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1.
《Marine pollution bulletin》2013,70(1-2):189-194
Irgarol 1051 is a common antifouling biocide and is highly toxic to non-target plant species at low ng/L concentrations. We measured up to 254 ng/L Irgarol in water and up to 9 ng/g dry weight Irgarol in sediments from Southern California recreational marinas. Irgarol’s metabolite, M1, concentrations were up to 62 ng/L in water and 5 ng/g dry weight in sediments. Another antifouling biocide, diuron, reached up to 68 ng/L in water and 4 ng/g dry weight in sediments. The maximum Irgarol concentrations in water were greater than the Irgarol concentration recommended as the plant toxicity benchmark (136 ng/L), suggesting that Irgarol concentrations may be high enough to cause changes in phytoplankton communities in the sampled marinas. Irgarol concentrations measured in sediments were greater than calculated Environmental Risk Limits (ERLs) for Irgarol in sediments (1.4 ng/g). Antifouling pesticide accumulation in sediments may present a potential undetermined risk for benthic organisms.  相似文献   

2.
The eddy covariance technique and the cuvette method were used to investigate water use efficiency in an irrigated winter wheat (Triticum asetivum L.)/summer maize (Zea mays L.) rotation system in the North China Plain. The results show that ecosystem water use efficiency (WUEe) changed diurnally and seasonally. Daily maximal WUEe appeared in the morning. WUEe generally peaked in late April in wheat field and in late July/early August in maize field. From 2003 to 2006, seasonal mean WUEe was 6.7–7.4 mg CO2 g−1 H2O for wheat and 8.4–12.1 mg CO2 g−1 H2O for maize. WUEe was much lower than canopy water use efficiency (WUEc) under small leaf area index (LAI) but very close to WUEc under large LAI. With the increase in LAI, WUEe enlarged rapidly under low LAI but slowly when LAI was higher than one. WUEe was greater on the cloudy days than on the sunny days. Under the same solar radiation, WUEe was higher in the morning than in the afternoon. The ratio of internal to ambient CO2 partial pressure (Ci/Ca) decreased significantly with the increase in photosynthetically active radiation (PAR) when PAR was lower than the critical values (around 500 and 1000 μmol m−2 s−1 for wheat and maize, respectively). Beyond critical PAR, Ci/Ca was approximately constant at 0.69 for wheat and 0.42 for maize. Therefore, when LAI and solar radiation was large enough, WUEe has negative correlation with vapor pressure deficit in both of irrigated wheat and maize fields.  相似文献   

3.
Geogenic arsenic in drinking water is a worldwide problem. For private well owners, testing (e.g., private or government laboratory) is the main method to determine arsenic concentration. However, the temporal variability of arsenic concentrations is not well characterized and it is not clear how often private wells should be tested. To answer this question, three datasets, two new and one publicly available, with temporal arsenic data were utilized: 6370 private wells from New Jersey tested at least twice since 2002, 2174 wells from the USGS NAWQA database, and 391 private wells sampled 14 years apart from Bangladesh. Two arsenic drinking water standards are used for the analysis: 10 µg/L, the WHO guideline and EPA standard or maximum contaminant level (MCL) and 5 µg/L, the New Jersey MCL. A rate of change was determined for each well and these rates were used to predict the temporal change in arsenic for a range of initial arsenic concentrations below an MCL. For each MCL and initial concentration, the probability of exceeding an MCL over time was predicted. Results show that to limit a person to below a 5% chance of drinking water above an MCL, wells that are ½ an MCL and above should be tested every year and wells below ½ an MCL should be tested every 5 years. These results indicate that one test result below an MCL is inadequate to ensure long-term compliance. Future recommendations should account for temporal variability when creating drinking water standards and guidance for private well owners.  相似文献   

4.
Parallel factor analysis of fluorescence excitation emission matrices of surface water samples of a globally large river (Yangtze River, China) watershed identified three classes of fluorescent dissolved organic matter (FDOM) that had ex/em = 280/330 nm, 305/385 nm and 350/450 nm respectively, resembling “peak T”, “peak M” and “peak C” commonly identified in natural water, respectively. Peak T (a tyrosine/tryptophan-like FDOM) did not show correlations to peak M or C which were humic-like substances, while a positive correlation (r = 0.935, p < 0.001) was present between the natural log-transformed maximum fluorescence intensity (Fmax) of peaks T and M indicating a tight link during their production and processing. Fmax values (in Raman unit nm?1) normalized to dissolved organic carbon (DOC) concentration were low, varying in ranges 15.93–85.95, 29.83–83.54 and 19.73–51.05 × 10?5 nm?1 (μmol/L)?1 for peaks T, M and C, respectively, in line with the history of strong photobleaching of the water samples as indicated by fairly high absorption spectral slope ratios (0.75–1.53 with a mean 1.03). Intermediate fluorescence index (FI) (1.46–1.83 with a mean 1.61) and small specific absorption at 254 nm (0.64–1.93 with a mean 1.15 m?1 mg?1 L) of the water samples, indicated the presence of both aquatic microbial DOM (e.g. peak T) and soil DOM (e.g. peak C). Peak C could be substantially removed by UV-A (320–400 nm) irradiation, while peak M was slightly increased when a microbe-containing water was exposed to the same UV-A irradiation. Taken together, peak C was attributed to diffuse soil source while peak M was likely attributed to joint effects of microbial activities and solar irradiation on the chromophores in the sample.  相似文献   

5.
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6.
This work investigates the likelihood of integrating the cheap and readily-available broadband multispectral MODIS data and in-situ measurements in quantifying and monitoring water quality status of an inland lake within Upper Manyame Catchment in Zimbabwe. Specifically we used MODIS images to quantify inland lake chlorophyll_a concentrations, as a proxy for predicting lake pollution levels. The findings of this study show a high chlorophyll_a concentration of 0.101 ± 0.128 μg/L within the Lake. The results further demonstrated that the chlorophyll_a concentration levels did not significantly vary (p = 0.788) between sites, except among depths (p = 0.05). Further, prediction results based on the relationship between observed and predicted chlorophyll_a produced a high R2 value of 0.89 and a root mean square error (RMSE) value of 0.003 μg/L. Moreover, the derived landuse maps of Upper Manyame Catchment indicated a significant variation in the percentage settlement in 1985, 1994 and 2010 change from 1985 to 2010. For instance, 8% increase in settlement in the period between 1994 and 2010 and over 12% increase from 1985 to 2010 and a decline in percent forest coverage (i.e. 9.8% in 1985 to 2.0% in the year 2010) in the catchment was observed. Overall, the findings of this study highlights the importance of free and readily-available satellite datasets (such as the multispectral MODIS and Landsat) in quantifying and monitoring water quality across inland lakes especially in data-scarce areas like Sub-Saharan Africa.  相似文献   

7.
Potential remediation of surface water contaminated with linear alkylbenzene sulfonates (LAS) and zinc (Zn (II)) by sorption on Spirulina platensis was studied using batch techniques. Results show that LAS can be biodegraded by Spirulina platensis, and its biodegradation rate after 5 days was 87%, 80%, and 70.5% when its initial concentration was 0.5, 1, and 2 mg/L, respectively. The maximum Zn (II) uptake capacity of Spirulina platensis was found to be 30.96 mg/g. LAS may enhance the maximum Zn (II) uptake capacity of Spirulina platensis, which can be attributed to an increase in bioavailability due to the presence of LAS. The biodegradation rates of LAS by Spirulina platensis increased with Zn (II) and reached the maximum when Zn (II) was 4 mg/L. The joint toxicity test showed that the combined effect of LAS and Zn (II) was Synergistic. LAS can enhance the biosorption of Zn (II), and reciprocally, Zn (II) can enhance LAS biodegradation.  相似文献   

8.
We present a geostatistics-based stochastic salinity estimation framework for the Montebello Oil Field that capitalizes on available total dissolved solids (TDS) data from groundwater samples as well as electrical resistivity (ER) data from borehole logging. Data from TDS samples (n = 4924) was coded into an indicator framework based on falling below four selected thresholds (500, 1000, 3000, and 10,000 mg/L). Collocated TDS-ER data from the surrounding groundwater basin were then employed to produce a kernel density estimator to establish conditional probabilities for ER data (n = 8 boreholes) falling below the selected TDS thresholds within the Montebello Oil Field area. Directional variograms were estimated from these indicator coded data, and 500 TDS realizations from conditional indicator simulation were generated for the subsurface region above the Montebello Oil Field reservoir. Simulations were summarized as 3D maps of median TDS, most likely salinity class, and probability for exceeding each of the specified TDS thresholds. Results suggested TDS was below 500 mg/L in most of the study area, with a trend toward higher values (500 to 1000 mg/L) to the southwest; consistent with the average regional groundwater flow direction. Discrete localized zones of TDS greater than 1000 mg/L were observed, with one of these zones in the greater than 10,000 mg/L range; however, these areas were not prevalent. The probabilistic approach used here is adaptable and is readily modified to include additional data and types and can be employed in time-lapse salinity modeling through Bayesian updating.  相似文献   

9.
Moringa oleifera (MO) seed extract coupled with electrocoagulation (EC) was used to remove fluoride from water. Different MO extract volumes (5.0, 12.5, and 25.0 mL of MO extract per water liter) were coupled with EC, using aluminum electrodes at different current density values (J = 0.7, 2.0, and 3.3 mA/cm2) and different electrode separations (1.0, 2.0, and 4.0 cm), tested in batch and recirculation experiments. Control experiments using MO extract and EC alone achieved 5% and 54% water defluoridation, respectively. Best experimental batch conditions were achieved using 12.5 mL of MO extract followed by EC (3.3 mA/cm2) with a 1.0 cm electrode separation, producing >90% fluoride removal. Recirculation experiments with the EC reactor were performed with DI water and tap water using 1.0 cm electrode separation, 12.5 mL of MO extract and different current densities. More than 90% fluoride removal was achieved with the EC/MO process, using 3.3 mA/cm2, in both DI and tap water after 30 and 60 min, respectively. An energy consumption index (ECI) was developed, which showed that 1.51 and 0.67 W/h/mg were achieved for batch experiments of EC alone and EC/MO extract, respectively. For EC/MO extract, recirculation experiments with tap and DI water resulted in 0.35 and 0.22 W/h/mg, respectively. A cost analysis showed that $0.18 will be needed to treat one cubic meter of water.  相似文献   

10.
《国际泥沙研究》2022,37(6):701-714
E. coli and Listeria monocytogenes (or L. monocytogenes) are bacteria affecting fresh produce that is harmful for health of humans and animals. If these bacteria are present in surface waterbody (e.g., irrigation canals), they will impair irrigation water quality and threaten produce safety. This paper studied the resuspension of E. coli and Listeria from bed sediment into irrigation water through several sets of laboratory experiments in an open channel flume. We studied three types of sediments using several flow rates in different velocities and shear stress. Bacteria's concentration in water increases with the bed shear stress. Two empirical relations were derived to correlate the concentration of E. coli and L. monocytogenes with the dimensionless bed shear stress. The experimental data favorably verified the relationships for sandy loam, loamy sand, and loam. The results showed that both bacteria could entrain from sand more efficiently compared to other sediments (i.e., sandy loam or loam). These relationships can be applied to water quality models for simulating E. coli and L. monocytogenes transport in irrigation canals for better managing irrigation water quality.  相似文献   

11.
A highly sensitive and specific enzyme immunoassay (EIA) is described for the detection of the atrazine metabolite hydroxyatrazine. Polyclonal antibodies were raised in rabbits by immunization with a hapten-bovine serum albumin (BSA) conjugate containing 8 hapten residues per molecule of BSA. An EIA with a horseradish peroxidase (HRP) hapten tracer was optimized in microtitre plates. A concentration of 50% B/B0 was found at 0.10 μg/L for hydroxyatrazine. A limit of determination for hydroxyatrazine was reached at approximately 0.01 μg/L, i.e. well below the maximum concentration permitted by the EU guidelines for drinking water and the drinking water ordinance of the FRG. The assay did not require concentration or clean-up steps for drinking water or ground water samples. Validation experiments confirmed a good accuracy and precision. Hydroxyatrazine is reported to be the main atrazine metabolite found in soil samples. As organic solvents are usually employed for soil extraction, the influence of methanol as representative organic solvent on the assay was examined. Up to a concentration of 5% (v/v) methanol, the organic solvent did not affect the assay.  相似文献   

12.
The flux of fluvial carbon from the terrestrial biosphere to the world's oceans is known to be an important component of the global carbon cycle, but within this pathway, the flux and return of carbon to the river network via sewage effluent has not been quantified. In this study, monitoring data from 2000 to 2016 for the dissolved organic carbon (DOC) concentration, biochemical oxygen demand, and chemical oxygen demand of the final effluent of sewage treatment works from across England were examined to assess the amount of DOC contributing to national‐scale fluvial fluxes of carbon. The study shows that the median concentration of DOC in final effluent was 9.4 compared with 4.8 mg C/L for all surface waters for the United Kingdom over the study period and that the DOC in final effluent significantly declined over the study period from 11.0 to 6.4 mg C/L. Rivers receiving sewage effluent showed a significant, on average 19%, increase in DOC concentration downstream of sewage discharges. At the scale of the United Kingdom, the flux of DOC in final effluent was 31 ktonnes C/year with a per capita export of 0.55 kg C/year and compared with an average annual flux of DOC from the United Kingdom of 859 ktonnes C/year, that is, only 3.6% of national‐scale flux. The lability of this DOC was limited, with only 7.4% loss of final effluent DOC concentration over in‐stream residence times of up to 5 days. The direct decline in DOC concentration from sewage treatment works was not large enough on its own to explain the declines observed in DOC concentration in U.K. rivers at their tidal limit.  相似文献   

13.
Consecutive rainfalls, due to changes in antecedent moisture, alter soil erosion processes, necessitating the implementation of suitable soil loss control methods. Biological soil microorganism approaches have been applied to control soil loss. However, information on the involvement of microorganisms in the soil loss and rill erosion processes has yet to be supplied. In this study, the individual and combined inoculation of cyanobacteria and bacteria was investigated during five consecutive rai...  相似文献   

14.
1,4-Dioxane is a contaminant of emerging concern, and there is significant uncertainty about how its environmental occurrence in groundwater is being assessed given the various analytical methods available. This study compiled public sampling records from 2000 to 2019 that included >106,000 analyses of 1,4-dioxane from 822 different U.S. sites. The 1,4-dioxane detection frequency in the entire dataset (including all methods) was 45%, and the median detected concentration was 10 μg/L, highlighting the dilute nature of 1,4-dioxane in environmental media and the importance of selecting methods with adequate sensitivity. The annual distribution of samples analyzed by each method type confirmed a shift towards methods designed for semi-volatile compounds (Method 8270 and Method 8270 SIM) that exhibited consistently lower reporting limits (median reporting limit for each year typically ≤1 μg/L). In contrast, the method designed for volatile compounds (Method 8260) exhibited less sensitivity for 1,4-dioxane (median reporting limit per year between 40 and 100 μg/L) and its use declined significantly over time with increasing use of the moderately sensitive Method 8260 SIM in later years. This shift contributed to an increase in the 1,4-dioxane detection frequency over time, with a strong correlation between the annual detection frequency and the median reporting limit. Sites where 1,4-dioxane was analyzed but not detected overwhelmingly used less-sensitive methods that may not have been adequate for the expected concentration levels. Given the sub-μg/L groundwater criteria issued for 1,4-dioxane by some regulatory agencies, more sensitive and accurate methods will be increasingly needed to assess compliance.  相似文献   

15.
To improve the knowledge of the regionally important Continental Terminal 3 (CT3) aquifer in south-western Niger, fifteen magnetic resonance soundings (MRS) were carried out in December 2005 in the vicinity of wells and boreholes. The output MRS geophysical parameters, i.e. water content and decay constants versus depth, were compared to hydrogeological characteristics, i.e. water table depth, total porosity, specific yield and transmissivity estimated from direct measurements, pumping tests and transient groundwater modelling. The MRS-determined parameters were then used to estimate the rates of groundwater recharge.Contained in poorly consolidated Tertiary sandstones, the CT3 aquifer's water table has continuously risen by 4 m in total over the past four decades. Additionally, a significant portion of this increase has occurred in the past decade alone, with an annual rise now ranging between 0.1 and 0.3 m depending on the monitored well. Increase in groundwater recharge due to land clearance and deforestation explains this situation. According to previous estimations, the pre-clearing recharge ranged from 1 to 5 mm per year in 1950–60 s, while more recent recharge rates (1990s–2000s) range from 20 to 50 mm per year. These recharge values are directly affected by estimated aquifer specific yield value, while the spatial variation of rates of water table rise can be attributed to large scale hydrodynamic heterogeneities in the aquifer. However, few field measurements were available to confirm these assumptions.The main results of this study are: (1) The water table depth and aquifer transmissivity are estimated from MRS output parameters with an average accuracy of ± 10% and ± 9% respectively. (2) The MRS-determined water content is linked to both the total porosity and the specific yield of the aquifer, but no quantitative formulation can be proposed as yet. (3) Using the average MRS-determined water content over the investigated area, i.e. 13%, the groundwater recharge rates can be estimated to be ~ 2 mm per year in the 1950–1960s (pre-clearing period), and ~ 23 mm per year for the last decade. (4) The variations in specific yield and transmissivity cannot explain by themselves the spatial variability of the rise of the water table. (5) The ranges in transmissivity and water content obtained from MRS are more realistic than the groundwater modelling outputs. Therefore, MRS could be used to better constrain the aquifer parameters in groundwater modelling with a dense site network.Finally, this work illustrates how MRS can successfully improve characterisation and transient multi-year groundwater balance of commonly found sedimentary aquifers, particularly when integrated with well observations and pumping tests.  相似文献   

16.
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17.
Thirteen adult Orconectes limosus males (carapace length 32.5 ± 2.48 mm; weight 10.8 ± 2.63 g) were radio-tagged and tracked during and after the spring mating period, April–June 2008. Average distances moved per day were higher in the mating period (14.9 ± 21.4 m) due to mate searching activity. During the mating period, movement did not correlate with water temperature, and crayfish were active during daylight hours. They moved rapidly upstream and downstream, a maximum 118 and 95 m per day, respectively. When water temperature increased over 10°C, this initiated the end of mating and the start of spawning, and the spring migration abruptly ceased. An influence of water temperature on movements was observed during the non-reproductive period. Orconectes limosus was highly mobile in small watercourses, signifying a threat of penetration into native crayfish habitats, and potentially enabling the transmission of crayfish plague. This threat was increased during the mating period due to increased activity.  相似文献   

18.
With the recent development of society and economy in the cities of Huludao and Jinzhou, Liaoning Province, China, environment and ecosystem problems have become increasingly serious in Jinzhou Bay, China, because of the increasing amount of heavy metal pollutants being discharged. To solve these problems, a water quality model of heavy metals coupled with a 3D hydrodynamic model is constructed to estimate the environmental capacity (EC) and total maximum allocated loads (TMALs) for Zn and Cd of three river catchments in Jinzhou Bay. According to the model, the ECs for Zn and Cd are approximately 17 and 8 tons per month, respectively, if the criterion obtained from HC5 values (fifth percentile of the SSD) is set as the control criterion (8.24 μg/L for Zn and 3.83 μg/L for Cd) in Jinzhou Bay, and the TMALs of the three river catchments are 4 and 1.7 tons per month.  相似文献   

19.
A start‐up study for biohydrogen production from palm oil mill effluent (POME) is carried out in a pilot‐scale up‐flow anaerobic sludge blanket fixed‐film reactor (UASFF). A substrate with a chemical oxygen demand (COD) of 30 g L?1 is used, starting with molasses solution for 30 days and followed by a 10% v/v increment of POME/molasses ratio. At 100% POME, a hydrogen content of 80%, hydrogen production rate of 36 L H2 per day, and maximum COD removal of 48.7% are achieved. Bio‐kinetic coefficients of Monod, first‐order, Grau second‐order, and Stover‐Kincannon kinetic models are calculated to describe the performance of the system. The steady‐state data with 100% POME shows that Monod and Stover‐Kincannon models with bio‐kinetic coefficients of half‐velocity constant (Ks) of 6000 mg COD L?1, microbial decay rate (Kd) of 0.0015 per day, growth yield constant (Y) of 0.786 mg volatile suspended solids (VSS)/mg COD, specific biomass growth rate (μmax) of 0.568 per day, and substrate consumption rate of (Umax) 3.98 g/L day could be considered as superior models with correlation coefficients (R2) of 0.918 and 0.989, respectively, compared to first‐order and Grau's second‐order models with coefficients of K1 1.08 per day, R2 0.739, and K2s 1.69 per day, a = 7.0 per day, b = 0.847.  相似文献   

20.
Batch and continuous flow adsorption experiments are carried out and the design of a full‐scale facility for removing dissolved natural organic matter (DNOM) from Catalan Lakewater is demonstrated. The adsorption efficiency is proportional to the temperature and the amount of adsorbent unlike pH increase. The highest DNOM removal rate is obtained at 35 °C, pH 4, and an adsorbent amount of 0.8 g L?1. Optimum contact time for batch studies is 60 min at equilibrium. Correlation constants (r) of Langmuir and Freundlich isotherms are 0.8905 and 0.9739, respectively. Based on the Freundlich isotherm, the highest adsorption capacity (qmax) obtained is 2.44 and 6.01 mg DNOM/g granulated activated carbon (GAC) for raw and enriched water, respectively. Consequently, the effects of adsorbent amount, bed depth, empty bed contact time, and organic loading on removal performance are investigated in the rapid small‐scale column test (RSSCT) columns. The targeted effluent concentration of 1 mg DNOM/L can easily be achieved in the columns. At the design capacity of the facility, 15 adsorption columns with dimensions of 7 m height, 4.33 m diameter, and 22 days of operation cycle are required to remove DNOM from raw water.  相似文献   

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