Spatial Distribution Trends Research Articles

<p class="ZootaxaTitle"><strong>Biodiversity of polychaetous annelids in Bahía de Todos Santos, Baja California México</strong></p>

The aim of this study was to describe and analyze the structure, distribution, and temporal variation in the composition of benthic polychaeta and their relation to abiotic characteristics in marine sediments along the continental shelf of Bahia de Todos Santos, Baja California, Mexico. Benthic macrofauna and environmental variables were collected to coordinated with a long-term ocean monitoring project known as the Southern California Bight Regional Monitoring Program. A total of nineteen stations were collected in September 1998, twenty stations in November 2003, fifteen stations in December 2013 and sixteen stations in September 2018. These data were compared to assess the response of benthic polychaete assemblages to natural and human induced changes in sediment characteristics. All stations were sampled using a Van Veen grab (0.1 m2) at depths between 15 to 206 m. Sites were selected using a multiple density nested random-tessellation stratified design. Environmental parameters measured included depth (m), sediment grain size <63µm (%), organic carbon (%), and concentration of metals: Co, Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn. A total of 11,854 polychaetous annelids were identified in 43 families, with the numerically dominant families for all years (Spionidae, Chaetopteridae, Cirratulidae, Maldanidae, Onuphidae, and Ampharetidae) accounting for 52.95% of individuals. The best represented families in 1998 were Spionidae, Maldanidae, Ampharetidae and Cirratulidae. In 2003 the best represented families were Spionidae, Maldanidae, Cirratulidae, and Onuphidae; in 2013 Chaetopteridae and Spionidae; and in 2018 Spionidae, Ampharetidae, Syllidae and Cirratulidae. The Bio-Env multivariate analysis showed that the factors that most correlated with the abundance and richness of families and had the greatest influence over spatial distribution trends for community structure were %Organic carbon and Cu concentration during 1998, % Organic carbon and depth in 2003 and Pb concentration in 2013.

Spatial Distribution and Temporal Trends in the Daily Precipitation Concentration across the Yarlung Tsangpo River Basin: Eastern Himalaya of China

Understanding the temporal inequality in precipitation is of great importance for water resource management, environmental risk management, and ecological conservation. This study investigated the spatial patterns and trends of the daily precipitation concentration over the Yarlung Tsangpo River Basin using the concentration index (CI) and the Lorentz asymmetric coefficient (LAC). A Mann–Kendall test and Hurst’s rescaled range analysis were used to detect the change in CI trends. The CI ranged from 0.58 to 0.65, suggesting that a quarter of the rainiest days contributed approximately 69–78% of the total precipitation. The LAC analysis indicated that the nonuniform distribution of precipitation was mainly attributed to a large proportion of days with light rainfall. Compared with that of the central region, the daily precipitation in the western and eastern regions was more irregular. At a seasonal scale, the dry season had a less homogeneous spatial distribution of CI compared to that of the wet season. Most areas exhibited no significant trends in CI from 1970 to 2017. A quarter of the stations presented a significant downward trend in CI, which were primarily found in the central and northern regions. In addition, the future trends of CI in most areas mostly agree with those of the current state; however, the majority of stations exhibited an uneven precipitation distribution in the dry season.

Progression of incidence and estimate of net survival from papillary thyroid cancers diagnosed between 2008 and 2016 in France

BackgroundAfter several decades of increasing incidence of papillary thyroid cancer (PTC), a change in this trend has been recently observed, particularly in the United States. This is attributed to the impact of new guidelines for the management of thyroid disease. The objective of this study was to describe the recent situation in France in terms of incidence and survival, taking account of tumor size. MethodsData from the FRANCIM network cancer registries, covering around 25% of the French metropolitan population, were analyzed. Distribution according to tumor size was determined in terms of frequency, trends in incidence and spatial distribution for the period 2008–2016. Analysis of net survival considered gender, age and tumor size. ResultsCancers of size≤5mm were predominant in patients diagnosed between 55 and 74 years of age. Incidence of≤5mm tumors in women and of 5–10mm tumors in men began declining in the early 2010s. Incidence of 10–20mm and 20–40mm tumors in men increased significantly throughout the period 2008–2016. For both men and women, the incidence of the largest tumors (>40mm) also increased, but not significantly. The spatial distribution of incidence showed great heterogeneity. Net survival was generally high, although decreasing with age and tumor size. ConclusionThe recent epidemiological situation in France is consistent with the hypothesis of recent progress in medical management of thyroid pathologies. Variations in incidence should be monitored for both small (<10mm) and larger tumors, and notably>40mm tumors. Net survival is generally high, although decreasing with age and tumor size.

Spatial Distribution and Temporal Trend Characteristics of Agro-Climatic Resources and Extreme Climate Events during the Soybean Growing Season in Northeast China from 1981 to 2017

Soybean is an important oil crop. Agro-climatic resources and extreme climate events during the growing season directly affect the crop growth and grain yield. In this study, we used historical climate data and phenology observation data to investigate the spatial distributions and temporal trends of agro-climatic resources and extreme climate events during the growing season for soybean in Northeast China (NEC). The results showed that during the soybean growing season, the thermal time increased while both the effective precipitation and photosynthetically active radiation (PAR) decreased. Within the growing season, the thermal time increased by 44.0°C day decade−1 during the vegetative stage but decreased by 16.5°C day decade−1 during the reproductive stage; the effective precipitation increased by 1.8 mm decade−1 during the vegetative stage but decreased by 7.3 mm decade−1 during the reproductive stage; PAR decreased by 6.5 and 11.9 MJ m−2 decade−1 during the vegetative and reproductive stages. The frequency of extreme cold days showed a decreasing trend during the four study phases of sowing to emergence, sowing-flowering, 15 days before flowering-flowering, and pod to physiological maturity. During the soybean growing season, the frequency of extreme heat days and the maximum number of consecutive dry days (CDD) increased, and the maximum number of consecutive wet days (CWD) and heavy precipitation days decreased. The results of this study could be used in selecting optimal management in soybean production in order to take advantage of beneficial climatic elements.

Understanding reservoir heterogeneity using variography and data analysis: an example from coastal swamp deposits, Niger Delta Basin (Nigeria)

Abstract For efficient reservoir management and long-term field development strategies, most geologists and asset managers pay special attention to reservoir chance of success. To minimise this uncertainty, a good understanding of reservoir presence and adequacy is required for better ranking of infill opportunities and optimal well placement. This can be quite challenging due to insufficient data and complexities that are typically associated with areas with compounded tectonostratigraphic framework. For the present paper, data analysis and variography were used firstly to examine possible geological factors that determine directions in which reservoirs show minimum heterogeneity for both discrete and continuous properties; secondly, to determine the maximum range and degree of variability of key reservoir petro-physical properties from the variogram, and thirdly, to highlight possible geological controls on reservoir distribution trends as well as areas with optimal reservoir quality. Discrete properties evaluated were lithology and genetic units, while continuous properties examined were porosity and net-to-gross (NtG). From the variogram analysis, the sandy lithology shows minimum heterogeneity in east-west (E–W) and north-south (N–S) directions, for Upper Shoreface Sands (USF) and Fluvial/Tidal Channel Sands (FCX/TCS), respectively. Porosity and NtG both show the least heterogeneity in the E–W axis for reservoirs belonging to both Upper Shoreface and Fluvial Channel environments with porosity showing a slightly higher range than NtG. The vertical ranges for both continuous properties did not show a clear trend. The Sequential Indicator Simulation (SIS) and Object modelling algorithm were used for modelling the discrete properties, while Sequential Gaussian Simulation (SGS) was used for modelling of the continuous properties. Results from this exercise show that depositional environment, sediment provenance, topographical slope, sub-regional structural trends, shoreline orientation and longshore currents, could have significant impacts on reservoir spatial distribution and property trends. This understanding could be applied in reservoir prediction and for generating stochastic estimates of petrophysical properties for nearby exploration assets of similar depositional environments.

Spatiotemporal dynamic evolution and driving factors of desertification in the Mu Us Sandy Land in 30\xa0years

The Mu Us Sandy Land is located in the middle of the farming pastoral ecotone of northern China. The direction of the development of desertification has a direct impact on the economy and development of the northern region. Six remote sensing images acquired during 1990–2017 served as data sources. Using an ENVI 5.3 and ArcGIS 10.3 platform an analysis was conducted of the dynamic changes nearly 30 years in desertified land using a center of gravity moving model, annual change rate, a transfer matrix, and an aeolian desertification index; the factors driving desertification were discussed. The research shows that the time period can be divided into three stages of desertification: development (1990–2000), rapid reversal (2000–2010), and stable reversal (2010–2017). A total of 1680 km2 of desertification were managed over the three stages. Spatially, the distribution of the center of desertification from west to east includes mild, moderate, severe, and extreme desertification, which is consistent with the spatial distribution trends of desertified land in the Mu Us Sandy Land. By the end of 2017, the degree of desertification of the Mu Us Sandy Land was in the central area > northwest > southwest > east > south. Nearly 30 years, the wind speed has decreased year by year at the rate of 0.1 m s−1, which directly reduce the ability to winds to transport soil in the Mu Us Sandy Land and promoted the reversal of desertification. From 1990 to 2010, the climate tended to become warmer and drier. Environmental protection policies along with human intervention and control of desertification have played important roles in reversing desertification. From 2010 to 2020, under the general background of a warm-wet climatic tendency, rational use of sand resources and strengthening scientific control of desertification inducing factors are the keys to reversing desertification.

Factors Controlling the Spatial Distribution and Temporal Trend of Nationwide Groundwater Quality in Korea

Factors controlling the spatial distribution and temporal trend of groundwater quality at a national scale are important to investigate for sustaining livelihood and ecological balance. This study evaluated groundwater quality data for 12 parameters (n = 6405 for each parameter), collected from 97 groundwater monitoring stations (=289 monitoring wells) for ten years. Spatial distribution of groundwater quality parameters varied through the regional scale. Six parameters: T, EC, Ca2+, Mg2+, HCO3−, and Cl− were having dominant increasing trend, remaining pH, Eh, Na+, K+, SO42−, and NO3− showed a dominant decreasing trend over time. Among land use types, the upland fields had the highest mean of groundwater NO3− (22.2 mg/L), confirming plenty of application of fertilizers (5–10 kg/a more than standard) to upland fields. Means of groundwater Cl− and Na+ (705.3 and 298.4 mg/L, respectively) in the residential areas are greater than those in other land use types by 408–685.9, 154.3–274.2 mg/L, respectively. Agricultural activities were the main controlling factor of groundwater NO3− contamination in rural areas, domestic activities were responsible for groundwater Cl− and Na+ in urban areas, and seawater intrusion was controlling groundwater Cl− in coastal areas (within 10 km from sea). Groundwater hydrochemistry was controlled by the mechanism of geogenic rock and evaporation dominance. The rock dominance mechanism indicated that groundwater was interacting with rocks and resulted in groundwater chemistry. The findings of this study showed that groundwater was mainly contaminated by anthropogenic factors in some rural and residential areas. Effective measures by government authorities are needed to improve the groundwater quality.

Spatial distribution and interannual trends of δ18O, δ2H, and deuterium excess in precipitation across North-Eastern Italy

NE Italy presents high-quantity, high-quality and easily exploitable groundwater resources that are seriously threatened by anthropogenic pressures. This study analyzes the oxygen and hydrogen isotopic composition of 2250 precipitation samples collected in 36 sites across the north-easternmost region of Italy, Friuli Venezia Giulia, between 1984 and 2015. This is an unprecedented dataset for North Italy with a high density of sampling sites and a decadal temporal extension. A series of both routine and original chemometric approaches were applied to investigate the temporal and spatial variability of the isotopic composition through relationships with geographical and weather variables. New statistical approaches were presented to model the seasonal and spatial patterns of isotopic composition as well as to summarize the large amount of isotopic data. Significant gradients of δ18O and δ2H were detected in the area due to the peculiar orography and climate of the region; the amplitude of the monthly patterns also presented similar gradients. The deuterium excess did not present a clear seasonality, but higher values were found in autumn. The deuterium excess-to-δ18O ratio exhibited typical patterns throughout the region when grouping the sites for altitude and continentality; in winter, large differences of δ18O were detected among groups, but deuterium excess remained almost unchanged. The inter-site correlations were moderately high across all the territory even for deseasonalized data. The local meteoric water line (using all the single samples δ2H=7.8·δ18O+8.9) was also estimated at annual and seasonal basis, evidencing the presence of spatial gradients according to the orographic and weather characteristics of the region. Statistically significant increasing interannual trends (0.23–0.87‰/y) were detected in 11 sites for deuterium excess; the presence of these trends was linked to local processes. Two multiple linear regression models were applied to reconstruct the isotopic composition of precipitation at a regional scale. The stepwise approach returned the best results with root mean square errors in the 0.5-1‰, 3.5–8.2‰ and 0.9–1.5‰ intervals for δ18O, δ2H, and deuterium excess, respectively. The deuterium excess was not modelled in winter, where no relationships were found with geographic variables.

Quantitative Evaluation of Human Health Risk of Heavy Metals in Soils Based on Positive Matrix Factorization Model and Geo-statistics

The aim of this study was to quantitatively assess the human health risks derived from different exposure paths of heavy metals in the soil. Zhangqiu county was selected as the study area, and 425 soil samples were collected to measure the As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn contents. A descriptive statistical method was used to assess the heavy metal pollution status of the soils, and the quantitative sources for human health were then determined based on positive matrix factorization (PMF) and geo-statistical techniques. The results show that the contents of As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn in the soils exceed background values, but do not exceed the risk screening values, indicating that there is slight heavy metals pollution in the soil. The sources of heavy metals in the soil can be divided into three categories. The spatial distribution of Cr and Ni is approximately the same, is similar to the spatial distribution trend of parent materials, and belongs to natural sources. Cd, Cu, and Zn are controlled by transportation. The spatial distribution is significantly affected by the location of road lines. The hot spot areas of Hg, Pb, and As correspond to the locations of the industrial park and the urban area. Industrial emissions and coal combustion increase the accumulation of Hg in the soil, and As, Pb, and Hg are classified as industrial sources. The contribution rate of industrial source is 41.85%, with transportation sources and natural sources being 33.79% and 24.36%, respectively. The non-carcinogenic and carcinogenic risks under the exposure paths of hand, breathing, and skin are within the acceptable level. For children, the sources of heavy metals with the largest carcinogenic (36.53%) and non-carcinogenic (36.01%) risks are industrial sources. However, transportation is the largest source of carcinogenic (34.98%) and non-carcinogenic (37.06%) risk for adults. Differential avoidance of heavy metal sources and exposure pathways is vital to reducing human health risks.

Evaluation and comparison of growing season metrics in arid and semi-arid areas of northern China under climate change

The differences of three key growing season metrics, namely, the start of growing season (SOS), the end of growing season (EOS) and the length of growing season (LOS), derived from ground observations, satellite-derived normalized difference vegetation index (NDVI) data and air temperature were compared, and the spatial distribution and temporal trend of NDVI-based growing season metrics were analyzed in the arid and semi-arid areas of northern China. The results show that the growing season metrics obtained by three methods were quite different. The temperature-based SOS dates were earlier than those observed at the four phenological sites, while the NDVI-based SOS dates were the latest. The EOS (LOS) derived from NDVI and temperature were later (longer) than the observed values. At 240 meteorological stations, temperature-based SOS and EOS dates were generally earlier than the NDVI-based results, leading to longer temperature-based LOS than that derived from NDVI. From 1982 to 2015, the NDVI-based SOS was advanced by 2.3 days per decade, and the NDVI-based EOS was delayed by 9.5 days per decade, causing a prolonged LOS of 11.8 days per decade. Earlier SOS, later EOS and prolonged LOS were significantly appeared at 44.3%, 40.6% and 52.6% of the vegetated area respectively. The significant advanced SOS was concentrated in the central Inner Mongolia, northern Hebei, northern Shanxi and northwestern Xinjiang, while the significant delayed EOS was mainly distributed in the majority of western and northern Xinjiang and northern Inner Mongolia, resulting in the significant prolonged LOS in most of the study area. Each method has its distinct advantages and disadvantages. It is suggested to use high spatial and temporal resolution satellite images and appropriate methods to establish phenological models for different land cover types and to take into account the powerful vegetation indices and key climatic factors such as daytime temperature and precipitation and their interactions, which are of great significance for large-scale and accurate phenological monitoring and assessment.

Spatial-temporal trends of rainfall erosivity and its implication for sustainable agriculture in the Wei River Basin of China

Water and soil are important natural resources for agricultural development. Soil erosion is a worldwide problem threatening sustainable agriculture development. Rainfall is one of the major natural factors that cause soil erosion. The study of the spatial distribution and temporal trends of rainfall erosivity is practical and important for the assessment of soil erosion hazards, the planning of soil and water conservation measures, and the sustainable agriculture development. In this study, the data of daily rainfall in the Wei River Basin from 1969 to 2018 were collected, the spatial and temporal variation characteristics of rainfall and rainfall erosivity were analyzed. The results show that the regional mean annual rainfall varies from 315.0 to 807.3 mm, which shows an increasing spatial trend from northwest to southeast. The mean annual rainfall erosivity in the basin ranges from 751.4 to 2600.0 MJ⋅mm⋅hm-2⋅h-1, which has a similar pattern of spatial distribution as the rainfall. The monthly rainfall erosivity changing pattern is a single-peak type. High erosivity of rainfall was mainly observed from July to September. The peaks mostly occur in July and August. The temporal trend of annual rainfall erosivity ranges from −6.6–10.1 MJ⋅mm⋅hm-2⋅h-1 per year, the Loess Plateau and the Qinling Mountains in the southern basin show an increasing trend, and the surroundings of Xifeng, Changwu and Huanxian have the statistical significance of P < 0.05. In the midstream and downstream of the basin and the Guanzhong Plain, the rainfall erosivity shows an insignificant decreasing trend. The North Atlantic Oscillation obviously influences the rainfall erosivity in the recent two decades. The study results may helpful for the scientific management, soil erosion prevention and sustainable agricultural development of the Wei River Basin.

Heavy metals and major anion content in groundwater of Tamoios coastal district (Rio de Janeiro/Brazil): assessment of suitability for drinking purposes and human health risk

ABSTRACT The coastal environment of Tamoios District (Rio de Janeiro State, Brazil) has been extensively modified by anthropogenic interference. Activities such as agriculture, livestock, and domestic wastewater discharge, expose groundwater to several toxic chemical elements. Some of these elements may accumulate and affect the potability of the water, making it unsafe for human consumption. Thus, hydrochemical characterisation of Tamoios groundwater was carried out with a variety of methods of representation (Piper Diagram, Hierarchical Clustering Analysis, Spearman’s correlation matrix, and groundwater suitability assessment), comparing six water quality standards and applying Nemerow Pollution Index (NPI). Human health risk assessment of eleven metals (Ba, Co, Cu, Cr, Sr, Mn, Mo, Ni, Zn, Al and V) and two anions (NO3 − and F−) was calculated by the Hazard Index, a tool developed by the United States Environmental Protection Agency to establish the potential health risk via chemical exposure in drinking water for adult and child population. Results showed that the concentration of Mn, NO3 −, Al and Cr were above the water quality standards for human ingestion. NPI classification defined 20% of the samples as slightly polluted and 40% as severely polluted. The spatial distribution of NPI values demonstrated that the samples neighbouring the coastline did not show excessive levels of heavy metals, NO3 − and F−. For both child and adult population, concentration of Co and NO3 − represented a risk to health. In addition, Cr and F− also represented heath risks to child population, the most vulnerable residents. Health risk for heavy metals and anions showed different spatial distribution trends. Poor quality groundwater and simultaneous exposure to different chemical compounds represented a health risk for both child and adult population in the study area.

A Trend Analysis of Leaf Area Index and Land Surface Temperature and Their Relationship from Global to Local Scale

Although the way in which vegetation phenology mediates the feedback of vegetation to climate systems is now well understood, the magnitude of these changes is still unknown. A thorough understanding of how the recent shift in phenology may impact on, for example, land surface temperature (LST) is important. To address this knowledge gap, it is important to quantify these impacts and identify patterns from the global to the regional scale. This study examines the trend and linear regression modeling of the leaf area index (LAI) and LST derived from the moderate resolution imaging spectroradiometer (MODIS) data, specifically to assess their spatial distribution and changing trends at the continental and regional scales. The change detection analysis of interannual variability in the global LAI and LST between two periods (2003–2010 and 2011–2018) demonstrates more positive LAI trends than negative, while for LST most changes were not significant. The relationships between LAI and LST were assessed across the continents to ascertain the response of vegetation to changes in LST. The regression between LAI and LST was negative in Australia (R2 = 0.487 ***), positive but minimal in Africa (R2 = 0.001), positive in North America (R2 = 0.641 ***), negative in Central America (R2 = 0.119), positive in South America (R2 = 0.253 *) and positive in Europe (R2 = 0.740 ***). Medium temperatures enhance photosynthesis and lengthen the growing season in Europe. We also found a significant greening trend in China (trendp = 0.16 ***) and India (trendp = 0.13 ***). The relationships between LAI and LST in these most prominent greening countries of the world are R2 = 0.06 and R2 = 0.25 for China and India, respectively. Our deductions here are twofold—(1) In China, an insignificant association appeared between greening trend and temperature. (2) In India, the significant greening trend may be a factor in lowering temperatures. Therefore, temperature may stabilize if the greening trend continues. We attribute the trends in both countries to the different land use management and climate mitigation policies adopted by these countries.

Effects of Cloud Liquid‐Phase Microphysical Processes in Mixed‐Phase Cumuli Over the Tibetan Plateau

AbstractNumerical simulations often overpredict precipitation over the Tibetan Plateau (TP). To examine the factors causing precipitation overprediction, different parameterizations of liquid‐phase microphysical processes (accretion, autoconversion, and entrainment mixing) are implemented into the Morrison microphysics scheme to simulate a TP precipitation event in summer with the Weather Research and Forecasting (WRF) model. The general spatial distribution and temporal trend of precipitation are captured by all simulations, but the precipitation rate is overpredicted. The results from sensitivity experiments suggest that compared to other examined liquid‐phase processes, the accretion process is more important in precipitation simulation over the TP region. Further investigation with the Heidke skill scores reveals that accretion parameterization that takes into account the raindrop size produces the most accurate results in terms of the total surface precipitation. This parameterization suppresses spurious accretion and does not produce liquid‐phase precipitation until cloud droplets are big enough. It is also confirmed that increasing the model resolution can reduce precipitation overprediction. Results from the case study are confirmed by the use of a 1‐month simulation.

Status, approaches, and challenges of ecosystem services exploration in Ethiopia: A systematic review

Healthy ecosystems benefit humans in various forms, and ecosystem services (ESs) are the benefits reaped by people in various forms. However, increase in global human population and the resulting anthropogenic activities have led to rapid alterations in the composition, structure, and functions of the ecosystems as well as their degradation, increasing the losses associated with ES values. Livelihoods of people in several developing countries are highly dependent on their surrounding ecosystems and the services they provide. Therefore, management and reduction of ecosystem modification are required; especially in developing countries, this requirement is even more urgent. In Africa, ecosystem-based studies are limited and in still in their initial stages. Hence, this paper examines dynamic Ethiopian ESs in Africa from 2010 to 2019 based on a systematic bibliometric analysis of articles from the Scopus database using a set of standard criteria. In total, 73 articles were published on Africa, including Ethiopia. The results reveal that the spatial distribution trend of ES studies is unevenly distributed, where most studies were conducted in the central highlands, followed by southwestern regions, with no studies on the western part of Ethiopia. Regarding service providing units (SPUs), the urban ecosystem and agroecosystem accounted for 25% and mixed ecosystems accounted for 20%. Furthermore, a total of 67 specific ESs were investigated by researchers, among which 81.25% of the specific ESs were classified into two ES categories. Provisioning ES (40.29%) dominated across all of the ES types while the cultural ES (5.97%) type has received little attention. Based on keywords, ESs were strongly linked to South Africa, Ethiopia, and biodiversity. In terms of the co-authorship network, authors from the United Kingdom, Italy, Burkina Faso, the Netherlands, and Germany actively collaborated with the Ethiopian researchers, and approximately 50% of the studies were aimed at estimating the value of the ESs through an applied mixed mode of ES study approaches. This review indicates that, due to land use land cover (LULC) changes from 1985 to 2015, approximately US$ 149.5 million or US$ 4.98 million annually in ES values were lost. Moreover, there is a critical need to extend ES studies to entire Ethiopia to capture the spatial and socioeconomic uniqueness of various ecosystems and focus more on multiple ES categories as a means to address ES synergies and provide unit-services to strengthen the relations among benefiting areas in Ethiopia.

Occurrence and distribution of polyhalogenated carbazoles (PHCs) in sediments from the northern South China Sea

Polyhalogenated carbazoles (PHCs) have been frequently detected in various environments and have gained increasing attention due to their dioxin-like toxicity. In this study, 28 surface sediments and three sediment cores were collected from the northern South China Sea (SCS) to investigate the spatial and temporal distribution trends of PHCs. The total concentrations of PHCs in the surface sediments ranged from 0.25 ng/g to 3.10 ng/g, with a median concentration of 1.50 ng/g. The composition profiles of PHCs in the surface sediments were dominated by 3,6-dichlorocarbazole (36-CCZ), 3,6-dibromocarbazole (36-BCZ), and 1,3,6,8-tetrabromocarbazole (1368-BCZ). The total organic carbon (TOC) based concentrations of 36-CCZ, 1-bromo-3,6-dichlorocarbazole, 1,3,6,8-tetrachlorocarbazole, and 1368-BCZ showed significant positive correlation with water depth (r = 0.58–0.88, p values < 0.01). On the contrary, the TOC based concentration of 2,3,6,7-tetrachlorocarbazole displayed a significant negative correlation with the water depth (r = −0.52, p < 0.01). However, no significant correlation was observed for 3-chlorocarbazole, 36-BCZ, and 1,3,6-tribromocarbazole (p values > 0.05). PHCs in sediment cores showed that congener profiles and concentrations of PHCs remained largely stable throughout the 1890s and 2010s. In addition, all the detected PHCs displayed a significant positive correlation with TOC content of the sediments. These unique spatial and temporal distribution patterns suggest that both terrigenous and natural marine sources contributed the observed PHCs in sediments of the northern SCS.

The Pollution Level, Spatial and Temporal Distribution Trend and Risk Assessment of Heavy Metals in Bohai Sea of China

Zhang, D.S.; Pei, S.S.; Duan, G.F.; Feng, X.B.; Zhang, Y.B., and Wu, J., 2020. The pollution level, spatial and temporal distribution trend and risk assessment of heavy metals in Bohai Sea of China. In: Bai, X. and Zhou, H. (eds.), Advances in Water Resources, Environmental Protection, and Sustainable Development. Journal of Coastal Research, Special Issue No. 115, pp. 354-360. Coconut Creek (Florida), ISSN 0749-0208.In recent years, the rapid industrialization and urbanization of coastal areas have caused serious environmental pressure on the Bohai Sea. The investigator collected the concentration of 7 heavy metals (As, Cu, Cd, Cr, Hg, Pb, Zn) in the Bohai Sea from 2013 to 2017.The results showed that: The main pollution factor of heavy metals in the sea water quality of the study area was Pb. The concentration of Hg increased significantly with the increase of depth. Hg and Cd, due to their high toxicity factors, are the main potential ecological risk factors of surface sediments in the study area. The main heavy metal pollution factor in living creatures is Pb. River discharge, oil exploitation, port area activities and atmospheric subsidence are the main sources of Marine environmental pollution. This study provides ideas for predicting the content of another medium heavy metal in the environment based on one medium.

Capturing Spatiotemporal Patterns in Presence-Absence Data to Inform Monitoring and Sampling Designs for the Threatened Dakota Skipper (Lepidoptera: Hesperiidae) in the Great Plains of the United States.

Declines among species of insect pollinators, especially butterflies, has garnered attention from scientists and managers. Often these declines have spurred governments to declare some species as threatened or endangered. We used existing presence-absence data from surveys for the threatened Dakota skipper Hesperia dacotae (Skinner) to build statistical maps of species presence that could be used to inform future monitoring designs. We developed a hierarchical Bayesian modeling approach to estimate the spatial distribution and temporal trend in Dakota skipper probability of presence. Our model included a spatial random effect and fixed effects for the proportion of two grassland habitat types: those on well-drained soils and those on poorly drained soils; as well as the topographic slope. The results from this model were then used to assess sampling strategies with two different monitoring objectives: locating new Dakota skipper colonies or monitoring the proportion of historically (pre-2000) extant colonies. Our modeling results suggested that the distribution of Dakota skippers followed the distribution of remnant grasslands and that probabilities of presence tended to be higher in topographically diverse grasslands with well-drained soils. Our analysis also showed that the probability of presence declined throughout the northern Great Plains range. Our simulations of the different sampling designs suggested that new detections were expected when sampling where Dakota skippers likely occurred historically, but this may lead to a tradeoff with monitoring existing sites. Prior information about the extant sites may help to ameliorate this tradeoff.

Assessment of the heterogeneity of hydraulic properties in gravelly outwash plains: a regionally scaled sedimentological analysis in the Munich gravel plain, Germany

The favorable overall conditions for the utilization of groundwater in fluvioglacial aquifers are impacted by significant heterogeneity in the hydraulic conductivity, which is related to small-scale facies changes. Knowledge of the spatial distribution of hydraulically relevant hydrofacies types (HF-types), derived by sedimentological analysis, helps to determine the hydraulic conductivity distribution and thus contribute to understanding the hydraulic dynamics in fluvioglacial aquifers. In particular, the HF-type “open framework gravel (OW)”, which occurs with the HF-type “bimodal gravel (BM)” in BM/OW couplings, has an intrinsically high hydraulic conductivity and significantly impacts hydrogeological challenges such as planning excavation-pit drainage or the prognosis of plumes. The present study investigates the properties and spatial occurrence of HF-types in fluvioglacial deposits at regional scale to derive spatial distribution trends of HF-types, by analyzing 12 gravel pits in the Munich gravel plain (southern Germany) as analogues for outwash plains. The results are compared to the reevaluation of 542 pumping tests. Analysis of the HF-types and the pumping test data shows similar small-scale heterogeneities of the hydraulic conductivity, superimposing large-scale trends. High-permeability BM/OW couples and their dependence on recognizable discharge types in the sedimentary deposits explain sharp-bounded small-scale heterogeneities in the hydraulic conductivity distribution from 9.1 × 10−3 to 2.2 × 10−4 m/s. It is also shown that high values of hydraulic conductivity can be interpolated on shorter distance compared to lower values. While the results of the HF-analysis can be transferred to other fluvioglacial settings (e.g. braided rivers), regional trends must be examined with respect to the surrounding topography.

Temporal and spatial distribution trends of human brucellosis in Liaoning Province, China.

Brucellosis is a natural epidemic zoonotic disease. Liaoning province, north-east of China, has been among the top 10 provinces with highest brucellosis incidence. In this study, the spatial and temporal distribution of brucellosis in Liaoning Province from 2006 through 2017 was analysed using the Bayesian theory of space-time modelling. The study found that in Liaoning Province, (a) all regions of the entire study area were stable counties; (b) the risk of brucellosis declined slowly with time without an obvious trend; (c) the declining trend of disease risk in three sub-hot-spot counties was faster than the overall trend, whereas in other counties, the trend was similar to the overall trend. Furthermore, the time and spatial trends of brucellosis incidence in Liaoning Province were calculated and analysed. These results may provide a theoretical and scientific basis for the public health department to develop targeted effective prevention and control measures for the disease.