This exploratory laboratory study was undertaken to develop and test an in situ bioremediation system intended to point the way toward a possible field application. The proposed method uses a water table management (WTM) system to deliver nutrients or other amendments to subsoil microorganisms for biostimulation and subsequent biodegradation of pollutants in the saturated and unsaturated zones of the soil. The study was carried out on packed soil columns and bioremediation of residual fertilizer nitrate was attempted. Different levels of organic carbon supplement (glucose C) were introduced into these columns via subirrigation in order to supplement the readily available organic carbon levels in the soil. The study was carried out in two experimental setups. The first setup investigated (i) the effect of addition of a high (970 mg L(-1)) and a low (120 mg L(-1)) glucose C level and (ii) the efficacy of using the subirrigation system as a method for nutrient delivery in bioremediation of leached nitrate. This setup was monitored with time, depth, and with reference to the nitrate residue in the soil solution. Leached nitrate was denitrified to less than 10 mg L(-1) nitrate N at both glucose levels. The second setup investigated the effect of a range of low levels of glucose C on nitrate decontamination, soil pH, and total microbial count in order to find out an optimal glucose C level that reduced the most nitrate and maintained the pH homeostasis of soil.

Agriculture↗

PubMedDate not supplied

Bioremediation of residual fertilizer nitrate: II. Soil redox potential and soluble iron as indicators of soil health during treatment.

The prospect of using wastewater containing high loads of soluble organic matter (OM) for removing residual agricultural chemicals (fertilizer, pesticide, or herbicide) in farm soil, although promising, could have adverse effects on soil agricultural quality as a result of development of redoximorphic features in the soil profile. In this study, the effect of organic carbon supplement for bioremediation of residual fertilizer nitrate on soil properties, redox potential (Eh), pH, and metal ion mobilization was studied using sandy soils packed in columns. The study was included in a general project, described elsewhere (Ugwuegbu et al., 2000), undertaken to evaluate use of controlled water table management (WTM) systems to supply organic carbon for creating a reduced environment conducive to denitrification of residual fertilizer nitrate leaching from the farm to subsurface water. The columns were subjected to subirrigation with water containing soluble organic carbon in the form of glucose. The work was carried out in two experimental setups and the long-term effect of a range of glucose concentrations on the Eh, pH, and soluble levels of Fe and Mn was investigated. From the results obtained, it could be concluded that excessive organic carbon supplement to soil can have adverse effects on soil quality and that Eh and soluble Fe are the two most practical parameters for monitoring soil health during treatment of farm chemicals.

Agriculture↗

PubMedDate not supplied

Should heart-lung transplant donors and recipients be matched according to cytomegalovirus serologic status?

Cytomegalovirus (CMV) infection is a major cause of morbidity and mortality after heart-lung transplantation. Primary CMV infections in previously seronegative recipients are more severe than reactivated or reinfections in seropositive patients, and this has led to a policy of obligatory donor-recipient CMV matching in several centers performing heart-lung transplantation. Of our 13 heart-lung transplants, three were done in CMV-seronegative patients who received CMV-positive grafts. The first patient did not seroconvert and exhibited no evidence of CMV infection despite close follow-up extending to almost 2 years. In the second patient, who required augmented immunosuppression because of recurrent lung rejection early postoperatively, fulminating CMV pneumonitis developed, which was ultimately controlled with ganciclovir and high-dose CMV immune globulin. As an outpatient, she is currently receiving ganciclovir maintenance therapy. The third patient, who received high-dose CMV immune globulin prophylaxis, had CMV isolated from her bronchoalveolar lavage fluid, as well as from urine, but remains clinically well 5 months after receiving her transplant. We conclude that the matching of donors and recipients for CMV serologic status is desirable, but not essential, before heart-lung transplantation. CMV immune globulin prophylaxis may be effective in preventing clinical CMV disease in patients receiving a CMV-mismatched graft, and severe CMV pneumonitis may be effectively treated by a combination of ganciclovir and high-dose CMV immune globulin therapy.

Adult↗