification and calibration of seawater using the H+ affinity spectrum

In 1819 Alexander Marcet proposed that seawater contains small amounts of all soluble substances and that the relative abundances of some of them were constant. This hypothesis is nowadays known as Marcet's Principle or the principle of constancy of the composition of seawater. Based on this principle, the present research tried to prove that it is possible to detect polluted seawater samples using the seawater H+ affinity spectrum by the application of the possibilities provided by chemometric tools. Seawater samples were classified using the principal component analysis (PCA) of the HBound spectra of the samples. It was concluded that the sampling points location does not have any influence in the cluster formation, while the season in which they were collected is significant. On the other hand, the seawater composition was calibrated using estuary water samples of different salinities. Once the major constituents were measured, the data analysis concluded that it is possible to make a calibration of the HBound spectrum vs. any of these constituents by means of partial least square (PLS) regression. Thus, the experimental evidence collected in this work confirms that it is possible to detect polluted sea or estuary water samples using these chemometric tools and the H+ affinity spectrum because with polluted samples these multivariate methods lead to incoherent results. So, suspect polluted zones may be monitored in a simple way with a low cost method and spending much less time.

Short- and long-term temporal variations in salinity and the oxygen, carbon and hydrogen isotopic compositions of the Hooghly Estuary water, India

The Hooghly River estuary provides a unique experimental site to understand the effect of monsoonal river discharge on freshwater and seawater mixing. Water samples collected bi-weekly for a duration of 17months were analyzed for salinity, δ18O, δ13CDIC, as well as δD to investigate the differential mixing of freshwater and seawater. The differences in salinity and δ18O of samples collected during low and high tides on the same day are strongly correlated suggesting a well mixed water column at our sampling site. Low salinity and depleted δ18O during monsoon is consistent with increased river discharge as well as high rainfall. We identified different slopes in a δ18O versus salinity plot for the estuary water samples collected during monsoon and non-monsoon seasons. This is driven by composition of the freshwater source which is dominated by rainwater during monsoon and rivers during non-monsoon months. Selected δD analyses of samples indicate that groundwater contributes significantly to the Hooghly Estuary during low rainfall times of the year. δ13CDIC measured in the water recorded low values towards the end of monsoon indicating low productivity (i.e. increased organic respiration) while progressively increasing δ13CDIC values from October till January as well as during some of the pre-monsoon months can be explained by increasing productivity. Very low δ13CDIC (~−20‰) suggests involvement of carbon derived from anaerobic oxidation of organics and/or methane with potential contribution from increased anthropogenic water supply. An estimate of seawater incursion into the Hooghly Estuary at different times of the year is obtained by using salinity data in a two-component mixing model. Presence of seawater was found maximum (31–37%) during February till July and lowest (less than or equal to 6%) from September till November. We notice a temporal offset between Ganges River discharge farther upstream at Farakka and salinity variation at the Hooghly Estuary. We believe that this time lag is a result of the physical distance between Farakka and Kakdweep (our sampling location) and put constraints on the travel time of river water during early monsoon.

Using a dual isotopic approach to trace sources and mixing of sulphate in Changjiang Estuary, China

Abstract The dual isotopic compositions of dissolved SO 4 2 - in aquatic systems are commonly used to ascertain SO 4 2 - sources and possible biogeochemical processes. In this study, the physical parameters, major anions and isotopic compositions of SO 4 2 - in water samples from Changjiang River (Nanjin) to the East Sea in Changjiang Estuary were determined. The salinity ranged from 0‰ to 32.3‰ in the estuary water samples. The Cl - , SO 4 2 - concentrations and δ18O–H2O values followed the salinity variations from freshwater to seawater, which indicated that mixing processes might be a major factor involved in the distribution of water and solutes. The contents and isotopic compositions of SO 4 2 - suggested that atmospheric deposition, evaporite dissolution and sulphide oxidation were the major sources of dissolved SO 4 2 - in the freshwater of Changjiang River. In addition, the mixing model calculated by contents and isotopic compositions of SO 4 2 - indicated that the mixing of freshwater and sea water was the major factor involved in SO 4 2 - distribution in Changjiang Estuary. However, slightly elevated δ18O–SO4 values were observed in the turbidity maximum zone, which suggested that biological processes might affect the O isotopic compositions of SO 4 2 - there.

A study on the relationship between BOD5 and COD in a coastal seawater environment with a rapid BOD measurement system

The dual objectives of this study are to: (1) examine the relationship between COD and BOD in seawater environment with a rapid but reliable method for the measurement of BOD in seawater, and (2) establish the relationship model between BOD(5) and COD in the firth of Dongbao River to predict the values of BOD(5). The first objective is met by the successful development of a technique utilizing bacteria-immobilized membrane flow cell for biodegradation process, coupled with fibre optic fluorescence detection for oxygen depletion quantitation. The technique has been applied to coastal seawater samples collected in the coastal area of Shenzhen, China. The BOD(5) and COD values for the samples are acquired and the results show that there is no apparent linear relationship existing between BOD(5) and COD in relatively clean seawater samples away from the shore. However, in estuary water samples containing relatively high concentration of sewage contamination, a linear correlation does exist between BOD(5) and COD. The linear relationship between the two parameters allows for the calculation of BOD(5) values based on COD data which can be measured more readily and precisely.

A study on the relationship between BOD5 and COD in coastal seawater environment with a rapid BOD measurement system

The dual objectives of this study are to: (1) examine the relationship between COD and BOD in seawater environment with a rapid but reliable method for the measurement of BOD in seawater, and (2) establish the relationship model between BOD(5) and COD in the firth of Dongbao River to predict the values of BOD(5). The first objective is met by the successful development of a technique utilizing bacteria-immobilized membrane flow cell for biodegradation process, coupled with fibre optic fluorescence detection for oxygen depletion quantitation. The technique has been applied to coastal seawater samples collected in the coastal area of Shenzhen, China. The BOD(5) and COD values for the samples are acquired and the results show that there is no apparent linear relationship existing between BOD(5) and COD in relatively clean seawater samples away from the shore. However, in estuary water samples containing relatively high concentration of sewage contamination, a linear correlation does exist between BOD(5) and COD. The linear relationship between the two parameters allows for the calculation of BOD(5) values based on COD data which can be measured more readily and precisely.

A most probable number method for estimating small numbers of campylobacters in water.

A most probable number (MPN) method capable of estimating as few as ten campylobacters per 100 ml of water is described. The method gave results close to those obtained by the viable count method of Miles, Misra & Irwin (1938) with graded suspensions of Campylobacter jejuni. The method was used to test raw water samples: counts were obtained ranging from 10 to 230 campylobacters per 100 ml for 11 49 coastal and estuary water samples, and from 10 to 36 campylobacters per 100 ml for 7 of 44 river samples. Campylobacters were isolated from an additional 24 of the 'negative' samples by testing 200 ml volumes by glass microfibre filtration and enrichment culture methods. The MPN method should prove to be a useful epidemiological tool particularly suited to the enumeration of campylobacters in particulate fluids.

Mathematical Modeling of Dissolved Oxygen in Mixed Estuaries

One of the basic difficulties in modelling DO in a given estuary is the uncertainities involved in the BOD and reaeration rates. The oxidation of both carbonaceous and nitrogenous substances simultaneously and their representation by first-order kinetics may be justified in estuaries. The carbonaceous and nitrogenous BOD rate coefficients have been determined from the standard BOD tests of estuary water samples by considering the two stages of BOD separately and by adjusting the time origin of nitrification stage. The available reaeration rate coefficient equations developed for nontidal systems and applied in modeling DO in tidal estuaries do not fully represent the tidal estuaries. A new reaeration rate coefficient equation has been developed for tidal systems. The proposed equation is related to the dispersion coefficient and is a function of flow depth and four-thirds power of tidal velocity.