中国土壤修复与治理的投融资政策最新进展与展望

中国目前的土壤污染修复资金主要来源于政府财政性投资,融资渠道较为单一。《土壤污染防治行动计划》实施后,如何满足实现土壤污染修复与治理目标的投资需求是一个迫切需要解决的问题,充分创新发挥市场力量,建立长效的融资政策机制是核心内容。本文评估了中国土壤污染修复与治理投融资政策现状,识别了投融资面临的关键问题和挑战,提出了"十三五"时期中国土壤修复与治理的投融资机制建设的政策建议,为"十三五"时期中国土壤修复投融资模式创新提供管理技术支撑。     

Tijuana Childhood Lead Risk Assessment Revisited: Validating a GIS Model with Environmental Data

The objective of this research was to determine the spatial distributions of childhood lead poisoning and soil lead contamination in urban Tijuana. The Bocco–Sanchez model of point-source emissions was evaluated in terms of validity and reliability. We compared the model's predicted vulnerable populations with observed cases of childhood lead poisoning in Tijuana, identified fixed point sources in the field, and analyzed 76 soil samples from 14 sites. The soil lead results were compared to the blood lead analyses performed on Tijuana children whose blood lead levels were ≥10 μg/dL, who reported that they did not use lead-glazed ceramics for cooking or storing food (n = 63). Using GIS, predicted vs observed risk areas were assessed by examining spatial patterns, including the distribution of cases per designated risk area. Chi-square analysis of expected vs observed values did not differ significantly at the p = 0.02 level, showing that the model was strikingly accurate in predicting the distribution of subjects with elevated blood lead. Results reveal that while point sources are significant, other sources of lead exposure are also important. The relative public health risk from exposure to lead in an urban setting may be assessed by distinguishing among sources of exposure and associating concentrations to blood lead levels. The results represent an iterative approach in environmental health research by linking environmental and human biomarker lead concentrations and using these results to validate an environmental model of risk to lead exposure.     

Soil Properties Predict Plant Community Development of Mitigation Wetlands Created in the Virginia Piedmont,USA

The study investigated vegetative and soil properties in four created mitigation wetlands, ranging in age from three to ten years, all created in the Virginia Piedmont. Vegetation attributes included percent cover, richness (S), diversity (H′), floristic quality assessment index (FQAI), prevalence index (PI), and productivity [i.e., peak above-ground biomass (AGB) and below-ground biomass]. Soil attributes included soil organic matter (SOM), gravimetric soil moisture (GSM), pH, and bulk density (D_b) for the top 10 cm. Species dominance (e.g., Juncus effusus, Scirpus cyperinus, Arthraxon hispidus) led to a lack of differences in vegetative attributes between sites. However, site-based differences were found for GSM, pH, and SOM (P < 0.001). Soil attributes were analyzed using Euclidean cluster analysis, resulting in four soil condition (SC) categories where plots were grouped based on common attribute levels (i.e., SC1 > SC2 > SC3 > SC4, trended more to less developed). When vegetation attributes were compared between SC groups, greater SOM, lower D_b, more circumneutral pH, and higher GSM, all indicative of maturation, were associated with higher H′ (P < 0.05), FQAI (P < 0.05), and total and volunteer percent cover (P < 0.05), and lower AGB (P < 0.001), PI (P < 0.05), and seeded percent cover (P < 0.05). The outcome of the study shows that site age does not necessarily equate with site development with soil and vegetation developmental rates varying both within and among sites. The inclusion of soil attributes in post-construction monitoring should be required to enhance our understanding and prediction of developmental trajectory of created mitigation wetlands.     

Diversity of Soil Nematodes in Areas Polluted with Heavy Metals and Polycyclic Aromatic Hydrocarbons (PAHs) in Lanzhou,China

This study investigated the soil nematode community structure along the Yellow River in the Lanzhou area of China, and analyzed the impact of heavy metals (Cd, Pb, Cr, Cu, and Zn) and polycyclic aromatic hydrocarbons (PAHs) on the nematode community. Soil samples from five locations (named A–E), which were chosen for soil analysis, showed significant differences in their heavy metal content (p < 0.01), as well as in the variety of nematodes (up to 41 genera) and families (up to 20) that were present. The different samples also differed significantly in the total PAH content (p < 0.05), as well as the six types of PAH present. Sites A–C showed the most severe contamination with heavy metals and PAHs; these sites had the lowest abundance of fungivores and omnivore/predators, but the proportion of bacteriovores was the highest (p < 0.05). Site E, in contrast, showed only minor pollution with heavy metals and PAHs, and it contained the highest abundance of plant parasites (p < 0.05). Several nematode ecological indicators were found to correlate with concentration of soil pollutants at all the sites tested: the maturity index (MI, in addition to plant parasites), plant parasite index (PPI), ΣMI (including all the soil nematodes), Shannon-Wiener diversity index (H′′), and Wasilewska index (WI). Disturbance to the soil environment was more severe when MI, ΣMI, and H′ values were lower. The results of the study show that the abundance and structure of the soil nematode communities in the sampling locations were strongly influenced by levels of heavy metals and PAHs in the soil. They also show that the diversity index H′ and the maturity index can be valuable tools for assessing the impact of pollutants on nematodes.     

Weathering of lead bullets and their environmental effects at outdoor shooting ranges

Lead contamination at shooting range soils is of great environmental concern. This study focused on weathering of lead bullets and its effect on the environment at five outdoor shooting ranges in Florida, USA. Soil, plant, and water samples were collected from the ranges and analyzed for total Pb and/or toxicity characteristic leaching procedure (TCLP) Pb. Selected bullet and berm soil samples were mineralogically analyzed with X-ray diffraction and scanning electron microscopy. Hydrocerussite [Pb3(CO3)2(OH)2] was found in both the weathered crusts and berm soils in the shooting ranges with alkaline soil pH. For those shooting ranges with acidic soil pH, hydrocerussite, cerussite (PbCO3), and small amount of massicot (PbO) were predominantly present in the weathered crusts, but no lead carbonate mineral was found in the soils. However, hydroxypyromorphite [(Pb10(PO4)6(OH)2] was formed in a P-rich acidic soil, indicating that hydroxypyromorphite can be a stable mineral in P-rich shooting range soil. Total Pb and TCLP Pb in the soils from all five shooting ranges were significantly elevated with the highest total Pb concentration of 1.27 to 4.84% (w/w) in berm soils. Lead concentrations in most sampled soils exceeded the USEPA's critical level of 400 mg Pb kg(-1) soil. Lead was not detected in subsurface soils in most ranges except for one, where elevated Pb up to 522 mg kg(-1) was observed in the subsurface, possibly due to enhanced solubilization of organic Pb complexes at alkaline soil pH. Elevated total Pb concentrations in bermudagrass [Cynodon dactylon (L.) Pers.] (up to 806 mg kg(-1) in the aboveground parts) and in surface water (up to 289 microg L(-1)) were observed in some ranges. Ranges with high P content or high cation exchange capacity showed lower Pb mobility. Our research clearly demonstrates the importance of properly managing shooting ranges to minimize adverse effects of Pb on the environment.     

Linking Soil Erosion to Instream Dissolved Phosphorus Cycling and Periphyton Growth

Phosphorus (P) is a limiting nutrient in freshwater systems and when present in runoff from agricultural lands or urban centers may contribute to excessive periphyton growth. In this study, we examined the link between soil erosion and delivery of eroded soil to streams during flow events, and the impact of that freshly deposited soil on dissolved reactive P (DRP) concentrations and periphyton growth under baseflow conditions when the risk of stream eutrophication is greatest. A microcosm experiment was designed to simulate the release of P from soil which had been amended with different amounts of P fertilizer to overlying water during baseflow conditions. Unglazed tiles, inoculated for five days in a second order stream, were incubated for seven days in microcosms containing soil with eight levels of soil Mehlich‐3 plant available phosphorus (M3P) ranging from 20 to 679 mg/kg M3P. Microcosm DRP was monitored. Following incubation tiles were scraped and the periphyton analyzed for chlorophyll a. Microcosm DRP concentrations increased with increasing soil M3P and equilibrium phosphorus concentration (EPC₀). Relationships between M3P, EPC₀, and DRP were nonlinear and increases in soil M3P and/or DRP had a greater impact on biomass accumulation when these parameters were above threshold values of 30 mg/kg M3P and 0.125 mg/L DRP. Significantly, this ecological threshold corresponds to the agronomic thresholds above which increased soil M3P does not increase plant response.     

Phosphorus concentrations in soil and subsurface water: a field study among cropland and riparian buffers

Riparian buffers can be effective at removing phosphorus (P) in overland flow, but their influence on subsurface P loading is not well known. Phosphorus concentrations in the soil, soil solution, and shallow ground water of 16 paired cropland-buffer plots were characterized during 2004 and 2005. The sites were located at two private dairy farms in Central New York on silt and gravelly silt loams (Aeric Endoaqualfs, Fluvaquentic Endoaquepts, Fluvaquentic Eutrudepts, Glossaquic Hapludalfs, and Glossic Hapludalfs). It was hypothesized that P availability (sodium acetate extractable-P) and soil-landscape variability would affect P release to the soil solution and shallow ground water. Results showed that P availability tended to be greater in crop fields relative to paired buffer plots. Soil P was a good indicator of soil solution dissolved (<0.45 microm) molybdate-reactive P (DRP) concentrations among plots, but was not independently effective at predicting ground water DRP concentrations. Mean ground water DRP in corn fields ranged from < or =20 to 80 microg L(-1), with lower concentrations in hay and buffer plots. More imperfectly drained crop fields and buffers tended to have greater average DRP, particulate (> or =0.45 microm) reactive P (PRP), and dissolved unreactive P (DUP) concentrations in ground water. Soil organic matter and 50-cm depth soil solution DRP in buffers jointly explained 75% of the average buffer ground water DRP variability. Results suggest that buffers were relatively effective at reducing soil solution and shallow ground water DRP concentrations, but their impact on particulate and organic P in ground water was less clear.     

结合《土壤污染防治行动计划》探讨中国土壤环境监管制度与标准值体系建设

2016年,中国国务院印发《土壤污染防治行动计划》(简称《土十条》),明确提出对农用地土壤实施分类管理,按照污染程度划分为优先保护类、安全利用类和严格管控类;对建设用地要防范新增污染,针对疑似污染地块,开展土壤环境状况调查评估,保障地块安全再利用;以影响农产品质量和人居环境安全的突出环境问题为重点,制定土壤污染治理与修复规划,组织开展治理与修复。实施严格的土壤环境质量保护、污染土壤的风险管控、高风险污染土壤的治理与修复是落实《土十条》的重要任务,也是建设我国土壤环境监管制度的重要内容。土壤环境标准是实施土壤环境管理的重要依据。本文基于《土十条》重要任务以及当前及今后一段时期国家土壤环境管理需求,以土壤环境管理需求为导向,探讨提出了包括土壤环境质量保护标准值、土壤环境风险管控标准值、污染土壤修复标准值的土壤环境标准值体系,可望为国家土壤环境标准体系的建立和标准制修订方法的发展提供技术参考。     

Controls on catchment-scale patterns of phosphorus in soil, streambed sediment, and stream water

Many models of phosphorus (P) transfer at the catchment scale rely on input from generic databases including, amongst others, soil and land use maps. Spatially detailed geochemical data sets have the potential to improve the accuracy of the input parameters of catchment-scale nutrient transfer models. Furthermore, they enable the assessment of the utility of available, generic spatial data sets for the modeling and prediction of soil nutrient status and nutrient transfer at the catchment scale. This study aims to quantify the unique and joint contribution of soil and sediment properties, land cover, and point-source emissions to the spatial variation of P concentrations in soil, streambed sediments, and stream water at the scale of a medium-sized catchment. Soil parent material and soil chemical properties were identified as major factors controlling the catchment-scale spatial variation in soil total P and Olsen P concentrations. Soil type and land cover as derived from the generic spatial database explain 33.7% of the variation in soil total P concentrations and 17.4% of the variation in Olsen P concentrations. Streambed P concentrations are principally related to the major element concentrations in streambed sediment and P delivery from the hillslopes due to sediment erosion. During base flow conditions, the total phosphorus (<0.45 microm) concentrations in stream water are mainly controlled by the concentrations of P and the major elements in the streambed sediment.     

THE EFFECTS OF CHLORINE,ELEVATED TEMPERATURE AND EXPOSURE DURATION OF POWER PLANT EFFLUENTS ON LARVAL WHITE PERCH Morone americana (Gmelin)1

ABSTRACT: Chlorine-temperature interaction studies with various exposure times were conducted on 25–day old larval white perch, Morone Americana, using total residual chlorine (TRC) concentrations of 0.0, 0.15, and 0.30 mg/1 TRC in combination with ΔTs of 2, 6, and 10 C above a base temperature of 18 C. Larval fish were exposed to the chlorine-temperature test conditions for exposure periods of 0.08, 2.0 and 4.0 hours. After each respective exposure period, chlorine concentrations were decayed naturally over a 1.0 to 1.5 hour period to < 0.01 mg/1 TRC; temperatures were decayed over a 4 hour period to 2.0 C above the base temperature. These test conditions were used to simulate chlorine and temperature conditions encountered in power plant discharge canals and near field receiving streams. The interactions of chlorine, ΔT and exposure duration as factors which caused death up to 36 hours after the exposure periods were established by regression model techniques. An initial interaction model showed that ΔT was not a factor which contributed to death. A predictive model for chlorine and exposure duration was constructed which showed that potential impact to larval white perch from chlorine at power facilities with once through cooling systems can be minimized by 1) using short duration exposures (< 1 hour) to chlorine in plants that chlorinate intermittently or 2) by rapid mixing in the receiving stream in plants that chlorinate on a low level (< 0.05 mg/1) continuous basis. Similar considerations should be given to cooling tower blowdown which contain chlorinated water.     

Phosphorus in surface runoff from calcareous arable soils of the semiarid Western United States

Management strategies that minimize P transfer from agricultural land to water bodies are based on relationships between P concentrations in soil and runoff. This study evaluated such relationships for surface runoff generated by simulated sprinkler irrigation onto calcareous arable soils of the semiarid western United States. Irrigation was applied at 70 mm h(-1) to plots on four soils containing a wide range of extractable P concentrations. Two irrigation events were conducted on each plot, first onto dry soil and then after 24 h onto wet soil. Particulate P (>0.45 microm) was the dominant fraction in surface runoff from all soils and was strongly correlated with suspended sediment concentration. For individual soil types, filterable reactive P (<0.45 microm) concentrations were strongly correlated with all soil-test P methods, including environmental tests involving extraction with water (1:10 and 1:200 soil to solution ratio), 0.01 M CaCl(2), and iron strips. However, only the Olsen-P agronomic soil-test procedure gave models that were not significantly different among soils. Soil chemical differences, including lower CaCO(3) and water-extractable Ca, higher water-extractable Fe, and higher pH, appeared to account for differences in filterable reactive P concentrations in runoff from soils with similar extractable P concentrations. It may therefore be possible to use a single agronomic test to predict filterable reactive P concentrations in surface runoff from calcareous soils, but inherent dangers exist in assuming a consistent response, even for one soil within a single field.     

Effect of Cadmium on Microbial Activity and a Ryegrass Crop in Two Semiarid Soils

Soil pollution with Cd is an environmental problem common in the world, and it is necessary to establish what Cd concentrations in soil could be dangerous to its fertility from toxicity effects and the risk of transference of this element to plants and other organisms of the food chain. In this study, we assessed Cd toxicity on soil microorganisms and plants in two semiarid soils (uncultivated and cultivated). Soil ATP content, dehydrogenase activity, and plant growth were measured in the two soils spiked with concentrations ranging from 3 to 8000 mg Cd/kg soil and incubated for 3 h, 20 days, and 60 days. The Cd concentrations that produced 5%; 10%;, and 50%; inhibition of each of the two soil microbiological parameter studied (ecological dose, ED, values) were calculated using two different mathematical models. Also, the effect of Cd concentration on plant growth of ryegrass (Lolium perenne, L.) was studied in the two soils. The Cd ED values calculated for soil dehydrogenase activity and ATP content were higher in the agricultural soils than in the bare soil. For ATP inhibition, higher ED values were calculated than for dehydrogenase activity inhibition. The average yields of ryegrass were reduced from 5.03 to 3.56 g in abandoned soil and from 4.21 to 1.15 g in agricultural soil with increasing concentrations of Cd in the soil. Plant growth was totally inhibited in abandoned and agricultural soils at Cd concentrations above 2000 and 5000 mg/kg soil, respectively. There was a positive correlation between the concentration of Cd in the plants and the total or DTPA-extractable concentrations of Cd in the soil.     

Nutrient Bioassays of Growth Parameters for Algae in the North Bosque River of Central Texas1

Abstract: Nutrient dose‐response bioassays were conducted using water from three sites along the North Bosque River. These bioassays provided support data for refinement of the Soil and Water Assessment Tool (SWAT) model used in the development of two phosphorus TMDLs for the North Bosque River. Test organisms were native phytoplanktonic algae and stock cultured Pseudokirchneriella subcapitata (Korshikov) Hindak. Growth was measured daily by in vivo fluorescence. Algal growth parameters for maximum growth (μ_max) and half‐saturation constants for nitrogen (K_N) or phosphorus (K_P) were determined by fitting maximum growth rates associated with each dose level to a Monod growth rate function. Growth parameters of native algae were compared between locations and to growth parameters of P. subcapitata and literature values. No significant differences in half‐saturation constants were indicated within nutrient treatment for site or algal type. Geometric mean K_N was 32 μg/l and for K_P 7 μg/l. A significant difference was detected in maximum growth rates between algae types but not between sites or nutrient treatments. Mean μ_max was 1.5/day for native algae and 1.2/day for stock algae. These results indicate that watershed‐specific maximum growth rates may need to be considered when modeling algal growth dynamics with regard to nutrients.     

Spatial Considerations in Wet and Dry Periods for Phosphorus in Streams of the Fort Cobb Watershed,United States

The Fort Cobb Watershed in Oklahoma has diverse biogeophysical settings and provides an opportunity to explore the association of water quality with a diverse set of landscapes during both wet (April 2007‐December 2009) and dry (January 2005‐March 2007) periods. The objective of this work was to identify spatial patterns in phosphorus (P) (soluble reactive P [SRP] and bioavailable P [BAP]) associated with landscape metrics for two distinct streamflow regimes. Spatial autocorrelation of P was evaluated using contiguous (side‐by‐side) and upstream (upstream:downstream) connectivity matrices. Biogeophysical metrics were compiled for each contributing area, and were partitioned based on association to P concentrations. Results for both SRP and BAP indicated that spatial autocorrelation was present (p < 0.05). There was more spatial autocorrelation and stream P concentrations were three to five times higher in the Wet phase than in the Dry phase (p < 0.05). Analysis with recursive partitioning resulted in higher R² with spatial autocorrelation than without spatial autocorrelation and indicated that lateral metrics (topography, soil, geology, management) were better predictors for SRP than instream metrics. During Wet phase, lateral metrics indicative of rapid surface and subsurface water movement were associated with higher P stream concentrations. This research demonstrated that we can detect landscapes more vulnerable to P losses and/or contaminations in either drought or very wet periods.     

Bioremediation of cutting fluids contaminated soil by Pleurotus tuber-regium Singer

This study investigated the effect of inoculation of Pleurotus tuber-regium, a Nigerian white rot fungus, period of incubation, different levels of contamination on cutting fluids degradation in contaminated soil over 30, 60, and 90 days. Control for different levels of cutting fluids was also used to compare rates of bioremediation of the contaminant in the soil. At the end of each incubation period, the mycelia-ramified substrate was separated from the soil layer and dried. The soil samples were analyzed for physico-chemical parameters; total petroleum hydrocarbon, lignin content by determining the acid detergent fraction (ADF), heavy metals content of the soil using flame atomic absorption spectrophotometer, and changes in the polyphenol oxidase and peroxidase activities were also determined after 1, 2, and 3 months. P. tuber-regium improved the nutrient status of the soil and increased enzyme activity was recorded. A reduction in the pH and heavy metal contents of the soil at all levels of cutting fluids concentrations was detected. The lignin in the rice straw decreased from 34.50% in the control to 8.06% at 30% cutting fluids concentration after 3 months of incubation. The highest TPH loss of 30.84% was recorded at 20% cutting fluids contamination after 3 months compared to 13.75% at the onset of the experiment. The improvement of the nutrient contents of the soil, bioaccumulation of heavy metals, degradation of TPH, lignin, and increased activity of polyphenol oxidase and peroxidase was due to biodegradation of the cutting fluids.     

Changes in Soil Properties After Establishment of Artemisia halodendron and Caragana microphylla on Shifting Sand Dunes in Semiarid Horqin Sandy Land, Northern China

In the semiarid Horqin sandy land of northern China, establishment of artificial sand-fixing shrubs on desertified sandy lands is an effective measure to control desertification and improve the regional environment. Caragana microphylla Lam. and Artemisia halodendron Turcz. ex Bess. are two of the dominant native shrub species, which are adapted well to windy and sandy environments, and thus, are widely used in revegetation programs to control desertification in Horqin region. To assess the effects of artificially planting these two shrub species on restoration of desertified sandy land, soil properties and plant colonization were measured 6 years after planting shrubs on shifting sand dunes. Soil samples were taken from two depths (0–5 cm and 5–20 cm) under the shrub canopy, in the mid-row location (alley) between shrub belts, and from nonvegetated shifting sand dune (as a control). Soil fine fractions, soil water holding capacity, soil organic C and total N have significantly increased, and pH and bulk density have declined at the 0–5-cm topsoil in both C. microphylla and A. halodendron. At the 5–20 cm subsurface soil, changes in soil properties are not significant, with exception of bulk density and organic C concentration under the canopy of A. halodendron and total N concentration under the canopy of C. microphylla. Soil amelioration processes are initiated under the shrub canopies, as higher C and N concentrations were found under the canopies compared with alleys. At the same time, the establishment of shrubs facilitates the colonization and development of herbaceous species. A. halodendron proved to have better effects in fixing the sand surface, improving soil properties, and restoring plant species in comparison to C. microphylla.     

Field Trial Assessment of Biological,Chemical, and Physical Responses of Soil to Tillage Intensity,Fertilization, and Grazing

Soil microbial populations can fluctuate in response to environmental changes and, therefore, are often used as biological indicators of soil quality. Soil chemical and physical parameters can also be used as indicators because they can vary in response to different management strategies. A long-term field trial was conducted to study the effects of different tillage systems (NT: no tillage, DH: disc harrow, and MP: moldboard plough), P fertilization (diammonium phosphate), and cattle grazing (in terms of crop residue consumption) in maize (Zea mays L.), sunflower (Heliantus annuus L.), and soybean (Glycine max L.) on soil biological, chemical, and physical parameters. The field trial was conducted for four crop years (2000/2001, 2001/2002, 2002/2003, and 2003/2004). Soil populations of Actinomycetes, Trichoderma spp., and Gliocladium spp. were 49% higher under conservation tillage systems, in soil amended with diammonium phosphate (DAP) and not previously grazed. Management practices also influenced soil chemical parameters, especially organic matter content and total N, which were 10% and 55% higher under NT than under MP. Aggregate stability was 61% higher in NT than in MP, 15% higher in P-fertilized soil, and also 9% higher in not grazed strips, bulk density being 12% lower in NT systems compared with MP. DAP application and the absence of grazing also reduced bulk density (3%). Using conservation tillage systems, fertilizing crops with DAP, and avoiding grazing contribute to soil health preservation and enhanced crop production.     

Modeling phosphorus concentrations in Irish rivers using land use, soil type, and soil phosphorus data

Modeling diffuse phosphorus (P) loss may indicate management strategies to minimize P loss from agricultural sources. An empirical model predicting flow-weighted phosphorus concentrations (MRP) was derived using data collected from 35 Irish river catchments. Monitoring records of riverine P and stream flow data were used to calculate MRP values averaged for the years 1991-1994. These data were modeled using land use, soil type, and soil P data. Soil type in catchments was described using soil survey classifications weighted according to their P desorption properties from laboratory results. Soil test P concentrations for the studied watersheds were obtained from a national database. Soil P levels were weighted based on the results of field experiments measuring P losses in overland flow from fields at different soil test P levels. The 35 catchments were statistically clustered into two populations (A and B) based on differences in soil type, specifically, soil hydrology. Catchments in Cluster A had predominantly poorly drained soils and comparatively higher MRP concentrations (0.03-0.17 mg L(-1)) than Cluster B areas (0.01-0.7 mg L(-1)) with mostly well-drained soils. Regression equations derived for A and B type catchments predicted MRP values with 68 and 62% of the variation explained in the models, respectively. Data extracted for the rest of the country were applied to the models to delineate areas at risk on a national scale. While the models were only moderately accurate they highlighted the influence of land management, specifically, high production grassland receiving high P inputs, in conjunction with the effect of soil type and soil hydrology on the transport of P to surface waters.     

A National Assessment of the Potential Linkage between Soil,and Surface and Groundwater Concentrations of Phosphorus

A meta‐analysis of three national databases determined the potential linkage between soil and surface and groundwater enrichment with phosphorus (P). Soil P was enriched especially under dairying commensurate with an increase in cow numbers and the tonnage of P‐fertilizers sold. Median P concentrations were enriched in surface waters receiving runoff from industrial and dairy land uses, and in groundwater beneath dairying especially in those aquifers with gravel or sand lithology, irrespective of groundwater redox status. After geographically pairing surface and groundwater sites to maximize the chance of connectivity, a subset of sites dominated by aquifers with gravel and sand lithology showed increasing P concentrations with as little as 10 years data. These data raise the possibility that groundwater could contribute much P to surface water if: there is good connectivity between surface and groundwater, intensive land use occurs on soils prone to leaching, and leached‐P is not attenuated through aquifers. While strategies are available to mitigate P loss from intensive farming systems in the short‐term, factors such as enriched soils and slow groundwater may mean that despite their use, there will be a long‐term input (viz. legacy), that may sustain surface water P enrichment. To avoid poor surface water quality, management and planning may need to consider the connectivity and characteristics of P in soil‐groundwater‐surface water systems.