An overlooked soil carbon pool in vegetated coastal ecosystems: National-scale assessment of soil organic carbon stocks in coastal shelter forests of China.

Protection and restoration of vegetated coastal ecosystems provide opportunities to mitigate climate change. Coastal shelter forests as one of vegetated coastal ecosystems play vital role on sandy coasts protection, but less attention is paid on their soil organic carbon (OC) sequestration potential. Here, we provide the first national-scale assessment of the soil OC stocks, fractions, sources and accumulation rates from 48 sites of shelter forests and 74 sites of sandy beaches across 22° of latitude in China. We find that, compared with sandy beaches, shelter forest plantation achieves an average soil desalination rate of 92.0 % and reduces the soil pH by 1.3 units. The improved soil quality can facilitate OC sequestration leading to an increase of soil OC stock of 11.8 (0.60-64.2) MgC ha-1 in shelter forests. Particulate OC (POC) is a dominant OC fraction in both sandy beaches and shelter forests, but most sites are >80 % in shelter forests. The low δ13C values and higher C:N ratios, which are more regulated by climate and tree species, together with high POC proportions suggest a substantial contribution of plant-derived OC. Bayesian mixing model indicates that 71.8 (33.5-91.6)% of the soil OC is derived from local plant biomass. We estimate that soil OC stocks in Chinese shelter forests are 20.5 (7.44-79.7) MgC ha-1 and 4.53 ± 0.71 TgC in the top meter, with an accumulation rate of 45.0 (6.90 to 194.1) gC m-2 year-1 and 99.5 ± 44.9 GgC year-1. According to coastal shelter forest afforestation plan, additional 1.72 ± 0.27 TgC with a rate of 37.9 ± 17.1 GgC year-1 can be sequestrated in the future. Our findings suggest that construction of coastal shelter forests can be an effective solution to sequester more soil carbon in coastal ecosystems.

Coordinative Management of Soil Resources and Agricultural Farmland Environment for Food Security and Sustainable Development in China.

Major problems in China's pursuit of sustainable agricultural development include inadequate, low-quality soil and water resources, imbalanced regional allocation and unreasonable utilization of resources. In some regions, overexploitation of soil resources and excessive use of chemicals triggered a web of unforeseen consequences, including insufficient use of agricultural resources, agricultural non-point source pollution and land degradation. In the past decade, China has changed its path of agricultural development from an output-oriented one to a modern, sustainable one with agricultural ecological civilization as its goal. First, the government has formulated and improved its laws and regulations on soil resources and the environment. Second, the government has conducted serious actions to ensure food safety and coordinated management of agricultural resources. Third, the government has planned to establish national agricultural high-tech industry demonstration zones based on regional features to strengthen the connection among the government, agri-businesses, scientific community and the farming community. As the next step, the government should improve the system for ecological and environmental regulation and set up a feasible eco-incentive mechanism. At the same time, the scientific community should strengthen the innovation of bottleneck technologies and the development of whole solutions for sustainable management in ecologically fragile regions. This will enhance the alignment between policy mechanisms and technology modes and effectively promote the sustainable development of agriculture in China.

Toxicity of Per- and Polyfluoroalkyl Substances to Aquatic Invertebrates, Planktons, and Microorganisms.

Per- and polyfluoroalkyl substances (PFASs), recognized worldwide as emerging pollutants, may pose a substantial threat to human health and our environment due to their stability, high concentrations, wide distribution, and easy accumulation. Ever since perfluorooctane sulfonate and perfluorooctanoic acid were recognized by the Stockholm Convention on Persistent Organic Pollutants, the public has become increasingly concerned about potential contamination and the environmental risks associated with PFASs. Ubiquitous PFAS contamination of drinking water, groundwater, surface water, and sediment has been detected, especially in areas with rapid industrial and economic development. Its accumulation in living organisms and foods has accentuated the importance of investigations into aquatic organisms at the bottom of the food chain, as the stability and integrity of the food web as well as the population quantity and structure of the aquatic ecosystem may be affected. This review provides a comprehensive summary of the toxic and toxicity-related effects of PFASs on aquatic plankton, aquatic invertebrates and microorganisms, the characteristics of different target aquatic organisms in toxicity investigations, and a feasibility evaluation of PFAS substitutes to provide valuable suggestions for further utilization and regulation of PFASs and their substitutes.

One stone two birds: Bone char as a cost-effective material for stabilizing multiple heavy metals in soil and promoting crop growth.

Remediation of farmland soils contaminated with high levels of multiple heavy metals near PbZn smeltery is still a great challenge. It is of great significance to find cost-effective green remediation technologies for stabilization of multiple heavy metals in soil and reduce metal accumulation in crops with ensured yield. In this study, we demonstrated that bone char (BC) is an effective heavy metal stabilizer which can substantially increase residual fractions of heavy metals and reduce metal accumulation in pea (Pisum sativum) with its enhanced growth. We chose the soils contaminated with high levels of Pb, Zn, Cu and Cd near the Baiyin PbZn smeltery as the tested soil. After 2 months of BC application, the relative mobile fractions (non-residual fractions) of Cu, Zn, Pb and Cd in the contaminated soil decreased while the residual fraction increased significantly. The leachability of Cu, Zn, Pb and Cd decreased by 91.2%, 38.6%, 67.6% and 54.3%, respectively compared with the control. BC application remarkably promoted pea growth and reduced accumulation of heavy metals in shoots. The mechanisms for stabilization of multiple heavy metals BC include ion exchange, surface complexation and subsequent mineralization, accompanied with release of Ca and phosphate. The immobilization of heavy metals led to their reduced toxicity to plant, and thus increased pea growth. The results show that BC is a cost-effective and sustainable heavy metal stabilizer with phosphate fertilization function. It can simultaneously immobilize multiple heavy metals in soil and facilitate crop production.

Phthalate esters contamination in vegetable-soil system of facility greenhouses in Jingmen, central China and the assessment of health risk.

Residual levels of six priority phthalate esters (PAEs) compounds in top soils and vegetables of 40 selected greenhouses in two typical facility vegetable greenhouse production areas of Jingmen (Hubei, central China) were determined. Total concentrations of six target PAEs (Σ6PAEs) in 72 vegetable and 40 soil samples ranged from 862 ± 209 to 4260 ± 385 µg kg-1 (dry weight, DW), and from 1122 ± 156 to 4134 ± 272 µg kg-1 (DW), respectively. Di-n-butyl phthalate and di-(2-ethylhexyl) phthalate (DEHP) are the two most frequently and massively detected in all samples. The highest Σ6PAEs appeared in leaf samples of Tuanlin, vegetable fruits of Zhongxiang and soils of Tuanlin. No carcinogenic risk was posed based on the results of health risk assessment, but non-carcinogenic risk of DEHP to children less than 6 years old in Tuanlin (all 24 sampling sites) and Zhongxiang (4/16 sampling sites) and people older than 6 years old in Tuanlin (19/24 sampling sites) were achieved from hazard quotient values. The contamination risk problem of PAEs in Tuanlin deserves greatest concern in Jingmen. Combined with the results of our former study, the health risks of target pollutants were clarified and the lack of survey data on PAE concentrations in facility vegetable greenhouses of central China was filled in. Due to high residuals and significant non-carcinogenic risk values, DEHP should be nominated as priority PAEs in China. Our study suggested better regulation for PAEs control in intensively managed greenhouses and references for revision of Chinese environmental standards.

Phthalate Ester Contamination in Intensively Managed Greenhouse Facilities and the Assessment of Carcinogenic and Non-Carcinogenic Risk: A Regional Study.

The contamination status and the potential carcinogenic and non-carcinogenic health risks from six phthalate esters (PAEs), nominated as priority pollutants by the United States Environmental Protection Agency (USEPA), were investigated in 40 typical greenhouses in three large-scale intensive greenhouse production areas in Jingmen city, Hubei province, central China. The total concentrations of PAEs in 40 soil samples and 80 vegetable samples ranged from 919 ± 134 to 7015 ± 475 µg kg-1 (dry weight, DW), and from 387 ± 63, to 11,683 ± 1313 µg kg-1 (DW), respectively. No carcinogenic risk was detected. The heat-map of the hazard quotient (HQ) values indicates the non-carcinogenic risks to children from di-n-butyl phthalate (DBP), at two sampling sites out of the 40, and from diethylhexyl phthalate (DEHP) (20 to young children and three to older children and adults) at 23 of the sites. The contamination risk from PAEs at Pengdun is of concern because only two of the 14 sampling sites selected there showed the non-carcinogenic risk to humans was unclear. The results of this study help to close a long-term knowledge gap resulting from a shortage of experimental data on PAE contamination in intensive greenhouse vegetable production in central China. The inclusion of DEHP in the Chinese list of priority pollutants is recommended, due to its increasing contamination and risk. This study provides valuable information for protected agricultural soil management and risk avoidance. It is a timely reminder to take PAE contamination and associated health risks into consideration, during the planning and introduction of intensively-managed greenhouse production systems.

Large-river dominated black carbon flux and budget: A case study of the estuarine-inner shelf of East China Sea, China.

Mobilization of terrestrial-derived and recalcitrant black carbon (BC), including char and soot, from land to ocean exerts a significant influence on the global carbon cycle. This study elaborated the occurrence and spatial distributions of BC, char, and soot concentrations, as well as their burial fluxes, in the estuarine-inner shelf surface sediments of the East China Sea (ECS), an epicontinental sea adjacent to Chinese high-intensity BC emission source regions. Using a combination of BC measurements in the Yangtze River water and coastal ECS aerosol samples, a preliminary BC budget was concurrently constrained. The spatial distribution of char concentrations resembled largely that of BC, but differed significantly from that of soot, indicating that char and soot exhibited different geochemical behaviors. In contrast to concentrations, BC, char, and soot burial fluxes exhibited highly consistent spatial patterns, and all declined as the distance from the coastline increased. For the coastal ECS, riverine discharge dominated (~92%) the total BC input, with the Yangtze River alone accounting for as high as ~72%. The area-integrated sedimentary BC sink flux (630 ±â€¯728 Gg/yr) in the coastal ECS was equivalent to the total BC influx (670 ±â€¯153 Gg/yr), which coincided well with the regional sediment budget. This suggested that the terrestrial-derived and recalcitrant BC could be regarded as an alternative geochemical proxy for tracing the sediment source-to-sink processes in this region. Comparisons between BC and co-generated polycyclic aromatic hydrocarbons (PAHs) budgets in the coastal ECS revealed similarities in their input pathways, but dramatic differences in their ultimate fates. Despite these, the ECS estuarine-inner shelf could serve as a major sink of these terrestrial-based materials in the global ocean.

Marine microplastics bound dioxin-like chemicals: Model explanation and risk assessment.

Microplastics have become one of the most pervasive emerging pollutants in the marine environment because of their wide occurrence and high sorption ability for hydrophobic organic contaminants (HOCs). Among the associated HOCs, dioxin-like chemicals (DLCs) can pose severe health risks; however, information on effects of microplastics bound DLCs is lacking. To fill this knowledge gap, this study integrated chemical analysis and in vitro bioassays to elucidate the potential dioxin-like effects of microplastics bound DLCs. Chemical analysis results demonstrated that styrofoams possessed significantly greater DLCs than other coastal or open ocean plastic particles. This was probably due to the presence of additives and greater sorption ability of expanded polystyrene. However, styrofoams did not show as strong dioxin-like effects as predicted by the bioanalysis equivalent model in bioassays. This could be attributed to the decreased DLC bioavailability and increased competition with the presence of styrene oligomers. Besides, bioassay results also demonstrated that aging increased the associated DLC concentrations, since extra sorption from surrounding environment occurred during prolonged retention periods. Finally, it was estimated that the leaching of DLCs could induce dioxin-like effects in marine organisms under 100% (11/11) and 18% (2/11) scenarios for aged pellets and styrofoams through aqueous or dietary exposures.

Application of catastrophe theory in comprehensive ecological security assessment of plastic greenhouse soil contaminated by phthalate esters.

Large amount of phthalate esters (PAEs) used as plasticizers in polyvinyl chloride (PVC) products has caused ubiquitous contamination to the environment and potential ecology security risk all around the world, especially in places plastic films were indispensably utilized due to the widely proposing of facility agriculture in China. A case of PAEs contamination in four suburb areas of Nanjing was analyzed and discussed in this study. A new frame work has been put forward based on multi-criteria evaluation model and mathematical method of catastrophe theory, using farming work, laboratory determination and relevant environmental standards to measure the ecology security risk of PAEs in study areas. The factors were selected based on the availability of the data and the local conditions. The assessment model involves the contamination status of PAEs in soil and vegetables, the contamination effects of PAEs to human and soil organisms and the contamination source of PAEs from plastic films and other products in the four study facility agriculture areas. An evaluation system of the model was composed of thirteen mesosphere indicators and twenty-five underlying indicators including total PAEs concentration in soils, single PAE concentration in soils, total PAEs concentrations in roots, leafy, solanaceous and stem vegetables, PAE human risks, soil microbial counts, microorganism diversity indices, atmospheric deposition of PAEs, whether sewage wastewater irrigation, planting mode of the facility agriculture areas and climate condition of study areas. The modified evaluation system was used in the assessment of ecology security of the same place based on the data of 2012, and the results suggested that the ecology security indicators were reliable and were agree well with the practical situation of the study areas. The results could provide guidance for the application of health risk assessment of soil environment for the strong objectivity of catastrophe theory compared with other evaluation methods.

Spatiotemporal Trends of Elemental Carbon and Char/Soot Ratios in Five Sediment Cores from Eastern China Marginal Seas: Indicators of Anthropogenic Activities and Transport Patterns.

Elemental carbon (EC), the highly recalcitrant carbonaceous material released exclusively from fossil fuel combustion and biomass burning, is a preferred geochemical agent for evaluating anthropogenic activities. We investigated the spatiotemporal trends of EC and char/soot ratios (char and soot, the two subtypes of EC, differ in formation mechanisms and physicochemical characteristics) in five sediment cores from eastern China marginal seas, spatially spanning from inshore coastal mud areas to offshore remote mud areas. The temporal profiles of EC depositional fluxes closely tracked socioeconomic development in China over the past ∼150 years, with the most pronounced increasing trend beginning in the early 1980s, commensurate with the implementation of national policy of Reform and Open in 1978. The temporal EC profiles in China differed significantly from those in European/American countries, reflecting their different socioeconomic development stages. The spatiotemporal trends of char/soot ratios were also highly informative. Temporally, they decreased from bottom to subsurface layers, indicating the switch of China from an agricultural economy to an industrial economy during the 20th century. Spatially, they decreased from inshore to offshore areas, suggesting the differential transport patterns of EC among these sampling regimes.

Assessment of toxicity of heavy metal-contaminated soils toward Collembola in the paddy fields supported by laboratory tests.

Effects on soil Collembola of Cu, Zn, Pb, and Cd pollution from Cu smelters over 40 years were investigated in paddy fields from an area of Eastern China. We compared the field effects to those observed in single-species laboratory tests employing the hemiedaphic collembolan Folsomia candida and the epedaphic Sinella curviseta obtained from laboratory cultures and exposed to field-collected polluted soil. The results indicated that different collembolan species responded differently to the pollution in the fields and could be divided into sensitive, indifferent, and tolerant types accordingly. The abundance of sensitive species decreased as the pollution increased, but this was not the same for indifferent and tolerant species. The dominant species changed from sensitive to tolerant species as the pollution increased. The reproduction of F. candida and S. curviseta was most sensitive to the contaminated soil compared to growth and survival; the sensitivity of the two species was similar. The growth was more sensitive than the survival for F. candida but not for S. curviseta. The growth and survival of F. candida were much more sensitive than those of S. curviseta. Sensitivity of field populations of F. candida (EC10 31 [15-46]) and hemiedaphic species Folsomia quadrioculata (EC10 52 [0.7-102]) were comparable with sensitivity of the reproduction of F. candida in the single-species tests (EC10 21 [14-27]), suggesting that single-species test based on laboratory cultures and field soil could be used to link laboratory and field data and then reflect the field situation. S. curviseta could be used as an epedaphic species in single-species tests and F. quadrioculata as an indicator species for assessment of field effect.

Occurrence and risk assessment of phthalate esters (PAEs) in vegetables and soils of suburban plastic film greenhouses.

Phthalate esters (PAEs) are suspected of having adverse effects on human health and have been frequently detected in soils and vegetables. The present study investigated their occurrence and composition in plastic film greenhouse soil-vegetable systems and assessed their potential health risks to farmers exposed to these widespread pollutants. Six priority control phthalates, namely dimethyl phthalate (DMP), diethyl phthalate (DEP), di-n-butyl phthalate (DnBP), butyl benzyl phthalate (BBP), di-(2-ethylhexyl) phthalate (DEHP) and di-n-octyl phthalate (DnOP), were determined in 44 plastic film greenhouse vegetables and corresponding soils. Total PAEs ranged from 0.51 to 7.16mgkg(-1) in vegetables and 0.40 to 6.20mgkg(-1) in soils with average concentrations of 2.56 and 2.23mgkg(-1), respectively. DnBP, DEHP and DnOP contributed more than 90% of the total PAEs in both vegetables and soils but the proportions of DnBP and DnOP in vegetables were significantly (p<0.05) higher than in soils. The average concentrations of PAEs in pot herb mustard, celery and lettuce were >3.00mgkg(-1) but were <2.50mgkg(-1) in the corresponding soils. Stem and leaf vegetables accumulated more PAEs. There were no clear relationships between vegetable and soil PAEs. Risk assessment indicates that DnBP, DEHP and DnOP exhibited elevated non-cancer risk with values of 0.039, 0.338 and 0.038, respectively. The carcinogenic risk of DEHP was about 3.94×10(-5) to farmers working in plastic film greenhouses. Health risks were mainly by exposure through vegetable consumption and soil ingestion.

Assessment of EDTA heap leaching of an agricultural soil highly contaminated with heavy metals.

The efficiency of heavy metal removal from soil by EDTA leaching was assessed in a column leaching experiment at the laboratory scale and field heap leaching at the pilot scale using a sandy loam sierozem agricultural soil contaminated with Cd, Cu, Pb, and Zn. Soil amendment and aging were conducted to recover leaching soils. The percentages of Cd, Cu, Pb, and Zn removed by column leaching were 90%, 88%, 90%, and 67%, respectively, when 3.9 bed volumes of 50mM EDTA were used. At the pilot scale, on-site metal removal efficiencies using the selected leaching procedure were 80%, 69%, 73% and 62% for Cd, Cu, Pb and Zn, respectively. EDTA leaching decreased soil CEC, total P, total K and available K concentrations but increased organic matter and total Kjeldahl N concentrations. The subsequent amendment and soil aging further reduced the DTPA-extractable heavy metals in the leached soils. Growth of the first crop of pak choi in the leached soil was inhibited but the second crop grew well after the soil was aged for one year and the concentrations of Cd and Pb in the edible parts were below the Chinese statutory limits. The results demonstrate the potential feasibility of the field leaching technique using EDTA combined with subsequent amendment and soil aging for the remediation of heavy metal-contaminated agricultural soils.

[Environmental damages assessment: establishment of system framework in China].

Health injury, properties compensation and ecological and environmental destruction caused by environmental pollutions have become the focuses of the government, the public and the society at present in China. The experiences of developed countries have revealed that the environmental damage assessment system must be established through development of environmental damage assessment legislations, technologies and funding guarantee system suitable for the nation's conditions based on the specific environmental situation and main issues. China has some experience in marine ecological environment, fishery resources damage assessment, forest resources damage assessment and remediation management of contaminated sites; however, the managing function of environmental damage assessment is assigned to different governmental departments. There are also shortcomings such as few cases of environmental public compensation, insufficient environmental privacy determination and compensation, etc. Based on the methods of materials and information collections, questionnaires, visiting environmental court and government sectors, interviews to assessment organizations and professionals, launching practical assessments to related cases and participating in environmental public lawsuits, the situation of environmental pollution damages in China was analyzed, the related legislation and management mechanism were reviewed, the corresponding assessment organizations regarding environmental damages were sort out, and the funding sources of environmental damage assessment were explored. Aiming at the main issues in Chinese environmental damage management, a standard and unified system for environmental damage assessment based on current managing and technological systems is important to improve the practical work in determination, assessment and compensation of environmental pollution damage in China, and to further explore the feasible environmental damage quantitative management.

[Assessment system for watershed ecological health in the United States: development and application].

To meet the water quality goals of the Clean Water Act, the environmental agencies in the United States (U.S.) have developed a comprehensive ecological assessment system of watershed health in the last two decades. The system employs a watershed approach, and includes a large set of hydrological, chemical, and biological indices, having become an essential part of the watershed water quality management system in the U.S. and provided strong support for the protection of water environment and the restoration of aquatic system. In this paper, the development and application of the ecological assessment system of watershed health by the U.S. environmental regulators, especially the U.S. Environmental Protection Agency (US EPA), were overviewed from the aspects of related laws and regulations, ecosystem function analysis, ecological health indicators, comprehensive assessment system, and monitoring and data management systems, and the health assessment systems for the rivers, lakes, estuaries, coasts, and wetlands adopted by the National$t1-1-1 Aquatic Resource Surveys (NARS) were introduced. Some suggestions for the future development of the scientific ecological assessment system of watershed health in China were put forward based on the understanding of the protection and remediation practices of our water environment.

[Environmental damage assessment: international regulations and revelation to China].

As the whole society gradually realizes the scarcity of nature resources and environmental value, countries all over the world have evolved and improved the system of environmental damage assessment through the practices of pollution prevention and ecological environmental protection. On one hand, in the research prospective, the practices of environmental damage assessment brought new challenges to environmental law, environmental economics, environmental science, environmental engineering, etc. On the other hand, they constantly promoted and developed relevant laws and regulations, techniques, working mechanism, and guidelines on procedure in practice. On the hasis of comparison and analysis of international practices and experiences from US, EU, and Japan, etc., this article identified relevant concepts, content, and scope of environmental damage assessment, and presented its scientific positioning and development direction. At present, both theory and practice of environmental damage assessment in China are in their infancy period. Considering current environmental situation and socioeconomic development features of China, learning international practices and experiences and raising the orientation of environmental damage assessment have great meaning in exploring the suitable environmental damage assessment system.

[Some thoughts of the comparison of risk based soil environmental standards between different countries].

Risk-based soil environmental standard is one of the important aspects in contaminated soil management which have already been widely used in many countries. However, because of diversity in geographical, biological, social-cultural, regulatory and scientific aspects among each country, there are great distinctions on both titles and values of these soil environmental standards between different countries. Risk-based soil environmental standards and derivation process were introduced and compared in detail. The variability was analyzed and explained through the comparison of sensitivity risk receptors, land utilizations and pathways of exposure among these countries. We suggest that the risk-based soil environmental standards among the developed countries could be classified as target value, screening value and intervention value, which aim to protect soil for sustainable development in the future, to determine whether there is potential unacceptable risk to specified acceptors, and whether further counter-actions should be conducted, respectively. At last, risk assessment of contaminated soils and establishment of risk-based soil environmental standards in China was proposed.

Copper uptake by Elsholtzia splendens and Silene vulgaris and assessment of copper phytoavailability in contaminated soils.

Tolerance and metal uptake are two essential characteristics required for phytoextraction of metals from contaminated soils. We compared tolerance and Cu uptake of Elsholtzia splendens (reported previously to be a Cu hyperaccumulator) with Silene vulgaris (the Imsbach population, a well-known Cu-tolerant excluder species), using 30 soils varying widely in total Cu concentration (19-8645 mg kg(-1)). We further investigated the effectiveness of different soil testing methods for predicting plant metal uptake. The results showed that both Elsholtzia splendens and Silene vulgaris were tolerant to Cu, especially Silene vulgaris. However, Elsholtzia splendens did not hyperaccumulate Cu, but behaved as a typical Cu excluder like Silene vulgaris. The concentrations of Cu in both plants correlated more closely with 1 M NH4NO3 extractable Cu, soil solution Cu, or effective Cu concentration determined using DGT, than with soil total Cu, EDTA extractable Cu or free Cu2+ activity. The relationships between soil solution properties and root Cu concentrations were further investigated using multiple regression. The results showed that increasing soil solution pH increased root Cu concentration when free Cu2+ activity was held constant, suggesting a higher phytoavailability of free Cu2+ at a higher pH. Soil solution DOC appeared to play two contrasting roles on the phytoavailability of Cu: (1) reducing Cu availability by complexing Cu; and (2) increasing Cu availability at the same level of free Cu2+ activity by providing a strong buffer for free Cu2+. The results are consistent with the intensity/capacity concept for phytoavailability of metals in soils.