Radionuclide content of Las Vegas Wash sediments

The Las Vegas Wash is an excavated waterway channel which drains all surface water and effluent discharge from sewage-treatment facilitates from the greater Las Vegas Metropolitan Area to Lake Mead. Fine and course sediment samples were collected at 100-m intervals and analyzed to determine the distribution of gamma-emitting radionuclides in the lower 5,500 m of the Las Vegas Wash. Results indicate depletion of long-lived fission products in upstream Wash sediments. However, trace levels of ¹³⁷Cs measured in downstream sediments suggest the resuspension and transport of radioactive fallout within the Wash. Levels of ⁴⁰K, ²³²Th, ²³⁵U, and ²³⁸U found in Wash sediments were consistent with levels typically found in southeast Nevada soils.     

Preliminary on-road measurement of the effect of oxygenated fuel on CO emissions near Las Vegas, Nevada

A preliminary measurement of an oxygenated fuel effect for in-use vehicles travelling at freeway speed was conducted near Las Vegas, NV, in January 1991 and May 1992. The experimental design was based on two principal factors: (1) the large volume of traffic that visits Las Vegas from Southern California on three-day holiday weekends and (2) the fact that, at the time of the study, the Las Vegas area used oxygenated fuels in the winter and Southern California did not. Measurements were conducted at carefully selected sites 20 km southwest of Las Vegas near Sloan, NV, and were accomplished with the Fuel Efficiency Automoblie Test (FEAT) remote sensor developed at the University of Denver. The January 1991 measurements were made during the Las Vegas oxyfuel season, while the May 1992 control measurements were made outside the oxyfuel season. Over 24,500 individual CO concentrations were measured; registration data from over 5,500 of these vehicles were obtained from the license plate numbers. After corrections for differences in velocity and mean age, the Las Vegas outbound (oxyfuel) CO emissions on Monday morning of the January holiday weekend showed a difference of -18% +/- 11% compared to the inbound (non-oxyfuel) CO emissions on Friday evening preceding the holiday weekend.     

Occurrence of antibiotics in water, sediments, aquatic plants, and animals from Baiyangdian Lake in North China

This study investigated the presence and distribution of 22 antibiotics, including eight quinolones, nine sulfonamides and five macrolides, in the water, sediments, and biota samples from Baiyangdian Lake, China. A total of 132 samples were collected in 2008 and 2010, and laboratory analyses revealed that antibiotics were widely distributed in the lake. Sulfonamides were the dominant antibiotics in the water (0.86-1563 ng L⁻¹), while quinolones were prominent in sediments (65.5-1166 μg kg⁻¹) and aquatic plants (8.37-6532 μg kg⁻¹). Quinolones (17.8-167 μg kg⁻¹) and macrolides [from below detection limit (BDL) to 182 μg kg⁻¹] were often found in aquatic animals and birds. Salvinia natans exhibited the highest bioaccumulation capability for quinolones among three species of aquatic plants. Geographical differences of antibiotic concentrations were greatly due to anthropogenic activities. Sewage discharged from Baoding City was likely the main source of antibiotics in the lake. Risk assessment of antibiotics on aquatic organisms suggested that algae and aquatic plants might be at risk in surface water, while animals were likely not at risk.     

Microplastics in aquatic environment: characterization,ecotoxicological effect,implications for ecosystems and developments in South Africa

Microplastics are small-size plastic piece scales (particles <?5 mm) in sediments and waters which interact with environment and organisms by various means. Microplastics are becoming a universal ecological concern since they may be a source of hazardous chemicals to marine organisms and environments. Recent research suggests microplastics could enable the transfer of hydrophobic aquatic pollutants or chemical additives to biota. Even though microplastic presence and interactions are recently being detected in marine and freshwater systems, the fate of microplastics is still very poorly understood. This literature review is a summary of the sources and transport of microplastics, their interactions with toxic chemicals and the methodologies for chemical quantification and characterization of microplastics. The environmental outcome and impact of microplastics in wastewater treatment plants were assessed as well as the trends and update on microplastic research in the South African aquatic ecosystem.

     

Occurrence, distribution, and sources of six phenolic endocrine disrupting chemicals in the 22 river estuaries around Dianchi Lake in China

The objectives of this study are to track the occurrence, distribution, and sources of phenolic endocrine disrupting compounds (EDCs) in the 22 rivers around Dianchi Lake in China, to estimate the input and output amounts of phenolic EDCs in the water system, and to provide more comprehensive fundamental data for risk assessment and contamination control of phenolic EDCs in aquatic environment. Six phenolic EDCs were systematically evaluated in water and surface sediment in the estuaries of those rivers. The water and sediment samples were preconcentrated by solid-phase extraction system and microwave-assisted extraction system, respectively. Phenolic EDCs were analyzed by GC-MS (Thermo Fisher Scientific, USA) after derivatization. Phenolic EDCs were found ubiquitously in the aquatic environment. The total concentrations ranged from 248 to 4,650 ng/L in water, and 113 to 3,576 ng/g dry weight in surface sediment. The residue amount of phenolic EDCs in Dianchi Lake was 258 kg/a. Concentrations of the phenolic EDCs in the Lake decreased with increase in distance to the estuaries of those rivers which run through urban and industrial areas. The rivers seriously contaminated by phenolic EDCs were Xin River, Yunliang River, Chuanfang River, Cailian River, Jinjia River, Zhengda River, and Daqing River which run through the old area of Kunming City. Satisfying correlations were observed between the concentrations of the target compounds in water and in surface sediment. NP1EO, NP2EO, and BPA were identified as the three predominant phenolic EDCs. There were significant correlations between phenolic EDCs and many basic water quality parameters. Urban and industrial areas are the major contributors for phenolic EDCs, especially in Kunming City. Compositional profiles of phenolic EDCs in surface sediment were similar to those in river water. The concentrations of phenolic EDCs in the rivers located in the northwest part of the valley were very high, and posed a potential risk to aquatic organisms and even human. The concentrations of NP2EO, NP1EO, and BPA were at moderate levels of other areas. The basic water quality parameters (TOC, TN, DO, and pH) play important roles on the distribution, fate, and behavior of phenolic EDCs in the valley.     

Pharmaceuticals and personal care products found in the Great Lakes above concentrations of environmental concern

The monitoring of pharmaceuticals and personal care products (PPCPs) has focused on the distribution in rivers and small lakes, but data regarding their occurrence and effects in large lake systems, such as the Great Lakes, are sparse. Wastewater treatment processes have not been optimized to remove influent PPCPs and are a major source of PPCPs in the environment. Furthermore, PPCPs are not currently regulated in wastewater effluent. In this experiment we evaluated the concentration, and corresponding risk, of PPCPs from a wastewater effluent source at varying distances in Lake Michigan. Fifty-four PPCPs and hormones were assessed on six different dates over a two-year period from surface water and sediment samples up to 3.2 km from a wastewater treatment plant and at two sites within a harbor. Thirty-two PPCPs were detected in Lake Michigan and 30 were detected in the sediment, with numerous PPCPs being detected up to 3.2 km away from the shoreline. The most frequently detected PPCPs in Lake Michigan were metformin, caffeine, sulfamethoxazole, and triclosan. To determine the ecological risk, the maximum measured environmental concentrations were compared to the predicted no-effect concentration and 14 PPCPs were found to be of medium or high ecological risk. The environmental risk of PPCPs in large lake systems, such as the Great Lakes, has been questioned due to high dilution; however, the concentrations found in this study, and their corresponding risk quotient, indicate a significant threat by PPCPs to the health of the Great Lakes, particularly near shore organisms.     

Tissue concentrations, bioaccumulation, and biomagnification of synthetic musks in freshwater fish from Taihu Lake, China

Synthetic musks are ubiquitous pollutants in aquatic environments. As hydrophobic chemicals, they can accumulate in terrestrial and aquatic organisms. Investigations into the bioaccumulation of these chemicals in aquatic ecosystem have, however, been limited, and previous results were inconsistent among species and ecosystem. Studies on this topic have been carried out in European countries, the USA, and Japan, but very few are known of the situation in China. The aim of this study was to investigate contaminant levels of musks in fish from Taihu Lake, the second largest freshwater lake in China, as well as bioaccumulation and biomagnification of the pollutants in the freshwater food chain. Five polycyclic musks and two nitro musks were determined in 24 fish species and nine surface sediment samples from Taihu Lake. HHCB (1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta[γ]-2-benzopyran) and AHTN (7-acetyl-1,1,3,4,4,6-hexamethyl-1,2,3,4-tetrahydronaphthalene) were the predominant contaminants in the fish samples, with concentrations ranging from below the limit of detection (LOD) to 52.9 and from <LOD to 7.5 ng/g lipid weight, respectively. Other contaminants were at low detection frequencies. The results indicated low concentrations of musks yet widespread occurrence of these contaminants in fish from Taihu Lake. Species-specific and lipid-related bioaccumulation characteristics were suggested, but no significant region-specific differences were observed. Normalized biota-sediment accumulation factors for HHCB and AHTN were noted to increase with trophic levels in fish. Trophic magnification factors were estimated at 1.12 for HHCB and 0.74 for AHTN. A biomagnification for HHCB, and probably biodilution for AHTN, in the freshwater food chain are indicated, when trophic magnification factors were concerned. However, the correlations between logarithmic concentrations of the chemicals and trophic levels were not statistically significant. Further study using long food chains in this lake is still needed.     

Seasonal and spatial distribution of nonylphenol in Shihwa Lake, Korea

Alkylphenols (APs) have been known as endocrine disruptors and consequently received much environmental concern. This study focused on seasonal variation and spatial distribution of nonylphenol (NP) in various matrixes including dissolved water, particulates, surface sediment, sediment trap and sediment core taken from Shihwa Lake and its adjacent areas. A total of 11 phenolic compounds including nonylphenol, t-octylphenol (t-OP) and bisphenol A (BPA) were measured in February, June and October 2002. NP is the most abundant chemical among the phenolic compounds and its concentrations in dissolved water, particulates and surface sediments from Shihwa Lake were measured as 17.4-1533.1 ng/l, 4.3-831.2 ng/l and 10.4-5054.1 ng/g dw, respectively. NP concentration in dissolved water varied with seasons and generally showed a decreasing order of June > October > February, while the seasonal trend was hardly found in sediment. High levels of NP were measured in surrounding industrial complexes, the concentrations was decreased gradually with distance from the industrial areas. NP in core samples showed an increasing trend toward the core depth. There exists a reasonable correlation between NP in dissolved water and in particulates, whereas the correlation between NP in dissolved water and in sediments is not significant. APs concentrations in Shihwa Lake were comparable to other highly polluted areas of the world and their possible effects on various organisms in the lake are discussed.     

Tetrabromobisphenol A: tissue distribution in fish, and seasonal variation in water and sediment of Lake Chaohu, China

Tetrabromobisphenol A (TBBPA) is the most widely used brominated flame retardants (BFRs). It has been detected in various environment media and has been approved to be high toxic to aquatic organisms. However, the exposure levels of TBBPA in the main watersheds in China have not been investigated sufficiently. In this study TBBPA concentrations in water, sediment and tissues of four fish species from Lake Chaohu were determined. Spatial and temporal distribution patterns of TBBPA in water and sediment, and the relationship among TBBPA concentrations in fish tissues and fish size were analyzed. The results showed that the maximum TBBPA concentration in sediment was 518 ng/g in March 2008. It is almost the highest value than those ever reported anywhere in the world. In lake water, TBBPA level reached the maximum value of 4.87???g/L in July. Tissue distributions of TBBPA in four fish species were similar, and the mean concentrations in the fish were in the range of 28.5?C39.4 ng/g, much higher than those reported in Japan, Europe, and the United States. The maximum concentrations of TBBPA were found in kidneys where TBBPA concentration was positively correlated with fish size of Cyprinus carpio. Results demonstrated a widespread distribution of TBBPA in Lake Chaohu. The source was mainly inflow rivers near the cities. The distribution coefficient among water, fish, and sediment was 1:28:117. This indicated that sediment was the main repository for TBBPA within Lake Chaohu. Furthermore, TBBPA may pose a potential ecological risk in the lake during summer.     

Distribution characteristics of nonylphenols in the artificial Lake Shihwa, and surrounding creeks in Korea

Nonylphenols were determined from the water, suspended particle, and sediment samples taken from the Lake Shihwa in Korea and its surrounding creeks flowing through municipal and industrial areas, and into the lake. The nonylphenols were detected at the concentration ranges of 0.0-41.3 microg/l, 0.0-116.6 and 0.3-31.7 mg/kg in water, suspended particle and sediment samples respectively. The contamination levels of nonylphenols were increased along the down stream. Considerably high levels of nonylphenols were found at the industrial area compared to the municipal area. No remarkable differences were found between the isomer patterns of nonylphenols for the sample matrices of each sampling site, i.e. water, suspended solids and sediment. Strong correlations between water and sediment with 10(5.2) of the mean partition coefficient (Koc ) were observed. These indicate that most of nonylphenols came from industrial wastewater at high level. It is thought that the water quality of the Lake Shihwa is affected greatly by industrial environments surrounding.     

An environmental fate, exposure and risk assessment of ethylene oxide from diffuse emissions

Ethylene oxide (EO) is mainly used as a chemical intermediate and as a fumigant and sterilizing agent. Through its manufacturing and intended uses, EO may be released into the environment. Therefore, an assessment of the environmental significance of those potential emissions was conducted. Data were collected describing pertinent physical properties, degradation and other loss mechanisms that control the fate of EO in the environment. Available aquatic and terrestrial ecotoxicity data were assembled and used as the basis of calculating critical toxicity values to characterize hazard. Environmental compartment concentrations of EO were calculated using Level III fugacity-based modeling. Six scenarios were developed to account for different climatic conditions in various portions of the US. Finally, potential regional-scale risks to aquatic and terrestrial wildlife were determined. In the conceptual model that was developed in this assessment, EO diffuses into air, partitions between environmental compartments, is transported out of the different compartments via advection, and undergoes abiotic and biological degradation within each compartment. All known emissions within the continental USA were assumed to enter a modeled region roughly the size of the State of Ohio. Organisms (receptors) were assumed to dwell in both terrestrial and aquatic compartments. Receptors were assumed to include small mammals, soil invertebrates, water column (pelagic) organisms, and sediment benthos. The goal of this assessment was to characterize any potential adverse risks to terrestrial and aquatic wildlife populations. Hazard Quotients (HQ) were calculated by dividing predicted concentrations of EO in air, water, sediment, and soil by their critical toxicity values. Maximum calculated HQ values in air were 1.52x10(-7), in water were 1.17x10(-5), in sediment were 2.25x10(-4), and in soil were 1.37x10(-5). The results of this assessment suggest that EO as currently manufactured and used does not pose adverse risks to aquatic or terrestrial wildlife. In all cases, the HQ values were much less than the maximum desired HQ value of 1.0 (4,400-6,600,000 times), indicating that the potential for diffuse emissions of EO to pose adverse environmental risks is quite low.     

Contamination of nonylphenolic compounds in creek water, wastewater treatment plant effluents, and sediments from Lake Shihwa and vicinity, Korea: comparison with fecal pollution

Nonylphenolic compounds (NPs), coprostanol (COP), and cholestanol, major contaminants in industrial and domestic wastewaters, were analyzed in creek water, wastewater treatment plant (WWTP) effluent, and sediment samples from artificial Lake Shihwa and its vicinity, one of the most industrialized regions in Korea. We also determined mass discharge of NPs and COP, a fecal sterol, into the lake, to understand the linkage between discharge and sediment contamination. Total NP (the sum of nonylphenol, and nonylphenol mono- and di-ethoxylates) were 0.32-875 μg L⁻¹ in creeks, 0.61-87.0 μg L⁻¹ in WWTP effluents, and 29.3-230 μg g⁻¹ TOC in sediments. Concentrations of COP were 0.09-19.0 μg L⁻¹ in creeks, 0.11-44.0 μg L⁻¹ in WWTP effluents, and 2.51-438 μg g⁻¹ TOC in sediments. The spatial distributions of NPs in creeks and sediments from the inshore region were different from those of COP, suggesting that Lake Shihwa contamination patterns from industrial effluents differ from those from domestic effluents. The mass discharge from the combined outfall of the WWTPs, located in the offshore region, was 2.27 kg d⁻¹ for NPs and 1.00 kg d⁻¹ for COP, accounting for 91% and 95% of the total discharge into Lake Shihwa, respectively. The highest concentrations of NPs and COP in sediments were found in samples at sites near the submarine outfall of the WWTPs, indicating that the submarine outfall is an important point source of wastewater pollution in Lake Shihwa.     

Developing a multimedia model of chemical dynamics in an urban area.

A multimedia model has been developed to account for the movement of semi-volatile organic compounds (SOCs) in an urban environment. The model, based on a Level III fugacity model of D. Mackay (Multimedia Environmental Models: The Fugacity Approach, Lewis Publishers, Boca Raton, FL, 1991), consists of six compartments: air, surface water, sediment, soil, vegetation, and an organic film that coats impervious surfaces. The latter is a newly identified compartment into which gas-phase SOCs partition and particle-phase SOCs are believed to be efficiently captured (M.L. Diamond, S.E. Gingrich, K. Fertuck, B.E. McCarry, G.A. Stern, B. Billeck, B. Grift, D. Brooker, T.D. Yager, Environ. Sci. Technol., 34 (2000a), 2900-2908). The model, parameterized for downtown Toronto, Ontario, Canada, and run with an illustrative emission rate for selected polycyclic aromatic hydrocarbons and homologues of polychlorinated dibenzodioxins, indicates that the film achieves the highest concentrations among media but that soils are the greatest sink for all but the least hydrophobic chemicals. The film "reflects" the more volatile chemicals into air, facilitates removal to surface waters by wash-off, and provides a surface on which photolytic degradation can occur. As such, the film is a transient sink that increases chemical mobility in urban areas by increasing air concentrations and the cycling of these compounds between air and urban surfaces and increasing water concentrations. Vegetation also accumulates SOCs, a portion of which is transferred to soil that reduces chemical mobility.     

Novel use of soil moisture samplers for studies on anaerobic ammonium fluxes across lake sediment-water interfaces

Small soil suction samplers have been used for several years to sample soil solution for chemical analysis in laboratory and glasshouse experiments. They are very cheap, effective and convenient. Here we describe for the first time their use in studies on sediment porewater. Bulk sediment from West Lake, a shallow hypereutrophic lake in Hangzhou, Zhejiang Province, China, was placed in laboratory microcosms and incubated in the dark at 25 degrees C for 182 days to evaluate the feasibility of using the samplers to extract sediment porewater and to estimate NH4+ flux across the sediment-water interface under anaerobic conditions. The results show that the samplers were capable of sequentially extracting sediment porewater, 15 ml of which could be readily extracted for analysis within 30-45 min by vacuum applied using a plastic syringe. The NH4+ flux under laboratory conditions was characterized by a fast phase during the initial 18 days of incubation followed by a slower linear phase, with average release rates of 11.6 and 3.6 mg N m(-2) d(-1), respectively.     

Comparison of microbial community between two shallow freshwater lakes in middle Yangtze basin, East China

In order to investigate the role of the microbial community in aquatic ecology and nutrient transformations in the development of eutrophication in large shallow freshwater lakes along Yangtze River, the microbial community in the depth-related sediment in Lake Chaohu and Lake Longganhu were compared. Lake Chaohu is one of the three most polluted lakes in China. However, the neighboring Lake Longganhu, a mesotrophic lake, is relatively pristine. The total phosphorous (TP) and total nitrogen (TN) concentration in water was detected at 0.193 mgl(-1) and 3.035 mgl(-1) for Lake Chaohu, 0.051 mgl(-1) and 0.774 mgl(-1) for Lake Longganhu, respectively. The population of the microorganisms with various ecological nutrient transforming functions (e.g. phosphate solubilizing, denitrifying and cellulose decomposing) and a batch of environmental parameters concerning the nutrient accumulating and transforming (e.g. total organic carbon, total nitrogen, and total phosphorous concentrations) were assayed in the depth-related sediment samples from several defined points in both lakes. The sediment samples from Lake Chaohu showed higher density of actinomycetes (P<0.05) and phosphate-solubilizing bacteria (P<0.001) and less profusion of denitrifying bacteria (P<0.05) and cellulolytic microbes (P<0.001), compared with those of Lake Longganhu. The data suggested that the current microbial community in the sediment of Lake Chaohu is in favor of sustaining or further accelerating the process of the lake eutrophication. A possible positive feedback loop which consists of sustained growth of microorganisms and gradual decline of lake eutrophic status is worth further discussing.     

Assessing estrogenic activity in surface water and sediment of the Liao River system in northeast China using combined chemical and biological tools

This paper investigated some selected estrogenic compounds (4-t-octylphenol: 4-t-OP; 4-nonylphenols: 4-NP; bisphenol-A: BPA; diethylstilbestrol: DES; estrone: E1; 17β-estradiol: E2; 17α-Ethinylestradiol: EE2; triclosan: TCS) and estrogenicity in the Liao River system using the combined chemical and in vitro yeast screen bioassay and assessed their ecological risks to aquatic organisms. The estrogenic compounds 4-t-OP, 4-NP, BPA, E1, E2 and TCS were detected in most of the samples, with their concentrations up to 52.1 2065.7, 755.6, 55.8, 7.4 and 81.3 ng/L in water, and up to 8.6, 558.4, 33.8, 7.9, <LOQ and 33.9 ng/g in sediment, respectively. However, DES and EE2 were not detected in the Liao River. The estrogen equivalents (EEQ) of the water and sediment samples were also measured by the bioassay. High estrogenic risks to aquatic organisms were found in the river sections of metropolitan areas and the lower reach of the river system.     

Distribution and bioaccumulation of selenium in aquatic microcosms

Closed-system microcosms were used to study factors affecting the fate of selenium (Se) in aquatic systems. Distribution and bioaccumulation of Se varied among sediment types and Se species. A mixture of dissolved (75)Se species (selenate, selenite and selenomethionine) was sorbed more rapidly to fine-textured, highly organic pond sediments than to sandy riverine sediments. Sulfate did not affect the distribution and bioaccumulation of (75)Se over the range 80-180 mg SO(4) liter(-1). When each Se species was labeled separately, selenomethionine was lost from the water column more rapidly than selenate or selenite. Selenium lost from the water column accumulated primarily in sediments, but volatilization was also an important pathway for loss of Se added as selenomethionine. Loss rates of dissolved Se residues were more rapid than rates reported from mesocosm and field studies, suggesting that sediment: water interactions are more important in microcosms than in larger test systems. Daphnids accumulated highest concentrations of Se, followed by periphyton and macrophytes. Selenium added as selenomethionine was bioaccumulated preferentially compared to that added as selenite or selenate. Organoselenium compounds such as selenomethione may thus contribute disproportionately to Se bioaccumulation and toxicity in aquatic organisms.     

The toxicity and concentrations of PAHs in creosote-contaminated lake sediment

Sediment samples, divided into three layers (0-10, 10-20 and 20-30 cm), were collected from 16 sites in Lake J?ms?nvesi, Central Finland. The acute toxicity of pore waters and elutriates (sediment + water 1:4 v/v) were studied by bioluminescence inhibition test and by immobilisation of water fleas (Daphnia magna Straus). Concentrations of polycyclic aromatic hydrocarbons (PAHs) in sediments and elutriates were measured by gas chromatography using flame ionization detection (GC/FID). The highest total PAH concentration was 3.3 mg/g dry weight in the sediment and up to 1.7 mg/l in the elutriate of the uppermost (0-10 cm) layer, also being the most toxic to photoluminencent bacteria and water flea. When sediment and water mix, like during dredging operations, toxic compounds may spread from the sediment to the water column and can pose on environmental risk.     

Dissipation of glyphosate and aminomethylphosphonic acid in water and sediment of two Canadian prairie wetlands

Glyphosate [N-(phosphonomethyl)glycine] is the active ingredient of several herbicide products first registered for use in 1974 under the tradename Roundup. The use of glyphosate-based herbicides has increased dramatically over the last two decades particularly in association with the adoption of glyphosate-tolerant crops. Glyphosate has been detected in a range of surface waters but this is the first study to monitor its fate in prairie wetlands situated in agricultural fields. An ephemeral wetland (E) and a semi-permanent wetland (SP) were each divided into halves using a polyvinyl curtain. One half of each wetland was fortified with glyphosate with the added mass simulating an accidental direct overspray. Glyphosate dissipated rapidly in the water column of the two prairie wetlands studied (DT₅₀ values of 1.3 and 4.8 d) which may effectively reduce the impact of exposure of aquatic biota to the herbicide. Degradation of glyphosate to its major metabolite aminomethylphosphonic acid (AMPA) and sorption of the herbicide to bottom sediment were more important pathways for the dissipation of glyphosate from the water column than movement of the herbicide with infiltrating water. Presently, we are not aware of any Canadian guidelines for glyphosate residues in sediment of aquatic ecosystems. Since a substantial portion of glyphosate entering prairie wetlands will become associated with bottom sediments, particularly in ephemeral wetlands, guidelines would need to be developed to assess the protection of organisms that spend all or part of their lifecycle in sediment.     

Concentrations,distributions, sources,and risk assessment of organochlorine pesticides in surface water of the East Lake,China

East Lake resides in the urban area of Wuhan City and is the largest urban lake in China. The concentrations of 16 organochlorine pesticides (OCPs) were analyzed in 108 surface water samples collected from the East Lake. The total concentrations of OCPs ranged from not detected to 120 ng L^?1 with predominance of δ-HCH, heptachlor, and α-HCH. The mean values of HCHs and DDTs were 7.40 and 5.70 ng L^?1, respectively, accounting for 40 and 31 % of the total OCPs. For the five lakelets in East Lake, Houhu Lake exhibited the highest concentrations of HCHs, DDTs, and total OCPs, which has been used actively for fisheries and surrounded by suburban rural areas and farmlands. Historical lindane or technical HCH input was probably the source of HCH, while technical DDTs might be the source of DDT in the East Lake. The ratio between heptachlor and its metabolic products indicated recent input of heptachlor. Although the combining ecological risks for all aquatic species in the East Lake calculated by species sensitivity distribution reached approximately 10^?5, the OCPs in the East Lake had slight effects on aquatic organisms. The carcinogenic risks and non-carcinogenic hazard indices of DDTs and HCHs indicated that water in the East Lake was not suitable as water sources for human. However, the results indicated the water quality was safe for people to swim in the urban lake.