Abandoned Coal Mine Drainage and Its Remediation: Impacts on Stream Ecosystem Structure and Function

The effects of abandoned mine drainage (AMD) on streams and responses to remediation efforts were studied using three streams (AMD-impacted, remediated, reference) in both the anthracite and the bituminous coal mining regions of Pennsylvania (USA). Response variables included ecosystem function as well as water chemistry and macroinvertebrate community composition. The bituminous AMD stream was extremely acidic with high dissolved metals concentrations, a prolific mid-summer growth of the filamentous alga, Mougeotia, and .10-fold more chlorophyll than the reference stream. The anthracite AMD stream had a higher pH, substrata coated with iron hydroxide(s), and negligible chlorophyll. Macroinvertebrate communities in the AMD streams were different from the reference streams, the remediated streams, and each other. Relative to the reference stream, the AMD stream(s) had (1) greater gross primary productivity (GPP) in the bituminous region and undetectable GPP in the anthracite region, (2) greater ecosystem respiration in both regions, (3) greatly reduced ammonium uptake and nitrification in both regions, (4) lower nitrate uptake in the bituminous (but not the anthracite) region, (5) more rapid phosphorus removal from the water column in both regions, (6) activities of phosphorus-acquiring, nitrogenacquiring, and hydrolytic-carbon-acquiring enzymes that indicated extreme phosphorus limitation in both regions, and (7) slower oak and maple leaf decomposition in the bituminous region and slower oak decomposition in the anthracite region. Remediation brought chlorophyll concentrations and GPP nearer to values for respective reference streams, depressed ecosystem respiration, restored ammonium uptake, and partially restored nitrification in the bituminous (but not the anthracite) region, reduced nitrate uptake to an undetectable level, restored phosphorus uptake to near normal rates, and brought enzyme activities more in line with the reference stream in the bituminous (but not the anthracite) region. Denitrification was not detected in any stream. Water chemistry and macroinvertebrate community structure analyses capture the impact of AMD at the local reach scale, but functional measures revealed that AMD has ramifications that can cascade to downstream reaches and perhaps to receiving estuaries.

Landfill Closure and Housing Values

The United States disposes roughly 60% of the municipal solid waste it generates each year in solid waste disposal facilities, commonly known as landfills. Hedonic pricing studies have estimated the external costs of landfills on neighboring housing markets, but the literature is silent on what happens to property values after the landfill closes. Original housing price data collected both before and after a landfill closure are used to estimate how a landfill closure affects neighboring property values. Results of both a hedonic pricing model and repeat-sales estimator are used in the analysis.

Patent foramen ovale closure in recreational divers: effect on decompression illness and ischaemic brain lesions during long-term follow-up

To test the effect of patent foramen ovale (PFO) closure on neurological events in divers.

Long-term propensity score-matched comparison of percutaneous closure of patent foramen ovale with medical treatment after paradoxical embolism

Patients with ischemic stroke or transient ischemic attack presumably related to patent foramen ovale (PFO) are at risk for recurrent cerebrovascular events. Differences in long-term clinical outcome were investigated among patients with percutaneous PFO closure and those who received medical treatment.

Early closure of ileostomy is associated with less postoperative nausea and vomiting

Background/Aims: Temporary loop ileostomy is increasingly used in colorectal surgery but necessitates secondary closure. We evaluated postoperative complications, particularly nausea and vomiting, in patients with early, intermediate, or late elective ileostomy closure. Methods: We included all patients undergoing ileostomy closure from 2001 to 2008. Time from ileostomy construction to closure was classified as early (EC, <12 weeks), intermediate (IC, 12–18 weeks), and late (LC, >18 weeks). Using multivariable logistic regression, we compared the frequency of postoperative complications between the groups. Results: We included 134 patients (87 males; median age 71 years, range 29–91). Carcinoma of the rectum (n = 67, 50%) was the main reason for ileostomy construction. The median time to ileostomy closure was 103 days (range 8–461). Among patients with EC, IC, and LC, postoperative nausea occurred in 50.0, 73.1, and 78.6%, respectively (p = 0.006), and postoperative vomiting in 22.5, 57.7, and 59.5%, respectively (p = 0.001). Adjusting for important covariates, the odds ratio for postoperative nausea was 2.0 (95% CI 0.76–5.1) for IC and 4.1 (95% CI 1.2–14.3) for LC compared to EC (p = 0.069). For postoperative vomiting, adjusted odds ratios were 3.8 (95% CI 1.4–10.4) for IC and 4.6 (95% CI 1.4–15.5) for LC (p = 0.012). Other complications did not differ between the groups. Conclusions: These findings suggest that early ileostomy closure might reduce postoperative nausea and vomiting.

Left atrial appendage closure with the Amplatzer cardiac plug in patients with atrial fibrillation

Percutaneous left atrial appendage closure (LAAC) has emerged as an alternative to oral anticoagulation (OA) for prevention of thromboembolic stroke in patients with non-valvular atrial fibrillation (NVAF).