Assessment of chlorophyll-a variations in high- and low-flow seasons in Apalachicola Bay by MODIS 250-m remote sensing

Chlorophyll-a (chl-a) is considered as a primary indicator for water quality and foods for oyster growth in Apalachicola estuarine ecosystem. Assessment of chl-a concentration variation in response to river inflow is important for estuarine environmental research and management. In this study, remote sensing analysis has been conducted to evaluate the effects of river inflow on chlorophyll concentrations in Apalachicola Bay of Florida in the northeast Gulf of Mexico. A remote sensing model for chl-a was improved and applied to map spatial distributions of chl-a by using Moderate Resolution Imaging Spectroradiometer (MODIS) 250-m resolution imageries in high-flow and low-flow seasons in 2001 and 2008. Chl-a values approximately ranged from the minimum 6 μg/l to the maximum 29 μg/l in the study period. Maximum chl-a concentration in high-flow season was almost twice above that in low-flow season. The averaged mean and minimum chl-a level in the high-flow season were approximately 42 and 28 % higher than those in low-flow season, respectively. The remote sensing mapping of chl-a was able to show spatial variations of chl-a in the entire bay under different flow conditions, which indicated its advantage over the traditional field data sampling for monitoring water quality over a large area of estuary. The MODIS 250-m remote sensing regression model presented from this study can be used to support monitoring and assessment of the spatial chl-a distribution in the bay for environmental research and management in Apalachicola Bay.     

Chemistry and long-term decomposition of roots of Douglas-fir grown under elevated atmospheric carbon dioxide and warming conditions

Elevated atmospheric CO(2) concentrations and warming may affect the quality of litters of forest plants and their subsequent decomposition in ecosystems, thereby potentially affecting the global carbon cycle. However, few data on root tissues are available to test this feedback to the atmosphere. In this study, we used fine (diameter < or = 2 mm) and small (2-10 mm) roots of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) seedlings that were grown for 4 yr in a 2 x 2 factorial experiment: ambient or elevated (+ 180 ppm) atmospheric CO(2) concentrations, and ambient or elevated (+3.8 degrees C) atmospheric temperature. Exposure to elevated CO(2) significantly increased water-soluble extractives concentration (%WSE), but had little effect on the concentration of N, cellulose, and lignin of roots. Elevated temperature had no effect on substrate quality except for increasing %WSE and decreasing the %lignin content of fine roots. No significant interaction was found between CO(2) and temperature treatments on substrate quality, except for %WSE of the fine roots. Short-term (< or = 9 mo) root decomposition in the field indicated that the roots from the ambient CO(2) and ambient temperature treatment had the slowest rate. However, over a longer period of incubation (9-36 mo) the influence of initial substrate quality on root decomposition diminished. Instead, the location of the field incubation sites exhibited significant control on decomposition. Roots at the warmer, low elevation site decomposed significantly faster than the ones at the cooler, high elevation site. This study indicates that short-term decomposition and long-term responses are not similar. It also suggests that increasing atmospheric CO(2) had little effect on the carbon storage of Douglas-fir old-growth forests of the Pacific Northwest.     

Feasibility of water purification technology in rural areas of developing countries

Water scarcity is threatening social and economic growth in rural areas of developing countries. There are potential markets for water purification technologies in these regions. The main focus of this article is to evaluate the social, economic and political feasibilities of providing water purification technologies to rural areas of developing countries. The findings of this research can serve as the basis for private investors interested in entering this market. Four representative regions were selected for the study. Economic, demographic, and environmental variables of each region were collected and analyzed along with domestic markets and political information. Rural areas of the developing world are populated with poor people unable to fulfill the basic needs for clean water and sanitation. These people represent an important group of potential users. Due to economic, social, and political risks in these areas, it is difficult to build a strong case for any business or organization focusing on immediate returns on capital investment. A plausible business strategy would be to approach the water purification market as a corporate responsibility and social investing in the short term. This would allow an organization to be well positioned once the economic ability of individuals, governments, and donor agencies are better aligned.     

Evaporative mass transfer behavior of a complex immiscible liquid

A series of laboratory experiments was conducted with a multiple-component immiscible liquid, collected from the Picillo Farm Superfund Site in Rhode Island, to examine liquid-vapor mass-transfer behavior. The immiscible liquid, which comprises solvents, oils, pesticides, PCBs, paint sludges, explosives, and other compounds, was characterized using gas chromatography and gas chromatography/mass spectrometry to determine mole fractions of selected constituents. Batch experiments were conducted to evaluate equilibrium phase-partitioning behavior. Two sets of air-stripping column studies were conducted to examine the mass-transfer dynamics of five selected target compounds present in the immiscible-liquid mixture. One set of column experiments was designed to represent a system with free-phase immiscible liquid present; the other was designed to represent a system with a residual phase of immiscible liquid. Initial elution behavior of all target components generally appeared to be ideal for both systems, as the initial vapor-phase concentrations were similar to vapor-phase concentrations measured for the batch experiment and those estimated using Raoult's law (incorporating the immiscible-liquid composition data). Later-stage removal of 1,2-dichlorobenzene appeared to be rate limited for the columns containing free-phase immiscible liquid and no porous medium. Conversely, evaporative mass transfer appeared to be ideal throughout the experiment conducted with immiscible liquid distributed relatively uniformly as a residual phase within a sandy porous medium.     

Mercury and other element exposure to tree swallows (Tachycineta bicolor) nesting on Lostwood National Wildlife Refuge, North Dakota

Elevated mercury concentrations in water were reported in the prairie wetlands at Lostwood National Wildlife Refuge, ND. In order to determine whether wildlife associated with these wetlands was exposed to and then accumulated higher mercury concentrations than wildlife living near more permanent wetlands (e.g. lakes), tree swallow (Tachycineta bicolor) eggs and nestlings were collected from nests near seasonal wetlands, semi-permanent wetlands, and lakes. Mercury concentrations in eggs collected near seasonal wetlands were higher than those collected near semi-permanent wetlands or lakes. In contrast, mercury concentrations in nestling livers did not differ among wetland types. Mercury and other element concentrations in tree swallow eggs and nestlings collected from all wetlands were low. As suspected from these low concentrations, mercury concentrations in sample eggs were not a significant factor explaining the hatching success of the remaining eggs in each clutch.     

Enhanced removal of heavy metals in primary treatment using coagulation and flocculation.

The goal of this study was to determine the removal efficiencies of chromium, copper, lead, nickel, and zinc from raw wastewater by chemically enhanced primary treatment (CEPT) and to attain a total suspended solids removal goal of 80%. Operating parameters and chemical doses were optimized by bench-scale tests. Locally obtained raw wastewater samples were spiked with heavy metal solutions to obtain representative concentrations of metals in wastewater. Jar tests were conducted to compare the metals removal efficiencies of the chemical treatment options using ferric chloride, alum, and anionic polymer. The results obtained were compared with those from other studies. It was concluded that CEPT using ferric chloride and anionic polymer is more effective than CEPT using alum for metals removal. The CEPT dosing of 40 mg/L ferric chloride and 0.5 mg/L polymer enhanced heavy metals removal efficiencies by over 200% for chromium, copper, zinc, and nickel and 475% for lead, compared with traditional primary treatment. Efficient metals capture during CEPT can result in increased allowable headworks loadings or lower metal levels in the outfall.     

Solomon versus selective fetoscopic laser photocoagulation for twin-twin transfusion syndrome: A systematic review and meta-analysis

This meta-analysis aims to compare the perinatal outcome of twin-twin transfusion syndrome (TTTS) pregnancies undergoing selective versus vascular equator (Solomon) fetoscopic laser photocoagulation (FLP). We performed a systematic search in PubMed and Web of Science from inception up to 25 July 2021. Studies comparing the Solomon and selective techniques of FLP for treatment of TTTS pregnancies were eligible. Random-effects or fixed-effect models were used to pool standardized mean differences (SMD) and log odds ratio. Seven studies with a total of 1664 TTTS pregnancies (n = 671 undergoing Solomon and n = 993 selective techniques) were included. As compared to the selective FLP, Solomon was associated with a lower risk of recurrent TTTS compared to the selective technique (Log odds ratio [OR]: −1.167; 95% credible interval [CrI]: −2.01, −0.33; p = 0.021; I²: 67%). In addition, Solomon was significantly associated with a higher risk of placental abruption than the selective technique (Log [OR]: 1.44; 95% CrI: 0.45, 2.47; p = 0.012; I²: 0.0%). Furthermore, a trend for the higher risk of preterm premature rupture of membranes was observed among those undergoing Solomon (Log [OR]: 0.581; 95% CrI: −0.43, 1.49; p = 0.131; I²: 17%). As compared to selective FLP, the Solomon technique for TTTS pregnancies is associated with a significantly lower recurrence of TTTS; however, it significantly increases the risk of placental abruption.     

Combining data-intelligent algorithms for the assessment and predictive modeling of groundwater resources quality in parts of southeastern Nigeria

Environmental Science and Pollution Research - Machine learning algorithms have proven useful in the estimation, classification, and prediction of water quality parameters. Similarly, indexical...     

Cooling of bat hibernacula to mitigate white-nose syndrome

White-nose syndrome (WNS) is a fungal disease that has caused precipitous declines in several North American bat species, creating an urgent need for conservation. We examined how microclimates and other characteristics of hibernacula have affected bat populations following WNS-associated declines and evaluated whether cooling of warm, little-used hibernacula could benefit bats. During the period following mass mortality (2013–2020), we conducted 191 winter surveys of 25 unmanipulated hibernacula and 6 manipulated hibernacula across Pennsylvania (USA). We joined these data with additional datasets on historical (pre-WNS) bat counts and on the spatial distribution of underground sites. We used generalized linear mixed models and model selection to identify factors affecting bat populations. Winter counts of Myotis lucifugus were higher and increased over time in colder hibernacula (those with midwinter temperatures of 3–6 °C) compared with warmer (7–11 °C) hibernacula. Counts of Eptesicus fuscus, Myotis leibii, and Myotis septentrionalis were likewise higher in colder hibernacula (temperature effects = –0.73 [SE 0.15], –0.51 [0.18], and –0.97 [0.28], respectively). Populations of M. lucifugus and M. septentrionalis increased most over time in hibernacula surrounded by more nearby sites, whereas Eptesicus fuscus counts remained high where they had been high before WNS onset (pre-WNS high count effect = 0.59 [0.22]). Winter counts of M. leibii were higher in hibernacula with high vapor pressure deficits (VPDs) (particularly over 0.1 kPa) compared with sites with lower VPDs (VPD effect = 15.3 [4.6]). Counts of M. lucifugus and E. fuscus also appeared higher where VPD was higher. In contrast, Perimyotis subflavus counts increased over time in relatively warm hibernacula and were unaffected by VPD. Where we manipulated hibernacula, we achieved cooling of on average 2.1 °C. At manipulated hibernacula, counts of M. lucifugus and P. subflavus increased over time (years since manipulation effect = 0.70 [0.28] and 0.51 [0.15], respectively). Further, there were more E. fuscus where cooling was greatest (temperature difference effect = –0.46 [SE 0.11]), and there was some evidence there were more P. subflavus in hibernacula sections that remained warm after manipulation. These data show bats are responding effectively to WNS through habitat selection. In M. lucifugus, M. septentrionalis, and possibly P. subflavus, this response is ongoing, with bats increasingly aggregating at suitable hibernacula, whereas E. fuscus remain in previously favored sites. Our results suggest that cooling warm sites receiving little use by bats is a viable strategy for combating WNS.