H-vector Research Articles

Heavy Metal Characteristics and Comprehensive Quality Index Evaluation of Soil-Crop System in 11 Cities of Yunnan Province, China

Yunnan province in China is a high background area of soil heavy metals, and agricultural planting and industrial and mining activities are relatively frequent, which aggravate soil heavy metal pollution. However, at present, there are few reports on the overall or large-scale soil-crop pollution and risk assessment of heavy metals in Yunnan Province. This study through 11 cities in Yunnan province of China farmland soil-crop systems of heavy metal lead, cadmium content, enrichment coefficient is analyzed, and using the method of potential ecological harm index, index of compressive quality to evaluate heavy metal pollution soil-crop system risk. Results showed that the average content of soil heavy metal Cd and Pb were 1.31 mg/kg, 64.17 mg/kg, which are higher than the background value of Yunnan province. The average contents of Pb and Cd in the edible parts of crops were 0.20 mg/kg, 0.08 mg/kg. The average content of heavy metals in crops in Diqing (Pb) and Nujiang (Cd) was 0.72 mg/kg and 0.148 mg/kg. The enrichment coefficients of heavy metals in edible parts of crops were the largest in Diqing (Pb) and Zhaotong (Cd). The average value of ecological risk index of Pb element in soil is 2.79, which indicates that the study area is in a slight ecological hazard, the average value of the ecological risk index of Cd in soil is 126.43. The average value of the comprehensive quality impact index (IICQ) is 4.27, which indicates that the study area is moderately polluted. In this study, the contents of heavy metals Cd and Pb in soils and crops in different administrative regions were determined, and the heavy metals Pb and Cd in soil-crop system of Yunnan province, China were evaluated, it is expected to have important scientific and theoretical significance for the safe use of cultivated land to export safe agricultural products and promote the sustainable development of agriculture in Yunnan Plateau.

HEAVY METALS CONTAMINATION OF SOLID WASTE DISPOSAL SITES IN UMUAHIA, ABIA STATE

The extent of soil contamination with heavy metals within the vicinity of four solid waste disposal sites in Umuahia were assessed. Four solid waste disposal sites were sampled at depth profiles of 0-10 cm, 10-20 cm and 20-30cm respectively. The soil samples were digested and subjected to heavy metal analysis using Atomic Absorption Spectrophotometer (AAS). The results obtained revealed a wide variation in the concentrations of different heavy metals at various sampling sites. The heavy metal concentrations of soil samples at solid waste disposal sites were higher than those obtained from the control site. Maximum concentrations of Pb, Hg, Cu, Zn, Cd and As, were 2.910.02 mg/l, 0.300.00 mg/l, 15.000.02 mg/l, 143.00.15 mg/l, 2.260.31 mg/l, and 0.050.00 mg/l respectively which were obtained from soils with depth profile 0 -10 cm. There was a depth- wise steady decrease in heavy metal concentrations in the soil samples analyzed. However, geo-accumulation (Igeo) index suggested significant contribution of cadmium to soil contamination. Geo-accumulation (Igeo) index of Cd ranged from 1.78 to 4.20, indicating very high contamination of the soil by Cd. But calculated pollution load index (PLI) ranged from 0.10 to 0.45, which does not indicate high pollution load status of the soil.

Ecological risk of heavy metals in lake sediments of China: A national-scale integrated analysis

Intensive anthropogenic activities, specifically, industrial and agricultural production, have resulted in heavy metal enrichment in lake sediment and threats to aquatic ecosystems and human health. Evaluating the potential ecological risk of heavy metals in lake sediment is essential for promoting appropriate lake management in aquatic ecosystems. Large-spatial scale risk evaluations of heavy metal pollution in lake sediment in densely populated countries such as China are lacking. We compiled sediment heavy metal (Cu, Pb, Zn, Ni, Cr, As, Hg, and Cd) data from 190 lakes distributed across five geographic zones in China published between 2000 and 2019, evaluated the potential ecological risk and identified heavy metal sources through positive matrix factorization. Five conclusions were drawn. (1) Regarding the eight collected heavy metals, 6.1–40.4% of 190 lakes exhibited higher concentrations than the Chinese soil background value, and the concentration in 6.2% of lakes exceeded the probable effect concentration. (2) Based on the potential ecological risk index (PERI) and sum of toxic units (STU), Cd and Hg were the major pollutants. (3) The PERI value notably decreased with increasing lake surface area, and small lakes (<10 km2) generally yielded high PERI values. Among the five Chinese geographic zones, the Eastern Plain Lake Zone and Inner Mongolia-Xinjiang Lake Zone exhibited higher potential ecological risk. Compared to natural lakes, urban lakes and reservoirs posed higher ecological risks, while freshwater lakes yielded higher PERI values than saltwater lakes and saline lakes. (4) In all lakes, lake sediment pollutants Cu and Zn mainly originated from traffic sources; Cd originated from agricultural activities; Pb and Hg were related to industrial activities; and Ni, Cr and As indicated mixed sources. (5) In the Eastern Plain Lake Zone, Yunnan-Guizhou Plateau Lake Zone and Northeast Plain and Mountain Lake Zone, industry was the dominant source of heavy metals in lake sediment, while in the Tibetan Plateau Lake Zone and Inner Mongolia-Xinjiang Lake Zone, except for industrial sources, agricultural sources played an important role. Our national-scale integrated analysis provides valuable references for both macroscale policy formulation and polluted lake restoration.

Qualitative Assessment of Groundwater Resources of Asadabad Plain using WQI, Cd, HPI, HEI, PoS and MI Indices in 2018

Qualitative Assessment of Groundwater Resources of Asadabad Plain using WQI, Cd, HPI, HEI, PoS and MI Indices in 2018

Health and Ecological Risks Associated with Heavy Metal Contamination in Surface Soils from Lagos Lagoon Wetlands, Lagos, Nigeria

&#x0D; &#x0D; &#x0D; Wetlands quality and spatial distribution are being threatened by anthropogenic drivers in addition to the emerging threats of climate change. In this study, selected heavy metals (Cd, Cr, Cu, Ni, Pb and Zn) in soils from Lagos lagoon wetlands were investigated to assess spatial distribution, ecological and health risks. The data obtained were subjected to statistical analysis using GraphPad 7.0 and SPSS 22.0. Spatial distribution mapping of heavy metals was performed using ArcGIS10.0 (ESRI, Redlands, CA, USA) with Kriging interpolation. Results showed that heavy metals in the soil varied significantly (p&lt;0.05). The contamination factors (CF) were generally low with the values for Cr, Ni, Cu, and Zn very low (&lt;1). The CF values for some of the sampling points showed that the soils are generally moderately contaminated by Pb, Cd and Cu. The modified degree of contamination of Pb (2.35) indicates a moderate degree of contamination while that of Cd (12.60) indicates a high degree of contamination of these wetland soils. The potential ecological risk index (RI) of Pb, Cd, Cr, Ni, Cu and Zn were 70.40, 2264.40, 0.68, 1.55, 13.65, and 2.29, respectively. The RI for Pb, Cr, Ni, Cu and Zn were less than 100, hence, low, while the RI value of Cd was a very high risk (RI ≥ 400). Soils from this wetland’s areas show serious significant potential ecological risk due to Cd. Additionally, children were more susceptible to the potential health risk irrespective of the carcinogenic or non – carcinogenic risk. There were no significant carcinogenic and non – carcinogenic risks for adults and children. This wetland assessment provided important information for policymaking to reduce the potential effects of soil contamination on humans and the eco-environment.&#x0D; &#x0D; &#x0D;

Biochelator Assisted Phytoremediation for Cadmium (Cd) Pollution in Paddy Field

To evaluate the efficacy of biochelators for phytoremediation of cadmium (Cd), effects of biochelators (humic acid, HA; polyaspartic acid, PASP; rhamnolipid, RLs) and synthetic chelator (sodium tripolyphosphate, STPP) on the growth, accumulation, and antioxidant index of Cd were investigated in Iris sibirica L. The results indicated that the addition of HA increased the dry weight of leaves and stems, and the addition of PASP, RLs, and STPP increased the growth of leaves but inhibited the growth of stems. The determination of Cd accumulation indicated that HA decreased the content of Cd in all tissues, while the addition of PASP, RLs, and STPP increased the accumulation of Cd in stems and roots. In addition, the determination of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) activities indicated that the treatment of PASP and RLs increased the activities of antioxidant enzymes, which might be beneficial to the resistance of Cd for Iris sibirica L. Overall, these results indicated that biochelators may improve the phytoremediation efficacy of Iris sibirica L. on Cd polluted paddy field. Among the tested chelators, PASP exhibited the best comprehensive efficacy and the highest commercial potential.

Placental cadmium, placental genetic variations, and birth size

Background Maternal cadmium (Cd) burden has been associated with offspring birth size measures, yet associations of placental Cd with birth size are less clear. Further, the role of genetics in these associations has not been examined. We investigated associations of placental Cd with birth size and placental genotypes. We also examined the potential role of placental genotypes as modifiers of placental Cd and birth size associations. Methods Participants were 490 mother-child pairs from the Omega and Placenta Microarray studies based in Seattle, WA. Placental Cd was measured using Agilent 7500 ICP-MS. The birth size was characterized using birth weight (BW), ponderal index (PI), and head circumference (HC). Eleven placental single nucleotide polymorphisms (SNPs) related to metal transport, growth regulation, endocrine response, and cell signaling were genotyped. Adjusted multivariable linear regression models were used to examine overall and sex-specific associations of placental Cd with birth size (BW, PI and HC), as well as associations of placental genotypes with placental Cd. Effect modification of placenta Cd and birth size associations by placental SNPs was examined using interaction terms and stratified analyses. Results Mean maternal age was 33.6 years (SD = 4.4). Mean and median placental Cd levels were 4.0 ng/g tissue (SD = 2.7 ng/g tissue) and 3.6 ng/g (IQR 2.5 − 5.2 ng/g), respectively. Overall, compared with infants in the lowest quartile for placental Cd, infants in the second (ß = −102.8 g, 95% CI: −220.7, 15.1), third (ß = –83.2 g, 95% CI: −199.3, 32.9) and fourth (ß = −109.2 g, 95% CI: −225.4, 7.1) quartiles had lower BW, though associations were not statistically significant (all p-values > .05, trend p-value = .11). Among male infants, infants in the second (ß = −203.3 g, 95% CI: −379.7, −27.0) and fourth quartiles (ß = −198.3 g, 95% CI: −364.2, −32.5) had lower BW compared with those in the first quartiles (p-values < .05, trend p-value = .08). Similar relationships were not observed among female infants, though infant sex-placental Cd interaction terms were not significant. Similarly, male, but not female, infants had marginally significant positive associations between placental Cd and ponderal index (trend p-value = .06). The minor rs3811647 allele of the placental transferrin gene (NCBI Gene ID: 7018) was associated with an increase in Cd among all infants (p-value = .04). We did not find differences in associations of placental Cd with birth size markers among infants stratified by rs3811647 genotype. Conclusions Placental Cd was inversely associated with BW among male infants. The rs3811647 SNP of the transferrin gene was associated with placental Cd.

Content and Ecological Risks of Heavy Metals in Soil with Different Land Uses in a Rapidly Urbanizing Area

Taking the Minhang District of Shanghai as a typical rapidly urbanizing area, and based on 595 soil samples from 36 plots, the content of eight heavy metals in soils from five different land uses were analyzed. The ecological risk was evaluated using the Nemerow composite index and the potential ecological risk index. The results showed that the variation coefficients of the heavy metals Zn and Cd were highest, and were notably affected by human activities. The content of heavy metals in industrial land soil was relatively high compared to residential land and cultivated land soils, and heavy metal content was lowest in public management and service land soil. The Nemerow composite index of Zn and Cd was high, corresponding to severe and moderate levels of pollution, respectively. The other heavy metals were found at warning or light levels of pollution. The potential ecological risks posed by heavy metals in the soils from different land uses, in descending order, were heavy-metal-related industry land > non-heavy-metal-related industry land≈residential land > cultivated land≈public management and service land. Industrial land had a greater risk of heavy metal pollution due to industrial operations, complex historical production, and widely variable levels of management. Heavy metal accumulation also tended to occur in residential land and cultivated land soils. Therefore, the prevention of soil heavy metal pollution in association with different land uses, and the control of associated risks during redevelopment, are key challenges in rapidly urbanizing area.

Evaluation of Health Risk from Concentrations of Heavy Metal in PM-10 and PM-2.5 particles at Sasang Industrial Complex of Busan, Korea

We investigated the distribution of hazardous heavy metals (As, Cr6+, Ni, Cd, Pb, and Mn) and estimated the health risk related to the heavy metals in fine dust (PM-10 and PM-2.5) of Sasang industrial complex, Busan, Korea. The concentration of fine dust in the industrial complex was 1.2 times higher than in a residential area, while harmful heavy metals showed a difference of at least 1.3 times (Cd) and up to 6.5 times (Ni). The concentration of fine dust and carcinogenic heavy metals in the industrial complex increased significantly compared to the residential area in spring (March to May) and winter (December to February) months. A risk assessment was performed using Monte-Carlo simulations containing a four-step procedure. During hazard identification, As, Cr6+ Ni, Cd, and Pb were categorized as human carcinogens and probable human carcinogens and evaluated for their levels of excess cancer risk. For concentrations of over 90% Cr6+ and As, the excess cancer risk was over 10-5 (1 person per 100,000). The non-cancer hazard index of As, Cr6+, Cd, and Mn was below the limit value of 1.

What types of novelty are most disruptive?

This work builds on recent advances in the study of novelty and impact to investigate whether novel scientific papers tend to disrupt the scientific literature, and whether some types of novelty are more disruptive than others. We develop a computational measure to capture the ways in which scientific articles are novel (e.g., developing a new method or presenting a new result). We also utilize Funk and Owen-Smith’s (2017) CD index to capture the different ways an article can influence a stream of literature: by consolidating (C) or disrupting (D) the status quo. Drawing upon classic sociology of science scholarship on the distinction between cumulative normal science research and non-cumulative paradigm shifts (Kuhn 1962; 1977), we develop hypotheses about which type of novelty is more likely to disrupt knowledge streams and which is more likely to consolidate them. By integrating data from the Web of Science (to measure the nature of scientific influence) with reflective essays written by authors of Citation Classics (to access novelty claims) and by joining computational text analysis with statistical analyses, we demonstrate clear and robust patterns between type of novelty and the nature of scientific influence. As we expected, articles that develop and present a new method tend to be more disruptive, likely because they tend to cross disciplinary divides, which boost creative insight and alters citation patterns (Abbott 2004; Koppman & Leahey 2019). To our surprise, new theory (especially the most abstract kind of theory) is associated with a more consolidating type of influence. This may be attributable to the nature of theory and theory-building, which tends to involve synthesis and bricolage.

Assessment of trace metal contamination in the Kol wetland, a Ramsar site, Southwest coast of India

The present study quantified the agrarian quality and assessment of 16 sediment samples in two seasons from the identified three representative zones (North, Center and south) of Kol wetlands in Vembanad system, situated in the west coast of Kerala, India. Estimated the pollution quality indices (Enrichment Factor, Geoaccumulation index and Contamination Factor), sediment quality (Organic matter, texture and nutrients) and their ecological risk . Water Quality parameters (pH, salinity, DO) of the residing habit were also examined. The overall seasonal analyses of sediment trace metal’s mean concentration of these three zones exhibited in the following order: Fe>Zn>Pb>Cr>Mn>Ni>Co>Cu>Cd. The nutrient quality parameters inferred high concentration with spatial disparity. The Enrichment factor of Co, Cr, Zn, Cu and Ni varies from moderate to severe; and the potential ecological index of Cd in the studied Kol sampling sites were likely to result in a dangerous situation in the near future. Water Quality of the surface water noticed a putrefied condition with negligible Dissolved Oxygen (DO) at Tholur (8) in the non monsoon season. While comparing the Sediment Quality Guidelines (SQGs) and the recommended food and Agriculture Organization (FAO) standard values, the Cd, Zn and Cu concentration were exceeded the recommended limit. These scenario alter the ecological and environmental feasibility of the habitat including the sediment dwelling organisms. Multivariate statistics Analysis infers the anthropogenic and domestic source input of Cd, Ni, Mn, Co and Cu in the central basin and the correlation pattern with respect to Pb, Zn, Total Sulfur (TS), NO2-N and NH4+-N indicates an agriculture input. Among these three distinct zones the cluster results shows that the central agriculture sites confronts elevated trace metal concentration.

Effects of Organic Fertilizers on Cd Activity in Soil and Cd Accumulation in Rice in Three Paddy Soils from Guizhou Province.

A greenhouse pot experiment was conducted to investigate the effects of organic fertilizer application on Cd activity in soil and Cd accumulation in rice in paddy soils with different levels of contamination from varying Cd sources in Guizhou Province (the soil types are NJ, which is a soil with a high geological background of Cd; and QX and JZ, which are anthropogenic Cd-polluted soils). The application of organic fertilizer increased the content of organic matter in the soil and reduced the concentration of acetic acid-extractable Cd in QX and JZ paddy soils. Organic fertilizer increased rice yields and significantly decreased the Cd concentration in brown rice. In the QX and JZ soils, however, the concentration of Cd in brown rice exceeded the allowable maximum levels (MLs) of Cd in China. In contrast, the concentration of Cd in brown rice in NJ soil met the MLs of Cd. Additionally, the average daily dose and the health risk index of Cd in NJ soil were much lower than those in QX and JZ soils. The results indicate that organic fertilizer application is a promising and economic means to control Cd pollution in paddy soil. Moreover, risk assessment shows that the risk of exposure to Cd in the high geological background soil (NJ) was much lower than that in anthropogenically polluted soils (QX and JZ).

Spatio-temporal Distribution Characteristic and Risk Assessment of Heavy Metals in Soils Around Centralized Drinking Water Sources in Wuhan

In the present study, the spatio-temporal distribution characteristics of heavy metals (Cd, Hg, As, Pb, Cr, Cu, Ni, and Zn) in soil around 19 centralized drinking water sources in Wuhan were investigated. Single-factor and comprehensive pollution indexes were used to determine soil pollution levels. The potential ecological hazard index was employed to evaluate soil potential ecological risks. The correlation and cluster analysis were conducted to identify pollution sources. The results showed that higher concentrations of heavy metals were present in soil from centralized drinking water source located in core area than suburb area of Wuhan. The concentrations of heavy metals in soil from centralized drinking water sources near the Yangtze River were higher than that in the sites near the tributaries of the Yangtze River. The average single potential ecological risk index of Hg, As, Pb, Cr, Cu, Ni, and Zn were lower than 40, which suggests a slight potential ecological risk. The average single potential ecological risk index of Cd was 80-160, which indicates a high potential ecological risk. The average comprehensive potential ecological risk index of heavy metals in soil around centralized drinking water sources in Wuhan was 142.12, which corresponded to a slight potential ecological risk. The correlation analysis showed that the sources of Cu, Pb, and Cr were similar and came from transport. The sources of Ni, As, Cr, and Cu were similar and could be attributed to metallurgical industries. The sources of Zn, Hg, and Cr were similar and could be related to antiseptic and catalytic industries. The long-term monitoring of Wuhan Dijiao and Baishazhou waterworks indicated that the concentrations of heavy metals around centralized drinking water sources in Wuhan were markedly decreased after 2017 and that ecological risk may be further reduced in the future.

Health significant alarms of toxic carcinogenic risk consumption of blood meal metals contamination in poultry at a gold mining neighborhood, northern Thailand.

The proposes of this study were to compare THg (total mercury), Pb(Lead), Cd(Cadmium), and Mn (Manganese) contamination in poultry blood between polluted areas (≤ 25km) and unpolluted areas (> 25km) adjacent to the largest gold mining in northern Thailand. The THg level in the free-grazing duck in polluted areas was significantly higher than unpolluted area. Both THg and Pb levels in free-grazing duck were also highest in polluted areas. In contrast, the level of (Mn) in chicken blood was the highest in polluted areas. Cadmium in farmed duck from polluted areas was significantly higher than unpolluted areas. The target hazard quotient (THQ) and hazard index (HI) of Hg, Pb, Cd, and Mn in all age groups in both areas did not exceed 1, meaning there is no possibility of the non-carcinogenic toxicity.Whereas, the incremental lifetime cancer risk (ILCR) of both Pb and Cd exceeded 1 × 10-4 in all age groups andthese were particularly higher in the polluted area and considered to yield significant health effects of increasingthe cancer risk. The ILCR in descending order for Pb and Cd was 13-18years old = 18-35years old > 6-13years old = 35-65years old > 3-6years old > 65 up years old, respectively. The results revealed that the human cancer risk related to consuming poultry blood contaminated with both Pb and Cd in all age groups must be of concern, especially 13-18 and 18-35years, it must be recommended to avoid raising animals in contaminated areas, especially free-grazing duck.

Divergent patterns of heavy metal accumulation in paddy fields affect the dietary safety of rice: a case study in Maoming City, China.

The objective of this work was to study the impact of large petrochemical plants and mining operations on the accumulation of heavy metals in farmland and rice, as well as assess their potential risks on human health. The contents of seven heavy metals, Cd, Pb, Cr, Ni, Co, Cu, and Mn, were monitored in a typical polluted paddy soil-rice system near a petrochemical plant and mining area in Maoming, China. The results showed that the content of Cd in the soil exceeds the standard rate by 100%, and the single factor pollution index of Cd was 5.12, which is considered heavy pollution. Excessive heavy metals can inhibit and poison the growth of rice plants. Rice plants can maintain a certain level of heavy metal content by reducing the absorption or interception in the root cells, leading to great differences in the distribution of different heavy metals in plant tissues. Cadmium, Cu, Co, and Mn are easily absorbed from the soil by rice roots, while other heavy metals are relatively difficult to absorb by rice roots. Cuprum, Cd, Co, Pb, and Cr were mainly accumulated in the root of rice, but Mn and Ni migrate to the above ground plant tissues quickly. The brown rice produced in the paddy fields in the study area was seriously polluted. The concentration of Cd, Pb, and Ni in brown rice exceeded the standard by 100%, and Cr in brown rice also exceeded the standard by 80%. If residents consume rice from the study area, their daily intake of Cr and Cd will be 1.02 and 3.24 times higher, respectively, than the standard limit recommended by the FAO/WHO. The irrigation streams were polluted due to the discharge of petrochemical plants and mining wastewater, causing the serious pollution of heavy metals in the surrounding paddy fields. The rice produced in this area poses a serious risk to consumers, and so this problem of pollution should be addressed.

Spatial Variation in Cadmium and Mercury and Factors Influencing Their Potential Ecological Risks in Farmland Soil in Poyang Lake Plain, China

Due to the irreversibility of heavy metal pollution, the presence of heavy metals in farmland soil is associated with severe ecological risks that endanger both the environment and human health. Cadmium (Cd) and mercury (Hg) are two toxic heavy metals found widely in polluted soil. Cd is not readily fixed in the soil and is therefore easily accumulated by plants, while Hg has a wide range of pollution sources. The aims of this study were to explore the spatial variation in Cd and Hg concentrations in farmland soil in Poyang Lake Plain, China, and to assess their potential ecological risks as influenced by natural and human factors. A total of 283 soil samples were obtained from Fengcheng city, central Jiangxi Province. Data were then analyzed using geostatistics, the potential ecological risk index, Pearson’s correlation analysis, and Geodetector. The results showed moderate variation in soil Cd and Hg concentrations, with a remarkable difference in their spatial distribution. Cd concentrations in the northwest and northeast of Fengcheng were below the regional background level in Jiangxi; in most remaining areas, Cd concentrations were between the regional background level and national risk screening value. Areas with Hg concentrations lower than the regional background level were largely concentrated in the south, east and north of Fengcheng, and gradually increased towards the central, where they exceeded the regional background level but were below the national risk screening value. Overall, the potential ecological risk level of Cd was predominantly low, while that of Hg was moderate. The comprehensive potential ecological risk was low in most areas for both Cd and Hg, with some scattered areas of moderate risk. Moreover, the comprehensive potential ecological risk index of both Cd and Hg was significantly correlated with soil pH, total phosphorous, elevation, distance from a river (p &amp;lt; 0.01), and distance from a road (p &amp;lt; 0.05). The most significant factor influencing the comprehensive potential ecological risk index of these two heavy metals was soil pH of 5.2–5.6, followed by total p ≤ 0.52 mg kg−1. In conclusion, moderate pollution of Cd and Hg occurred in farmland soil in Poyang Lake Plain where their comprehensive potential ecological risk level was generally low and mainly influenced by soil pH and total phosphorous.

Pollution Characteristics, Distribution and Ecological Risk of Potentially Toxic Elements in Soils from an Abandoned Coal Mine Area in Southwestern China

Acid mine drainage (AMD) from abandoned coal mines can lead to serious environmental problems due to its low pH and high concentrations of potentially toxic elements. In this study, soil pH, sulfur (S) content, and arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), lead (Pb), nickel (Ni), zinc (Zn), iron (Fe), manganese (Mn), and mercury (Hg) concentrations were measured in 27 surface soil samples from areas in which coal-mining activities ceased nine years previously in Youyu Catchment, Guizhou Province, China. The soil was acidic, with a mean pH of 5.28. Cadmium was the only element with a mean concentration higher than the national soil quality standard. As, Cd, Cu, Ni, Zn, Mn, Cr, and Fe concentrations were all higher than the background values in Guizhou Province. This was especially true for the Cd, Cu, and Fe concentrations, which were 1.69, 1.95, and 12.18 times their respective background values. The geoaccumulation index of Cd and Fe was present at unpolluted to moderately polluted and heavily polluted levels, respectively, indicating higher pollution levels than for the other elements in the study area. Spatially, significantly high Fe and S concentrations, as well as extremely low pH values, were found in the soils of the AMD sites; however, sites where tributaries merged with the Youyu River (TM) had the highest Cd pollution level. Iron originated mainly from non-point sources (e.g., AMD and coal gangues), while AMD and agricultural activity were the predominant sources of Cd. The results of an eco-risk assessment indicated that Cd levels presented a moderate potential ecological risk, while the other elements all posed a low risk. For the TM sites, the highest eco-risk was for Cd, with levels that could be harmful for aquatic organisms in the wet season, and may endanger human health via the food chain.

Refining tree size and dose–response functions for control of invasivePinus contorta

AbstractExotic conifers are rapidly spreading in many regions of New Zealand, as well as in many other countries, with detrimental impacts on both natural ecosystems and some productive sector environments. Herbicides, in particular the active ingredient triclopyr, are an important tool to manage invasive conifers, yet there is a paucity of information that quantifies the amount of herbicide required to kill trees of different sizes when applied as a basal bark treatment. Two sequential experiments were conducted to define the amount of triclopyr required to kill individual invasive lodgepole pine (Pinus contortaDouglas ex Loudon), trees of different sizes when applied in a methylated seed oil to bark (either the whole stem or base of the tree) and to determine which tree size variates (height, diameter at breast height [DBH], crown diameter [CD]) or derived attributes (crown area, crown volume index) best characterized this dose–response relationship. The outcomes of the dose–response research were compared with field operations where triclopyr was applied to the bark of trees from an aerial platform. Applying the herbicide to the whole stem, as opposed to the base of the tree only, significantly increased treatment efficacy. The tree size variates DBH, CD, crown area, and crown volume index all provided good fits to the tree mortality data, with &gt;91% prediction accuracy. Of these variates, CD provided the most practical measure of tree size for ease of in-field calculation of dose by an operator. Herbicide rates used in field operations were seven to eight times higher than lethal doses calculated from experimental data. Our results highlight the potential for substantial reductions in herbicide rates for exotic conifer control, especially if dose–response data are combined with remotely sensed quantitative measurements of canopy area or volume using new precision technologies such as unmanned aerial vehicles.

Induced changes of pyrolysis temperature on the physicochemical traits of sewage sludge and on the potential ecological risks

Biochar from sewage sludge is a low-cost sorbent that may be used for several environmental functions. This study evaluates the induced effects of pyrolysis temperature on the physicochemical characteristics of sewage sludge (SS) biochar produced at 350 (SSB350), 450 (SSB450) and 600 (SSB600), based on the metal enrichment index, metal mobility index (MMI), and potential ecological risk index (PERI) of Cd, Cu, Pb, and Zn. Increased pyrolysis temperature reduced the biochar concentration of elements that are lost as volatile compounds (C, N, H, O, and S), while the concentration of stable aromatic carbon, ash, alkalinity, some macro (Ca, Mg, P2O5, and K2O) and micronutrients (Cu and Zn), and toxic elements such as Pb and Cd increased. Increasing the pyrolysis temperature is also important in the transformation of metals from toxic and available forms into more stable potentially available and non-available forms. Based on the individual potential ecological risk index, Cd in the SS and SSB450 were in the moderate and considerable contamination ranges, respectively. For all pyrolysis temperature biochar Cd was the highest metal contributor to the PERI. Despite this, the potential ecological risk index of the SS and SSBs was graded as low.

Pollution Characteristics and Assessment of Heavy Metals in Atmospheric Deposition in Core Urban Areas,Chongqing

Pollution characteristics and risk of heavy metals in atmospheric deposition in core urban areas of Chongqing were investigated for one year from December 2017 to November 2018.Six functional zones:suburb, education area, residential area, commercial area, transportation hub, and industrial-residential area in Chongqing were selected for monthly atmospheric deposition collection. Concentrations of Cd, Cr, Ni, and Pb were analyzed using AAS. The potential ecological risk index and geoaccumulation index were used to evaluate the heavy metals pollution. Results show that the concentrations of Cd, Cr, Ni, and Pb in the atmospheric deposition were 1.59, 72.68, 20.99, and 101.17 mg·kg-1, respectively, and their annual deposition fluxes were 0.39, 8.04, 2.41, and 10.41 mg·(m2·a)-1, respectively. Concentrations of heavy metals in autumn were significantly higher than those in the other three seasons, especially for Cd, and their deposition fluxes in winter were lowest. The potential ecological risk index of Cd was biggest, achieving a very high ecological hazard level, while the ecological risk of Cd and Pb in industrial-residential area was highest, and that of Cr and Ni, respectively, were highest in transportation hub and residential area. The geoaccumulation index indicated that the pollution of Cd was the highest, and that of Cr, Ni, and Pb was very low. The pollution in industrial-residential area and transportation hub was high, while that in the suburb was relatively low.