@@ -40,9 +40,6 @@ With the rapid and sustained increase in population growth in the last 50 years,
A major component in such fertilizers is nitrates. With this conventional intensification, accompanied by depleted soil from monocropping to sustain food and fodder demand, a large portion of fertilizer is unabsorbable. Their runoff into water bodies leads to eutrophication as the nitrates provide nutrients for algae, facilitating bloom (Figure 5). As such, the Netherlands’ position as a global agricultural powerhouse, with 54% of its surface area used as farmland, has led it to develop the worst water quality in the EU (Fraters et al., 2021). Rainfall and irrigation have caused runoff from agricultural areas to spread through the highly interconnected river system and into the Dutch coastline. This process is especially heightened in the Netherlands as major agricultural provinces, such as Noord-Brabant, Gelderland and Zuid-Holland in the country are are characterized by a highly interconnected watershed network, where rivers, streams, and tributaries eventually discharge into the sea. This creates a direct pathway for nutrient runoff from farmlands into marine ecosystems.
(Ærtebjerg et al., 2001;Groendo , 2018)
**Figure 4.** Distribution of Provences in the Netherlands on a map.
Furthermore these anthropogenic activities have led to the development of marine dead zones due to the hypoxic and toxic conditions related to nitrate-induced algal bloom and decomposition (Figure 5). As the nitrogenous compounds are uptaken by present algae for nutrients, the resultant algal bloom has a wide array of consequences. The overgrowth of algae first leads to the blockage of sunlight for the shallow primary producers of the marine food chains. As such, these plants are unable to perform photosynthesis and die, causing damaging rippling affects across the food web. Additionally, some of these algae produce toxins, leading to harmful algal blooms (HABs), directly poisoning local life. As this algae begins to decay due to nutrient depletion and overpopulation, bacterial decomposers break down this organic matter. This decomposition process uptakes large amounts of dissolved oxygen in the water bodies, creating hypoxic conditions. These hypoxic conditions create dead zones that have insufficient oxygen to support marine life. Fish and other marine life either migrate to oxygen rich areas or die off. This leads to a loss of coastal biodiversity, while subsequently posing dangers to human health as well (Sanseverino et al., 2016). Another byproduct of algal decomposition is the release of carbon dioxide into the water. Carbon dioxide dissolves in the water, forming carbonic acid (H₂CO₃), lowering the pH of the water, contributing to ocean acidification. Such acidification decreases the availability of calcium carbonate which is crucial for marine organisms like corals, mollusks and plankton physiology (Rastelli et al., 2020). Oxygen depletion and ocean acidification have also have shown to lead to mass proliferation of hypoxia tolerant species such as Noctiluca scintillans, which is toxic to fish, and damage to shallow marine vegetation (do Rosário Gomes et al., 2014; Glibert, 2017.)
