Different nitrogen (N) fractions from 14 sediments from the shallow lakes in the middle and lower reaches of Yangtze River area before and after N release experiments were investigated, and the content of different N fractions, and contribution of different N fractions to the N released from sediments were also studied. Ion-exchangeable form (IEF-N), carbonate form (CF-N), iron-manganese oxide form (IMOF-N) and organic matter-sulfide form (OSF-N) accounted for 2.72~17.67%, 0.47~4.43%, 1.18~3.49% and 31.05 to 71.61% to total N, respectively. The N released was higher than 50% from IEF-N, approximately 35% from OSF-N, 6 and 8% from CF-N and IMOF-N on the average. Approximately 27.32~70.02% of IEF-N, 10.37~32.11% of CF-N, 11.37~33.43% IMOF-N and 2.02~8.19% OSF-N were released. For the sediments that were slightly polluted, IEF-N was the main N fraction that may be released and its contribution to total N released was more than 63.07%, for the sediments that TN was higher than 3,540.27 mg·kg-¹, OSF-N would become the main N fraction that can be released and its contribution to total N released was more than 45%.

This study investigated particulate matter (PM) granulometry delivered in source area runoff as a function of hydrologic transport and settling. At a Baton Rouge, LA paved urban watershed, event runoff volume and PM load were “fully captured” and recovered in settling tanks. Events were differentiated as mass-limited (ML) or flow-limited (FL) and PM differentiated into suspended (1 to ~25 μm), settleable (~25 to 75 μm), sediment (75 to 4,750 μm) fractions; and also particle size distributions (PSDs). Suspended sediment concentration (SSC)-turbidity relationships were unique for FL events compared to ML events; while 60 min of quiescent settling produced a single distinct relationship across all events. ML events transported higher proportions of settleable and sediment mass compared to higher suspended mass for FL events. Event-based ratios of settled and unsettled turbidity as well as SSC mass were statistically different for ML and FL events. For the same settling conditions, treatment of ML and FL events were statistically different. Results demonstrated that PM separation by a unit operation was a deterministic function of granulometry, hydrodynamics, unit operation mechanisms and loads, but significantly influenced by the indeterminate nature of local climate; and hydrology which drives PM delivery and is not known a priori. Combining the influences of scour and lack of maintenance, unit operation performance is non-stationary and cannot be described by a single value. Treatment should be tied to an effluent concentration; granulometry and load.

Sandstorms which distribute a great number of particles are a special atmospheric occurrence and are uncommon in northern China. This study was conducted to determine, for the first time, the concentration of organochlorine pesticides (OCPs) in sandstorm depositions. Samples were collected from urban areas of Beijing and a total of eight OCPs were measured. All samples contained OCP residues. The total hexachlorocyclohexane (HCHs) concentration ranged from 20.6 to 59.8ng g⁻¹ and the total dichlorodiphenyltrichloroethane (DDTs) concentration ranged from 12.0 to 14.3ng g⁻¹. Furthermore, increasing HCH contamination was observed from the northwest to the southeast and a uniform distribution of DDT contamination was discovered in Beijing. Analysis of the sources of contamination showed that HCHs in the sandstorm depositions were derived from a relatively old source of lindane, and DDTs mainly originated from an old source of dicofol in Beijing. The preliminary pollution assessment of the samples indicated that HCH levels might be categorized as low pollution and DDT levels might be categorized as no pollution. The present study suggests that sandstorm depositions may not produce the special risk of adverse health effect from OCPs for the residents of Beijing, China.

Metal (Cu, Mn, Ni, Zn, Fe) concentrations in marine sediment and zooplankton were investigated in Izmir Bay of the Eastern Aegean Sea, Turkey. The study aimed to assess the levels of metal in different environmental compartments of the Izmir Bay. Metal concentrations in the sediment (dry weight) ranged between 4.26-70.8 μg g-¹ for Cu, 233-923 μg g-¹ for Mn, 14.9-127 μg g-¹ for Ni, 25.6-295 μg g-¹ for Zn, 12,404-76,899 μg g-¹ for Fe and 38,226-91,532 μg g-¹ for Al in the Izmir Bay. Maximum metal concentrations in zooplankton were observed during summer season in the inner bay. Significant relationships existed between the concentrations of certain metals (Al, Fe, Mn and Ni) in sediment, suggesting similar sources and/or similar geochemical processes controlling such metals. Higher concentrations of Cu, Zn and percent organic matter contents were found in the middle-inner bays sediments. Based on the correlation matrix obtained for metal data, organic matter was found to be the dominant factor controlling Cu and Zn distributions in the sediment. In general, mean Cu and Zn levels in the bay were above background concentrations in Mediterranean sediments. Zooplankton metal concentrations were similar to sediment distributions.

The bioremediation of petroleum contaminated soil was investigated using a laboratory scale aerated reactor. The Indigenous bacteria, Stenotrophomonas multophilia, were isolated from the contaminated sites near to Jordan Petroleum Refinery and used further in the bioremediation experiments. First order kinetic equation has been proven to satisfactorily describe the biodegradation of petroleum contained in soil in the presence of the isolated bacteria. The results also showed that the first order kinetic constants for the different bioreactors vary between 0.041 and 0.0071/day. The overall kinetic constant k' was determined based on food-to-microorganisms ratio and found to be 0.02/day.

In order to investigate the Urias Coastal Lagoon (UCL) hydrodynamics, a vertically integrated semi-implicit, non-linear, finite difference model, has been applied. The flow dynamics in this model has been described by the depth integrated shallow water equations and has been forced by prescribed free surface elevations at the open boundary in the inlet of the lagoon. The predicted instantaneous tidal elevation and the vector field of tidal velocities, reflect reasonably well the flood and ebb conditions in the coastal lagoon. Maximum tidal velocities of 0.6 m/s at the navigation channel of the lagoon and tidal ranges of 1.2 m were predicted for spring tides. Residual current of 0.01–0.06 m/s have also been predicted. The advection-diffusion process of a hypothetical pollutant released at two discrete points in the UCL depended on the intensity of water circulation; sites with slow instantaneous tidal velocities and residual currents of small magnitude presented slow advection and diffusion of the pollutant and may be considered vulnerable to the contamination, specifically the head of the lagoon where the pollutant was difficult to be removed by the tidal currents. The main channel, where the tidal currents exceed 0.6 m/s and the residual currents reached 0.06 m/s, behaved as a natural conduct for the pollutant motion. The forces involved in water circulation within the channel would be the best driving mechanism to flush contaminants from the UCL into the Ocean.

Urine-treated soils make a significant contribution to gaseous N losses to the atmosphere. Our goal was to investigate the influence of clay type and content on ammonia (NH₃) and nitrous oxide (N₂O) emissions from urine under different wetting-drying soil conditions and to relate these results to urine-N transformation processes in soil. Three types of silt loam soils and synthetic sand-clay aggregates with three different clay-dominated materials (kaolinite, montmorillonite and vermiculite) were used in this laboratory study. Bulk soil, 4-4.75 mm and 9.5-11.2 mm aggregates were incubated with synthetic urine at 50% and 75% saturation under aerobic conditions. Repeated urine application affected the properties of the aggregates depending on the type of clay present. Greater clay content increased aggregate stability and reduced NH₃ volatilization. The variation in clay ammonium (NH₄ ⁺) fixation capacities was reflected in NH₃ volatilization as well as in the onset of N₂O emissions, occurring first from kaolinite-dominated and last from vermiculite-dominated soils. Nitrous oxide production was greater in aggregates than in bulk soil, a difference that consistently increased with repeated urine applications for kaolinitic and vermiculitic treatments. A dual-peak N₂O emission pattern was found, with the second maximum increasing with the number of urine applications. Emission of ¹⁵N-labeled N₂ was found at 75% saturation in kaolinite and vermiculite-dominated samples. Anaerobic conditions were less pronounced with montmorillonite-dominated samples because shrink-swell action caused aggregate breakage.

Atrazine-contaminated soil may require remediation to mitigate ground and surface water contamination. We determined the effectiveness of nano zerovalent iron (nano ZVI) to dechlorinate atrazine (2-chloro-4ethylamino-6-iso-propylamino-1,3,5-triazine) in contaminated water and soil. This study determined the effects of iron sources, solution pH, Pd catalyst and presence of Fe or Al sulfate salts on the destruction of atrazine in water and soil. Our results indicate nano ZVI can be successfully used to remediate atrazine in water and soil. Aqueous solution of atrazine (30 mg l⁻¹) was treated with 2% (w/v) of nano ZVI and 5% (w/v) of commercial ZVI. Although, iron dose in nano ZVI treatment was less than that in commercial ZVI treatment, atrazine destruction kinetic rate (k obs) of nano ZVI treatment (1.39 days⁻¹) was around seven times higher than that of commercial ZVI treatment (0.18 days⁻¹). Reductive dechlorination was the major process in destruction of atrazine by nano ZVI. The dechlorination product was 2-ethyl-amino-4-isopropylamino-1,3,5-triazine. Lowering the pH from 9 to 4 increased the destruction kinetic rates of atrazine by nano ZVI. Moreover, nano ZVI/Pd enhanced destruction kinetic rates of atrazine (3.36 day⁻¹). Pd played the important role as a catalyst during treatment of atrazine by nano ZVI. Atrazine destruction kinetic rates were greatly enhanced in both contaminated water and soil treatments by nano ZVI when sulfate salts of Fe(II), Fe(III) or Al(III) was add with the following order of removal rates: Al (III) (2.23 day⁻¹) > Fe (III) (2.04 day⁻¹) > Fe(II) (1.79 day⁻¹). The same results were found in atrazine-nano ZVI-soil incubation experiments.

The removal of ⁶⁵Zn from tidal water by underlaying sediment cores collected in a mangrove forest and a tidal creek that drains this forest in Sepetiba Bay (SE Brazil) was investigated. After 30-h experiments in laboratory microcosms, the ⁶⁵Zn half-removal times from tidal creek and mangrove forest sediments were 8.7 ± 1.8 and 9.2 ± 0.9 h respectively. Depth penetration of ⁶⁵Zn was mainly restricted to the upper 3 cm in mangrove forest cores, while detectable ⁶⁵Zn activities were found in all layers (0-7 cm depth) of tidal creek cores. An unexpected ⁶⁵Zn release back to the overlaying water was observed for one of the tidal creek experiments in the 12-18 h interval (corresponding to a return of 17% of the initial ⁶⁵Zn activity in overlaying water), suggesting a reversibility of the ⁶⁵Zn removal process (e.g., by adsorption) in tidal creek sediments. The results indicate that mangrove-vegetated sediments allowed a lower vertical mobility of Zn than observed in creek sediments and mangrove sediments appear to be less susceptible to a reversion in the process of zinc removal from overlaying water, suggesting a greater capacity to retain this metal near the water-sediment interface. This first radiotracer approach on the mangrove sediments removal of Zn from tidal waters supports earlier experimental studies employing stable Zn, contributing for a better understanding of the metal uptake kinetics by such sediments and suggesting that these sediments act as active sinks for trace metals.

Concentrations of mercury (Hg) were measured in six dated cores from four lakes in western Whatcom County, Washington, USA, that were at various bearings from a chlor-alkali plant, two municipal waste incinerators and a municipal sewage sludge incinerator. The importance of atmospheric emissions of Hg from these local municipal and industrial sources was evaluating by comparing the temporal trends in sedimentation of the lake cores with the emission history of each Hg species and by examining the geographical distribution of Hg sedimentation in relation to the region's primary wind pattern. Local municipal and industrial sources of atmospheric Hg were not responsible for the majority of the Hg in the upper layer of sediments of Whatcom County lakes because of (1) the significant enrichment of Hg in lake sediments prior to emissions of local industrial and municipal sources in 1964, (2) smaller increases in Hg concentrations occurred after 1964, (3) the similarity of maximum enrichments found in Whatcom County lakes to those in rural lakes around the world, (4) the inconsistency of the temporal trends in Hg sedimentation with the local emission history, and (5) the inconsistency of the geographic trends in Hg sedimentation with estimated deposition. Maximum enrichment ratios of Hg in lake sediments between 2 and 3 that are similar to rural areas in Alaska, Minnesota, and New England suggest that global sources of Hg were primarily responsible for increases of Hg in Whatcom County lakes beginning about 1900.