A microbial perspective on balancing trade-offs in ecosystem functions in a constructed stormwater wetland

Constructed wetlands (CWs) are increasingly considered for secondary wastewater treatment, removing both conventional contaminants and emerging pollutants, notably pharmaceutical and personal care products (PPCPs). However, the CW design and operational conditions to biodegrade PPCPs as micropollutants may promote greenhouse gas (GHG) emissions, raising sustainability concerns. This meta-analysis investigates the relationship between PPCP removal (caffeine, ibuprofen, naproxen, diclofenac, ketoprofen, carbamazepine, sulfonamide compounds) and GHG emissions (methane, carbon dioxide, nitrous oxide) in CWs. We uniquely integrate two sets of studies, as prior research has not linked PPCP biodegradation with GHG emissions. Data from 26 papers identify factors driving PPCP removal and 26 publications inform GHG emission factors. Spearman's correlation coefficient and multiple linear regression assess parameter effects and interlinkages. Results highlight biological processes, particularly secondary metabolism or co-metabolism, as pivotal for PPCP removal and GHG emissions, with inlet PPCP concentration, carbon load, and temperature being significant influencers (p < 0.05). Challenges persist in optimizing operations to improve PPCP removal and abate GHG emissions simultaneously. Still, CW depth, influent chemical oxygen demand (COD), hydraulic retention time, and subsurface flow wetland configuration emerge as strategic parameters. This study underscores the need for integrated approaches to enhance PPCP removal and decrease GHG emissions in CWs, thereby advancing sustainable water management practices.

Greenhouse gas emissions from constructed wetlands are mitigated by biochar substrates and distinctly affected by tidal flow and intermittent aeration modes.

Enhanced nitrogen removal and greenhouse gas reduction via activated carbon coupled iron-based constructed wetlands

Feeding strategies and manure management for cost-effective mitigation of greenhouse gas emissions from dairy farms in Wisconsin

Greenhouse gases emissions and carbon budget estimation in horizontal subsurface flow constructed wetlands with different plant species

Executive Summary: The California Climate Action Registry, which was initially established in 2000 and began operation in Fall 2002, is a voluntary registry for recording annual greenhouse gas (GHG) emissions. The purpose of the Registry is to assist California businesses and organizations in their efforts to inventory and document emissions in order to establish a baseline and to document early actions to increase energy efficiency and decrease GHG emissions. The State of California has committed to use its ''best efforts'' to ensure that entities that establish GHG emissions baselines and register their emissions will receive ''appropriate consideration under any future international, federal, or state regulatory scheme relating to greenhouse gas emissions.'' Reporting of GHG emissions involves documentation of both ''direct'' emissions from sources that are under the entity's control and indirect emissions controlled by others. Electricity generated by an off-site power source is consider ed to be an indirect GHG emission and is required to be included in the entity's report. Registry participants include businesses, non-profit organizations, municipalities, state agencies, and other entities. Participants are required to register the GHG emissions of all operations in California, and are encouraged to report nationwide. For the first three years of participation, the Registry only requires the reporting of carbon dioxide (CO2) emissions, although participants are encouraged to report the remaining five Kyoto Protocol GHGs (CH4, N2O, HFCs, PFCs, and SF6). After three years, reporting of all six Kyoto GHG emissions is required. The enabling legislation for the Registry (SB 527) requires total GHG emissions to be registered and requires reporting of ''industry-specific metrics'' once such metrics have been adopted by the Registry. The Ernest Orlando Lawrence Berkeley National Laboratory (Berkeley Lab) was asked to provide technical assistance to the California Energy Commission (Energy Commission) related to the Registry in three areas: (1) assessing the availability and usefulness of industry-specific metrics, (2) evaluating various methods for establishing baselines for calculating GHG emissions reductions related to specific actions taken by Registry participants, and (3) establishing methods for calculating electricity CO2 emission factors. The third area of research was completed in 2002 and is documented in Estimating Carbon Dioxide Emissions Factors for the California Electric Power Sector (Marnay et al., 2002). This report documents our findings related to the first areas of research. For the first area of research, the overall objective was to evaluate the metrics, such as emissions per economic unit or emissions per unit of production that can be used to report GHG emissions trends for potential Registry participants. This research began with an effort to identify methodologies, benchmarking programs, inventories, protocols, and registries that u se industry-specific metrics to track trends in energy use or GHG emissions in order to determine what types of metrics have already been developed. The next step in developing industry-specific metrics was to assess the availability of data needed to determine metric development priorities. Berkeley Lab also determined the relative importance of different potential Registry participant categories in order to asses s the availability of sectoral or industry-specific metrics and then identified industry-specific metrics in use around the world. While a plethora of metrics was identified, no one metric that adequately tracks trends in GHG emissions while maintaining confidentiality of data was identified. As a result of this review, Berkeley Lab recommends the development of a GHG intensity index as a new metric for reporting and tracking GHG emissions trends.Such an index could provide an industry-specific metric for reporting and tracking GHG emissions trends to accurately reflect year to year changes while protecting proprietary data. This GHG intensity index changes while protecting proprietary data. This GHG intensity index would provide Registry participants with a means for demonstrating improvements in their energy and GHG emissions per unit of production without divulging specific values. For the second research area, Berkeley Lab evaluated various methods used to calculate baselines for documentation of energy consumption or GHG emissions reductions, noting those that use industry-specific metrics. Accounting for actions to reduce GHGs can be done on a project-by-project basis or on an entity basis. Establishing project-related baselines for mitigation efforts has been widely discussed in the context of two of the so-called ''flexible mechanisms'' of the Kyoto Protocol to the United Nations Framework Convention on Climate Change (Kyoto Protocol) Joint Implementation (JI) and the Clean Development Mechanism (CDM).

Livestock production is under growing public and scientific scrutiny for its greenhouse gas (GHG) emissions. This article contains a preliminary assessment of the inclusion of upstream life-cycle GHG emissions in concentrated feeds design, using the most common nonlinear programming optimization algorithms to determine feed composition. First, GHG emissions are included as costs in a single criteria optimization problem. The unit price of GHG emissions was obtained using a genetic algorithm. Second, GHG emissions are included as a target function to minimize in a multi criteria optimization problem using goal attainment programming. Results obtained after both optimization methods were applied to two case studies, namely fattening pigs and rabbit feeds. Changing ingredients in concentrated feed blends has a marginal effect on GHG emissions due to mandatory nutritional constraints. If the optimization is unconstrained, the maximum possible decrease in GHG emissions is 27.5% for the pigs feed, accompanied by increasing costs and a decrease in feed nutritional quality. To maintain nutritional integrity, the maximum possible reduction in GHG emissions is 7.5%. Considering cost as an optimization variable in the problem, the maximum decreases are even lower. It is possible to decrease emissions by 71% for the rabbits feed, but the cost of the reduction is higher than the opportunity cost for farmers to reduce GHG emissions using other strategies. These results are qualitatively robust but critically depend on feed ingredients GHG emissions and cost data.

Quantifying the impact of energy consumption sources on GHG emissions in major economies: A machine learning approach

Major US electric utility climate pledges have the potential to collectively reduce power sector emissions by one-third

Hydrogen peroxide-aged biochar mitigating greenhouse gas emissions during co-composting of swine manure with rice bran.

Adding Corbicula fluminea altered the effect of plant species diversity on greenhouse gas emissions and nitrogen removal from constructed wetlands in the low-temperature season

Loss of nitrate from agricultural lands to surface waters is an important issue, especially in areas that are extensively tile drained. To reduce these losses, a wide range of in-field and edge-of-field practices have been proposed, including constructed wetlands. We re-evaluated constructed wetlands established in 1994 that were previously studied for their effectiveness in removing nitrate from tile drainage water. Along with this re-evaluation, we measured the production and flux of greenhouse gases (GHGs) (CO, NO, and CH). The tile inlets and outlets of two wetlands were monitored for flow and N during the 2012 and 2013 water years. In addition, seepage rates of water and nitrate under the berm and through the riparian buffer strip were measured. Greenhouse gas emissions from the wetlands were measured using floating chambers (inundated fluxes) or static chambers (terrestrial fluxes). During this 2-yr study, the wetlands removed 56% of the total inlet nitrate load, likely through denitrification in the wetland. Some additional removal of nitrate occurred in seepage water by the riparian buffer strip along each berm (6.1% of the total inlet load, for a total nitrate removal of 62%). The dominant GHG emitted from the wetlands was CO, which represented 75 and 96% of the total GHG emissions during the two water years. The flux of NO contributed between 3.7 and 13% of the total cumulative GHG flux. Emissions of NO were 3.2 and 1.3% of the total nitrate removed from wetlands A and B, respectively. These wetlands continue to remove nitrate at rates similar to those measured after construction, with relatively little GHG gas loss.

Changing the order and ratio of substrate filling reduced CH4 and N2O emissions from the aerated constructed wetlands

A significant amount of embodied greenhouse gas (GHG) emissions have been and are currently being traded in the globalized economy. The conventional territorial approach to the control of GHGs released within a country fails to account for a large portion of GHGs for which a country may take responsibility, particularly from the perspective of consumption. Given the large volume of products traded among nations, a series of studies have underscored the need for the global monitoring of GHG emissions not only generated from production but also driven by consumptive activities. This study develops time-series GHG emission inventories from 1995 to 2009 from both production- and consumption-based perspectives in the case of South Korea and analyzes the factors that influence the increase and the decrease of GHG emissions. This empirical analysis has determined that production-based activities are more responsible for GHG emissions in South Korea than consumption-based activities. The analysis also found that the trade surplus of embodied GHG emissions in South Korea ranged from 0.31 to 1.01 tons per capita. A decomposition analysis showed that developments in environmental technology play a significant role in the reduction of GHG emissions, associated with a 45 % gross change in GHG emissions. However, this reduction was offset by increases in demand and changes in the input structure to energy-intensive sectors. The change of input structure is a critical factor contributing to trend in increasing embodied GHG emissions in not only South Korea but also nations linked with global trade.

Rivers play an important role in greenhouse gas emissions. Over the past decade, because of global urbanization trends, rapid land use changes have led to changes in river ecosystems that have had a stimulating effect on the greenhouse gas production and emissions. Presently, there is an urgent need for assessments of the greenhouse gas concentrations and emissions in watersheds. Therefore, this study was designed to evaluate river-based greenhouse gas emissions and their spatial-temporal features as well as possible impact factors in a rapidly urbanizing area. The specific objectives were to investigate how river greenhouse gas concentrations and emission fluxes are responding to urbanization in the Liangtan River, which is not only the largest sub-basin but also the most polluted one in Chongqing City. The thin layer diffusion model method was used to monitor year-round concentrations of pCO2, CH4, and N2O in September and December 2014, and March and June 2015. The pCO2 range was (23.38±34.89)-(1395.33±55.45) Pa, and the concentration ranges of CH4 and N2O were (65.09±28.09)-(6021.36±94.36) nmol·L-1 and (29.47±5.16)-(510.28±18.34) nmol·L-1, respectively. The emission fluxes of CO2, CH4, and N2O, which were calculated based on the method of wind speed model estimations, were -6.1-786.9, 0.31-27.62, and 0.06-1.08 mmol·(m2·d)-1, respectively. Moreover, the CO2 and CH4 emissions displayed significant spatial differences, and these were roughly consistent with the pollution load gradient. The greenhouse gas concentrations and fluxes of trunk streams increased and then decreased from upstream to downstream, and the highest value was detected at the middle reaches where the urbanization rate is higher than in other areas and the river is seriously polluted. As for branches, the greenhouse gas concentrations and fluxes increased significantly from the upstream agricultural areas to the downstream urban areas. The CO2 fluxes followed a seasonal pattern, with the highest CO2 emission values observed in autumn, then successively winter, summer, and spring. The CH4 fluxes were the highest in spring and the lowest in summer, while N2O flux seasonal patterns were not significant. Because of the high carbon and nitrogen loads in the basin, the CO2 products and emissions were not restricted by biogenic elements, but levels were found to be related to important biological metabolic factors such as the water temperature, pH, DO, and chlorophyll a. The carbon, nitrogen, and phosphorus content of the water combined with sewage input influenced the CH4 products and emissions. Meanwhile, N2O production and emissions were mainly found to be driven by urban sewage discharge with high N2O concentrations. Rapid urbanization accelerated greenhouse gas emissions from the urban rivers, so that in the urban reaches, CO2/CH4 fluxes were twice those of the non-urban reaches, and all over the basin N2O fluxes were at a high level. These findings illustrate how river basin urbanization can change aquatic environments and aggravate allochthonous pollution inputs such as carbon, nitrogen, and phosphorus, which in turn can dramatically stimulate river-based greenhouse gas production and emissions; meanwhile, spatial and temporal differences in greenhouse gas emissions in rivers can lead to the formation of emission hotspots.