Contribution Of Organic Matter Research Articles

Influence of rhizosphere activity on litter decomposition in subtropical forest: implications of estimating soil organic matter contributions to soil respiration

AbstractLitter decomposition plays an important role in the carbon cycle and is affected by many factors in forest ecosystems. This study aimed to quantify the rhizosphere priming effect on litter decomposition in subtropical forest southwestern China. A litter decomposition experiment including control and trenching treatments was conducted using the litter bag method, and the litter decomposition rate was calculated by litter dry mass loss. Trenching did not change soil temperature, but increased the soil water content by 14.5%. In this study, the interaction of soil temperature and soil water content controlled the litter decomposition rate, and explained 87.4 and 85.5% of the variation in litter decomposition in the control and trenching treatments, respectively. Considering changes in soil environmental factors due to trenching, the litter decomposition rates were corrected by regression models. After correction, the litter decomposition rates of the control and trenching treatments were 32.47 ± 3.15 and 25.71 ± 2.72% year–1, respectively, in the 2-year period. Rhizosphere activity significantly primed litter decomposition by 26.3%. Our study suggested a priming effect of rhizosphere activity on litter decomposition in the subtropical forest. Combining previous interaction effect results, we estimated the contributions of total soil organic matter (SOM) decomposition, total litter decomposition, and root respiration to soil respiration in the subtropical forest, and our new method of estimating the components of soil respiration provided basic theory for SOM decomposition research.

Hydrocarbon source potential and paleodepositional environment of the (Devonian) Barreirinha formation on the south edge of the Amazonas basin border, Brazil

The present work aims to study the depositional paleoenvironment and the hydrocarbon source potential of the (Devonian) Barreirinha Formation, in the southern portion of the Amazonas basin. To accomplish this task, the geochemical parameters (total organic carbon, Rock-Eval pyrolysis, total sulfur and total nitrogen, whole oil hydrocarbons, and biomarkers) and palynofacies of 22 samples distributed in three outcrops are studied. Total organic carbon (TOC) values in the collected samples vary between 1.42% and 5.56%, indicating great variation in the production and preservation of organic matter. The sulfur content, ranging from 0.05 to 2.90%, indicates deposition in a marine environment. Rock-Eval pyrolysis parameters also reflect variations in the depositional conditions of this formation. The potential for hydrocarbon generation varies from low to excellent, noting that the samples that have the highest values of generation potential (S2) have higher TOC levels. This characteristic is justified by the good quality of the organic matter, since such samples have high hydrogen index (HI) values and low oxygen index (OI) values, indicating type I/II kerogen. The low free hydrocarbon (S1) values present in the samples (<0.5 mg HC/g rock) indicate immaturity, as shown by the Tmax (<440 °C) and by the production index (PI < 0.1). For total oil hydrocarbon chromatographic analysis, the largest contribution of algal organic matter is explicit for terrestrial-aquatic reasons (TAR <1). Furthermore, the pristane and phytane isoprenoid ratios (Pr/Phy) indicate differences between anoxic and oxic environments. Saturated biomarkers allow us to state that the organic matter present in the samples has a marine origin with terrestrial contributions and low thermal maturation. Palynofacies analysis shows that there is a predominance of amorphous organic matter (AOM), with a moderate amount of palynomorphs and subordinate amounts of phytoclasts. In the ternary diagram, these percentages allow us to infer that the depositional paleoenvironment was a distal platform with oxic-anoxic variation.

Characterization of organic matter from the Cretaceous sedimentary and volcano-sedimentary strata from Livingston Island, Antarctic Peninsula: Insights from organic petrology, molecular proxies and carbon and hydrogen isotopes

Rock samples from the Early to Late Cretaceous marine and non-marine strata of Livingston Island, South Shetland Islands, Antarctica, were studied. Organic matter (OM) originates predominantly from terrestrially-derived organic particles. Mostly highly fragmented plant remains, and locally vitrinite/semifusinite as part of plant compressions/imprints or thin vitrain/fusain lenses, are present. Bulk geochemical results indicate Type III kerogen with poor hydrocarbon generation potential. Tmax and molecular proxies (i.e hopane and sterane isomerization ratios, MPI-1, etc.), together with the local presence of oily droplets, argue for an early oil window maturity, probably caused by regional volcanic activity. In contrast to the results of petrography and Rock-Eval pyrolysis, molecular composition of extractable OM is dominated by short-chain n-alkanes, saturated fatty acids (FAs) and n-alkanols implying a major contribution of autochthonous OM. This contradiction is most likely caused by decomposition of OM from plant tissues, the predominance of wood remains (i.e., xylites) and the low input of FAs from cuticular waxes. The presence of terrestrial OM is indicated by plant wax-derived lipids and resinous compounds. Prominent even carbon number predominance in the short-chain n-alkane range argue for deposition/decomposition under reducing environmental settings, most probably caused by high sedimentation rates and quick burial. Terpenoid biomarker compositions indicate contribution from conifers, whereas input from phytoplankton/algal organic matter is evidenced by C27 steroids, the presence of 4-methyl steranes and dinosterol. Low concentrations of hopanoids and C15 and C17 branched n-FAs argue for limited bacterial input. Only in one sample from Hannah Point, a difference between the δ13C values of the short-chain versus long-chain n-alkanes was obtained, arguing for mixed OM sources (i.e., autochthonous input, land plants). The presence of charred organic matter in most of the studied samples, together with the considerable concentrations of combustion-derived PAHs, argue for the common occurrence of wildfires within the terrestrial environments. Despite the active volcanic arc settings, the compound specific carbon and hydrogen isotopes do not record significant changes in climatic/hydrological conditions, although some short-term events cannot be ruled out. Instead, the δ13C and δ2H isotopic fractionation is most likely caused by the specific biosynthetic mechanisms of the plants and the global carbon and hydrogen cycles.

New Insights into Microbial Interactions with Dissolved Organic Matter in Acid Mine Drainage with the Integration of Microbial Community and Chemical Composition Analysis

Acid mine drainage (AMD) environments are one of the most extreme ecosystems on earth, and their biogeochemical cycling has been widely studied. However, the carbon cycling underlying microbial interactions with dissolved organic matter (DOM) is poorly understood in these environments. Here, we evaluated the relationships between microbial populations and DOM pools in an AMD lake by combining high-throughput microbial and chemical compositional analyses. The results demonstrated that microalgae were the predominant primary producers in the system and significantly contributed to the total DOM concentration in the water column, whereas DOM chemodiversity was correlated with bacterial community diversity. Network analyses further revealed that DOM associated with microalgae had low diversity but high relative abundance, suggesting microalgal selective organic matter contribution to the DOM pool. Conversely, diverse DOM molecules with generally low abundance were associated with heterotrophic acidophiles, including members of Alphaproteobacteria, Actinobacteria, Firmicutes, and Acidobacteria. Moreover, microalgae and bacteria exhibited predominantly positive co-occurrences with potential metabolic interactions via DOM exchange. Taken together, this study provides new insights into the microbe–DOM interactions in extreme AMD ecosystems and has significant implications for understanding the carbon cycle and microbial metabolism in extreme environments.

Post-glacial evolution of alpine environments in the western Mediterranean region: The Laguna Seca record

In an effort to understand how alpine environments from the western Mediterranean region responded to climate variations since the last glacial-interglacial transition, a detailed chronological control and sedimentological analysis, supported by magnetic susceptibility, total organic carbon and C/N data, were carried out on the sedimentary record of Laguna Seca (LS). This is a latitudinal and altitudinally (2259 masl) key alpine wetland site located in the easternmost area of the Sierra Nevada, southern Iberian Peninsula, where sediments accumulated during Heinrich Stadial 1, Bølling-Allerød (B-A) and the Younger Dryas (YD) - previously unrecorded in alpine Sierra Nevada. Climate controlled sedimentation in LS and three coarse-grained and one fine-grained facies association are differentiated, which help us decipher the paleoenvironmental evolution of LS: (1) subaerial cohesionless debris flows during a paraglacial stage; (2) till or nival diamicton during a small glacier/nivation hollow stage; (3) massive mudstone by suspension settling of clays into standing water during a lacustrine stage; and (4) frost-shattering breccia deposited inside the lacustrine stage, probably during the YD, and linked to a periglacial substage. The development of a previously existing small glacial cirque during the Last Glacial Maximum (LGM) in the LS basin at an elevation between 2500 and 2300 m could be supported by the important availability of slope sediments glacially-conditioned such as debris flows, reworked by paraglacial slope processes during the first deglaciation stages, confirming previous studies of landforms in the catchment area and the LGM-Equilibrium Line Altitude estimation above 2400 masl in Sierra Nevada. Mean sediment accumulation rates in the LS sedimentary units (4.21 and 0.28 mm/yr during the paraglacial - small glacier/nivation stage and the lacustrine stage, respectively) confirm that geomorphic activity accelerated just after glaciers retreated due to a slope adjustment and high availability of glacially conditioned sediments. An abrupt change in paleoenvironmental and paleoclimatic conditions occurred in LS at ∼ 15.7 cal kyr BP. This change was probably due to an increase in temperature and precipitation in the western Mediterranean region during the B-A. At LS, this resulted in significant ice-melt, forming a deep-water lake in LS with important organic matter contribution until the end of the Early Holocene (except in the YD when the lake level probably dropped), but elsewhere a general glacier recession in the Sierra Nevada and an expansion of the Mediterranean forest in the southern Iberian Peninsula. Finally, the general long-term aridification that occurred during the Middle Holocene until the present in the western Mediterranean region triggered an important environmental change transforming LS into an ephemeral wetland with an increase in aquatic productivity.

Carbon and Nitrogen Contents Driven by Organic Matter Source within Pichavaram Wetland Sediments

Differences in grain size, total organic carbon (OC), total nitrogen (TN), OC/TN ratios, and stable isotope (δ13C and δ15N) were assessed in sediments from areas covered by mangrove and saltmarsh vegetation within Pichavaram estuary (Southeast India). The mean percentage contents of silt and clays (70 vs. 19%), OC (5.7 vs. 2.0%), and TN (0.39 vs. 0.14%) were consistently higher in the mangrove as compared to those observed in the saltmarsh tidal zone. These differences may obey the higher deposition and retention of fine particles in the presence of a mangrove root system that may facilitate the accumulation and preservation of organic matter within these sedimentary systems. Further, higher OC and TN contents were associated to higher terrestrial or mangrove-derived organic matter contribution with lighter δ13C signatures (−26.0‰) in both sedimentary tidal zones, whereas lower OC and TN contents were associated to heavier δ13C signatures. This study is in agreement with previous studies which indicate that the presence of wetland vegetation may increase the carbon and nutrient storage capacity within estuarine ecosystems, highly relevant information for the establishment of further conservation strategies for blue carbon ecosystems at global scales.

Oil Shale of Rif region: natural adsorbents for environmental cleaning

Oils shales are the largest energy resource in the world and are widely used in the development of industrial fuel and petroleum activities. Oil shale is one of the important mineral resources in Morocco and it has a large reserve, the most important of which is of Timahdit, Tarfaya, and Tangier. Nowadays, the increasing concentration of toxic organic species (Antibiotics, Colorants) in soils and domestic, agricultural, and industrial wastewater has become a major environmental concern. for this reason, we have focused on the interactions of raw oil shale deposits with toxic organic species as part of an additional valuation of national energy resources. Our work is focused on the contribution of organic matter on antibiotic retention, as well as the role of hydrophobic interactions on the molecules-mineral surfaces. The results of the characterizations show the possible contribution of raw oil shales in the accumulation of organic pollutants in soil and water. Thermally treated oil shell powders can be good mineral sorbents for environmental cleaning.

Efficacy of different green manuring crops to soil fertility, yield and seed quality of T. aman rice

A series of experiments were conducted on the Agronomy farm and laboratory of Sher-e-Bangla Agricultural University to demonstrated a promising way of increasing soil organic matter, total N in pre sown and postharvest land by green manure cultivation and reducing the inorganic fertilizer inputs in rice production and finally observed the quality of grown T. aman seed in laboratory condition. Several green manures were found more potential in two years regarding their plant height, dry biomass production and better performance concerning organic matter, nitrogen and potassium contribution to soil and increased rice yield. Morphological characteristics of eight green manure crops were studied and incorporated at 45DAS for decomposition. One month after decomposition of green manure, rice (BRRI dhan66) plant was transplanted with 100% NPK (F1) and 50% NPK (F2) and pre sown rice soil, post-harvest soil nutrient statuses were studied. Result showed that Pre shown rice soil increased 0.5 to 0.6% SOM (2nd year), 0.04% soil N (both year) and 0.04% soil K (1st year) which ultimately increase rice yield 62% to 68% (with F1) and 10% to 42% in 1st and 2nd year. Post-harvest soil nutrient status shown the positive balance of (0.1% to 1%) organic matter and total N (0.04% to 0.7%) in the 1st years and 2nd years and P was found drastically increased in 2nd year, respectively. Germination%, germination energy%, seedling length, fresh and dry weight of six month stored rice seedling also found highest from S. rostataand S. aculeataunder laboratory condition. Incorporation of Sesbaniaaculeata, S. rostrata, V. unguiculataand Crotalaria junceaas GM with N significantly influenced the grain yield of rice and pre and post-harvest soil. Asian J. Med. Biol. Res. 2021, 7 (4), 298-311

Analysis of mechanisms of soil potassium‐holding capacity using different soils of China

AbstractSoil is the most important source of K for plants; many studies have focused on soil K status and phytoavailability. However, there is still a lack of quantitative explanation for how soils hold plant‐available K. Based on the previous study, the ability to hold plant‐available K for soil was defined as soil potassium‐holding capacity (SKHC). Therefore, this study aimed to investigate the mechanisms underlying SKHC. Fourteen soils from different sites in China were collected and the contribution of soil organic matter (SOM) and clay minerals to SKHC were analyzed based on waterlogging simulation experiments, chemical determination, and data‐fitting analysis. Results showed that SKHC mainly depended on the absorption and holding effects of exchangeable sites deriving from both SOM and clay minerals (presented as cation exchange capacity [CEC]) and nonexchangeable sites deriving from clay minerals, which contributed 14.7 and 82.5%, respectively, to SKHC, at similar soil water‐soluble K levels. After removing the SOM from the soil, the average SOM and CEC decreased from 26.0 to 7.73 g kg–1 and from 13.7 to 11.8 cmol kg–1, respectively. The SOM contributed an average of 24.5% to CEC, with the remaining 75.5% provided by clay minerals. Further analysis showed when SOM increased by 1%, CEC increased by 1.14 cmol kg–1, a relative proportion of 8.32% of the initial soil. Therefore, SKHC is mainly determined by the nonexchangeable sites of soil clay minerals, and increasing CEC by improving SOM content to enhance SKHC should be an effective but slow approach.

Overexploitation and decline in kelp forests inflate the bioenergetic costs of fisheries

AbstractAimFisheries ecosystems are subject to long‐term shifts in food web structure as a result of exploitation and environmental change. These shifts can be gradual and unresolved by decadal‐scale time series. The aim of our study was to determine long‐term legacy effects of overexploitation and changes to the composition of basal organic matter sources on the trophic structure of marine food webs.LocationNew Zealand.Time periodApproximately 1250 AD to the present; the complete history of human occupation in New Zealand.Major taxa studiedMesopredatory fishes.MethodsWe used whole tissue (δ13C and δ15N) and amino acid‐specific (δ15NAA) stable isotope analyses of bone collagen and muscle tissue from five fishes spanning the period of human occupation of New Zealand to resolve the bioenergetic consequences of long‐term shifts in food web structure. Stable isotope analysis of amino acids provided the basis for resolution of changes in trophic level in the absence of information on δ15N at the base of the food web during pre‐industrial times.ResultsOur analyses indicate likely declines in the contribution of organic matter derived from kelps in four species, and intraspecific increases in trophic levels in three species of the five fishes studied between European colonization (AD 1650–1800) and the present‐day regime of industrialized fishing and environmental change (AD 1953–2018), but little change during the prehistoric time period spanning early Māori occupation (AD 1250–1450) to European colonization. Analysis of the bioenergetic costs of the observed shifts in food web structure indicate a 179% increase in basal organic matter requirements to support mesopredatory fish.Main conclusionsThese data provide a rare case study on the consequences of legacy effects of exploitation and environmental change for bioenergetics of fish communities relevant to ongoing changes in global marine ecosystems. Overexploitation and decline in kelp forests have inflated the bioenergetic costs of these fisheries.

Contribution of clay on storage and adsorption capacities of the Middle Permian marls, South China

A significant gas show appeared in JY66-1 well when it was drilled into the Middle Permian limestone-marl alternation interval, high-resolution scanning electron microscopic (SEM) observation shows that clay-related pores were developed extensively. There have been a lot of comprehensive studies on the origin of organic-matter pores and their pore size distribution, but few studies on the scales of clay-related pores and their contributions to the total pore volume and surface area. In this paper, we conducted thin section and SEM observation, mercury intrusion, low pressure N2 adsorption and high-pressure CH4 adsorption experiments, to characterize the pore volume and surface area of Mg-clay-bearing samples. The result suggests that the pore volume of clay-related pores mainly derives from the Intra-aggregate pores of 5–100 nm pore size, while the absolute and relative contributions of Interlayer pores (smaller than 2 nm) and Intra-tactoid pores (2–5 nm) to the total pore volume are small. Based on TOC contents and inorganic mineral compositions, a multiple regression analysis was carried out on the contributions of organic-matter and clay-related pores to pore volume in the pore-diameter ranges of smaller than 2 nm, 2–5 nm, 5–100 nm and larger than 100 nm. Although the contribution of clay-related pores (including inter-aggregate pores, Intra-aggregate pores, Intra-tactoid pores, Interlayer pores) to the total pore volume is comparable to that of organic-matter pores, the latter still contributes most of the pore surface area and CH4 adsorption site. It can be interpreted by the fact that the specific surface area of the dominant Intra-aggregate pores is significantly smaller than that of organic-matter pores. The conclusion of this study can be applied for the analyses of storage and adsorption capacity in all gas shales containing both organic and clay minerals.

Responses of the marine carbonate system to a green tide: A case study of an Ulva prolifera bloom in Qingdao coastal waters

As an environmental nuisance, Ulva prolifera green tides have occurred annually in the southern Yellow Sea since 2007. While it is expected that high levels of biological activity during these blooms can alter seawater carbonate chemistry, there has been little research on the responses of marine carbonate system to green tides. Here, the effects of the bloom on the carbonate system were examined on three cruises in June, July, and September, corresponding to the early-, late-, and after-bloom periods of the U. prolifera bloom in Qingdao coastal waters in 2018. Among these three stages, the pH (National Bureau of Standards scale), dissolved inorganic carbon (DIC), total alkalinity (TA), and partial pressure of CO2 (pCO2) were all affected by bloom, with the highest pH and lowest DIC and TA concentrations of the surface seawater occurring at the late-bloom stage. While pCO2 continuously increased from the beginning to the end of the bloom. TA increased by ∼40 μmol kg−1 between the early- and after-bloom periods likely due to the shifts in the carbonate system equilibrium caused by increased CO32− concentrations and the organic matter released by U. prolifera during decomposition. Compared to nearby areas with no U. prolifera bloom, the green tide, along with increasing temperature, reduced the pH and DIC but increased the TA and pCO2. This large-scale bloom also turned the coastal waters from being an atmospheric CO2 sink to a strong source, with the estimation of air-sea CO2 fluxes about 1.69 ± 1.70, 2.28 ± 1.16, and 7.44 ± 5.84 mmol m−2 d−1 during the early-, late-, and after-bloom periods, respectively. This bloom event also promoted the formation of CaCO3 and was an important source of low molecular weight organic acids. These new findings provide nuances for the current conversations on the role of biological processes in modulating marine carbonate system and the contribution of organic matter to alkalinity.

Safe drinking water for rural communities using a low-cost household system. Effects of water matrix and field testing

The relationship between turbidity (T) and ultraviolet C (UVC) disinfection is still not clearly understood, as well as no attention has been paid to the contribution of natural organic matter (NOM). The present work assessed the influence of particulate and NOM on the UVC disinfection efficiency in terms of E. coli and MS2 removal at bench collimated beam (CB) and flow-UVC systems, both in the laboratory and in the field (Colombia). The flow-UVC reactor was installed as part of a household water treatment (HWT) system consisting of filtration + UVC disinfection. Tests were performed according to the WHO standards using fine test dust, humic acid (HA), and MS2 and E. coli as microbiological indicators. CB results showed a significant decrease in the inactivation rate of MS2 in the presence of small concentrations of HA (3.5 mg/L), with killing dose increasing a 65%, vs. non-significant effects of turbidity in the range of 0–20 NTU. Following the same trend, in flow-UVC tests the inactivation efficiency of MS2 decreased solely in the presence of HA. At the same HA concentration and flow rate, an increase in turbidity of 17.6 NTU showed a negligible effect. Conversely, in the presence of HA, UVT254 dropped from 88.7% (0 mg/L HA) to 73.3%, reducing MS2 inactivation by 1–2 log-units. Finally, the HWT system could be classified as protective working at flow rates ≤5 L/min. However, in the presence of 3.5 mg/L HA (UVT254 < 75%), it presented a limited protection for viruses.

Tracing organic matter sources in the estuarine sediments of Vanga, Kenya, and provenance implications

Mangrove ecosystems can potentially and indirectly modulate the effects of sea level rise due to their ability to trap and retain sediments. In order to gain a better understanding of the potential sediment sources and dynamics in the mangroves of Vanga, Kenya, inter-seasonal riverine, estuarine and coastal/marine sediments together with agricultural soil and mangrove tissues were studied. Elemental ratios (C/N) and carbon (δ13C) stable isotope composition, were analysed to disentangle sources of sediment organic matter (SOM) in the Vanga, Estuary. The organic carbon (C) content, C/N ratios and δ13C values ranged between 0.1 and 2.4%, 9.9 to 35.5 and −24.8 to −19.9‰ respectively. These contents were also as expected relatively higher in mangrove tissues than in all the sediment samples. δ13C values of mangrove sediments were higher than those of the mangrove tissues, which was attributed to rapid decomposition, dilution by freshwater and mineral organic matter (OM) discharged by the Umba River as well as outwashing by ebb tides. On average, C/N ratios were also observed to be greater than 10 in all samples collected during both the dry and wet season. This has been shown to reflect a pronounced contribution of allochthonous organic matter. Using a combination of δ13C values and C/N ratio, the dominance of riverine POM was also evident from a Bayesian Stable Isotope Mixing Model in R-program (SIMMR) that indicated OM source mixing but with a dominant (∼60%) contribution of riverine OM. The observed and modeled variability of SOM in the Vanga estuary points to the hypothesized influence of the Umba River on Vanga Estuary sediments but with evidence of potential material exchange and influence of tidal fluxes within the estuary.

Neutral Sugar Content and Composition as a Sensitive Indicator of Fire Severity in the Andisols of an Araucaria–Nothofagus Forest in Southern Chile

Wildfire induces soil alterations that have a long-term impact on soil organic matter (SOM) quality. We postulated that after different fire severities, the neutral sugars in soils can be used as an indicator of soil organic matter quality after fire. The aim of this study was to determine the contribution of neutral sugar, bulk and occluded particulate organic matter (oPOM) affected by wildfire, at different soil depths in an Araucaria–Nothofagus Forest, four years post-after fire. The concentration and composition of the neutral sugars in the soils clearly comprised the major fraction in the unburned soil. Medium- and high-severity fires caused a drastic reduction in soil sugars in the bulk soil as well as in the oPOM fractions. The 13C-CPMAS NMR spectroscopy analysis revealed a high contribution of recalcitrant carbon to the decomposition such as aryl–C and aryl–O derived from charred material, whereas the abundance of O–alkyl C and alkyl C functional groups were decreased. The neutral sugars (Galactose+Mannose/Xilose+Arabinose) revealed a major microbial origin in fire affected areas as the ratio was &gt;2. Therefore. Therefore, we suggest that the neutral sugar content of soil should be used for monitoring both short- and long-term changes in SOM altered by fires.

Extreme precipitation accelerates the contribution of nitrate sources from anthropogenetic activities to groundwater in a typical headwater area of the North China Plain

Identification of diffused nitrate (NO3–) sources in groundwater is challenging in headwater areas with diverse land-uses, multiple potential inputs and intensification of precipitation. Although NO3– sources in headwater areas with different land-uses have been observed, the mechanisms of the impact of extreme precipitation on NO3– transport to groundwater and NO3– sources in these areas are not well understood. In this study, dual isotopic compositions of NO3– (δ15N-NO3– and δ18O-NO3–) and hydrochemical data were measured in groundwater samples during August 2014-January 2017 under four land-uses: natural vegetation (NV), farmland (FL), economic forestland (EF), and residential areas (RA). An isotope mixing model (SIAR) was applied to determine the main NO3– sources and the governing factors. Affected by extreme precipitation, the rates of exceeding the WHO standard of NO3– (45 mg/L) increased to 93.3%, 65.6%, 100%, and 46.7% for groundwater samples from RA, FL, EF, and NV, respectively, when comparing with 88.7%, 56.6%, 92.9%, and 6.1% of samples collected before extreme precipitation from RA, FL, EF and NV, respectively. SIAR results showed that the contribution of anthropogenetic activities to NO3– in groundwater was accelerated after extreme precipitation. Before extreme precipitation, soil N (43.5%) and organic matter of soil (32.3%) were the dominant NO3– source in NV, and manure/sewage made substantial contributions to NO3– concentrations in groundwater, accounting for 55.8%, 56.2%, and 52.7% in RA, FL, and EF, respectively. In NV, the contributions of organic matter of soil increased to 46.8% and the contribution of soil N decreased to 28.9%. The contributions of chemical fertilizers in soil increased from 15.2% to 31.3% and there was a corresponding decrease in the contribution from manure/sewage (41.1%) in FL, although the contribution of NO3– from manure/sewage increased in EF (66.3%) and RA (57.6%). Assessing temporal variation of NO3– sources in the headwater areas of the North China Plain can help to protect water resource and avoid further deterioration of water quality during land-use management and extreme precipitation in the future.

Assessment of Total Petroleum Hydrocarbons and Polycyclic Aromatic Hydrocarbons in Wastewater from Selected Flow Stations in Agbada II, Rivers State

Aims: This study evaluates total petroleum hydrocarbon (TPH) and polycyclic hydrocarbons (PAHs) concentrations in wastewaters from three locations of the oil-producing flow station in Rivers State.&#x0D; Study Design: By experiment and the results obtained by analytical means.&#x0D; Place and Duration of Study: This work was conducted at the Department of Industrial Chemistry/Petrochemical Technology, School of Science and Laboratory Technology, University of Port Harcourt, Choba, Rivers State, Nigeria between February and August, 2021.&#x0D; Methodology: The evaluation was done using gas chromatography-Flame Ionization Detector (GC-FID), and Gas Chromatography-Mass Spectrometer Detector (GC-MSD).&#x0D; Results: Results obtained showed low levels of total petroleum hydrocarbons ranging from 0.051, 0.119, and 0.07 mg/l and 0.01, 0.06, and &lt; 0.01 mg/l for polycyclic aromatic hydrocarbons for the three locations, respectively. The results also revealed that the concentrations of the total petroleum hydrocarbons of the samples from the three locations were highest at carbon atom 17 suggesting a biogenic contribution of organic matter. The chromatographs obtained gave evidence that the nature of the contamination was minimally crude oil, because crude oil normally distributes in broad range, as observed in the locations samples as against the narrower carbon range of C8 to C40 characteristics of refined products. The pristane/phytane ratios, which were 0.925, 0.891 and 0.372 for the three samples, depicted an oxygenated environment. The C17/pristane ratios (39.53, 38.93, and 31.48) for all three locations revealed that the wastewaters were slightly weathered. The low concentrations as well as absence of high molecular weight polycyclic aromatic hydrocarbons and higher concentrations of low molecular weight polycyclic aromatic hydrocarbons support the petrogenity of the wastewaters. &#x0D; The phenanthrene/anthracene ratios (1.26, 0, and 0) for the three samples confirm the nature of the wastewaters. In addition, the absence of benzo(a)anthracene to chrysene ratio for all three samples point to proper treatment of the wastewaters.&#x0D; Conclusion: From this study, the level of total petroleum hydrocarbons (TPH) and polycyclic hydrocarbons (PAHs) obtained from all the samples were lower than the maximum recommended levels by the Department of Petroleum Resources (DPR). This study recommends constant monitoring in the total petroleum hydrocarbons and polycyclic hydrocarbons concentrations because even at its low concentrations can be injurious to health of the people residing within the facility and beyond.

The potential of Nephrolepis biserrata fern as ground cover vegetation in oil palm plantation

Abstract. Satriawan H, Fuady Z, Ernawita. 2021. The potential of Nephrolepis biserrata fern as ground cover vegetation in oil palm plantation. Biodiversitas 22: 4808-4817. Nuisance plants or weeds are commonly found in agricultural landscapes including in oil palm plantations. Despite being considered as weeds, several of them have the potential to be used as ground cover vegetation including Nephrolepis biserrata (Sw). Schott. This fern species exhibits beneficial characteristic as ground cover plant especially in terms of the contribution of organic matter and soil moisture through the prevention of evapotranspiration. The objective of this research is to explore the potential of N.biserrata as ground cover vegetation in oil palm plantations based on the assessment of its ecological characteristics regarding the growth and decomposition rate, tolerance to shade, organic contents and carbon accumulation. The split plot experimental design was used with the age of oil palm plants was used as main plot while in the sub-plots the spacing of N. biserrata was used at three varying distances 10x10cm, 20x20 cm, and 30x30 cm, each treatment had three replicates. Nine parameters observed were the percentage of growth, the percentage of ground cover, plant height, fronds number per plant, leaves number per plant, Leaf Area Index, dry weight (g), nutrient content in plant tissue, and potential carbon stock. Results showed that N. biserrata showed rapid growth in covering the ground surface (8-12 weeks after planting), had rapid decomposition rate (30-60 days), tolerant to shading which was characterized by the highest percentage of growth up to 81.16% and covering area up to 95.9%, accumulated organic contents of N (1.23-1.53%), P (0.18-0.22%), and K (1.4-1.67%), respectively. In addition, total dry weight biomass obtained was 27.1 ton/ha, accumulated carbon in plant of 0.9 tons C/ha/year, and amount of soil carbon stock 76.4-97.4 tonnes/ha/year. The results of this study suggest that Nephrolepis biserrata is a potential plant to be utilized as a ground cover plant in oil palm plantations.

Incorporation of uncertainty to improve projections of tidal wetland elevation and carbon accumulation with sea-level rise.

Understanding the rates and patterns of tidal wetland elevation changes relative to sea-level is essential for understanding the extent of potential wetland loss over the coming years. Using an enhanced and more flexible modeling framework of an ecosystem model (WARMER-2), we explored sea-level rise (SLR) impacts on wetland elevations and carbon sequestration rates through 2100 by considering plant community transitions, salinity effects on productivity, and changes in sediment availability. We incorporated local experimental results for plant productivity relative to inundation and salinity into a species transition model, as well as site-level estimates of organic matter decomposition. The revised modeling framework includes an improved calibration scheme that more accurately reconstructs soil profiles and incorporates parameter uncertainty through Monte Carlo simulations. Using WARMER-2, we evaluated elevation change in three tidal wetlands in the San Francisco Bay Estuary, CA, USA along an estuarine tidal and salinity gradient with varying scenarios of SLR, salinization, and changes in sediment availability. We also tested the sensitivity of marsh elevation and carbon accumulation rates to different plant productivity functions. Wetland elevation at all three sites was sensitive to changes in sediment availability, but sites with greater initial elevations or space for upland transgression persisted longer under higher SLR rates than sites at lower elevations. Using a multi-species wetland vegetation transition model for organic matter contribution to accretion, WARMER-2 projected increased elevations relative to sea levels (resilience) and higher rates of carbon accumulation when compared with projections assuming no future change in vegetation with SLR. A threshold analysis revealed that all three wetland sites were likely to eventually transition to an unvegetated state with SLR rates above 7 mm/yr. Our results show the utility in incorporating additional estuary-specific parameters to bolster confidence in model projections. The new WARMER-2 modeling framework is widely applicable to other tidal wetland ecosystems and can assist in teasing apart important drivers of wetland elevation change under SLR.

Assessment of children's exposure to carbonaceous matter and to PM major and trace elements

Particulate matter (PM) pollution is one of the major environmental concerns due to its harmful effects on human health. As children are particularly vulnerable to particle exposure, this study integrates the concentration of PM chemical compounds measured in the micro-environments (MEs) where children spend most of their time to assess the daily exposure and inhaled dose. PM samples were analysed for organic and elemental carbon and for major and trace elements. Results showed that the MEs that contribute most to the children's daily exposure (80%) and inhaled dose (65%) were homes and schools. Results indicated that the high contribution of particulate organic matter (POM) indoors indicate high contributions of indoor sources to the organic fraction of the particles. The highest concentrations of PM chemical compounds and the highest Indoor/Outdoor ratios were measured in schools, where the contribution of mineral elements stands out due to the resuspension of dust caused by the students and to the chalk used in blackboards. The contribution of the outdoor particles to inhaled dose (24%) was higher than to the exposure (12%), due to the highest inhalation rates associated with the activities performed outdoor. This study indicates the importance of indoor air quality for the children's exposure and health.