Hydrogen sulfide ameliorates lead-induced morphological, photosynthetic, oxidative damages and biochemical changes in cotton

Poisonous lead (Pb), among heavy metals, is a potential pollutant that readily accumulates in soils and thus adversely affects physiological processes in plants. We have evaluated how exogenous H₂S affects cotton plant physiological attributes and Pb uptake under Pb stress thereby understanding the role of H₂S in physiological processes in plants. Two concentrations (0 and 200 μM) of H₂S donor sodium hydrosulfide (NaHS) were experimented on cotton plants under Pb stress (0, 50, and 100 μM). Results have shown that Pb stress decreased plant growth, chlorophyll contents, SPAD value, photosynthesis, antioxidant activity. On the other hand, Pb stress increased the level of malondialdehyde (MDA), electrolyte leakage (EL), and production of H₂O₂ and uptake of Pb contents in all three parts of plant, viz. root, stem, and leaf. Application of H₂S slightly increased plant growth, chlorophyll contents, SPAD value, photosynthesis, and antioxidant activity as compared to control. Hydrogen sulfide supply alleviated the toxic effects of lead on plant growth, chlorophyll contents, SPAD value, photosynthesis, and antioxidant activity in cotton plants. Hydrogen sulfide also reduced MDA, EL, and production of H₂O₂ and endogenous Pb levels in the three mentioned plant parts. On the basis of our results, we conclude that H₂S has promotive effects which could improve plant survival under Pb stress.     

Effects of sewage sludge amendments on pesticide sorption and leaching through undisturbed Mediterranean soils

The Gharb region in Morocco is an important agricultural zone where soils receive pesticide treatments and organic amendments to increase yields. The groundwater aquifer in the Gharb region is relatively shallow and thus vulnerable. The objective of this work was to study the influence of organic amendments on diuron, cyhalofop-butyl and procymidone leaching through undisturbed soil columns. Two soils were sampled from the Gharb region, a Dehs (sandy soil) and a R’mel (loamy clay soil). Following elution (124.5 mm), the amount of pesticide residues in the leachates of the sandy soil (0.06–0.21 %) was lower than in those of the loamy clay soil (0.20–0.36 %), which was probably due to preferential flow through the loamy clay soil. The amount of procymidone leached through the amended soil columns was greater than the control for the sandy soil only. The organic amendments did not significantly influence diuron and cyhalofop-butyl leaching in either of the soils. The application of organic amendments affected the amounts of dissolved organic matter (DOM) eluted and thus pesticide leaching as a function of soil-type. Nevertheless, in some case, the formation of pesticide-DOM complexes appeared to promote pesticide leaching, thus increasing groundwater contamination risks.     

Modeling sediment and nitrogen export from a rural watershed in eastern Canada using the soil and water assessment tool

Watershed simulation models can be used to assess agricultural nonpoint-source pollution and for environmental planning and improvement projects. However, before application of any process-based watershed model, the model performance and reliability must be tested with measured data. The Soil and Water Assessment Tool version 2005 (SWAT2005) was used to model sediment and nitrogen loads from the Thomas Brook Watershed, which drains a 7.84 km rural landscape in the Annapolis Valley of Nova Scotia, Canada. The Thomas Brook SWAT model was comprised of 28 subbasins and 265 hydrologic response units, most of them containing agricultural land use, which is the main nonpoint nitrogen source in the watershed. Crop rotation schedules were incorporated into the model using field data collected within Agriculture and Agri-Food Canada's Watershed Evaluation of Beneficial Management Practices program. Model calibration (2004-2006) and validation (2007-2008) were performed on a monthly basis using continuous stream flow, sediment, and nitrogen export measurements. Model performance was evaluated using the coefficient of determination, Nash-Sutcliff efficiency (NSE), and percent bias (PBIAS) statistics. Study results show that the model performance was satisfactory (NSE > 0.4; > 0.5) for stream flow, sediment, nitrate-nitrogen, and total nitrogen simulations. Annual corn, barley, and wheat yields were also simulated well, with PBIAS values ranging from 0.3 to 7.2%. This evaluation of SWAT demonstrated that the model has the potential to be used as a decision support tool for agricultural watershed management in Nova Scotia.     

Validation of plant based bioassays for the toxicity testing of Indian waters

Plant-based bioassays have recently gained remarkable popularity among the toxicological/eco-toxicological assessment procedures. The reasons for their wide use are comparative simplicity, sensitivity, and cost-effectiveness as well as a good correlation with other toxicity tests. The present study describes the use of two plant bioassays, Allium cepa test and seed germination test in the evaluation of the toxicity/genotoxicity of industrial waste water and river water and standardization with the commonly occurring pollutants in Indian waters namely heavy metals and phenolics. Both tests were standardized to suit the Indian conditions, and the local varieties were used. Both bioassays responded significantly with the test range of heavy metals and phenolics. The toxicity of heavy metals was in the order of Cu > Ni > Cd in both the tests whereas 2,4-dinitrophenol was the most toxic among the phenolic compounds. Cabbage, millet, and cucumber, respectively, were found to be the most sensitive in the seed germination test for the test heavy metals and phenols. Significant amounts of chromosomal abnormalities including bridges, stickiness, and fragmentations were recorded with both the industrial waste water and the XAD concentrated river water samples by A. cepa test.     

Assessment of methane emission and oxidation at Air Hitam Landfill site cover soil in wet tropical climate

Methane (CH₄) emissions and oxidation were measured at the Air Hitam sanitary landfill in Malaysia and were modeled using the Intergovernmental Panel on Climate Change waste model to estimate the CH₄ generation rate constant, k. The emissions were measured at several locations using a fabricated static flux chamber. A combination of gas concentrations in soil profiles and surface CH₄ and carbon dioxide (CO₂) emissions at four monitoring locations were used to estimate the CH₄ oxidation capacity. The temporal variations in CH₄ and CO₂ emissions were also investigated in this study. Geospatial means using point kriging and inverse distance weight (IDW), as well as arithmetic and geometric means, were used to estimate total CH₄ emissions. The point kriging, IDW, and arithmetic means were almost identical and were two times higher than the geometric mean. The CH₄ emission geospatial means estimated using the kriging and IDW methods were 30.81 and 30.49 g m^?2 day^?1, respectively. The total CH₄ emissions from the studied area were 53.8 kg day^?1. The mean of the CH₄ oxidation capacity was 27.5 %. The estimated value of k is 0.138 year^?1. Special consideration must be given to the CH₄ oxidation in the wet tropical climate for enhancing CH₄ emission reduction.     

Economic growth,technology, and CO2 emissions in BRICS: Investigating the non-linear impacts of economic complexity

Environmental Science and Pollution Research - Upgrading economic structures and producing less pollution-intensive goods are indispensable for achieving Sustainable Development Goals (SDGs) in...     

Composting of municipal solid waste by different methods improved the growth of vegetables and reduced the health risks of cadmium and lead

Environmental Science and Pollution Research - Reutilization of putrescible municipal solid wastes (MSW) in agriculture can provide valuable plant nutrients. However, it may pose serious...     

Intercomparison of INAA and ICP-MS results for thorium determination in Pakistani diet

A pilot study on ingestion and organ content of trace elements of importance in radiological protection was to be carried out in Pakistan. Baseline analytical data on daily dietary intake of thorium was to be measured using Instrumental Neutron Activation Analysis (INAA) technique. To determine the accuracy and reliability of our technique, some samples were measured in Pakistan using INAA and in Japan using Inductively Coupled Plasma-Mass Spectrometry. For intercomparison of results overall mean Z-scores were calculated. The results showed validity of our technique. Mean value of 232Th concentration in Pakistani diet samples using INAA technique is 0.0062 +/- 0.0028 microg/g and with ICP-MS technique is 0.0069 +/- 0.0032 microg/g.     

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.