A soil core collected in a tidal freshwater marsh in the Waccamaw National Wildlife Refuge (Georgetown, SC) exuded a particularly strong odor of cow manure upon extrusion. In order to test for manure and determine its provenance, we carried out microbial source tracking using DNA markers for Bacteroides, a noncoliform, anaerobic bacterial group that represents a large proportion spectrum of the fecal population. Three core sections from 0–3 cm, 9–12 cm, and 30–33 cm were analyzed for the presence of Bacteroides. The ages of core sediments were estimated using²¹⁰Pb and¹³⁷Cs dating. All three core sections tested positive for Bacteroides DNA markers related to cow or deer feces. Because cow manure is stockpiled, used as fertilizer, and a source of direct contamination in the Great Pee Dee River/Winyah Bay watershed, it is very likely the source of the Bacteroides that was deposited on the marsh. The mid-points of the core sections were dated as follows: 0–3 cm, 2009; 9–12 cm, 1999, and 30–33 cm, 1961. The presence of Bacteroides at different depths/ages in the soil profile indicates that soils in tidal freshwater marshes are, at the least, capable of being short-term sinks for Bacteroides and, may have the potential to be long-term sinks of stable, naturalized populations.

Adsorption is one of the best methods for arsenic removal from water which is established in the last few decades. Biosorption by natural biosorbents and agricultural by-product is an environmental friendly approach and has proved to be a cost-effective and non-hazardous technology for the removal of heavy metals from water. This paper describes batch test findings conducted to evaluate the feasibility of using sugarcane bagasse (SCB) as an industrial by-product of sugar industry to remove arsenic (As) from water and compare the results with the efficiency of activated carbon (AC) for arsenic (As) removal. The effects of three parameters, such as pH, adsorbent dosage (Cₐ), and initial metal concentration (C₀) on the adsorption of arsenic were evaluated by using response surface methodology (RSM). It is discovered that AC and SCB removed up to ~89 and ~98 % of arsenic, respectively. The uptake capacities yielded from the batch experiment were about 31.25 mg/g for AC at pH ~7.4 and 11.9 mg/g for SCB at pH ~9. The equilibrium times achieved were 120 and 150 min for SCB and AC, respectively. This study shows that SCB is an efficient low-cost biosorption for arsenic removal from water.

Ecotoxicological impacts (survivorship, growth) of two detergents, the linear alkylbenzene sulfonates (LAS) and the nonionic surfactants, nonylphenol ethoxylate (NPE), were examined on two branching coral species (Stylophora pistillata and Pocillopora damicornis). Nubbins assays (n = 1,890, 24-h exposures, 203-day monitoring) revealed high mortality in 1 and 5 mg/l detergents concentrations (for both species combined, LAS LC₅₀ = 1.99 mg/l; NPE LC₅₀ = 2.16 mg/l). Assays further showed detergent as species-specific mortalities (Stylophora LAS LC₅₀ = 1.00 mg/l; NPE = 3.03 mg/l; Pocillopora LAS LC₅₀ = 2.21 mg/l; NPE = 2.26 mg/l), also influenced by genotype-specific mortalities, phenomena which could downgrade genetic diversity of corals in the field, leaving frequently or chronically affected areas with detergent-resistant genotypes. Results revealed that LAS detergents were significantly more detrimental to coral nubbins than NPE detergents, resulting in high mortality and reduced tissue growth on substrates. Surprisingly, nubbins exposed to second and third LAS treatments exhibited significant higher survivorship levels than after the first exposure, whereas in all NPE treatments, nubbins’ survivorship did not significantly differ in the repeated exposures as compared to the first set of assays. This outcome, while adding to our knowledge for the toxicity of various detergents, highlights the need to reduce repeated sewage spills. Furthermore, it is recommended that reef managers should emphasize disparate detergents’ ecotoxicity on corals when establishing environmental policies.

Vanadium (V) is an essential trace element for certain biological enzymatic reactions but becomes toxic at higher concentrations. The impact of V at concentrations of 0 − 500 mg/kg V(V) spiked in soils on soil enzymatic activities, and microbial diversity was investigated in soybean pot experiments. The results from sequential extraction of soil V indicated increasing V mobilizable fractions with increase of soil V concentrations. The soil sulfatase activity decreased drastically from 2.35 − 5.55 to 0.30 − 0.88 μmol methylumbelliferon (MUB)/[h g soil] with increasing soil V loading at different vegetative stages. Surprisingly, the activity of soil phenol oxidase increased from 0 − 0.73 to 3.74 − 7.61 μmol L-3,4-dihydroxyphenylalanine (DOPA)/[h g soil] with increasing soil V concentrations at different vegetative stages probably due to oxidation stress caused by V in soils. These observations were not affected by the presence of soybean plants. In comparison, soil phosphatase, protease, and ß-glucosidase showed no significant reaction to V concentrations in soil. Both fungal and bacterial communities changed significantly at different levels of V treatments. Accordingly, V may pose a threat to some biologically mediated functions in soils even at low bioavailable amounts.

Management strategies that prevent the onset of nuisance and noxious cyanobacteria blooms are needed to preserve the integrity and safety of freshwater resource uses. Scientifically defensible data are needed regarding efficacy of proactive approaches in order to assist water resource managers in making informed decisions. As phosphorus availability has been indicated as a crucial aspect of cyanobacteria presence/dominance in freshwater systems, the integration of novel technologies to inactivate phosphorus is a critical component to achieve improved water quality. Phoslock (Phoslock Water Solutions, Ltd.) phosphorus locking technology is composed of the element lanthanum in a bentonite clay matrix that has a high specificity to bind and inactivate soluble reactive phosphorus. This research evaluated the phosphorus binding efficiency of Phoslock in aqueous and sediment matrices and the consequent impact on algae assemblage composition and water quality parameters. Laguna Niguel Lake in California afforded an opportunity to evaluate the operational effectiveness of Phoslock in a system historically plagued by high phosphorus concentrations, potentially toxic cyanobacteria (Aphanizomenonflos-aquae dominant), and lake closures. Phoslock was able to rapidly (<2 weeks) and significantly (p < 0.0005) decrease total (>80 %) and free reactive (>95 %) phosphorus in the water column and shift potentially releasable sediment phosphorus fractions to residual forms after treatment. Despite documented cyanobacteria blooms and high pretreatment cell densities, cyanobacteria levels remained below or near detection limits and only comprised a small fraction of the algae assemblage following Phoslock application. This study provides water resource managers an information on operational implementation and efficacy of a phosphorus binding technology.

During an extended period from 2010–2012 ambient air quality researches, concentration of nitrogen dioxide (NO₂) in the air was measured applying the passive method. In order to evaluate the spatial distribution of pollutants and the major sources, 12 sampling sites across the region were chosen. Additionally, the seasonal changes of this pollutant under different meteorological conditions (air temperature, humidity, wind speed and direction) were investigated. The long-term study showed 3.8 times higher NO₂concentrations in the Mažeikiai urban area (24.2 μg m⁻³) as compared to other locations in the region (6.3 μg m⁻³). This confirms the assumption that the main source of NO₂in this area is motor vehicle exhaust fumes. The analysis of the results obtained in different seasons showed a significant difference (p < 0.05) in NO₂concentrations under different meteorological conditions. The increase in NO₂concentrations was recorded in the winter and late autumn seasons, due to reduced solar radiation and lower temperatures. Cluster analysis results showed that sampling sites can be grouped into different classes based on NO₂main source, motor vehicles and traffic intensity.

A photodegradation technology based on the combination of ultraviolet radiation with ozone (UV/O₃) for degrading tri(chloropropyl) phosphate (TCPP) was developed in the present study. Parameters affecting the degradation of TCPP were optimized, and the developed technology was successfully applied to degrade TCPP in two real wastewater samples. The results showed that reaction time, ozone concentration, the initial acidity of reaction solution, and the initial concentration of TCPP in aqueous solution contributed to the degradation efficiency of TCPP. Under the optimized disposal conditions, 100 mg/L of TCPP aqueous solution with a pH value of 7 can be degraded effectively in 60 min with an ozone concentration of 66.2 mg/L. In detail, the yield rates of Cl⁻and PO₄³⁻was high up to 98.9 and 98.2 %, respectively; and total organic carbon (TOC) removal rate was high up to 94.3 %. Method application demonstrated that TCPP can be degraded effectively in pond water. However, only 83.2 and 61.9 % of Cl⁻and PO₄³⁻were produced, and the TOC removal rate was only 81.3 % after 60 min exposure in the effluent discharged from a wastewater treatment plant. Therefore, the presence of interferences may hinder the degradation of TCPP in real wastewater, but its potential application for real wastewater is promising in the future after appropriate domestication and evaluation.

Groundwater is the principal source of drinking water for at least one third of Earth’s human inhabitants. Thus, protection of groundwater is a critical issue in many locales. Nitrates and other contaminants that impact human health are of particular concern. Mapping of aquifer vulnerability to pollution is a critical first step in implementing groundwater management protection programs; however, mapping is often constrained by generalizations inherent in model formulation and availability of data. In this study, a groundwater vulnerability model, which employs data extracted from widely available national and statewide geospatial datasets, is used to evaluate regional groundwater pollution risk in the Elkhorn River Basin, Nebraska, USA. The model, implemented in a geographic information system (GIS), is specifically structured to address risks of nitrate contamination in agricultural landscapes; thus, land use is a key factor. Modeled groundwater vulnerability was found to be positively correlated with nitrate concentrations obtained from sampled wells. The results suggest that the approach documented here could be used effectively to model regional groundwater pollution risk in other areas.

Investigations on the pollution of groundwater with pathogenic microorganisms, e.g. tracer studies for groundwater transport, are constrained by their potential health risk. Thus, microspheres are often used in groundwater transport studies as non-hazardous surrogates for pathogenic microorganisms. Even though pathogenic microorganisms occur at low concentrations in groundwater, current detection methods of microspheres (spectrofluorimetry, flow cytometry and epifluorescence microscopy) have rather high detection limits and are unable to detect rare events. Solid-phase cytometry (SPC) offers the unique capability of reliably quantifying extremely low concentrations of fluorescently labelled microorganisms or microspheres in natural waters, including groundwater. Until now, microspheres have been used in combination with SPC only for instrument calibration purposes and not for environmental applications. In this study, we explored the limits of the SPC methodology for its applicability to groundwater transport studies. The SPC approach proved to be a highly sensitive and reliable enumeration system for microorganism surrogates down to a minimum size of 0.5 μm, in up to 500 ml of groundwater, and 0.75 μm, in up to 1 ml of turbid surface water. Hence, SPC is proposed to be a useful method for enumerating microspheres for groundwater transport studies in the laboratory, as well as in the field when non-toxic, natural products are used.

Phosphorus (P) release and flux at sediment-water interface was hypothesized to vary with studied catchment branches due to differences in water chemistry of recharging groundwater. Stream water, seepage water, groundwater, and resurgence groundwater were collected, and their dissolved reactive P (DRP) concentrations and related water chemistry variables (pH, dissolved oxygen, cations, and anions) were measured to identify P sources in seepage water and resurgence groundwater and to look into their impacts on stream water DRP. Results showed that the groundwater-carried P concentrations were negligible, and, thus, not a direct source of DRP to stream water. However, the upwelling groundwater could contribute to stream water DRP by dissolving calcite-bound P in top sediments of branch 15. The seepage experiment indicated that in branch14, sediment release of reducible P was minimal. Furthermore, the presence of impermeable clay layer over the streambed of branch 14 prevented the transport of water and nutrients from beneath sediments to stream water, further reducing the P flux across the sediment-water interface. This study revealed that in branch 14, the recharge of anoxic groundwater did not significantly influence stream water P, due directly to its low P concentration, or indirectly to the lack of reducible P and the poor hydrological connectivity in bottom sediments. These results showed that differences between P soluble concentrations in small catchment streams can be explained by physicochemical processes at the sediment-water interface. More investigation is needed to assess whole catchment P dynamics.