ABSTRACT
Infiltration basins have been widely used for stormwater runoff management. However, their longevity could be compromised over time, up to the point of operational failure. This research study showed that a 'failed' infiltration basin can 'transition' into a wetpond/wetland-like practice and provide water quality benefits. Performance evaluation over three years showed that the transitioned infiltration basin reduced the discharge event mean concentrations of total phosphorus (TP), dissolved phosphorus (DP), particulate phosphorus (PP), NOx-N (nitrate+nitrite), total Kjeldahl nitrogen (TKN), organic-N (ON), and total nitrogen (TN) during most storm events. Exports of TP, DP, ON, and TKN masses were observed only during the coldest periods. The cumulative mass removals were 61% TP, 53% DP, 63% PP, 79% NOx-N, 51% TKN, 45% ON, and 64% TN. The dry-weather nutrient concentrations combined with the environmental conditions at the transitioned basin indicated that sedimentation, adsorption, denitrification, and volume reduction were the removal mechanisms.
Subject(s)
Nitrogen/chemistry , Phosphorus/chemistry , Water Pollutants, Chemical/analysis , Water Purification/methods , Environmental Monitoring , Hydrogen-Ion Concentration , Maryland , Rain , Waste Disposal, Fluid/methods , Water Movements , Water Quality , WetlandsABSTRACT
The water quality performance of a 'failed' stormwater infiltration basin that has 'transitioned' to a wetpond/wetland has been evaluated over a three-year period. Total suspended solids, heavy metals, and chloride in highway runoff and discharge from the transitioned basin were measured during 38 storm events. The transitioned basin provided significant reductions in TSS Event Mean Concentrations (EMCs) and mass in the runoff. Reductions in metal EMCs generally occurred. Chloride followed a seasonal cycle of high loading and mass export during colder periods, and gradual reductions in both EMCs and mass during other periods. The cumulative mass reductions were 89% TSS, 73% copper, 63% lead, 55% zinc, and 45% chloride for the study period. Combined with the dry-weather water quality in the transitioned basin, the mechanisms of pollutant removal were identified as volume reduction, sedimentation, adsorption, and dilution. The presence of wetpond/wetland features, including hydrophytic vegetation enhanced the pollutant removal processes.
Subject(s)
Water Pollutants, Chemical/analysis , Water Purification/methods , Water Quality , Wetlands , Environmental Monitoring , Maryland , Rain , Water MovementsABSTRACT
OBJECTIVE: Sarcolipin (SLN) is a novel 31-amino-acid protein associated with the sarcoplasmic reticulum (SR) whose function in cardiac muscle is poorly defined. In this study, we tested the hypothesis that SLN is a regulator of SR Ca(2+) transport function by overexpressing SLN in adult rat ventricular myocytes which express low levels of SLN. METHODS: Expression of SLN mRNA in rat tissues was analyzed by Northern blot as well by RT-PCR analysis. To define the role of SLN in cardiac muscle contractility, we overexpressed SLN in adult rat ventricular myocytes using adenoviral gene transfer techniques. Localization of SLN in the adult rat ventricular myocytes was determined using confocal microscopy. Myocyte contractility and calcium transients were measured using edge detection and Fura 2AM. RESULTS: Our results demonstrate that overexpression of SLN decreased the cell shortening significantly when compared to control myocytes, whereas the time to peak contraction was not altered. In addition, SLN overexpression prolonged the time of 50% relaxation. Calcium transient analysis shows that time to 50% decay of [Ca(2+) ]i was markedly prolonged in SLN-overexpressing myocytes (control -245.0+/-3.78 vs. SLN -199.0+/-3.25 ms, p<0.001). However, there were no significant differences in peak amplitudes of [Ca(2+)](i) between SLN-overexpressing and control myocytes. We further demonstrate that SLN is localized within the SR membrane similar to PLB and SR Ca(2+) ATPase. Co-immunoprecipitation studies indicate that SLN can physically interact with phospholamban. CONCLUSIONS: We conclude that SLN may play an important role in regulating the SR calcium ATPase pump, possibly by interacting with phospholamban.
