Anthropogenic Inputs Research Articles

Characteristics of Dissolved Organic Matter Impacted by Different Land Use in Haihe River Watershed, China.

It is important to explore characteristics of dissolved organic matter (DOM) in the riverine system due to its critical role in the carbon cycle. This study investigated the distribution characteristics and sources of DOM based on excitation emission matrix three-dimensional fluorescence technology and parallel factor (EEM-PARAFAC) analysis at two rivers in northern China strongly impacted by human activities. The results show that the fluorescence intensity of terrestrial humic-like substances increased during summer in Haihe River. The intensity was significantly higher than in spring due to terrestrial detritus from runoff conveyance. The fluorescence intensity of protein-like substances in spring was the highest and decreased in summer. This feature of DOM in the Duliujian River was related to the increase in precipitation and surface runoff in the wet season and the rapid degradation of mixed DOM in the dry season. An analysis of HIX, BIX and FI showed a low degree of DOM humification and more endogenous contributions from microbial and phytoplankton degradation. Seasonal variations of dissolved organic carbon (DOC) and chromophoric DOM (CDOM, a335, thereinto C1) suggest that chromophores, particularly terrestrial substances, regulate the temporal patterns of DOM in the two rivers. Combined with the analysis of the proportion of land use types in riparian buffers, tillage had a great impact on DOM content and hydrophobicity in Haihe River watershed. Domestic wastewater and industrial sewage discharge contribute more DOM to Duliujian River watershed, which was indicated by more abundant protein-like components (212.17 ± 94.63 QSU in Duliujian River;186.59 ± 238.72 QSU in Haihe River). This study highlights that different land use types resulted in distinctive sources and seasonal dynamics of DOM in rivers. Meanwhile, it should be considered that the estimation of carbon cycling should involve monitoring and evaluating anthropogenic inputs into rivers.

Isotopes of nitrate and gadolinium fingerprints to assay human inputs in Guarani Aquifer System

The use of environmental tracers brings comprehensive benefits to the management of water resources since it helps to prevent their pollution, minimize public health risks, and thus reduce the impact of urbanization. In Brazil, the Guarani Aquifer System (GAS) has strategic and environmental importance, making its preservation and sustainable exploitation mandatory. The present study aimed at evaluating sources of contamination in the GAS using the combination of geochemical data and two environmental tracers: nitrate isotopes (15NNO3 and 18ONO3) and one rare earth element (Gadolinium-Gd). For that, five wells-four exploiting the GAS and one the Bauru Aquifer System (BAS)-were selected to discuss the human inputs in groundwater used for public supply in an urban area. Traditional physicochemical analyses were conducted for six campaign samplings and nitrate monitoring for this period was evaluated on a time scale, also considering the accumulated rainfall. Besides that, the double isotopic method (DIM), e.g., δ18ONO3 e δ15NNO3, was applied to identify the fractionation and enable the distinction of the nitrate contamination source. In addition, the determination of anomalies of Gd, a wastewater-derived contaminant, was also performed to verify recent human inputs in groundwater. The results show that the local existence of nitrate in the GAS and BAS-even at low concentrations (values from 0.26 to 6.68mg L-1)-originated from anthropogenic inputs (septic waste), as indicates the typical isotopic signals ratio in the isotopic approach. Associated with that, the evaluation of Gd permitted the separation of groundwater samples into older or more recent leakages. The use of environmental tracers to assess anthropogenic inputs in groundwater reiterates the importance of adopting more effective protection strategies for water resources management systems, in order to prevent contamination.

The Role of Cymodocea nodosa and Caulerpa prolifera Meadows as Nitrogen Sinks in Temperate Coastal Lagoons

In coastal lagoons, marine benthic macrophyte meadows can be an important element in the resistance to eutrophication of the ecosystem, as they can function as temporary nitrogen sinks, limiting the availability of this nutrient for opportunistic organisms. The role of nitrogen sinks for two dominant macrophyte species of Mediterranean coastal lagoons, the seagrass Cymodocea nodosa and the seaweed Caulerpa prolifera, was analysed by two different approaches: (i) studying nitrate (NO3-) and ammonium (NH4+) uptake kinetics of aboveground tissues in a laboratory and (ii) estimating nitrogen stocks and demands of meadows under natural conditions. The studies were carried out in the coastal lagoon of the Mar Menor, which has been subjected to high anthropogenic nitrogen inputs for decades. While both macrophytes were efficient in exploiting NH4+ from the water column, only C. prolifera showed a high NO3- uptake capacity. Large N pools in the C. nodosa and C. prolifera meadows of the Mar Menor were detected, suggesting that these habitats may have the potential to be essential reservoirs for this nutrient. However, the major role of belowground tissues of the seagrasses in nitrogen accumulation may determine important differences between the two species in temporary N storage and sequestration. The data on N demands for the meadows of both macrophytes in the Mar Menor suggest an important contribution of these habitats in controlling the inputs of this nutrient into the lagoon. We conclude that C. nodosa and C. prolifera meadows can play a key role as a sink for dissolved inorganic nitrogen in temperate coastal lagoons, being an important mechanism of resistance to eutrophication.

Effect of Agricultural Structure Adjustment on Spatio-Temporal Patterns of Net Anthropogenic Nitrogen Inputs in the Pearl River Basin from 1990 to 2019

Worldwide urbanization has brought dramatic changes in agricultural structures, as well as serious agricultural non-point source pollutions of nitrogen and phosphorus. However, understanding the effect of agricultural structure adjustment on net anthropogenic nitrogen inputs (NANI) has been still limited. In this paper, statistical data from the agricultural statistical Yearbook, the National Economic and Social Development Statistical Bulletin were collected from 1990 to 2019 in the Pearl River Basin, China, and used to analyze the spatial and temporal patterns of NANI and its influencing factors. The results indicated that the agricultural structure adjustment has significantly influenced the spatial and temporal patterns of NANI in the last 30 years in the Pearl River Basin. The NANI decreased from 1990 to 2019, and had a spatial pattern of higher values in the upstream areas and lower in the downstream areas. In terms of the nitrogen input sources of NANI, in the economically developed regions downstream, nitrogen inputs are dominated by food/feed nitrogen, which accounted for an average of 49.6% of total nitrogen inputs. In upstream areas with relatively low economic development, fertilizer nitrogen accounted for an average of 54.9% of total nitrogen inputs. A novel nitrogen input source index of NANI, namely the ratio of agricultural nitrogen inputs to non-agricultural nitrogen inputs of NANI(ASNA), was also proposed to characterize the impact of the agricultural industry restructuring on NANI changes over time. Similar to the characteristics of NANI from 1990 to 2019, the ASNA showed a decreasing trend in the study area. Moreover, agricultural variables (agricultural land area, nitrogen fertilizer consumption and livestock farming density) tended to contribute less to the explained ASNA variances, while the contributions of the non-agricultural factors (population density and non-agricultural GDP) increased from 1990 to 2019. This indicated that the contribution of nitrogen inputs from agricultural sources to the NANI decreased while the contribution of nitrogen inputs from non-agricultural sources increased, with the shifts of agricultural sectors to the secondary and tertiary sectors in the Pearl River Basin. Our findings also suggest that differently regional targeting should be considered for the nitrogen pollution management in the Pearl River Basin, which focuses on the nitrogen pollution management of non-agricultural sources in the downstream areas, and but highlights agricultural nitrogen pollution management in the upstream areas.

A Critical Gap in Seagrass Protection: Impact of Anthropogenic Off-Shore Nutrient Discharges on Deep Posidonia oceanica Meadows.

In the Mediterranean, anthropogenic pressures (specifically those involving nutrient loads) have been progressively moved to deeper off-shore areas to meet current policies dealing with the protection of marine biodiversity (e.g., European Directives). However, conservation efforts devoted to protecting Posidonia oceanica and other vulnerable marine habitats against anthropogenic pressures have dedicated very little attention to the deepest areas of these habitats. We studied the remote influence of off-shore nutrient discharge on the physiology and structure of deep P. oceanica meadows located nearest to an urban sewage outfall (WW; 1 km) and an aquaculture facility (FF; 2.5 km). Light reduction and elevated external nutrient availability (as indicated by high δ15N, total N and P content and N uptake rates of seagrass tissues) were consistent with physiological responses to light and nutrient stress. This was particularly evident in the sites located up to 2.5 km from the WW source, where carbon budget imbalances and structural alterations were more evident. These results provide evidence that anthropogenic nutrient inputs can surpass critical thresholds for the species, even in off-shore waters at distances within the km scale. Therefore, the critical distances between this priority habitat and nutrient discharge points have been underestimated and should be corrected to achieve a good conservation status.

Spatial-Temporal Dynamics of Anthropogenic Nitrogen Inputs in the Rapid Developing Chaohu Lake Basin

Due to the agricultural and industrial activities in rapidly urbanized basins, nitrogen (N) inputs have increased significantly, causing a variety of environmental issues. These challenges require an accurate assessment of the contributions of the driving factors, particularly in the Chaohu Lake Basin, which faces the double pressures of urban expansion and agricultural production. The research shows: (1) From 1990 to 2018, the trajectory of net anthropogenic N inputs (NANI) exhibited a three-stage pattern (uptrend stage, fluctuation stage, and downtrend stage), with an average value of 13,482 kg N km−2 year−1. The primary source was fertilizer N application, which made up approximately 79% of the NANI. Human food and animal feed imports, biological nitrogen fixation, and atmospheric N deposition composed 8%, 6%, and 6%, respectively. (2) Rapid urbanization enhanced the NANI in a short time stage. However, long-term analysis had shown a declining trend in nitrogen inputs, indicating that urbanization could improve fertilizer efficiency and introduce cleaner energy sources. (3) The NANI in urban watersheds were estimated at 20,700 kg N km−2 year−1, which was 3.4 times higher than in agricultural watersheds. Fertilizer N application was used in urban watersheds, as well as human food and animal feed imports. Urbanization drove the N input of food and feed mainly in urban watersheds but had no influence in agricultural watersheds and mixed watersheds. Since urban basins were the main source of nitrogen inputs, it was crucial to support environmental management efforts to reduce N pollution.

Seasonal Variations of Dissolved Organic Matter in Urban Rivers of Northern China

Dissolved organic matter (DOM) is ubiquitously present in aquatic environments, playing an important role in the global carbon cycle and water quality. It is necessary to reveal the potential sources and explore spatiotemporal variation of DOM in rivers, especially in urban zones impacted by human activities. It was designed to aim to explore spatiotemporal variations of DOM in urban rivers and ascertain the influencing factors. In this study, dissolved organic carbon (DOC) concentrations, UV-Vis absorption spectroscopy, and 3D fluorescence spectroscopy combined with parallel factor analysis were utilized to characterize DOM composition in urban rivers (the Jiyun, Chaobai, and Yongding rivers) in Tianjin city, northern China. The results showed that DOC (1.28 to 25.85 mg·L−1), generally, was at its highest level in spring, followed by summer, and lowest in autumn and winter, and that the absorption parameters E250:365 (condensation degree/molecular weight, 7.88), SUVA254 (aromaticity, 3.88 L mg C−1 m−1), a355 (content of chromophores, 4.34 m−1), a260 (hydrophobicity, 22.02 m−1), and SR (molecular weight, 1.08) of CDOM (chromophoric DOM) suggested that DOM is mainly composed of low-molecular-weight fulvic acid and protein-like moieties, and had the capability of participating in pollutant migrations and transformations. The results demonstrated significant seasonal differences. Generally, high DOC content was detected in rivers in urban suburbs, due to anthropogenic inputs. Three fluorescence components were identified, and the fluorescence intensity of the protein class reached the highest value, 294.47 QSU, in summer. Different types of land use have different effects on the compositions of riverine DOM; more protein-like DOM was found in sections of urban rivers. The correlation between DOC concentration and the CDOM absorption coefficient was found to be unstable due to deleterious input from industrial and agricultural wastewater and from domestic sewage from human activities. HIX and BIX elucidated that the source of CDOM in three river watersheds was influenced by both terrestrial and autochthonous sources, and the latter prevailed over the former. Geospatial data analysis indicated that CDOM in autumn was sourced from plant detritus degradation from forest land or from the urban green belt; construction land had a great influence on DOC and CDOM in riparian buffer areas. It was revealed that DOM in the watershed is highly impacted by nature and human activities through land use, soil erosion, and surface runoff/underground percolation transport; domestic sewage discharge constituted the primary source and was the greatest determiner among the impacts.

A framework for prioritizing contaminants in retrospective ecological assessments: Application in the Milwaukee Estuary (Milwaukee, WI).

Watersheds are subjected to diverse anthropogenic inputs, exposing aquatic biota to a wide range of chemicals. Detection of multiple, different chemicals can challenge natural resource managers who often have to determine where to allocate potentially limited resources. Here, we describe a weight-of-evidence framework for retrospectively prioritizing aquatic contaminants. To demonstrate framework utility, we used data from 96-h caged fish studies to prioritize chemicals detected in the Milwaukee Estuary (WI, USA; 2017-2018). Across study years, 77/178 targeted chemicals were detected. Chemicals were assigned prioritization scores based on spatial and temporal detection frequency, environmental distribution, environmental fate, ecotoxicological potential, and effect prediction. Chemicals were sorted into priority bins based on the intersection of prioritization score and data availability. Data-limited chemicals represented those that did not have sufficient data to adequately evaluate ecotoxicological potential or environmental fate. Seven compounds (fluoranthene, benzo[a]pyrene, pyrene, atrazine, metolachlor, phenanthrene, and DEET) were identified as high or medium priority and data sufficient and flagged as candidates for further effects-based monitoring studies. Twenty-one compounds were identified as high or medium priority and data limited and flagged as candidates for further ecotoxicological research. Fifteen chemicals were flagged as the lowest priority in the watershed. One of these chemicals (2-methylnaphthalene) displayed no data limitations and was flagged as a definitively low-priority chemical. The remaining chemicals displayed some data limitations and were considered lower-priority compounds (contingent on further ecotoxicological and environmental fate assessments). The remaining 34 compounds were flagged as low or medium priority. Altogether, this prioritization provided a screening-level (non-definitive) assessment that could be used to focus further resource management and risk assessment activities in the Milwaukee Estuary. Furthermore, by providing detailed methodology and a practical example with real experimental data, we demonstrated that the proposed framework represents a transparent and adaptable approach for prioritizing contaminants in freshwater environments. Integr Environ Assess Manag 2023;19:1276-1296. © 2022 SETAC.

Nitrate-dependent anaerobic methane oxidation (N-DAMO) as a bioremediation strategy for waters affected by agricultural runoff.

Agricultural drainage ditches are subjected to high anthropogenic nitrogen input leading to eutrophication and greenhouse gas emissions. Nitrate-dependent anaerobic methane oxidation (N-DAMO) could be a promising remediation strategy to remove methane (CH4) and nitrate (NO3-) simultaneously. Therefore, we aimed to evaluate the potential of N-DAMO to remove excess NO3- and decrease CH4 release from agricultural drainage ditches. Microcosm experiments were conducted using sediment and surface water collected from three different sites: a sandy-clay ditch (SCD), a freshwater-fed peatland ditch (FPD), and a brackish peatland ditch (BPD). The microcosms were inoculated with an N-DAMO enrichment culture dominated by Candidatus Methanoperedens and Candidatus Methylomirabilis and supplemented with 13CH4 and 15NO3-. A significant decrease in CH4 and NO3- concentration was only observed in the BPD sediment. In freshwater sediments (FPD and SCD) the effect of N-DAMO inoculation on CH4 and NO3- removal was negligible, likely because N-DAMO microorganisms were outcompeted by heterotrophic denitrifiers consuming NO3- much faster. Overall, our results suggest that bioaugmentation with N-DAMO might be a potential strategy for decreasing NO3- concentrations and CH4 emission in brackish ecosystems with increasing agricultural activities where the native microbial community is incapable of efficient denitrification.

A comprehensive assessment, source input determination and distribution of persistent organic pollutants (POPs) along with heavy metals (HMs) in reservoir lake sediments from Çanakkale province, Türkiye.

This study presents the distribution of persistent organic pollutants (POPs), polycyclic aromatic hydrocarbons (PAHs) and heavy metals (HMs) in the sediments from four dams and two ponds in the Çanakkale city, Türkiye. The total concentration varied from 41.47 to 145.45ng/g d.w. for PAHs; 1.40-14.96ng/g d.w. for organochlorine pesticides (OCPs) and 0.13-3.31ng/g d.w. for polychlorinated biphenyls (PCBs). The total polychlorinated dibenzo-p-dioxins/furans (∑PCDD/Fs) concentrations varied between 7.35 and 63.46pg/g d.w. The HM distribution in sediments ranged from 9.41 to 21.13mg/kg d.w. for As; 0.20-0.39mg/kg d.w. for Cd; 19.4-281.68mg/kg d.w. for Cr; 23.50-118.25mg/kg d.w. for Pb and 118.9-374.82mg/kg d.w. for Zn. This paper also elucidates possible sources of POP and HMs in sediment by using diagnostic ratios. The calculated ratios were shown that anthropogenic input is the source of these pollutants in sediments. Principal component analysis showed that the low molecular weight of POPs is considerably related and correlated, while high molecular weight pollutants have made another group and highly correlated with each other. The results indicated that anthropogenic pollution is mainly related to atmospheric input. Anthropogenic pollutants are more apparent at Atikhisar and Bakacak dams close to urbanized locations. Rather than the anthropogenic impact, based on the measured data interpretation, the global climate change effect was seen in Bakacak dam. The overall concentration of all pollutants revealed that Atikhisar and Bakacak sediments are high-level polluted areas according to several types of sediment guidelines.

Influence of nitrogen inputs, dam construction and landscape patterns on riverine nitrogen exports in the Yangtze River basin during 1980–2015

A quantitative understanding of different N sources and the factors controlling riverine N fluxes is critical for optimizing water pollution control strategies. However, the lack of a comprehensive understanding of N pollution legacy effects and human alteration of landscapes (e.g., dam construction and land use/land cover) hinders development of efficient N management strategies. This study integrated long-term (1980–2015) net anthropogenic nitrogen inputs (NANI) and different forms of N exports, hydroclimate data, dam construction and landscape metrics to elucidate N sources and the factors controlling N fluxes in the Yangtze River basin (YRB). Over the 36-year study period, annual NANI in the YRB increased from 4166 to 8571 kg N km−2 yr−1. Riverine concentrations of total nitrogen (TN), dissolved inorganic nitrogen (DIN) and dissolved organic nitrogen (DON) increased ∼ 3-fold, ∼3-fold and ∼ 36-fold during 1980–2015, respectively, whereas riverine particulate nitrogen (PN) decreased by ∼ 90 %. Such long-term riverine N export dynamics were driven by elevated NANI, landscape configuration change and dam construction activities. Inclusion of these variables in multiple linear regression models explained 91 %, 83 % and 96 % of the annual variability in riverine DIN, DON and PN fluxes, respectively. Estimated riverine TN flux from sum of predicted DIN, DON and PN fluxes showed high agreement with measured values (R2 = 0.92, Nash–Sutcliffe coefficients = 0.91), indicating strong efficacy for the developed regression models. Separation of annual riverine N exports into current year NANI versus legacy source contributions indicated that legacy sources contributed ∼ 49 % (26–82 %), 51 % (<1–78 %), 95 % (87–98 %) and 56 % (36–86 %) of riverine DIN, DON, PN and TN exports, respectively. The release of legacy N from the landscape is associated with increases in dam construction, urban density, and the number of small area farm operations between 1980 and 2015. This study highlights the potential of aggregating multiple historical N input datasets, along with changes in land use and river regulation to model long-term riverine N export dynamics. The results of the study provide a foundation for developing integrated watershed N management strategies that address both current and legacy N pollution.

Net Anthropogenic Nitrogen Input and Its Relationship with Riverine Nitrogen Flux in a Typical Irrigated Area of China Based on an Improved NANI Budgeting Model

Excessive nitrogen (N) inputs from human activities in the watershed have resulted in water quality deterioration and other biological hazards. It is therefore critical to fully understand the anthropogenic N inputs and their potential impacts on regional water quality. In this study, a modified net anthropogenic nitrogen input (NANI) budgeting model considering the irrigation N input was developed and applied to investigate spatial–temporal variations of anthropogenic N inputs and their relationship with riverine N flux from 2005 to 2019 in a semi-arid irrigated watershed, Ulansuhai Nur watershed (UNW), China. The results showed that the annual average anthropogenic N inputs reached 14,048.0 kg N km−2 yr−1 without a significant temporal change trend. Chemical N fertilizer was the major contributor for watershed NANI and accounted for 75.3% of total NANI. Hotspots for N inputs were located in the central part of the watershed. In this study, watershed NANI does not have a significant regression relationship with riverine N export during the study period. Riverine N export showed an obvious decreased trend, which mainly was attributed to human activities. In addition, approximately 1.92% of NANI was delivered into the water body. Additionally, the N inputs into the watershed by the irrigation water accounted for 9.9% of total NANI. This study not only expands the application range of the NANI model in irrigated watersheds, but also provides useful information for watershed N management strategies.

Reconstructing eutrophication trends of a shallow lake environment using biomarker dynamics and sedimentary sterols

Major extractable lipid biomarkers (hydrocarbons, sterols and fatty acids) were assessed in Lake Seeburg, a shallow eutrophic lake that has increasingly been suffering from cyanobacterial blooms due to continued anthropogenic nutrient inputs over the last decades. Over the course of one year (2018/19), the distributions of these compounds were analyzed in the inflow, the lake water, and the topmost sediments (0–2 cm) to assess their origin and transfer into the lake deposits. Principal component analysis (PCA) was used to cluster the studied biomarkers into 5 groups with similar characteristics. These groups were comprised of (i) compounds delivered from external sources via the inflow, (ii) autochthonous compounds formed in the lake by eukaryotes or (iii) bacteria, (iv) compounds accumulating in the surface sediment, and (v) C27 to C29 stenols together with their degradation products, C27 to C29 5α(H)-stanols. Their seasonal partition clearly revealed that C27 stenols mainly derived from autochthonous sources within the lake, whereas C29 stenols largely reflect allochthonous material reaching the lake via the inflow. Analysis of stenol plus stanol concentrations with depth in two lake sediment cores (≈30 and 50 cm) found highest C27 to C29 ratios in surface sediments with lowest ratios at depth. These signals are interpreted to reflect the increasing trend of eutrophication of Lake Seeburg and, thus, enhanced autochthonous organic matter production in the lake over the last decades. The abundances of C27 vs. C29 stenols, summed with their respective degradation products, 5α(H)-stanols, are considered as suitable molecular indicators to qualitatively reconstruct historical eutrophication trends.

Geochemical Responses to Natural and Anthropogenic Settings in Salt Lakes Sediments from North-Eastern Romanian Plain

Chemical analysis was performed on sediment core samples collected from three salt lakes, Amara Lake, Caineni Lake, and Movila Miresii Lake, located in the northeast of the Romanian Plain. The concentration of 10 main elements, 6 heavy metals (HMs), 8 rare earth elements (REEs), and 10 trace elements (TEs)-determined using neutron activation analysis (NAA)-showed variability dependent on the depth sections, lake genesis and geochemical characteristics (oxbow, fluvial harbor/liman and loess saucer type). The assessment of pollution indices (contamination factor, pollution load index, geoaccumulation index, and enrichment factor) highlighted low and moderate degrees of contamination for most of the investigated elements. Principal component analysis (PCA) extracted three principal components, explaining 70.33% (Amara Lake), 79.92% (Caineni Lake), and 71.42% (Movila Miresii Lake) of the observed variability. The principal components extracted were assigned to pedological contribution (37.42%-Amara Lake, 55.88%-Caineni Lake, and 15.31%-Movila Miresii Lake), salts depositions (due to the lack of a constant supply of freshwater and through evaporation during dry periods), atmospheric deposition (19.19%-Amara Lake, 13.80%-Caineni Lake, and 10.80%-Movila Miresii Lake), leaching from soil surface/denudation, rock weathering, and mixed anthropogenic input (e.g., agricultural runoff, wastewater discharges) (13.72%-Amara Lake, 10.24%-Caineni Lake, and 45.31%-Movila Miresii Lake).

Can copper isotope composition in oysters improve marine biomonitoring and seafood traceability?

This study provides the first geographic and temporal large-scale analysis of Cu stable isotope compositions in indigenous oysters to biomonitor anthropogenic Cu inputs in aquatic systems. It includes oyster samples from French marine environments with distinct Cu-pollution levels and histories and extends over several decades of biomonitoring. Sample series composed of oysters from the same season and similar size/age intended to avoid biological biases. Oysters in macrotidal estuaries (Loire and Gironde, Western France) display fluctuating Cu concentrations without clear temporal trends, challenging to infer anthropogenic influence. Conversely, the time series of their Cu isotope ratios indicate a constant proportion of natural and anthropogenic Cu sources since the 1980s. In contrast, Cu isotope compositions in oysters from the progressively developing locales (urbanization and recreational boating) of Arcachon and Vilaine bays shift positively over time, along with increasing Cu concentrations. This finding suggests a gradual augmentation in the bioaccumulation of anthropogenic Cu over time. Thus, Cu isotope compositions in oysters is an unambiguous and robust approach to pinpoint anthropogenic Cu contamination in marine biomonitoring. Furthermore, Cu concentrations combined with isotope compositions yield site-specific fingerprints allowing geographic discrimination among oysters. This two-dimensional Cu signature is promising as a tool for seafood traceability.

Decline of insects and arachnids driven by nutrient enrichment: A meta-analysis.

Recent studies have documented global declines in insects and their relatives, but the exact mechanisms explaining these patterns are not fully understood. A potential driver underlying arthropod population declines is increases in anthropogenic inputs of nitrogen (N) and phosphorus (P). Here, we synthesize the effects of N, P, and combined N + P enrichment on the abundance of hexapods (insects and collembola) and arachnids from 901 experiments reported in 84 studies. We found that N and combined N + P enrichment caused significant decreases in the abundance of these groups overall. While arthropod responses to nutrient enrichment across aquatic and terrestrial habitats and in temperate as well as tropical climatic zones differed in magnitude, our results suggest that arthropods are decreasing similarly in response to nitrogen and phosphorus enrichment. Further, despite previously shown differences in the nutrient demands of different insect metamorphosis groups, we found consistent negative effects of N + P enrichment on all groups. Our results also showed that the negative effects of nutrient additions are stronger for aquatic insects that are considered more sensitive to changes in physical-chemical parameters in their environments, Ephemeroptera, Plecoptera, and Trichoptera (EPT), compared with other aquatic insects. In addition, N + P enrichment reduced the abundance of above-ground and below-ground arthropods, suggesting that a similar mechanism driving arthropod community change is acting on both groups. These findings suggest that changes in elemental cycles are a potential cause of the ongoing global decline of arthropods and underscore the serious effects of nutrient enrichment on ecological systems.

Background construction for tracing metal inputs in estuarine sediments of the Liaodong Bay (NE China): Linear-regression method

Intertidal sediments are a significant reservoir of trace metals originating from human activities and natural weathering. However, the absence of geochemical background levels and the heterogeneity of sediment components are challenging to quantify the extent of trace metal contamination. For distinguishing the contribution of natural and anthropogenic inputs, dynamic background functions were established by linear regressions of trace metals (i.e., Zn, Cr, Ni, Cu, Cd, and Pb) against normalizer Al in three cores of the Daliao River estuary. Lead-210 geochronology indicated that trace metals have accumulated rapidly in the sediments since 1985 CE. The calculation results of enrichment factors and excess fluxes confirmed that the increased contents of Zn and Cd were contaminated by human activities. Conversely, the increased contents of others (i.e., Cr, Ni, Cu, and Pb) were attributed to variations in geological background levels, driven by the combination of grain size and organic matter. Overall levels of trace metals were at medium-low ecological risks (MSQG-Q: 0.19–0.38), and Ni at high-medium ecological risks (PEL-QNi > 0.5) in recent decades. Interestingly, these Ni probably originated from natural weathering rather than anthropogenic inputs because sediment quality guidelines lacked consideration for the differences in regional background levels and grain size. This procedure could provide the fundamental framework for regional investigations of spatial and temporal contamination, applied to other similar intertidal zones of sediment quality management.

HYDROGEOCHEMICAL BEHAVIOUR AND GROUNDWATER SUITABILITY OF VISLON AREA, PART OF WRD WATERSHED, CHANDRAPUR DISTRICT, MAHARASHTRA, INDIA

An attempt has been done to understand the hydrogeochemical characteristics of groundwater from shallow aquifers of Vislon village, a part of WRD watershed (Lat. 20º06’30"N and Long. 79º 07' 00"E). The appropriateness of groundwater has also been checked for various purposes. The groundwater from study area is alkaline and slightly saline in nature. The Ca2+ &gt; Mg2+ &gt; Na+ &gt; K+ and HCO3 - &gt; SO4 2- &gt; Cl- &gt; NO3 - was the ascendancy of cations and anions. The earth metals (Ca + Mg) found to exceed the alkali metals (Na + K). The positive correlation interpreted from interrelationship of Na+ vs Cl- exhibited, silicate weathering process for liberation of ions in groundwater at rock-water interface. In addition the non-lithological source, anthropogenic inputs were also inferred indicating the agricultural fertilizers and domestic wastewaters. All the groundwater samples from the study area are suitable for drinking as well as domestic use. The groundwater from study area is also suitable for irrigation purpose with negligible exceptions

Additional N Input May Alter the Species-Specific Blue Carbon Cycling Differently in Mangroves

Aquaculture is one of the fastest-growing economic activities in the world that results in a high amount of nitrogen-rich wastewater discharge into mangroves and affects the plant tissue’s decomposition. However, a comprehensive analysis of above- and belowground litter affected by the nitrogen (N) input is rare. This study investigated the responses of above- and belowground litter decomposition to the different levels of N input in decomposition rates, chemical components, and the release of chemical compounds. Exogenous N input had stimulating, retarding, or even no effect on plants’ litter decomposition and nutrient release in mangroves. The above- and belowground litter decompositions had different responses to anthropogenic N addition and varied among different mangrove species. The mechanism of the impacts of anthropogenic nitrogen input varies depending on species identity, litter composition, and additional N level. These results show that N enrichment in mangroves can be beneficial and detrimental to ecosystem function. For the native mangrove species, Kandelia obovata and Avicennia marina , the belowground tissues that had a direct correlation with carbon accumulation were significantly influenced by the additional N input. The worldwide problem of offshore aquaculture effluent discharge is a potential risk to the ecological function of mangroves in carbon storage.

Half of global agricultural soil phosphorus fertility derived from anthropogenic sources

The use of mineral phosphorus (P) fertilizers, often referred to as anthropogenic phosphorus, has dramatically altered the global phosphorus cycle and increased soil phosphorus fertility and crop yields. Quantifying agriculture’s reliance on anthropogenic phosphorus requires estimates of its contribution to agricultural soil fertility. Here we present a model of soil phosphorus dynamics simulating phosphorus availability in agricultural soils for individual countries from 1950 to 2017. Distinguishing between anthropogenic and natural phosphorus pools and accounting for farming practices, agricultural trade and crop–livestock recycling, we estimate that the global anthropogenic contribution to available phosphorus in agricultural soils was 47 ± 8% in 2017. Country-level anthropogenic phosphorus signatures vary according to cumulative fertilizer use and phosphorus availability in soil inherited pre-1950, with negligible influence of the trade of feed and food products. Despite different historical trajectories, we find that Western Europe, North America and Asia are similarly reliant on anthropogenic phosphorus, with nearly 60% of the total available phosphorus of anthropic origin in 2017. Conversely, anthropogenic phosphorus inputs in Africa remained low over the study period, contributing only around 30% of available phosphorus. The unequal reliance of agricultural soil fertility and food production systems on anthropogenic phosphorus resources highlights the need for a fairer management of the world’s remaining phosphate rock resources. About half of the current available phosphorus in agricultural soil globally is derived from anthropogenic sources, according to country-scale simulations of phosphorus dynamics between 1950 and 2017.