In order to observe the spatial phosphorus (P) fractions transformations in sediments in relation to bacterial abundance and enzyme hydrolysing organic P-alkaline phosphatase (APA), samples from 35 stations from eutrophic Sulejow Reservoir were taken in spring after flood and in summer after cyanobacterial bloom breakdown. The results show pronounced fluctuations: decrease of average total P in sediments, despite organic matter delivery after cyanobacterial bloom, in parallel with increase of labile P (8.3%) and Ca-bounded P (16.6%) fractions and decline of organic P fraction (28.5%). Higher alkaline activity in sediments in the spring delivered nutrients to water column and supported cyanobacterial bloom development during the summer. Positive correlation between APA and organic P (r = 0.37, p < 0.01, n = 70) and negative with labile inorganic P (r = −0.44, p < 0.01, n = 70) in sediments proved significant role of the APA in phosphorus transformation in sediments and internal loading in the reservoir. During summer, APA was significantly related to bacterial number (r = 0.36, p < 0.01, n = 35) and bacterial abundance was correlated to organic matter content (r = 0.36, p < 0.01, n = 35). Such pattern of temporal variations of P transformation in sediments indicates order of solutions for enhancement of recultivation effects of eutrophic dam reservoirs: (1) reduction of organic matter supply in spring and (2) sediment inactivation during summer.

The effects of cadmium (Cd) and/or paraquat (PQ) toxicity on photosynthesis in maize leaves were examined by measurement of gas exchange and chlorophyll content in hydroponically cultured plants. It was found that growth rate was distinctly influenced only by 100 µM Cd treatment. Chlorophyll a and chlorophyll b decreased along with the increase of Cd concentration, while PQ spraying, alone and combined with Cd, increased chlorophyll a content on the third and seventh experimental days. Generally, carotenoid content increased in response to Cd and PQ and reached the highest levels at 100 µM Cd. Rate of photosynthesis in maize decreased after Cd treatment. CO₂ assimilation was approximately 60% reduced at 50 µM Cd and 70% reduced in the presence of 100 µM Cd. PQ toxicity was partly overcome after the third day of exposure. Transpiration and stomatal conductance in maize leaves decreased on the third day along with Cd concentration and PQ spraying, except for the 25-µM Cd-treated plants. On the tenth day, the 25-µM Cd-treated plants and those from PQ-treated variants showed an increase of transpiration and stomatal conductance. Maize exhibited an ability to accumulate Cd in high quantities, especially in the roots—over 4,500 mg Cd/kg dry weight.

Column experiments were conducted using ideal natural sands and stainless-steel beads to examine the complete dissolution behavior of an organic immiscible liquid. Trichloroethene was used as the representative organic liquid. The elution curves exhibited multi-step behavior, with multiple extended periods of relatively constant contaminant flux. These secondary steady-state stages occurred at concentrations several orders-of-magnitude below aqueous solubility for the well-sorted sands. In contrast, the secondary steady-state stages occurred within 1 log of aqueous solubility for the poorly sorted sand. The non-ideal behavior is hypothesized to result from constraints to hydraulic accessibility of the organic liquid to flowing water, which may be expected to be mediated by the pore-scale configuration of the flow field and the fluid phases.

The batch sorption experiments were carried out using a novel adsorbent, freshwater macrophyte alligator weed, for the removal of basic dye malachite green from aqueous solution. Effects of process parameters such as initial solution pH, contact time, adsorbent concentration, particle size, and ion strength were investigated. The adsorbent was characterized by FT-IR. The adsorption of malachite green by alligator weed was solution pH dependent. The adsorption reached equilibrium at 240 min for two particle size fractions. The pseudo-first-order equation, Ritchie second-order equation, and intraparticle diffusion models were tested. The results showed that adsorption of malachite green onto alligator weed followed the Ritchie second-order equation very well and the intraparticle diffusion played important roles in the adsorption process. The Langmuir and Freundlich equations were applied to the data related to the adsorption isotherms and the observed maximum adsorption capacity (q max) was 185.54 mg g⁻¹ at 20°C according to the Langmuir model. The effects of particle size, adsorbent concentration, and ionic strength on the malachite green adsorption were very marked. The alligator weed could serve as low-cost adsorbents for removing malachite green from aqueous solution.

Metal dispersal in the Danube and Maritsa drainage basins resulting from metal mining activities in Bulgaria has been assessed through the collection of 611 samples of river water, river channel and floodplain sediment, and mine waste from over 218 sites. Concentrations of Cd, Cu, Pb, and Zn in river water were found to be highest in close proximity to locations of Cu and Pb-Zn mining regions in the Maritsa catchment. Downstream dispersal of solute metals in these catchments, and into the River Danube, was found to be limited by physical dilution and a well-buffered pH environment. Dispersal of contaminant metals in channel and floodplain sediment was found to be extensive. Contamination was particularly severe in the Rivers Timok and Iskar (Danube catchment) and the Topolnitsa, Chepelarska, and Arda Rivers (Maritsa catchment) and creates the potential of transboundary dispersal of contaminant metals.

Water hardness is well known to affect the toxicity of some metals; however, reports on the influence of hardness during incubation or acclimation on later toxicity to metals have been conflicting. We incubated rainbow trout (Oncorhynchus mykiss) near the confluence of two streams, one with soft water and one with very-soft water (average incubation hardnesses of about 21 and 11 mg/L as CaCO₃, respectively). After developing to the swim-up stage, the fish were exposed for 96-h to a mixture of cadmium (Cd) and zinc (Zn) in water with a hardness of 27 mg/L as CaCO₃. The fish incubated in the higher hardness water were about two times more resistant than the fish incubated in the extremely soft water. This difference was similar or greater than the difference that would have been predicted by criteria hardness equations had the fish been tested in the different acclimation waters. We think it is plausible that the energy demands for fish to maintain homeostasis in the lower hardness water make the fish more sensitive to metals that inhibit ionoregulation such as Cd and Zn. We suggest that if important decisions were to be based upon test results, assumptions of adequate hardness acclimation should be carefully considered and short acclimation periods avoided. If practical, incubating rainbow trout in the control waters to be tested may reduce uncertainties in the possible influences of differing rearing water hardness on the test results.

The salinization of Mirror Lake in the White Mountains of New Hampshire has been ongoing steadily since Interstate 93 (I-93) was built through the NE subcatchment of the lake in the fall and winter of 1969-1970. Salt added to I-93 during winter as a deicer has been transported to the lake by different quantified, hydrologic pathways, but primarily from the Northeast Tributary, which was intersected by I-93. Now, surprisingly, after the New Hampshire Department of Transportation has spent more than $500,000 on recent structural modifications to divert salt from I-93 away from the Northeast subcatchment of Mirror Lake, applications of salt to a small, town road traversing the other two subcatchments for the lake and servicing a new housing development, have become the major source of salt to the lake. Streamflow from these two subcatchments currently provides more than three times as much salt to the lake as from I-93, and the salt concentration in the lake continues to rise.

Significant quantities of the broiler chicken (Gallus gallus domesticus) litter produced in the USA are being applied to pasture lands. The traditional surface- broadcast application of animal manure onto permanent pasture, however, may lead to high concentration of nutrients and pathogenic microorganisms near the soil surface that could be transported off site by runoff water. Subsurface banding of poultry litter has the potential to reduce nutrient and pathogen losses through runoff. However, this has not been thoroughly investigated. In this study, we used rainfall simulations to examine the effect of broiler litter application methods on the longevity of nutrient and Escherichia coli losses in runoff by successive runoff events. Runoff plots were constructed on Hartsells fine sandy loam (Typic Hapludults) soil with permanent Kentucky 31 tall fescue (Festuca arundinacea) pasture in Crossville, AL. Treatments included two methods of litter application (surface broadcast and subsurface banding), commercial fertilizer, and control (no litter or fertilizer applied). To evaluate the longevity of nutrient losses, simulated rainfall (110 mm h⁻¹) was applied to each plot on days 1, 7, and 14 following litter and fertilizer applications. Total P (TP), inorganic N, and E. coli concentrations were all significantly greater in runoff from broadcast litter application than the subsurface litter banding treatments. The TP losses from broadcast litter applications averaged 6.5 times those from subsurface litter applications. About 81% of the runoff TP concentration was in the form of dissolved reactive phosphorus for both litter application methods. The average losses of NO₃-N and total suspended solids from subsurface litter banding plots were 358 g ha⁻¹ and 68 kg ha⁻¹ compared to 462 and 60 kg ha⁻¹ for the broadcast method, respectively. This study shows that subsurface banding of broiler litter into perennial grassland can substantially reduce nutrient and pathogen losses in runoff compared to the traditional surface-broadcast practice.

This study aimed at determining the water quality of River Sirimon and River Kongoni, Ewaso Ng'iro North Basin, Kenya. Water quality analysis of these two rivers was done for a period of 5 months between November 2005 and February 2006. Portable Palintest equipment was used for the chemical analysis. The study established that there were sulphates concentrations of 22 mgL⁻¹ in the Kongoni River water associated with the use of commercial fertilisers as compared to mean values of 7 mgL⁻¹ along Sirimon River; phosphate concentrations were 1.3 mgL⁻¹ in Kongoni and 0.15 mgL⁻¹ in Sirimon and salinity 3 mgL⁻¹ in Kongoni and 0.47 mgL⁻¹ in Sirimon. On average, mean nitrates concentrations of 1.7 mgL⁻¹ were recorded for Kongoni River, which were higher than those recorded for Sirimon River (0.033 mgL⁻¹). These concentration levels were however within the standard levels set by WHO for example 50 mgL⁻¹ for nitrates (WHO 2008). River Kongoni has two major irrigated horticultural farms across it which were likely polluting the river during the time of this study.

For a half century, total suspended solids (TSS) has been the most commonly utilized particulate matter (PM) gravimetric index for wastewater. While TSS has been extended to urban runoff, runoff phenomena are unique. Runoff is unsteady and transports heterodisperse inorganic granulometry, giving rise to the PM index, suspended sediment concentration (SSC). With respect to PM-associated chemical oxygen demand (CODp) in runoff, it is hypothesized that, while the TSS method can represent effluent CODp, the SSC method is required to represent influent CODp. CODp and PM indices (TSS and SSC) for runoff events with mass balances and manual sampling are analyzed to investigate this hypothesis. This study examined a series of rainfall-runoff events captured from an instrumented fully paved urban catchment subject to traffic loadings in Baton Rouge, LA. Results indicate TSS generated substantial event-based mass balance errors for CODp and Δm p (mg/g) across a hydrodynamic separator (HS) as compared to SSC. TSS underestimates sediment-bound COD (>75 µm), a significant portion (maximum of 63% and median of 50%) of influent load. Negative bias by the TSS method for influent CODp load increases as the heterodisperse particle size distribution becomes coarser. Above a PM of 250 mg/L, underestimation of CODp by the TSS method is statistically significant. Utilizing the SSC method, CODp reduction by a HS upstream of a batch clarifier (BC) indicates that a HS does not provide CODp reduction, compared to a BC with 60 min of residence time. Representative PM and CODP assessment suggests frequent BMP and drainage system maintenance to ensure proper operation and reduce pollutant elution.